United States
Environmental Protection
.Agency
Implications for Coral Reef
Management in American Samoa

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June 2007
EPA/600/R-07/069
www.epa.gov/ncea
Climate Change and Interacting Stressors: Implications for
Coral Reef Management in American Samoa
Global Change Research Program
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Washington DC 20460

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DISCLAIMER
This document has been reviewed in accordance with U.S. Environmental Protection
Agency policy and approved for publication. Mention of trade names or commercial products
does not constitute endorsement or recommendation for use.
ABSTRACT
Climate variability and change can negatively impact sensitive coral reef ecosystems by
altering sea surface temperatures, ocean carbonate concentrations, sea level, storm surges,
precipitation patterns, stream flows to the coast, salinity, and pollution loads. This report focuses
on the coral reefs of American Samoa as a case study for how managers can approach (1)
assessments of reef vulnerabilities to climate change and interacting stressors, (2) identification
of adaptive management strategies in response, and (3) integration of management options with
existing decision processes and mandates. Large-scale climate stressors are reviewed along with
information on localized stressors in American Samoa to assess reef vulnerabilities to climate-
related impacts such as coral bleaching. Based on this information, this report presents some
adaptive management strategies that could be implemented immediately (e.g., water quality
improvements), in the near-term (e.g., enhanced strategic monitoring), and in the long-term (e.g.,
resilience planning). In each case, management options are considered in a decision making
context - i.e., in terms of how such strategies relate to existing plans, processes, and mandates.
Preferred Citation:
U.S. Environmental Protection Agency (EPA). (2007) Climate change and interacting stressors: Implications for
coral reef management in American Samoa. Global Change Research Program, National Center for Environmental
Assessment, Washington, DC; EPA/600/R-07/069. Available from the National Technical Information Service,
Springfield, VA, and online at http://www.epa.gov/ncea.
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CONTENTS
LIST OF TABLES	v
LIST OF FIGURES	v
PREFACE	vi
AUTHORS AND REVIEWERS	viii
REVIEWERS	viii
EXECUTIVE SUMMARY	ix
1.	INTRODUCTION	1
1.1.	GOAL OF THIS REPORT	1
1.2.	AMERICAN SAMOA AND ITS CORAL REEFS	2
1.3.	ROADMAP TO THIS REPORT	5
2.	STRESSORS ASSOCIATED WITH CLIMATE VARIABILITY AND CHANGE	8
2.1.	CHANGES AND FLUCTUATIONS IN SEA SURFACE TEMPERATURES	8
2.2.	CHANGES AND FLUCTUATIONS IN WEATHER PATTERNS	11
2.3.	OCEAN CHEMISTRY	13
2.4.	SEA LEVEL RISE	13
2.5.	INDIRECT EFFECTS OF CLIMATE CHANGE ON ULTRAVIOLET (UV)
RADIATION STRESS	14
3.	STRESSORS ASSOCIATED WITH LOCAL ACTIVITIES AND EVENTS	15
3.1.	POOR WATER QUALITY	15
3.2.	DISEASES AND OPPORTUNISTIC SPECIES	17
3.3.	OVER-FISHING AND RESOURCE EXTRACTION	18
3.4.	CONCLUSIONS	19
4.	VULNERABILITIES OF AMERICAN SAMOA'S REEFS TO INTERACTING
STRESSORS	20
4.1.	APPROACH	20
4.2.	VULNERABILITIES TO CLIMATE CHANGE AND INTERACTING LOCAL
STRESSORS	22
4.2.1.	Climate Change: Sea Surface Temperatures	22
4.2.2.	Water Pollution and Climate Change	26
4.2.3.	Extreme Weather Events and Climate Change	30
4.2.4.	Coral Diseases, Opportunistic Species, and Climate Change	32
4.2.5.	Over-Fishing, Resource Extraction and Climate Change	34
4.2.6.	Conclusions	34
4.3.	INFORMATION GAPS	34
4.4.	SUSTAINING RESILIENCE	35
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5.	ADAPTIVE MANAGEMENT STRATEGIES AND DECISION-MAKING
OPPORTUNITIES	37
5.1.	IMMEDIATE TIME FRAME: IMPLEMENT WATER QUALITY
IMPROVEMENTS	39
5.2.	NEAR-TERM TIME FRAME: DEVELOP AND IMPLEMENT
HYPOTHESIS DRIVEN MONITORING AND RESEARCH	42
5.3.	LONG-TERM TIME FRAME: DESIGN AND IMPLEMENT RESILIENT
MP A NETWORKS	46
6.	CONCLUSIONS	50
REFERENCES	52
APPENDIX	59
IV

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LIST OF TABLES
4-1.	Summary of coral bleaching surveys on Tutuila Island	23
5-la.	Research questions and activities that could be integrated into local management
activities	44
5-lb. Research activities appropriate for external agencies or researchers	45
5-2. Factors that may confer resilience to coral bleaching	48
LIST OF FIGURES
1-1. Islands of the Territory of American Samoa	2
1-2.	Logic diagram for assessment of ecosystem vulnerabilities to climate change
and other interacting stressors, and identification of priority management actions	6
2-1.	Variations of the Earth's average surface temperature (°C) from the year 1000
to 2100	9
2-2. Comparison of the variation in the mean land and ocean surface temperatures
from years 1880-2000	 10
2-3. Monthly mean sea surface temperatures in the vicinity of Tutuila Island,
American Samoa	11
4-1. Trends in coral populations, 1982-2001 	21
4-2. Locations on Tutuila Island where studies have been conducted	24
4-3. Trends in mean coral density on the Aua transect, Pago Pago Harbor, 1917-2001 	28
4-4. Human population density distribution for 2000 (a), and projected to 2025 (b)	31
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PREFACE
The goal of EPA's Global Change Research Program is to assess the potential
implications of climate change for water quality, air quality, human health, and ecosystem
health, and to provide decision makers with information and tools for incorporating
considerations of climate change into decision making processes. The Ecosystem Focus Area
examines the effects of climate change and other interacting stressors on freshwater and coastal
ecosystems with the goal of improving society's ability to manage these ecosystems in the
context of continuing climate change.
Ecosystems show a variety of responses to climate change, and coral reef ecosystems are
especially sensitive. Climate variability and change can either directly or indirectly affect sea
surface temperatures, ocean carbonate concentrations, sea level, storm surges, precipitation
patterns, stream flows to the coast, salinity, and pollution loads-all of which must be considered
in the design of effective strategies for management of coral reefs and their ecosystem services.
Yet, current management decisions are often being made without knowledge of sensitivities to
climate change and without information on options for best management practices in the context
of climate change. Thus, there is an urgent need for studies that link an understanding of climate
change effects to management options that are compatible with local decision processes.
This report focuses on the coral reefs of American Samoa as a case study for the
development of a general approach for (1) assessing reef vulnerabilities to climate change and
interacting stressors, (2) identifying adaptive management strategies in response, and (3) placing
management options in the context of existing decision processes and mandates. A review of
large-scale climate stressors is combined with information on localized stressors in American
Samoa to assess reef vulnerability to climate-related impacts such as coral bleaching. Based on
this information, this report presents several adaptive management strategies that could be
implemented over immediate, near-term, and longer-term time frames. The report also discusses
the importance of considering these options in a decision making context-i.e., identifying how
such strategies relate to existing plans, processes, and mandates.
The information presented in this report supports EPA's strategic Goal 4 (Healthy
Communities and Ecosystems) as well as the EPA Office of Water's responsibilities under the
Clean Water Act to "restore and maintain the chemical, physical and biological integrity of the
Nation's waters" and the EPA Office of Research and Development's mission to "provide
leadership in addressing emerging environmental issues and in advancing the science and
technology of risk assessment and risk management." EPA is also a member of the U.S. Climate
Change Science Program (CCSP), which integrates federal research on climate and global
change across its thirteen member agencies. This report contributes to two of the CCSP's five
major goals: Goal 4, "Understand the sensitivity and adaptability of different natural and
managed ecosystems and human systems to climate and related global changes" and Goal 5,
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"Explore the uses and identify the limits of evolving knowledge to manage risks and
opportunities related to climate variability and change." Finally, this report responds directly to
priority needs of the U.S. Coral Reef Task Force, of which EPA is a member. The USCRTF has
named climate change and coral bleaching as a key focal area of concern for coral reef research
and management and has called for the development of appropriate management strategies in
response.
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AUTHORS AND REVIEWERS
The Global Change Research Program in EPA's Office of Research and Development
was responsible for preparing this document. Major portions of this report were prepared by
TN & Associates, Inc., under EPA Contract No. 68-C-04-004. Jordan West served as the EPA
Work Assignment Manager, providing overall direction and coordination of this project, and is a
co-author.
AUTHORS
Eric E. Mielbrecht
Emerald Coast Environmental Consulting
Washington, DC 20016
Jordan M. West
Global Change Research Program
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Washington, DC 20460
REVIEWERS
This report benefited greatly from reviews by David Ayre, Charles Birkeland, Arthur
Dahl, Christopher Hawkins, Peter Houk, Wendy Wiltse, and Dan Catanzaro, who provided
excellent suggestions for additions, clarifications, and references.
ACKNOWLEDGEMENTS
Discussion and input from local managers in American Samoa was also crucial to the
refining of the report: these managers included Peter Craig, Nancy Daschbach, and Edna
Buchan. The authors thank David Eskew and Dan Catanzaro of TN & Associates, Inc., for
assistance with project management and valuable feedback throughout the project.
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EXECUTIVE SUMMARY
A major goal of this report is to provide the natural resource managers of American
Samoa, in particular the Governor's Coral Reef Advisory Group (CRAG), with some
management options to help enhance the capacity of local coral reefs to resist the negative
effects of climate change. This effort supports the U.S. Environmental Protection Agency's
(EPA) Global Change Research Program in its goal to improve scientific capabilities for
evaluating the effects of climate change on ecosystems (especially in the context of other local
stressors such as water pollution) and develop adaptation strategies. This information is needed
because current management decisions are often being made without sufficient information on
climate change. American Samoa was chosen for this study due to the interest of local managers
in climate change issues and preliminary indications that climate change should be considered an
emerging stressor of concern in American Samoa.
A secondary goal of this report is to introduce a simple conceptual model (Figure ES-1)
to support managers outside American Samoa in the thought process of planning and conducting
similar assessments at their own locations. Section 1 introduces the model as a series of steps in
a logical process for (1) assessing those local ecosystem vulnerabilities that potentially occur
when climate change and existing local stressors overlap and compound each other, (2)
identifying tractable management responses, and (3) evaluating how such responses may be
compatible with existing management activities. Section 2 reviews climate variability and
change stressors in relation to American Samoa, while Section 3 reviews other (non-climate),
local interacting stressors. Section 4 synthesizes scientific information available from the
literature on the incidence and degree of reef responses to such stressors in order to assess local
reef vulnerabilities. This leads to the examination of potential management strategies and their
relation to existing decision-making opportunities in Section 5.
Based on available literature, three local coral reef ecosystem vulnerabilities were
identified in American Samoa: (1) climate change alone was determined to be a stressor based on
past bleaching events, (2) vulnerabilities could exist due to the combined stresses of poor water
quality and climate change, and (3) also of concern, but lacking substantiation, are the potential
alterations of cyclones/extreme precipitation events and increases in coral diseases due to climate
change.
In order to address the top vulnerabilities to combined climate change and poor water
quality stressors, an adaptive management approach is recommended. This approach supports
immediate actions by managers based on current knowledge and promotes future refinement as
additional information becomes available. Key to adaptive management for climate change is
the idea of sustaining ecosystem resilience. Two basics tenets underlie the resilience approach:
reduction or elimination of non-climate stresses and protection of adequate and appropriate
habitat.
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Adaptive
Management
Strategies
Decision-
Making
Opportunities
Other Interacting
Stressors
Climate Variability
and Change
Local Coral Reef
Ecosystem Vulnerabilities
Priority
Actions
Figure ES-1. Logic diagram for assessment of
ecosystem vulnerabilities to climate change and
other interacting stressors, and identification of
priority management actions.
When the results of the vulnerability assessment are coupled with an adaptive
management approach to enhance resilience to climate change, three categories of priority
management actions emerge:
1.	immediate time frame - implement water quality improvements
2.	near-term time frame - develop and implement hypothesis-driven monitoring and
research, and
3.	long-term time frame - design and implement resilient marine protected area (MPA)
networks, with strong village community outreach and involvement.
These priority actions are tailored to ease their integration into existing management projects.
With these ideas and the tools provided in the Appendix, management plans may be enhanced by
insights into the effects of climate change on this valuable marine resource.
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1. INTRODUCTION
1.1. GOAL OF THIS REPORT
Coral reef ecosystems are especially sensitive to changes in climate. Climate variability
and change can either directly or indirectly affect sea surface temperatures, ocean carbonate
concentrations, sea level, storm surges, precipitation patterns, stream flows to the coast, salinity,
and pollution loads-all of which must be considered for the design of effective strategies for
management of coral reefs and their ecosystem services. While global-scale stressors such as
temperature changes are beyond the control of local reef managers, there are other actions that
managers can take to enhance the capacity of natural systems to persist in the face of continued
climate variability and change. These actions center on (1) reducing the localized stressors that
interact with climate change stressors to compromise the ability of coral reef systems to naturally
moderate the effects of climatic perturbations and (2) accounting for patterns of variability in
resilience to climate change when planning and managing networks of marine protected areas.
While simple in concept, the above approach can prove difficult to implement in an
efficient and effective way. Geographic patterns of climate variability (and their effects on sea
surface temperatures, currents, etc.) differ among and within regions, as do the combinations of
localized stressors that are unique to any given reef area. Thus, no single management plan will
be optimal for all reef systems. Rather, the effectiveness of any reef management strategy will
hinge on skillful application of general principles that are used to guide place-based analyses of
specific vulnerabilities and to identify priority management responses that are most likely to be
effective in that particular reef location. In this report the coral reefs of American Samoa are
used as a case study to create simple guidelines for place-based assessment and identification of
adaptive management options for coral reef systems.
This report will (1) introduce a simple conceptual model for assessing reef vulnerabilities
and potential responses, (2) apply the model to American Samoa's reefs, in particular, and (3)
identify priority management actions. The conceptual model will help guide coral reef managers
through the thought process of identifying stressors, assessing reef vulnerabilities, and using the
information to identify priority management actions that could be incorporated into local
management strategies to maximize long term reef resilience in the face of a changing climate.
The goal is to provide resource managers in American Samoa with information that supports an
informed understanding of collective risks and provides a systematic approach for application of
this understanding to management decision processes. To begin, this report presents some
background information on American Samoa and its reefs followed by an overview of the
conceptual model that will serve as a roadmap for the remainder of the report.
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1.2. AMERICAN SAMOA AND ITS CORAL REEFS
The Territory of American Samoa consists of five volcanic islands (Tutuila, Aunu'u, Ofu,
Olosega, and Ta'u) and two atolls (Swains Island and Rose Atoll) in the central South Pacific
Ocean (Figure 1-1). Tutuila Island is approximately 170°W and 14°S. Surrounding these
islands are 296 km2 of coral reefs that are home to over 890 species of fish, 237 species of algae,
200 species of coral, and many other invertebrates (Waddell, 2005; Wilkinson, 2004). Most reef
areas in American Samoa are comprised of fringing reefs that are close to shore (<200 m).
Generally, these fringing reefs include a shallow reef flat (0-1 m depth) situated between the
shore and outer edge of the reef, where coral tops can be exposed at low tide. The prominent
seaward edge of the reef flat is the reef crest, beyond which the reef front or face drops off into
deeper water. At most sites, the reef front descends at a slope of 30-90° to a depth of 10-30 m
where the reef transitions to a gently sloping sand flat. Well developed lagoons are uncommon
in American Samoa (Green, 1996).
AMERICAN SAMOA
Tutuila
Manu'a
Ofu
Olosega
Aunu'u
Ta'u
Swain
Samoa Manu'^Xpose
Tutuila
American Samo
Figure 1-1. Islands of the Territory of American Samoa. Courtesy of
Francesca Riolo, Mappamondo GIS.
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Nearly 80% of the coral populations in American Samoa are comprised of eight coral
genera: Montipora, Porites, Acropora, P avona, Goniastrea, Montastraea, P ocillopora, and
Galaxea (in decreasing order according to Fisk and Birkeland, 2002). Another 33-54 genera,
depending on location, make up the remainder (Fisk and Birkeland, 2002; Maragos et al., 1994).
These coral reefs and their biological diversity provide important benefits to the people of both
American Samoa and the U. S. mainland. The coral reefs currently support local subsistence and
artisanal fisheries, provide coastal protection, and offer recreational opportunities to residents
and visitors. There is also great "existence value" placed on coral reefs as unique natural
resources by the U.S. public (Heywood, 1995). Combined, these benefits have been
economically valued at over $10 million per year for American Samoa (Spurgeon et al., 2004),
further underscoring the importance of this resource and the need for careful management.
Coral
reefs are unique
ecosystems with
both biological
and geological
characteristics.
Most reef-
building corals
consist of tiny
animals called
polyps that are
connected by
living tissue and
form a surface
veneer that covers
and builds the
colony s shared Aerial view of coral reefs in American Samoa. (Photo by Eric Mielbrecht.)
calcium carbonate
skeleton. In fast growing species, a colony's calcium carbonate skeleton can grow several
centimeters in a year. Together, a community of coral colonies may build a reef at an average
vertical accretion rate of 1-10 millimeters per year (Smith and Buddemeier, 1992).
Coral polyps rely on a symbiotic relationship with single-celled microalgae
(zooxanthellae) that live in large numbers within their body tissues and give the colonies their
many vibrant colors. These zooxanthellae capture solar energy through photosynthesis and
create nutrients that are shared with the host coral in exchange for a protected living space and
coral nutrients (e.g., nitrogen). Because their primary need is sunlight (and little else), corals are
uniquely adapted to shallow, clear, oligotrophic (low nutrient), tropical and subtropical waters
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(Buddemeier et al., 2004). This adaptation to stable conditions renders the coral-algal symbiosis
vulnerable to acute environmental fluctuations such as climate-related sea surface temperature
anomalies. Coral bleaching is one potential result.
Coral bleaching, or the paling of coral tissues, is characterized by in situ degradation or
loss of the symbiotic zooxanthellae from coral tissues, usually as a stress response (Brown,
1997a). If the zooxanthellae and associated pigments are lost, the white calcium carbonate
skeleton is seen through the translucent coral tissue, giving the coral the appearance of having
been bleached. The coral colony can die if the zooxanthellae association is not quickly re-
established (within weeks) (Harriot, 1985). Coral bleaching can be induced in the laboratory or
field by high or low temperatures, intense light, absence of light, changes in salinity, infectious
disease, or other physical or chemical stresses (Buddemeier et al., 2004; Jokiel, 2004; Hoegh-
Guldberg, 1999; Brown, 1997a).
Widespread coral bleaching began to attract global attention after the first, carefully
tracked, broad-scale bleaching event that occurred in association with the severe 1982-83 El
Nino-Southern Oscillation (EN SO) (Glynn, 1984). The rate of occurrence (annually in some
areas) and large scale of mass bleaching events since the early 1980s is in stark contrast to the
trend of the first half of the 20th century, during which time bleaching events were localized and
linked to local stress events (Glynn, 1993; Jokiel and Coles, 1990; Williams Jr. and Bunkley-
Williams, 1990; Goreau, 1964). This increase in the scale of bleaching has led to the suggestion
that climate change-related increases in
annual sea surface temperatures and
occurrences of ENSO conditions may be
responsible (Hoegh-Guldberg, 1999;
Pittock, 1999). ENSO results in the
development of regions of unusually
warm water throughout the equatorial
Pacific and Indian Oceans. Significant
coral bleaching is especially likely when
these warming anomalies overlap with
seasonal maximum water temperatures.
Indeed, coral bleaching correlates with
ocean thermal anomalies, and there is
substantial evidence that elevated
temperatures are the chief cause of large-
scale, mass bleaching events (Hoegh-
Guldberg, 1999; Brown, 1997a; Glynn,
1993; Williams and Bunkley-Williams,
1990).
A partially bleached Acropora coral. The white
portions have lost the golden brown algae
(zooxanthellae) that normally give the tissues their
color. (Photo by Eric Mielbrecht.)
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In American Samoa, widespread coral bleaching occurred in 1994, 2002, and 2003
(Hansen et al., in preparation-b; Craig et al., 2005; Wilkinson, 2004; Fisk and Birkeland, 2002;
Green, 2002). Unusually high sea surface temperatures (>29.9°C) were recorded in the region
during the summer months of those years (Hansen et al., in preparation-b; Goreau and Hayes,
1995). Data from a limited number of monitoring studies have indicated that there was
significant variability in bleaching and recovery within and among locations during these events,
but an understanding of the reasons for this variability remains incomplete.
Any attempt to understand the effects of climate-related stressors will require
consideration of the interaction with localized stressors associated with human activities. Over
95% of American Samoa's roughly 60,000 inhabitants live on Tutuila, the largest island. Its
population is growing rapidly and is expected to double in the next 30 years. The steepness and
small size of the island force the human population to concentrate on the narrow coastal plains,
where heightened development and commercial activity have affected nearby reefs (Craig et al.,
2005). For example, industrial and domestic wastes and land development have resulted in water
pollution in the form of toxic contaminants, excess nutrients, and sedimentation influxes to coral
reef waters (DiDonato and Paselio, 2006).
Fortunately, the traditional Samoan way of life, or fa 'asamoa, with its strong family and
village kinship, promotes sharing and maintaining land, sea, and water resources for the good of
the whole community. With this motivation 26.7 km of coral reef areas have been included in
marine protected areas (MPAs) in the Territory of American Samoa (about 9% of the total reef
area) (Craig et al., 2005; Green, 1997). This includes the National Park of American Samoa,
administered by the National Park Service; Fagatele Bay National Marine Sanctuary,
administered by the National Oceanic & Atmospheric Administration; The Vaoto Marine Park,
administered by the Territorial Government; Rose Atoll National Wildlife Refuge, administered
by the U.S. Fish and Wildlife Service; and community-based MPAs, administered by the local
village communities with assistance from the Territorial Government (Craig et al., 2005).
Additionally, Governor Tauese Sunia furthered this process in 2000 when he pledged that the
American Samoa Government would establish no-take areas to protect at least 20% of the
surrounding coral reefs by 2010. The resource conservation management processes of existing
MPAs in American Samoa are an excellent infrastructure for integrating the adaptation options
developed in this report.
1.3. ROADMAP TO THIS REPORT
The goal of this report is to provide the natural resource managers of American Samoa
with an assessment process and some basic adaptation options that can be integrated into existing
and future management decisions in order to enhance the resilience of coral reefs to climate
change impacts. In support of this goal, a simple conceptual model is presented as a structure for
the remainder of the report (Figure 1-2).
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Adaptive
Management
Strategies
Decision-
Making
Opportunities
Other Interacting
Stressors
Climate Variability
and Change
Local Coral Reef
Ecosystem Vulnerabilities
Priority
Actions
Figure 1-2. Logic diagram for assessment of
ecosystem vulnerabilities to climate change and
other interacting stressors, and identification of
priority management actions.
Section 2 introduces current scientific understanding of the presence and effects of
stressors associated with climate variability and change. An account of local stressors that are
likely to have the greatest impact on the reefs of American Samoa follows in Section 3. The
combined information on stressors-including an analysis of potential interactions among climate
and local stressors-is then presented in Section 4 as a means for managers to characterize the
vulnerabilities of local reefs in American Samoa to coral bleaching and other climate-related
impacts. This includes a summary and review of past coral bleaching events in American Samoa
and a discussion of patterns of variability in bleaching and mortality associated with different
resilience characteristics.
In Section 5, the results of the vulnerability assessment are used to identify some
adaptation options that may be location-specific or specific to a whole region. These options
range from uncomplicated actions that could be implemented immediately, to more complex
longer-term strategies. In situations where the strategies readily overlap with existing
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management decision processes in American Samoa, the report identifies certain options as
potential candidates for priority actions. Section 6 concludes that, in the future, as the
assessment process continues and more information becomes available through continued
research, more complex adaptation strategies may be developed, thereby increasing the overlap
between available management strategies and the decision-making processes that make them
possible. The current aim, then, is to facilitate rapid incorporation of simpler adaptation options
into today's management decisions while simultaneously developing a battery of more complex
options for integration into future resource management decisions. All are crucial elements of a
strategy to help the sensitive coral reef ecosystems of American Samoa maintain long-term
resilience in the face of on-going climate variability and change.
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2. STRESSORS ASSOCIATED WITH CLIMATE VARIABILITY AND CHANGE
Climate variability and change add a variety of chronic and acute large-scale stresses to
coral reefs. Large-scale climate stressors act as an overlay on already-existing local stressors
(e.g., disease outbreaks, pollution) and generate layers of interactions that can cause complex
reef responses. Climate change occurs on all temporal and spatial scales, from brief but severe
storms to multi-seasonal ENSO conditions, decadal droughts, and shifts in temperature and sea
level over centuries. In this section, a number of climate-related stressors of particular concern
to coral reefs are reviewed.
2.1. CHANGES AND FLUCTUATIONS IN SEA SURFACE TEMPERATURES
The concentration in the atmosphere of carbon dioxide (CO2), the primary heat trapping
gas, has increased during the 20th century and currently is at the highest level of the past 420,000
years (IPCC, 2001b). The Earth's surface temperature has also risen during this time. This trend
is projected to continue even if concentrations of heat trapping gases are rapidly stabilized.
According to the IPCC (2001b), the global mean surface temperature has increased by
0.6 ħ 0.2°C during this period and is projected to rise an additional 1.4-5.8°C during the 21st
century (Figure 2-1). To date, no precedent has been found in 10,000 years of paleoclimate data
for this rate of warming.
Warming of the sea surface parallels past land-surface air temperature changes
(Figure 2-2). Sea surface temperatures have increased globally by 0.4-0.8°C since the late 19th
century and are projected to increase another 1-2°C by 2100 (IPCC, 2001b). Historically,
environments where coral reefs have thrived have had a high degree of temperature stability, and
available data indicate that temperatures in tropical oceans have fluctuated less than 2°C over the
past 18,000 years (Thunnell et al., 1994). Corals have adapted to this stability and in many
locations live close to their upper thermal limits (Goreau, 1992). They can become stressed if
exposed to increases in water temperature as little as 1-2°C above average summer maximum
temperatures, the result being bleaching and potential mortality (Hoegh-Guldberg, 1999; Brown,
1997a).
Meanwhile, from the 1970s to today, temperature anomalies associated with ENSO
events have also been more frequent, persistent, and intense. The El Nino segment of the
Southern Oscillation cycle results in the development of regions of unusually warm water
throughout the eastern and central equatorial Pacific Ocean. The combination of climate-driven
sea surface warming and more frequent and intense ENSO conditions over the past two decades
have already resulted in a significant increase in coral bleaching (Wilkinson, 2004; Hoegh-
Guldberg, 1999; Brown, 1997a; Glynn, 1993). The most extensive and intense bleaching event
to date was in 1997-1998 and coincided with the strongest ENSO disturbance on record (Hoegh-
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Departures in temperature in °C (from the 1990 value)
Observations, Northern Hemisphere, proxy data
4.5
4.0
3.5
3.0
2.5
0.5
0.0
1000
1100
1300
1400
1600
1800
1900
2000
2100
Figure 2-1 Variations of the Earth's average surface temperature (°C) from
the year 1000 to 2100. The temperature scale is the departure from the 1990
value. Years 1000-1860 are reconstructed from tree rings, corals, ice cores, and
historical records. From 1000-1860, the black line is the 50-year average, and the
gray region is the 95% confidence limit. Years 1860-2000 are from instrumental
records. From 1860-2000, the black line is the 10-year average. Years 2000-
2100 are projections from several model scenarios, with the gray region showing
the full range of predictions.
Source: IPCC, 2001a.
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Figure 2-2. Comparison of the variation in the m ean land and
ocean surface temperatures from years 1880-2000. Temperature
scale is the departure from the 1961-1990 mean. Ocean surface
temperatures closely parallel global surface temperatures, although with
reduced amplitude.
Source: National Climate Data Center, 2005.
Guldberg, 1999). Wide-scale bleaching also occurred during the ENSO events of 1982-1983 and
1987-1988 (Hoegh-Gul dberg, 1999).
While climate model projections show little change or only a small increase in amplitude
for ENSO events over the next 100 years, there is evidence that a gradual shift to more consistent
ENSO-like conditions will occur and that La Nina conditions (the cooler segment of the
Southern Oscillation cycle) will become increasingly unusual (TPCC, 2001b). In addition,
climate change is expected to cause greater extremes in drought and heavy rainfall during ENSO
events (IPCC, 2001b) and has already begun to heighten cyclone intensity (Emanuel, 2005).
These affects are discussed further in Section 2.2.
10

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In American Samoa, there has been a trend of increasing average sea surface
temperatures since 1982 according to satellite measurements (Figure 2-3), with the warmest
seasons occurring in 1994, 2002, and 2003. These warm periods coincided with ENSO-related
Pacific Ocean conditions in 2002/2003. However, sea surface temperatures were not abnormally
elevated in American Samoa during the other strong ENSO years of 1983 and 1997/98.
American Samoa appears to be located far enough West and South in the central Pacific Ocean
to not be consistently influenced by the ENSO cycle.
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1994- Major
bleaching
2002- Minor
2003- Major
bleaching
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Date






Figure 2-3. Monthly mean sea surface temperatures in the vicinity of Tutuila
Island, American Samoa. Points are monthly means, bars above are maximum mean
weekly temperature for the year. Trend-line shows a long-term temperature increase of
~0.28°C per 10 years. Temperature data are from the Reynolds/National Centers for
Environmental Prediction integrated satellite and in situ sea surface temperature
databases.
Source: NASA Jet Propulsion Laboratory, 2005.
2.2. CHANGES AND FLUCTUATIONS IN WEATHER PATTERNS
Cyclones are a regular feature of many tropical regions. Although they can be quite
damaging to coral reefs and surrounding ecosystems, healthy reef systems have thus far been
able to recover from their intermittent, acute effects. Recent scientific study has shown that
11

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cyclone intensity has
increased over the last 30
years in some regions
(Emanuel, 2005).
Projections show that
cyclones are expected to be
more intense (5-10%
increase in peak wind) in
the future, with greater
associated precipitation (20-
30% increase) (Emanuel,
2005; Trenberth, 2005;
IPCC, 2001a). There has
been no evidence or
prediction of changes in
cyclone frequency, tracks,
or areas of formation.
Overall, global
average precipitation is
projected to increase in the
future (IPCC, 2001b).
Geographic and temporal
patterns of precipitation are
also likely to change, with
greater extremes in
localized events such as Hurricane Linda (1997), an example of a Pacific cyclone.
,	_ . (Photo courtesy of the National Aeronautics and Space
intense downpours. During A^^i^tion fNASa] )
the 20th century,
precipitation increased over the tropical oceans and land areas. This trend is expected to
continue along with increasing frequency and intensity of rainfall events. One of the larger
increases in mean precipitation is expected in the tropical oceans, with the equatorial Pacific
Ocean seeing a greater than 20% change under some modeling scenarios (IPCC, 2001b).
American Samoa is situated just south of this region and is expected to see a mean increase in
precipitation of approximately 5% in the next century (IPCC, 200 lb). Increasing precipitation
can cause a variety of impacts on coral reefs, including greater transport of land-based sediments,
nutrients, and contaminants along with extension of low-salinity plumes in the vicinity of
streams and rivers. Stress-related mortality events for coral reefs are more possible with the
increasing frequency and intensity of these events (McCarthy et al., 2001).
12

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From 1981 to 2005 American Samoa has been impacted by six tropical cyclones: Esau in
1981, Tusi in 1987, Ofa in 1990, Val in 1991, Heta in 2004, and Olaf in 2005. The strongest and
most damaging in recent history were Ofa and Val, which were both category 4 cyclones (Green,
2002). There has been at least one recent extreme rain event that caused widespread flash floods
and mudslides. It occurred on May 18-19, 2003 and was called the Pago Pago/Fagatogo flood.
Approximately 25-40 cm of rain fell in approximately 24 hours (Brakenridge et al., 2003).
2.3.	OCEAN CHEMISTRY
Surface seawater CO2 concentrations are predominately driven by atmospheric CO2
levels. As CO2 dissolves in seawater, the pH of the seawater decreases, shifting the relative
concentrations of carbonate (CO3 ") and bicarbonate (HCO3") ions. Many reef building
2~i~	2
organisms use the calcium (Ca ) and CO3 " ions in seawater to build calcium carbonate (CaCC>3)
skeletons. The reduction of either component can affect the rate or quality of skeletal deposition
2+
(Kleypas et al., 1999). Ca is very abundant in seawater and is not affected by climate change;
however, CO3 " is much less abundant, such that even a small decrease in seawater pH caused by
increasing atmospheric CO2 will substantially decrease its concentration, reducing the
calcification rates of reef building organisms (Buddemeier et al., 2004).
In laboratory experiments, a doubling of atmospheric CO2 (a level expected to be reached
in nature before 2100, if current rates of increase continue) (IPCC, 2001b) caused coral
calcification rates to decrease by 11-37% (McCarthy et al., 2001; Kleypas et al., 1999). Such
reductions in calcification rates in nature would mean that corals would build their skeletons
more slowly and/or less densely. Less dense skeletons could be more easily broken during storm
events or other physical impacts. In general, reef structures can only grow and persist when
CaCC>3 deposition rates exceed (or at least equal) erosion rates. Given this, the possibility of
significantly slowed reef-building-or even a complete reversal and loss of reef structures-
becomes a concern.
American Samoa is in a region of the tropical Pacific Ocean where calcification rates are
projected to decrease with climate change over time, but not as rapidly as at higher latitudes
(Kleypas et al., 1999). Calcification rates in American Samoa may have already decreased
approximately 10% from rates prior to industrial revolution (1880). Rates may decrease an
additional 10-20% by the year 2100, based on model projections (Kleypas et al., 1999).
2.4.	SEA LEVEL RISE
Global average sea level has risen between 0.1 and 0.2 meters in the 20th century,
according to long-term tide gauge data from locations in Northern Europe (IPCC, 2001a).
During the 21st century, the sea level is expected to rise another 0.09-0.88 meters, primarily due
to thermal expansion and the melting of glaciers and ice shelves (IPCC, 2001a). This translates
to an average annual rise of 0.9-8.8 mm a year, a rate that is within the ability of most healthy
13

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reefs to match through growth (Smith and Buddemeier, 1992). However, growth rates in some
areas may be slowed enough by chronic stresses and changes in ocean chemistry (see Section
2.3) to cause deeper reefs to fall below available light depth limits (Buddemeier et al., 2004).
Historically, South Pacific sea level rise has been consistent with the global average, and this
trend is expected to continue (McCarthy et al., 2001). Therefore, future sea-level rise in
American Samoa is likely to be in the range of 0.09-0.88 meters over the next century.
2.5. INDIRECT EFFECTS OF CLIMATE CHANGE ON ULTRAVIOLET (UV)
RADIATION STRESS
UV-related stress is an important concern for coral reefs because it can exacerbate coral
bleaching, irrespective of water temperatures (Gleason and Wellington, 1993; Lesser et al.,
1990). Conditions that result in elevated levels of visible and UV light may be indirectly
compounded by climate variability and change (Zepp, 2003; Hoegh-Guldberg, 1999). The
penetration of UV radiation in the water column varies by location. It ranges from meters in
coastal regions to tens of meters in the open ocean and changes over time at a given location
(Zepp, 2003). Variability in the amount of UV-absorbing organic matter in the water column,
which is primarily responsible for UV attenuation, accounts for these differences in UV
penetration. During times of exceptionally calm and clear water conditions (such as ENSO
conditions, which are likely to increase in frequency and duration in the next 100 years [IPCC,
2001b]), greater penetration of UV radiation increases the potential for UV-exacerbated coral
bleaching (Zepp, 2003; Gleason and Wellington, 1993). There has been little evidence that
climate change directly influences the intensity of solar radiation reaching the Earth's surface,
except possibly by large-scale changes in cloud cover.
Preliminary findings from a recent study in American Samoa show that water above the
fringing reef face at several locations on Tutuila Island is quite transparent to UV light.
Attenuation of UV light in near-shore American Samoa water was less than measured in coral
reef areas of the Florida Keys (Hansen et al., in preparation-b). Information on variability over
time and analysis of the potential ramifications for coral reefs in American Samoa are not yet
available.
14

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3. STRESSORS ASSOCIATED WITH LOCAL ACTIVITIES AND EVENTS
In addition to stressors associated with large-scale climate variability and change, a wide
variety of additional stressors result from localized human activities. These activities range from
acute disturbances (e.g., sedimentation stress associated with coastal development activities) to
chronic disturbances (e.g., nutrient stress associated with ongoing agricultural activities). Coral
reefs are less likely to recover if stresses increase in number and severity (Buddemeier et al.,
2004; Hoegh-Guldberg, 1999). When combined with large-scale climate stressors, the effects of
local stressors may be exacerbated. This section provides a brief overview of common local
stressors of concern for coral reefs. Details of how local stressors in American Samoa may
interact with climate stressors to generate particular patterns of reef vulnerability will be
discussed in Section 4.
3.1. POOR WATER QUALITY
Corals thrive in the clear, nutrient-poor, and uncontaminated waters of tropical marine
environments. Inputs of excessive nutrients, contaminants, and particulates from land-based
sources can harm corals directly by interfering with biochemical and reproductive processes or
indirectly by reducing light availability for photosynthesis and promoting the growth of
phytoplankton, macroalgae, sponges, and ascidians (all of which can out-compete corals for
space) (Fabricius, 2005; Brown, 1997a; Hubbard, 1997).
The various forms of excess nutrient loading caused by human activity generally result in
local, chronic stress. Incompletely treated sewage, agricultural fertilizers, animal wastes, and
increased terrestrial runoff due to land disturbances are all common sources of excess N and P in
marine systems. Furthermore, nutrient pollution can increase exponentially in developing
countries with rapid population growth (Wilkinson, 1996).
The impacts of excessive nutrients due to sewage input have been clearly documented in
a case study of Kaneohe Bay, Hawaii (reviewed in Brown, 1997b). Coral reefs in Kaneohe Bay
were exposed to high amounts of nutrient-rich sewage from 1963-1977, which caused
considerable changes in the reef community structure. A successional shift occurred when a
species of green algae (which flourished in the nutrient-rich water) smothered existing corals and
led to domination of the site by particle feeders such as zoanthids, sponges, and barnacles. Three
years after the relocation of the sewage outfall, the particle feeders had disappeared. Within six
years, the algal community had declined and a high number of coral recruits were seen over the
reefs (Brown, 1997b).
Contaminants are toxic or bioactive man-made chemicals that have found their way onto
coral reefs as part of waste streams discharged to the ocean, as accidental spills, as a result of use
of antifouling biocides, or as components of terrestrial runoff (Buddemeier et al., 2004). They
include oil and fuels, insecticides, herbicides, heavy metals, and other industrial and household
15

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chemicals. Fuel or other chemical spills can be common near busy harbors or industrial areas.
Runoff containing insecticides and herbicides can be common in reefs adjacent to agricultural
fields. Storm water runoff from urban and suburban regions can be another route of contaminant
input. Such contaminants can cause a range of sublethal to lethal effects on corals (Haynes and
Johnson, 2000).
A 1974-75 study of chronically oil-polluted reefs in close proximity to an oil terminal in
the northern Gulf of Eilat in the Red Sea showed higher coral mortality rates, smaller numbers of
breeding colonies, and lower coral larvae settlement rates when compared to a control reef
nearby (Loya, 2004). Local laboratory studies supported these field observations (Loya, 2004).
Studies on the Great Barrier Reef have shown that contaminants such as heavy metals and
pesticides have been making their way into reef organisms from terrestrial sources. These
contaminants alter reproductive success and interfere with photosynthesis and may pose a threat
to Great Barrier Reef coral communities if toxic concentrations are reached (Haynes and
Johnson, 2000).
Terrestrial runoff also often contains sediment that increases turbidity and reduces
available light for photosynthetic activity on the reef. High sedimentation rates can kill coral
tissue within a period of a few days (Fabricius, 2005). Lower sedimentation rates reduce
photosynthetic yields, increase relative respiration rates, and increase carbon losses through
greater mucus output
(Riegl and Brancha,
1995). Sediment
accumulation can also
inhibit the
establishment of new
coral colonies by
covering suitable
settlement surfaces.
Because sediment can
become repeatedly re-
suspended when the
water is disturbed, its
effects can be
widespread in space
and time (Buddemeier A sediment plume caused by terrestrial runoff. (Photo courtesy of
et al., 2004).	the National Oceanic and Atmospheric Administration [NO A A].)
Unchecked erosion caused by dredging, construction activities, agriculture, logging,
dumping, mining, and land reclamation, can all result in increased sedimentation and elevated
turbidity. Extensive nearby dredging has reduced coral cover and diversity at sites in Thailand
16

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and Bermuda (Cook et al., 1996; Brown et al., 1990). Logging, together with poor agricultural
practices in Southeast Asia and changes in agricultural methods in Australia, have threatened
adjacent coral reefs by vastly increasing sediment delivery to the near-shore environment in both
places (Buddemeier et al., 2004). Coral communities adjacent to areas of enhanced erosion or
where re-suspension of sediments is common will probably continue to experience increasing
chronic stress with periodically-intense acute episodes. Climate variability and change may
magnify this chronic stress and increase the frequency of acute events in some places through
increased precipitation or intensity of rain events (Hubbard, 1997).
The quality of the offshore waters around American Samoa is generally considered to be
good (Craig et al., 2005). However, near-shore and stream water quality is quite variable, with
some areas exhibiting poor water quality (e.g., Pago Pago Harbor) (Craig et al., 2005; ASEPA,
2004; Green et al., 1996). Water pollution in American Samoa is primarily from non-point
sources in the form of excessive nutrient and bacteria loading and excessive erosion and
sediment runoff during storm events (DiDonato and Paselio, in review; ASEPA, 2004).
Generally, poor water quality in streams or at the shoreline (measured as nutrient or bacteria
content) correlates well with human population density, and even more so near areas not serviced
by the municipal sewage treatment system (DiDonato and Paselio, in review). Past dredging and
filling operations for road construction and other near-shore construction projects have also
impacted coral reefs in Pago Pago Harbor and other areas around Tutuila Island (Cornish and
DiDonato, 2004; Green et al., 1996; Dahl, 1981; Dahl and Lamberts, 1977).
3.2. DISEASES AND OPPORTUNISTIC SPECIES
Outbreaks of coral diseases and pressures from opportunistic marine organisms represent
additional potentially-escalating sources of both acute and chronic stresses for coral reefs. Coral
diseases (i.e., any impairment of vital bodily functions) can be caused by pathogens and
parasites, or by abiotic stresses including excessive water-born nutrients (Bruno et al., 2003).
Corals do possess a variety of defense mechanisms that protect them from invasion by
pathogens. However, these defenses can be weakened by chronic environmental stresses and can
lead to the emergence of latent infections (Bruno et al., 2003; Peters, 1997).
Coral reef diseases in the Caribbean were first reported during the mid-1970s. The first
major coral mortality in the greater region was caused by white plague disease, which appeared
in Florida in 1975. This was followed by two acute Caribbean-wide epizootic events that
changed the structure and morphology of shallow water coral reef communities in the early
1980s. The first, major mortality event was the die-off of the black sea urchin (Diadema sp.) due
to an unknown pathogen. Second, and even more significant, was the die-off of the dominant
acroporid corals due to white band disease, which resulted in major losses of coral cover, spatial
heterogeneity, and reef biodiversity (Weil, 2004). Other diseases have also endangered the
17

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future integrity of many coral reef communities in the Caribbean by their widespread chronic
persistence (reviewed in Weil, 2004).
Relatively little is currently known about coral diseases on Indo-Pacific reefs. Either
disease is less prevalent, or disease distribution and abundance has been underestimated due to a
lack of study (Willis et al., 2004). Preliminary results from recent surveys for coral disease in
American Samoa show that diseases are present in American Samoa, but the effects are minimal
compared to the large scale epizootic events that have taken place in the Caribbean (Aeby,
2005).
The crown-of-thoms starfish (COTS), Acanthaster planci, whose juveniles and adults
feed directly upon corals, is an opportunistic species that can devastate large areas of reef if a
population outbreak occurs. The starfish is a natural inhabitant of Indo-Pacific reefs, and
populations are normally low (6 to
20/km2). However, where
population outbreaks occur,
densities can exceed 500/km2 with
resulting coral mortality of up to
99% in extreme cases (Brown,
1997b; Zann, 1992). There is no
simple condition that leads to the
dramatic variation in COTS
populations or the ensuing
widespread coral destruction that
has been observed (Brown, 1997b;
Zann, 1992).
COTS population
outbreaks in American Samoa
have been infrequent but highly damaging to some coral communities around Tutuila Island.
The only documented outbreak began in 1977 and remained active until 1980, when live coral
became limited (Zann, 1992). Coral mortality in Fagatele Bay on Tutuila Island was estimated
to be 95% (Green, 2002; Zann, 1992).
3.3. OVER-FISHING AND RESOURCE EXTRACTION
Over-harvesting of reef resources can create myriad stresses that are often difficult to
avoid. Coral reef systems have long been a resource for food, but other organisms of many types
are also taken as souvenirs or decorations or for the aquarium trade (Buddemeier et al., 2004;
Wilkinson, 1996). Over-fishing, or the unsustainable fishing or collection of particular
organisms, is a chronic problem worldwide and has impacted the entire marine ecosystem
(Pandolfi et al., 2003; Jackson et al., 2001). Coral reefs are highly productive systems but have
18
Crown-of-Thorns Starfish (COTS). (Photo courtesy of
Lara Hansen.)

-------
low net productivity that can not sustain heavy fishing pressures. Over-fished reef communities
often decline rapidly due to shifts in ecosystem dynamics. For example, herbivores play an
important role in the competitive balance between coral and macroalgae on the reef, so over-
fishing or even light fishing of herbivorous fish or invertebrates can lead to enhanced macroalgae
growth and concomitant loss of coral cover (Wilkinson, 1996). The methods used in fishing and
gathering reef organisms can also have destructive effects through removal of target species.
Dynamite fishing and the use of toxic chemicals to take fish result in destruction of non-target
organisms, as do net fishing, gleaning, and physical impacts from boat anchoring. The chronic
and wide-ranging nature of such over-fishing stresses can contribute to a hampered ability of
coral reefs to recover from other acute, harmful events (Wilkinson, 1996).
3.4. CONCLUSIONS
The emerging challenge for successful coral reef resource management lies in
understanding how stressors associated with large-scale climate variability and change will add
to, modify, or act synergistically with the localized non-climate stressors described above. For
example, coral diseases may increase rapidly with increasing sea surface temperatures (Harvell
et al., 2002; McCarthy et al., 2001). Also, coastal population growth and an ever-increasing
dependence on fertilizers and pesticides for agriculture-coupled with a greater frequency of
extreme rain events in the tropics-may amplify nutrient and contaminant pollution in terrestrial
runoff as well as sediment deposition. The next section highlights an assessment of the
particular combinations of climate and non-climate stressors most likely to be of greatest concern
for causing vulnerabilities to the reefs of American Samoa.
19

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4. VULNERABILITIES OF AMERICAN SAMOA'S REEFS TO INTERACTING
STRESSORS
4.1. APPROACH
An assessment of local coral reef ecosystem vulnerabilities in the face of combined
climate change and local stressors is central to the conceptual model presented in Figure ES-1.
Here, climate and local stressors specific to the coral reefs of American Samoa are reviewed,
with special attention given to collective interactions. The vulnerabilities that emerge from this
assessment are candidates for priority action by local resource managers and stakeholders.
While the original intent of this vulnerability assessment was to be as specific as possible
with regard to particular locations and conditions around American Samoa, in reality the ability
to be specific is limited by a lack of available information. The examples presented come from a
limited collection of studies, most of which were not originally designed to address climate
change questions or effects of local stressors. They are general resource monitoring projects,
hypothesis-driven studies of limited scope, or qualitative observations made by credible
scientists and local agency personnel. Gaps in available information are often large due to the
infrequency or inconsistency of these reports. However limited, the best available information is
presented here, and the data gaps that have emerged are addressed with the goal of validating and
expanding these findings in the future.
One dataset that is repeatedly referred to in this assessment comes from the only island-
wide, long-term, and systematic coral monitoring project available for American Samoa. These
data are contained in a series of reports by Birkeland et al. (2002; 1987), Green (2002; 1996),
Green and Hunter (1998), Green et al. (1999), and Fisk and Birkeland (2002) (which have been
recently summarized by Birkeland et al., 2004). Figure 4-1 is derived from Birkeland et al.
(2004) and indicates trends in the mean percent coral cover determined from surveys at five
locations in 1982, 1985, 1988, 1995, 1998, and 2001. This figure is based on summarized data
and not a re-analysis of raw data. A subset of transect locations most consistently surveyed were
chosen; however, the researchers involved and methods used vary between dates. Also, coral
reefs are inherently heterogeneous, which leads to naturally high variability over time and
between locations. Therefore, this figure is used to illustrate trends and may not accurately
reflect island-wide conditions.
The method used in this assessment involved the superimposition of information
regarding coral bleaching and local stressors (e.g., water quality, coral disease) over these long
term coral population trends for the purpose of evaluating potential vulnerabilities. Evidence of
potential vulnerabilities emerged where: (1) a single stress was extreme; (2) stresses overlapped
in time and location; or (3) stresses occurred in rapid succession.
Identification of vulnerabilities to multiple stressors is a necessary first step toward
understanding and supporting overall reef resilience. Holling (1973) first characterized
20

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s-
D
>
o
O
s-
O
o
100
80
60
40
20
Major
Cyclones
U
Coral
Bleaching
1980 1985 1990 1995 2000 2005
Year
Figure 4-1. Trends in coral populations, 1982-2001. The approximate
dates of major acute stresses have been indicated. Mean percent coral
cover for reef slope surveys was calculated for Cape Larsen, Fagasa Bay,
Masefau Bay, Rainmaker Hotel, and Fagatele Bay survey sites (2-3 m
and 6 m survey depths combined). The 1982 point does not include
Fagatele Bay (both depths). The 1998 point does not include Fagasa Bay
(6 m), Masefau Bay (6 m), or Rainmaker Hotel (2-3 m). Error bars are ħ
1 SD calculated between sites.
Source: Birkeland et al., 2004.
ecological resilience - as the ability of ecological systems to absorb changes of state variables,
driving variables, and parameters, and still persist. Since then, usage of the term has expanded to
include the speed of return of a system to equilibrium after a disturbance, as well as the
magnitude of disturbance that can be absorbed by the system before it shifts from one stable state
to another (Gunderson, 2000; Nystrom et al., 2000). Thus, ecosystem phase shifts-dramatic
shifts in community structure from one stable equilibrium to another-are probable when
resilience is low.
In the case of coral reefs, resilience to coral bleaching is dependent upon a combination
of factors: coral resistance to bleaching, coral survival during bleaching, and reef recovery after
bleaching-related mortalities have occurred (West et al., 2005). Reefs that are under chronic or
acute stress from a variety of local sources are likely to have a reduced capacity to remain
resilient in the face of large-scale temperature anomalies that trigger bleaching events. Indeed,
there have been multiple instances in which coral bleaching is believed to have contributed to a
21

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phase shift from a community dominated by reef-building organisms to one dominated by non-
reef-building organisms such as fleshy algae and soft corals (Ostrander et al., 2000; Done, 1999).
The followings sub-sections review accounts of climate change-related impacts on coral
communities in American Samoa and infer the likely compounding role of local or regional
stresses that may overlap or occur in rapid succession with climate stress. In each case, a
qualitative assessment of coral reef ecosystem vulnerability and resilience to climate change-
related impacts is provided.
4.2. VULNERABILITIES TO CLIMATE CHANGE AND INTERACTING LOCAL
STRESSORS
4.2.1. Climate Change: Sea Surface Temperatures
There is considerable and growing evidence that the coral communities of American
Samoa are susceptible to periodic extremes in sea surface temperatures associated with climate
change. In American Samoa, coral bleaching becomes theoretically probable when local sea
surface temperatures exceed 30.3°C, one degree above the local mean maximum sea surface
temperature (NOAA Coral Reef Watch, 2005). Local reports of coral bleaching correlate well
with regional sea surface temperatures near this threshold in 1994, 2002, and 2003 (see Section
2.1 and Figure 2-3).
The most extensive and best documented coral bleaching events in American Samoa
occurred in 1994, 2002, and 2003. Bleaching that occurred in 1994 was described by Goreau
and Hayes (1995) as part of a coral bleaching study in the South Pacific Ocean. In 2002, coral
bleaching was quantified by both Fisk and Birkeland (2002), and Green (2002). Hansen et al. (in
preparation-b), in a specific study of bleaching variability on Tutuila Island, quantified coral
bleaching during its height in 2003. Together, these studies provide the most rigorous
information available on local coral reef responses to elevated sea surface temperatures.
In 1994, coral bleaching around Tutuila Island occurred in 40% of colonies, according to
semi-quantitative surveys (Goreau and Hayes, 1995) at six sites (Table 4-1). This is the greatest
proportion of coral bleaching damage recorded on the outer reef in American Samoa to date. It
was also the greatest proportion of bleaching observed in the Goreau study, which also included
reefs in French Polynesia and the Cook Islands. Locations around Tutuila Island with a large
proportion of observed bleaching damage (approximately 50%) were Masefau Bay,
Atauloma/Afao Bay, and Faga'alu Bay (Goreau and Hayes, 1995) (Table 4-1, Figure 4-2).
Coral bleaching in 2002 was sporadic and less prevalent in American Samoa when
compared to 1994 and 2003 (Table 4-1). Two parallel studies recorded coral bleaching as part of
general benthic organism monitoring at 11 similar sites (three additional sites were surveyed by
Green) in March of 2002 on Tutuila Island (Figure 4-2) (Fisk and Birkeland, 2002; Green, 2002).
Fisk & Birkeland (2002) found bleaching to be variable, with a combined frequency of 2.3% of
22

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Table 4-1. Summary of coral bleaching surveys on Tutuila Island
Date
Source
Number of
sites
Mean percent of
colonies bleached,
(min-max)
Bleaching-sensitive
species
(proportion bleached)
1994
(August)
Goreau & Hayes
(1995)
6
40%
Porites, Montipora,
Diploastrea, Acropora,
Pocillopora, Merulina,
Pachyseris,
Gardinoseris,
Astreopora,
Montastrea curta,
Pavona, Favia, Favites,
Sarcophyton
2002
(March)
Fisk & Birkeland
(2002)
11
2.3% (0.4-9%)
Montastraea curta (57-
71%)
Porites lichen. (15-
33%)
2002
(March)
Green
(2002)
14
Low, 1-10%
(none to 1-10%)
Montastraea curta
(50%
Porites sp.
Acropora sp.(10-50%)
Pocillopora sp.(10-
30%)
2003
(February)
Hansen et al.
(in preparation)
7
10.4% (6-23%)
Acropora sp. (>30%)
Pocillopora sp. (>30%)
23

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Yf13 Masefau
Tafeu nK#' Bay
Cove

Fagafue
Bay
Pago Pago
Mai ota
Fagasa
Tafuna
Fagamalo
Amanave
1
Leone
Atauloma
Bay
Alofau
unu u
Island
Airport
Lagoon
Fagatele
Bay
-f. =
j .
Pago Pago
Pago Pago
Utulei
Faga'alu
Fatumafuti
Nu'uuli Yf
%
_
Harbor
Figure 4-2. Locations on Tutuila Island where studies have been conducted.
Embayments or nearby villages are named. Major fringing and offshore reef
formations are indicated in pink. Courtesy of Dan Catanzaro, T N & Associates,
Inc.
coral colonies bleached at the Tutuila Island sites (10 m depth). Bleaching was greatest at
Fagatele Bay (9%); however, five of the 11 sites showed no bleaching. Green (2002) determined
coral bleaching to be low (1-10% of corals) using a semi-quantitative method to survey a wider
area and depth range than that surveyed by Fisk and Birkeland (Table 4-1). Again, bleaching
was variable, with moderate (10-30%) bleaching observed at Fagafue and Fagasa on the north
side of Tutuila Island (Figure 4-2). Both of these studies documented great variability in
bleaching susceptibility between genera, with bleaching of up to 71% of individuals of some
genera (Table 4-1) (Fisk and Birkeland, 2002; Green, 2002).
The 2003 bleaching event was quantified during its peak in February and March. The
proportion of bleached colonies was reported to be 10.4%, based on preliminary data from seven
sites around Tutuila Island (Table 4-1) (Hansen et al., in preparation-b). Preliminary findings
show that bleaching was greatest in Vatia Bay on the north side of Tutuila Island (Figure 4-2),
24

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with 23% of surveyed
colonies bleached.
Overall, bleaching was
most common in plate
and branching
Acroporids and
branching
Pocilloporids and often
exceeded 30% of a
local population (Table
4-1). Areas dominated
by these species were
heavily impacted by
subsequent mortality
when resurveyed in
June and August
(Hansen et al., inpreparation-b).
The above accounts confirm that coral reefs in American Samoa are vulnerable to
abnormally elevated sea surface temperatures. The proportions of total coral that bleached may
seem low, but the extent of bleaching observed in sensitive Pocillopora,Acropora, and
Montastrea species was disproportionately high (10-70%) (Table 4-1) (Hansen et al., in
preparation-b; Fisk and Birkeland, 2002; Green, 2002). Significant live coral cover was lost in
areas dominated by these species. Also pointing toward a trend of increasing vulnerability to
climate change is the observation that temperature-related coral bleaching at some level has
occurred in American Samoa annually since 2002 (Hansen et al., in preparation-b; Fenner, 2005,
2004; Fisk and Birkeland, 2002; Green, 2002).
The long-term resilience to bleaching of these reef communities is still in question.
There is little specific information on the recovery of bleached areas in American Samoa due to
sporadic surveying. There is also limited comparison and analysis of changes in coral species
richness and diversity. Full recovery from major bleaching events can take from 2-10+ years,
depending on previous population diversity and cover (Glynn, 1993). The only basis for
resilience assessment is comparison in the long-term region-wide coral monitoring project
summarized by Birkeland et al. (2004). Based solely on general monitoring of coral cover
conducted at limited sites in 1998 and 2001, this summary shows that strong recovery was taking
place in American Samoa following a historic low in 1995 (Figure 4-1). This strong resilience
capacity in the coral reef ecosystem suggests that while vulnerable, the coral community of the
last two decades has been resilient enough to avoid drastic ecosystem phase changes following
past acute perturbations.
Bleached corals in American Samoa. (Photo by Eric Mielbrecht.)
25

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4.2.2. Water Pollution and Climate Change
Elevated sea surface temperatures, combined with nutrient pollution, increased
sedimentation, and chemical pollution, could stress reefs beyond their ability to recover (Hoegh-
Guldberg, 1999; Hughes, 1994; Goreau, 1992). Poor water quality is potentially the most
widespread of local stressors that-in combination with climate change stressors-may fully test
the resilience of coral communities in American Samoa. Increased terrestrial runoff, due to
greater precipitation and more intense rain events that are expected with climate change, coupled
with a rapidly growing human population may increase the impacts of land-based water
pollution.
The quality of the offshore waters around American Samoa is considered to be generally
good (Craig et al., 2005). However, near-shore and stream water quality is quite variable, with
some areas exhibiting poor water quality (e.g., Pago Pago Harbor) (Craig et al., 2005; ASEPA,
2004; Green et al., 1996). In American Samoa, water pollution is primarily from non-point
sources in the form of excessive nutrient and bacteria loading from faulty or improperly
constructed septic tanks and animal wastes from pen areas. Poor agricultural practices and other
land disturbances also promote excessive erosion and sediment runoff during storm events,
thereby further polluting the water (DiDonato and Paselio, in review; ASEPA, 2004). Generally,
poor water quality in streams or at the shoreline (measured as nutrient or bacteria content) is
proportional to human population density, especially near areas not serviced by the municipal
sewage treatment systems (DiDonato and Paselio, 2006; DiDonato, 2005; DiDonato, 2004;
Hansen et al., in preparation-b). Non-point sources of water pollution such as these are
challenging to manage; however, the American Samoa Environmental Protection Agency
(ASEPA) is monitoring and addressing these problems in a number of ways.
Water pollution in streams and along the shoreline is summarized annually in the water
quality monitoring and assessment processes for the Territory as required by the Clean Water
Act. These data are important for identifying water quality problems and provide some insight
into potential pollution stresses on coral reefs. In 2004, ASEPA assessed 67.9 km of ocean
shoreline out of a total of 239.8 km in American Samoa for aquatic ecosystem protection
(ASEPA, 2004). ASEPA considered the water quality to bQ fully supportive of aquatic
ecosystems for 23.7 km of the assessed shoreline. The remaining 44.3 km of assessed shoreline
was deemed supportive but threatened by one or more water quality impairments. This suggests
that coral reefs in 65% of the assessed shoreline may be experiencing stress due to one or more
pollutants. Pollutants measured included polychlorinated biphenyls (PCBs), metals (mercury,
arsenic, etc.), excess nutrients (nitrogen [N], phosphorous [P], etc.), organic enrichment/low
dissolved oxygen, pathogenic bacteria, and turbidity (ASEPA, 2004).
The water quality of a larger area of shoreline was monitored for human health
parameters. ASEPA assessed approximately 134 km of ocean shoreline for swimming risk and
60 km of ocean shoreline for fish consumption risk. Frequent pathogenic bacteria contamination
26

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along 117 km of shoreline (87% of total assessed) elevated health risk associated with
swimming. Health risk associated with fish consumption was estimated to be high for 12.7 km
of shoreline (21% of total assessed and primarily in Pago Pago Harbor) due to PCBs and metals
found in local fish tissue (ASEPA, 2004). While not necessarily an indicator of direct threats to
aquatic life, these contaminants are potential indicators of water quality problems that could
affect coral reefs. For example, the major sources of shoreline bacteria contamination in
American Samoa are reported by ASEPA to be poorly constructed or maintained septic systems
and wastes from animal pen areas (piggeries), both of which are also significant sources of
nutrient pollution stress to coral reefs (ASEPA, 2004).
This partial assessment of shoreline water quality begins to put into perspective the extent
of water quality issues identified by the ASEPA. ASEPA is expanding the areas monitored but
currently focuses much of its shoreline monitoring on areas where human use is common,
development is extensive, and population density is high. Thus, impacted areas may be
disproportionately represented. Regardless, heavily developed and populated areas have a
demonstrated impact on the quality of the near-shore environment.
Pago Pago Harbor is an example of an area where poor water quality has been implicated
in coral population decline. The Harbor is the economic and governmental center of the
Territory and houses a busy industrial port, most of the island's heavy industry, and high
population density. With harbor development and industrialization came extreme eutrophication
and chronic chemical pollution from numerous industries and from periodic fuel spills, all of
which have been linked to a significant decline in coral species diversity, abundance, cover, and
colony size (Green et al., 1996; Dahl, 1981; Dahl and Lamberts, 1977). Additionally, many of
the fringing reefs in the Harbor
were destroyed by dredging and
filling operations and near-shore
construction as part of
infrastructure improvements
(Green etal., 1996; Dahl, 1981;
Dahl and Lamberts, 1977).
Water quality in Pago
Pago Harbor and the
surrounding watershed has
improved in the recent past due
to extensive regulatory and
mitigation efforts, but it is still
an area where aquatic
ecosystems and human health
have the potential to be
Pago Pago Harbor, American Samoa. (Photo by Eric
Mielbrecht.)
27

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negatively impacted. Shoreline water quality in the harbor is considered impaired for human
swimming and fish consumption, and aquatic life is considered threatened (ASEPA, 2004).
Prior to its industrialization, Pago Pago Harbor supported numerous healthy coral
communities and was the location of the first coral surveys on Tutuila Island (the Aua transect)
(Mayor, 1924). The Aua transect is a single transect located in the outer harbor that was
surveyed in 1917, 1973, 1980, 1998, and 1999. It is approximately 270 m long and traverses the
reef from the shoreline near the village of Aua to the reef face. Surveys of this historic transect
show a 75% decline in coral cover between 1973 and 1998, and an 82% decrease since 1917
(Figure 4.3). This accelerated declining trend since 1973 suggests a connection between
industrialization in Pago Pago Harbor and decreasing coral cover when compared to island-wide
coral cover trends, which have been increasing since 1995 (Figure 4-1) (Craig et al., 2005;
Green, 1996; Dahl and Lamberts, 1977). Figure 4-3 is based on data summarized in two reports
and not on a reanalysis of raw data. Survey methodologies varied between dates. Also, coral
reefs are inherently heterogeneous, which leads to naturally high variability over time and
between areas. Therefore, this figure is used to illustrate trends in mean coral density for a single
transect and may not accurately reflect Pago Pago Harbor as a whole. Yet, casual observations
of corals in this area by local scientists suggest that overall coral cover may have decreased even
more at this site between 1980 and 2000 than Figure 4-3 shows.

Figure 4-3. Trends in mean coral density on the Aua transect, Pago Pago
Harbor, 1917-2001. Error bars are ħ1 SD based on the division of the transect
into nine end-to-end squares. Data are from Dahl, 1981; Birkeland and Green,
1999.
28

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However, these same observations show that recently there has been a trend of recovery
that parallels improving water quality in the harbor (Craig, 2005). Since 1995 and the advent of
increasing pollution controls, coral cover island-wide has increased (Figure 4-1) (Craig et al.,
2005; Green, 1996; Dahl and Lamberts, 1977).
Faga'alu is another area within Pago Pago Harbor where poor water quality has impacted
coral communities (Houk et al., 2005). Recent work by Houk et al. (2005) addressed non-point
source pollution stress on coral reefs at six locations around Tutuila Island, including Faga'alu.
Based solely on benthic surveys, Houk et al. determined that Faga'alu was heavily impacted
from land-based pollution and sediment loading, which resulted in comparatively low coral
abundance and density ( 2005). A gravel quarry upstream from this site has been reported as a
source of sediment input at this location (Hansen et al., in preparation-b).
The extent of this decline is consistent with the notion that the resilience capacity of the
coral community at this location in Pago Pago Harbor may be compromised and that these
populations have become vulnerable to dramatic ecosystem changes (Houk et al., 2005; Green et
al., 1996; Dahl and Lamberts, 1977). The addition of climate change-related stresses in the form
of potentially greater storm-related terrestrial runoff and elevated sea surface temperatures may
compound water quality stressors in the Harbor. It is possible that bleaching has already
impacted Harbor coral populations. In 2002, bleaching was reported in the Aua area (Green,
2002). However, this area was not surveyed for bleaching in 1994 or 2003.
Most perennial streams on Tutuila Island are small, with low average flows that influence
only a small portion of the adjacent reef. However, stream flows increase greatly during heavy
rain events, sending large plumes of sediment onto the reefs. Careless development on coastal
lands, where the land has been extensively disturbed and natural buffer zones have been covered,
enhances the transport of sediments and pollutants directly to the ocean during extreme rain
events. Increasing precipitation and more frequent and intense extreme rain events in this region
caused by climate change may worsen the chronic and acute stresses of storm water runoff on
Tutuila Island.
Coral communities may also be impacted by poor water quality at other locations around
Tutuila Island, especially where local human populations are burgeoning. The population of
American Samoa is roughly 60,000 people. It is growing rapidly at an annual rate of more than
2%. This is much higher than the U.S. national average of 0.9% (U.S. Census Bureau, 2005).
The majority of American Samoa's population lives on the narrow coastal plain on the south side
of Tutuila Island. Figure 4-4a shows a current population density of seven to nine people per
hectare in this area (2000 population data). Stream water quality is already considered impaired
in many of these populated watersheds, and shoreline aquatic life may already be threatened
(ASEPA, 2004). By 2025, population density is expected to almost double to 16-18 people per
hectare in some watersheds. Figure 4-4b depicts the population in the year 2025, based on the
current growth rate.
29

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The concentration of humans and associated development on the limited coastal areas
increases the potential for anthropogenic stresses to adjacent reefs (Wilkinson, 1996). Without
appropriate community involvement, education, regulation, and infrastructure support (waste
water treatment facilities, maintained drainages and wetlands, etc.), terrestrial sources of
sediments, nutrients, and pollution are all expected to increase, adding to chronic water quality
stress to adjacent coral reefs. Inevitably, this will further tax the ability of these coral
communities to remain resilient in the presence of increasing regional and global stressors.
4.2.3. Extreme Weather Events and Climate Change
American Samoa is subject to periodic tropical cyclones and extreme rain events, both of
which could increase in severity with climate variability and change. Tutuila Island has been
impacted by six tropical cyclones from 1981 to 2005: Esau in 1981, Tusi in 1987, Ofa in 1990,
Val in 1991, Heta in 2004, and Olaf in 2005. The strongest and most damaging in recent history
were Ofa and Val, both category 4 cyclones (Green, 2002). Cyclone Ofa brought winds up to
250 kilometers per hour, and cyclone Val produced winds up to 260 kilometers per hour and
remained near Tutuila Island for five days. These two cyclones caused substantial damage to
live coral and structural damage to reef framework deposits and overturned and destroyed large
coral colonies island-wide (Birkeland et al., 2002; Green, 2002; Green et al., 1999). Heavy
precipitation also accompanied these cyclones, causing extreme terrestrial runoff that transported
significant amounts of sediment and nutrients to the near-shore environment (Craig et al., 2005).
There has been at least one recent extreme rain event not associated with a cyclone, which
caused widespread flash floods and mudslides. This was the May 18-19, 2003 Pago
Pago/Fagatogo flood, during which approximately 25—40 cm of rain fell in approximately 24
hours (Brakenridge et al., 2003). Associated impacts on near-shore water quality and coral reefs
were not assessed at the time.
The long-term coral monitoring project measured a precipitous decrease in coral cover
around Tutuila Island between 1987 and 1995, which was attributed to the 1990 and 1991
cyclones (Figure 4-1) (Birkeland et al., 2002; Green, 2002). This is a good example of the
potential effects of successive stresses. However, these events do not seem to have exhausted
the resilience capacity of the coral ecosystem around Tutuila Island. Signs of recovery were
already apparent in 1995 as indicated by the abundance of crustose coralline algae, which had
begun to cement and stabilize the dead coral rubble. The crustose coralline algae also presented
an ideal substrate for rapid recruitment of new coral colonies (Birkeland et al., 2002).
Cyclones are regular occurrences to which coral reefs in American Samoa have adapted
over thousands of years. While cyclones are occasionally quite destructive, coral populations in
American Samoa appear to show strong signs of recovery within three to five years (Figure 4-1).
However, cyclone intensity has increased over the last 30 years and is expected to escalate
according to climate change projections (Emanuel, 2005; IPCC, 2001b).
30

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Density per hectare
0-3
4-6
7-9
H 10-12
B| 13-16
ĤI 16-
H id-21
Olesega
Is and Populaben Density per hectare
Ofii
as
4
O'eu^a
216
4
Ta'u
692

Density per hectare
0-3
4-6
7-9
1 10-12
13-
ĤĤ 16-18
ĤĤ 19-21
Olescga
Irtanri Population f>nnğy per nectnr*
433	.7
seoa 162	.3
i 736	2
Figure 4-4. Human population density distribution for 2000
(a), and projected to 2025 (b). Shading refers to population
density within major watersheds. Major fringing and offshore
reef formations are indicated in pink. Courtesy of Dan Catanzaro,
T N & Associates, Inc.
31

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Such negative effects on coral cover could be further exacerbated if cyclones were to
regularly overlap with, precede, or follow warm water events. The probability of successive or
overlapping cyclone events and mass bleaching events may increase if there is a shift toward
more consistent ENSO-like conditions as projected by climate models (IPCC, 2001b). In
American Samoa, the 1994 bleaching event followed closely after the destructive 1990 and 1991
cyclones and dealt another blow to coral populations island-wide. Coral monitoring was too
infrequent to distinguish cyclone and bleaching effects on island coral cover, but it is probable
that the historic low coral cover reported in 1995 was due to the relatively close succession of
these three events. This
supports the notion that
coral communities in
American Samoa
become very vulnerable
when a rapid series of
large-scale acute stresses
like this occur.
Additionally, there is
evidence that some
sites-such as the shallow
reef flat areas of
Fagatele Bay and Pago
Pago Harbor-have
actually not recovered as
well as other areas
(Birkeland et al., 2004).
4.2.4. Coral Diseases, Opportunistic Species, and Climate Change
Coral communities in American Samoa face a potentially escalating vulnerability to the
stresses of coral disease when combined with climate change. Outbreaks of disease can occur
naturally, but they may also be worsened by changes in the natural balance of ecosystems
brought on by climate variability and change (Buddemeier et al., 2004; Harvell et al., 2002;
McCarthy et al., 2001; Williams Jr. and Bunkley-Williams, 1990). Pathogen development rates,
reduced cool-season restrictions on pathogen populations, and host susceptibility to infection
may all be influenced by warming sea surface temperatures (Harvell et al., 2002).
Very little was known of the status of coral diseases in American Samoa until recently
(Work and Rameyer, 2002). In 2004 and again in 2005, Aeby (2005) performed quantitative
surveys for coral diseases at seven sites around Tutuila Island as a follow-up to a 2002
exploration. Preliminary results from these surveys show that disease prevalence is very low
Cyclone damage in American Samoa. (Photo by Eric
Mielbrecht.)
32

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(<1% of coral colonies surveyed), but statistical site-to-site comparisons have not been
completed. Indications of at least 10 different diseases were found; however, histopathological
verification is still in progress (Aeby, 2005). These studies show that coral disease is present in
American Samoa although its effects are minimal compared to the large-scale epizootic events
that have taken place in the Caribbean (see Section 3.4). Current vulnerability of the American
Samoa coral reef ecosystem to diseases may be low, but resource managers are concerned that
the reefs may become increasingly vulnerable if local diseases are aggravated by climate change.
There is the potential for coral disease to spread with increasing sea surface temperatures
(Harvell et al., 2002; McCarthy et al., 2001). Other local stresses, such as increasingly poor
water quality, can also increase the
severity of coral diseases (Bruno et
al., 2003).
Population outbreaks of
predatory Crown-of-Thorns Starfish
(COTS) in American Samoa have
been infrequent but highly damaging
to some coral communities. The only
documented outbreak began in 1977
on Tutuila Island and remained active
until 1980 (Zann, 1992). This
outbreak was unexpected since
COTS were rare on the island in
previous decades, as learned though
interviews with elderly fisherman (Zann, 1992; Birkeland et al., 1987). Coral mortality in
Fagatele Bay on Tutuila Island was as high as 95%, while the other islands apparently were not
affected by the outbreak (Green, 2002; Zann, 1992). Not until 1998 did Fagatele Bay show signs
of recovery of coral cover (Birkeland et al., 2004). However, the cyclones of 1990 and 1991 and
the mass bleaching event in 1994 may have hampered this recovery.
Across the Pacific, a simple cause for periodic dramatic increases in COTS numbers has
eluded scientists; however, several hypotheses have been formulated (Brown, 1997b; Zann,
1992). Among them are suggestions that COTS outbreaks in the southern and western Pacific
are correlated with ENSO events (Zann, 1992) and that outbreaks may be linked to reef
disturbances related to increased sea temperatures (Hoegh-Guldberg, 1999) or input of excess
nutrients from nearby land, particularly during periods of heavy precipitation (Brown, 1997b).
Coral populations in American Samoa have already shown great vulnerability to past COTS
outbreaks. These outbreaks may become more frequent or more extensive if there is indeed a
link between climate change and COTS outbreaks.
Diseased Pocillopora coral. (Photo by Eric
Mielbrecht.)
33

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4.2.5.	Over-Fishing, Resource Extraction and Climate Change
Researchers and managers agree that the reefs in American Samoa are over-fished (Craig
and Green, 2005; Craig et al., 2005). Recent surveys confirm that there are relatively few or
only small sizes of fish commonly taken for food (Craig and Green, 2005). However, there is
still an abundance of small herbivorous surgeonfish and parrotfish that can help control
populations of macroalgae on the reefs (Craig et al., 2005). Without these herbivores, rapidly-
growing macroalgae would likely out-compete corals and crustose coralline algae.
Subsistence fishing has declined substantially over the past two decades, primarily due to
the move toward a cash-based economy and away from a subsistence lifestyle, but also due to
declines in reef fish and invertebrates (Craig et al., 2005; Tuilagi and Green, 1995). Artisanal
catch has fluctuated greatly since 1987 and suffered a steady decline after SCUBA-based spear
fishing exceeded sustainable catch in 1998 (Craig et al., 2005). Incidental damage to the reef
from such fishing practices is infrequent; however, damage from illegal dynamite and poison-
based methods has been observed more frequently.
Climate change is impacting, and will continue to impact, marine and estuarine fish
(Roessig et al., 2004). Changes in coral reef fish communities may occur, which can alter
interdependent relationships with coral populations. Coral bleaching mortality and the resulting
loss of reef complexity may be a key factor in reducing abundances and biodiversity of reef
fishes. However, comparatively little is known of the physiological thermal tolerance limits of
reef fish (Roessig et al., 2004). This undermines an understanding of how climate change may
interact with local reef fish populations and again, how these changes will affect coral
communities. Currently there is not enough information to determine the vulnerabilities to coral
communities and to coral and reef fish interdependence when fishing pressures are compounded
with climate change stressors.
4.2.6.	Conclusions
This section focused on assessing the ecosystem vulnerabilities that increase when local
stressors are compounded with potential climate change stressors. Comparisons were limited by
the available data, and conservative inferences were made where feasible. Numerous other
combinations of stressors are possible, but research is inadequate in American Samoa-and often
globally-to assess the full range of potential vulnerabilities. The following sections will discuss
in more detail how the limitations of this assessment could be addressed with monitoring and
research resources, and how reef resilience could be supported through strategic management.
4.3. INFORMATION GAPS
Studies addressing climate change issues in American Samoa are limited. Studies that
address the effects of local stressors on coral reefs are also few. Only recently have climate
change questions been integrated into local hypothesis-driven research or monitoring efforts
34

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(Hansen et al., in preparation-a; Hansen et al., in preparation-b; Mielbrecht and Hansen, in
preparation; Birkeland, 2003), and findings from these studies are still pending. Fortunately,
American Samoa does benefit from one long-term coral monitoring project and several studies
that, although limited in scope, directly address local stresses.
The evaluation of local coral reef ecosystem vulnerabilities would benefit greatly from
studies that specifically address interactions of climate change and local stressors, or even
examine local stressors that overlap in place or time, or occur in rapid succession. No specific
accounts of these kinds of interactions were available at the time this report was written.
Inferences were made from information that exists for single stressors in separate timeframes or
locations around American Samoa, and sometimes from other global locations, to assess
hypothetical vulnerabilities. Clearly, there is much room for improvement of this initial
assessment as more data become available.
Specifically, the resource managers of American Samoa would benefit from local
information derived from hypothesis-driven studies in key areas. It is recommended that efforts
include gathering comprehensive information in the areas of near-shore water quality, coral
bleaching, and resilience-conferring biological and physical factors in coral communities.
Incorporating these elements into a comprehensive, hypothesis-driven monitoring and research
plan for the Territory is a suggested first step and could yield valuable information within a short
period of time. However, it is impossible to address all of these issues at once. Suggested
priorities for research and monitoring are discussed in Section 5. The interrelation of resilience
capacity, vulnerability, and resource management planning is further developed in the next sub-
section.
4.4. SUSTAINING RESILIENCE
The information presented in this report reveals existing patterns of vulnerability in the
coral communities of American Samoa and touches upon the range of innate resilience capacity
of its coral reefs to climate change and other stresses. Understanding, maintaining, and
enhancing this resilience capacity through appropriate resource management efforts could help
reduce vulnerability in the face of climate change (Hughes et al., 2005; West et al., 2005;
Tompkins and Adger, 2004). The impacts of climate change are already a reality in American
Samoa and are expected to increase. Local conditions are changing with rapid population
growth so the potential is high for associated stresses on the environment to also increase.
Resource managers would benefit by focusing on specific stresses and combinations of stresses.
However, they ought to also consider a broader concept of resilience when developing longer
term management strategies (Hughes et al., 2005; West et al., 2005; Tompkins and Adger, 2004).
Sustaining the resilience of the overall reef ecosystem is an on-going endeavor. It
includes identifying resilient coral reef areas and the factors that confer resilience, strategically
using marine protected areas, and embracing creative and adaptive management strategies. Coral
35

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reef resource managers are not always able to directly regulate nearby anthropogenic sources of
stress, which makes it difficult to address these issues. However, managers often have the ability
to direct marine protected area (MP A) designation and associated planning. Therefore, one of
the most effective strategies may be for managers to become familiar with resilience theories and
share these ideas with the local village communities and other stakeholders while incorporating
resilience concepts into local MPA planning processes. Excellent tools are available for
understanding and enhancing coral reef resilience to climate change through adaptive
management strategies. These concepts, along with specific recommendations to resource
managers in American Samoa, will be further developed in the next section.
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5. ADAPTIVE MANAGEMENT STRATEGIES AND DECISION-MAKING
OPPORTUNITIES
Using an adaptive management paradigm that incorporates resilience, this section aims to
(1) provide the natural resource managers of American Samoa with some tractable priority
management strategies for coping with the vulnerability of coral reefs to climate change, and (2)
identify where these strategies may be readily integrated into existing and future decision-
making opportunities. This exercise represents the final phase of the logic process introduced in
Figure ES-1.
Given that information on climate change issues in American Samoa is presently limited,
potential strategies must necessarily fall within an "adaptive management approach"
(Gunderson, 2000). Here, management plans are thought of as hypotheses, and actions are
experimental tests. This approach supports immediate action by managers of coral reef
resources, based on what is already known about climate change and possible interacting
stressors, while allowing flexibility for refinement as new information becomes available (West
and Salm, 2003).
In the context of a changing climate, successful adaptive management will require
integration of resilience concepts into existing management activities. Resilience to climate
stresses can be enhanced through two primary acts: (1) reducing or eliminating interacting non-
climate stresses, and (2) protecting sufficient and appropriate habitat, including populations that
already show strong resilience (Hansen et al., 2003). While management activities may already
address some of these issues independent of climate change, building sufficient resilience for
future climate change stress necessitates including an additional margin of safety.
A variety of stakeholders are involved at multiple levels in the management of coral reef
resources in American Samoa. Any successful coral reef management activity in American
Samoa will depend on strong village community involvement. It is vital that the traditional
family and leadership structure be included. To date, the most successful conservation actions
have only come about with the commitment of the local community (e.g., Matu'u village stream
water quality improvements described in Buchan and Matatumua, 2004).
At the center of the stakeholder structure are several local and federal governmental
agencies and local institutions that are directly responsible for the management decision
processes, policy enforcement, and scientific research for American Samoa's coral reef systems.
Together, these agencies and institutions comprise the Governor's Coral Reef Advisory Group
(CRAG), a committee that works under a mandate from the Office of the Governor of American
Samoa to manage coral reefs in American Samoa. The CRAG also serves as a local working
group of the U. S. Coral Reef Task Force (CRAG, 2005). The CRAG membership includes local
government agencies (American Samoa Environmental Protection Agency, Department of
Marine and Wildlife Resources, Department of Commerce), federal agencies (the National Park
37

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of American Samoa, the
Fagatele Bay National Marine
Sanctuary), and other
institutions (e.g., the
American Samoa Community
College) that are concerned
with coastal and coral reef
resources. The Department of
Marine and Wildlife
Resources manages a large
proportion of marine
resources in American Samoa,
either directly or by working
closely with local
communities in such areas as
community-based fisheries
management. The National
Park of American Samoa and Fagatele Bay National Marine Sanctuary independently manage
the resources within their boundaries, but their activities are coordinated through the CRAG.
Furthermore, American Samoa is not alone in addressing these complex resource
management issues. Pacific island nations such as nearby Samoa, the Kingdom of Tonga, Fiji
and the Republic of Palau are beginning to address climate change issues at different levels. The
South Pacific Regional Environment Programme (SPREP) in Samoa has been a strong force in
organizing regional studies and planning. It has made significant progress in investigating the
potential socio-economic and ecological effects of climate change (Campbell and de Wet, 2000;
Jones et al., 2000; 1998; Nunn and Waddell, 1992). Pursuing partnerships with SPREP and
other organizations may help American Samoa stretch resources and promote the sharing of
region-specific information. Additionally, global resources are available, such as the U.S. Coral
Reef Watch Program and associated Coral Reef Early Warning System, which are designed to
provide managers with real-time sea surface temperature information and coral bleaching risk
analyses (see Appendix). However, the management strategies outlined below will be discussed
within the American Samoa specific context and the CRAG's existing management concerns and
activities.
Priority management actions that derive from the integration of the vulnerability analysis,
resilience concepts, and stakeholder capacities/concerns, fall into three general categories
according to the time frames over which they might be implemented: immediate, near-term and
long-term. Management strategies that may be implemented immediately are those that (1) are
supported by existing research or by monitoring data that show a clear existing need and (2) may
Village communities are key stakeholder groups for all
management actions in American Samoa. (Photo courtesy of
the National Park Sendee [NPS].)
38

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be adapted readily into current management activities. Previous identification of "key issues" by
resource managers and support in the form of mandates from existing government regulations or
laws further emphasize the immediate relevance of these strategies. This is where the first aspect
of resilience planning (elimination of non-climate stresses) is addressed. Non-climate stresses
are those "traditional" stresses (see Section 3) that are already recognized as threats to reef
health. Resource managers often have the ability to address these immediately at local scales
and can begin to include the needed margin of safety to accommodate the potentially-increasing
stress of climate change.
Near-term strategies are those that center on hypothesis-driven research and monitoring
to fill information gaps, especially where the strategies easily overlap with current management
activities. Baseline monitoring and hypothesis-driven monitoring have often been advocated by
resource managers but have yet to be fully acted upon due to lack of information on optimum
design and/or limited financial and human capacity. These are considered near-term activities
because there is a crucial need to address basic information gaps by finalizing and implementing
hypothesis-driven monitoring and research programs in the next several years. Such near-term
activities allow assessment of the effectiveness of "immediate" actions taken today and provide
data to support the adaptive management process. They also provide needed information for
future long-term management steps.
Long-term management strategies involve large-scale management concepts and provide
the framework for designating the adequate and appropriate habitat needed to sustain resilience.
They provide a clear direction and goal for shorter-term actions and are continually adapted from
interim findings. They also require a more holistic vision of the large-scale coral reef system, its
many stresses, and how the stresses will change over time. These management strategies will be
refined as new information becomes available and can provide guidance for developing the
information gathering process. The following sections expand on some of these potential
priority actions across the three time frames.
5.1. IMMEDIATE TIME FRAME: IMPLEMENT WATER QUALITY
IMPROVEMENTS
The vulnerability assessment indicates that (1) water pollution is likely to be a chronic
stressor to coral reefs in American Samoa, (2) human population pressure-which is projected to
increase dramatically in coming decades- will likely contribute to further deterioration in water
quality, and (3) such multiple stressors will likely render American Samoa's coral reefs more
vulnerable to climate change by reducing reef resilience. The CRAG (2004) has already
acknowledged the severity of these problems, and the ASEPA has begun to better assess and
address water pollution issues. Thus, the first and most immediately beneficial management
strategy would be to expand activities that improve water quality.
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Land-based, non-point sources of water pollution are currently listed as key threats to
coral reefs by the CRAG. They are the primary cause of water quality problems in streams and
along the shoreline, according to ASEPA. Thus, it would be straightforward to expand existing
management activities. Improvements in highly-impacted areas would immediately benefit coral
communities and increase reef resilience to climate change (Hansen, 2003; Hughes et al., 2003;
Hoegh-Guldberg, 1999). While improving water quality is a complex issue, it could be
successfully addressed through the expansion of regulation enforcement, community education
and involvement, and best management practices.
The CRAG, which has been working on comprehensive strategies for managing
American Samoa's unique coral reef resources, has highlighted four key threats to coral reefs in
its Three-Year Local Action Strategy for 2003-2007 (LAS) (CRAG, 2004). These include water
pollution, population pressure, climate change, and overfishing. At least three of these four key
threats (climate change, water pollution, and population pressure) are highly inter-related
according to the scientific assessment presented in this report and could be addressed
simultaneously through support of certain water quality projects that are already underway. For
example, the LAS advocates monitoring of coral health parameters for impacts of water pollution
in support of the American Samoa Coastal Non-point Pollution Control Program (ASCNPCP).
Additionally, and more importantly, the LAS proposes that the CRAG develop, coordinate, and
implement education and outreach programs that can help the growing human population
understand non-point source pollution, the effects of pollution on coral and human health, and
how everyone can help reduce it. These are all justified priority actions that should begin as
soon as possible.
The ASCNPCP is an already-existing management framework through which near-shore
water pollution can be improved. The comprehensive ASCNPCP includes strategies to monitor
water quality for ecosystem and human needs, organize and coordinate efforts to reduce land-
based pollution, and also evaluate the effectiveness of management actions. ASEPA established
this program to address water quality problems that appeared in assessments mandated by
Section 305b of the Clean Water Act and embraces cooperation with the CRAG and other local
agencies involved in coastal management. Established programs include providing waste
automobile oil collection facilities, the inspection of home sewage containment and treatment
facilities, the inspection of animal holding facilities (piggeries), and the permitting and
inspection of construction and earth moving operations for erosion control. The findings of this
report clearly support the expansion of such existing programs and establishment of additional
programs that would improve near-shore water quality and evaluate the effectiveness of projects
that aim to reduce water quality stress to corals.
With sufficient village community motivation and involvement, mitigation efforts
through the ASCNPCP can be very effective in improving water quality. For example, small-
scale pig farms in the Matu'u village watershed contaminated the stream with a high level of
40

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bacteria and nutrients and were a source of
leptospirosis exposure to the public. Through
ASCNPCP projects, which included regular stream
water monitoring, community education/outreach,
and enforcement of environmental and public
health regulations, the average bacteria load in the
stream was reduced by over 90%. Leptospirosis
risk was also reduced. Annual N and P loads to the
near-shore environment were reduced by 58% and
43%, respectively (Buchan and Matatumua, 2004).
This example illustrates the importance of
community outreach and education in managing
water pollution in American Samoa, which will be
vital as the human population grows. The issues of
climate change can be incorporated into these
outreach programs. Human, health concerns add
further weight to mandates for water quality
improvements.
Additional resilience building can be incorporated into the ASCNPCP and other ASEPA
decision-making processes beyond the immediate need for improving near-shore water quality.
The ASEPA establishes and enforces water quality criteria for water parameters and
contaminants and is establishing specific biocriteria for local aquatic ecosystems, including coral
reefs (American Samoa Administrative Code, 2005). Anticipatory safety buffers for interacting
climate change stressors should be considered by managers and decision-makers when water
quality criteria are modified. Bio-criteria focus on the biological response of organisms to
environmental stressors. Established bio-criteria parameters should distinguish between climate
change and water quality stressors where possible and also be sensitive to potential interactions
between climate change and water quality stressors.
In summary, this report further underscores the importance of this already-recognized
issue by showing that poor water quality can increase the vulnerability of reefs when
compounded with climate change stressors. This supports taking the following actions in the
immediate time frame:
•	Implement improvements in water quality through the expansion and enhancement of the
ASCNPCP.
•	Expand village community outreach and education as part of the ASCNPCP process and
emphasize the human health benefits of improving water quality.
Water quality testing by researchers in
American Samoa. (Photo by Eric
Mielbrecht.)
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Climate change is not the only reason to act on these issues as water pollution can also be
an important human health threat if surface waters and food become sources of pathogens or
contaminants. Thus, a focus on water quality may yield concomitant advantages in the form of
increased protection of human health, improvements in the condition of coral reef ecosystems,
and greater reef resilience in the face of future climate variability and change.
5.2. NEAR-TERM TIME FRAME: DEVELOP AND IMPLEMENT HYPOTHESIS
DRIVEN MONITORING AND RESEARCH
While a variety of interesting and useful studies have been conducted on American
Samoa's coral reefs in the past, there is insufficient information to systematically and
simultaneously compare trends in coral condition, bleaching incidence and severity, water
quality, and other stressors at individual sites. An
expansion of research and monitoring programs
would help fill vital information gaps and continue
to test hypotheses on climate change and interacting
stressors in American Samoa. These near-term
monitoring and research actions would provide
critical information for both on-going "immediate"
actions and long-term strategies. Furthermore, as
an important part of the adaptive management
paradigm, specific monitoring would be required to
determine whether on-going management actions
are successful (e.g., water pollution is being
measurably reduced) and effective (e.g., coral
condition and/or reef resilience improve as a result).
The capacity of small island agencies to
undertake complex research and monitoring is often
limited. The demands of the additional monitoring
and research that is needed to address these climate
change related questions are large but worthwhile as
climate change is quickly moving to the top of the
list of conservation threats (Hannah et al., 2005). In order to help accommodate limited local
capacity, research and monitoring recommendations have been divided into two categories: (1)
questions that can be more easily integrated into existing or proposed local management
activities (Table 5-la) and (2) questions that maybe more appropriate for the added capacity of
visiting researchers or external agencies, with local or external funding (Table 5-lb).
This list of suggested basic research questions is presented to help direct hypothesis-
driven research and monitoring in order to address the crucial information gaps revealed in the
Researchers monitor coral reef
condition in American Samoa. (Photo
by Eric Mielbrecht.)
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vulnerability assessment. These questions focus on identifying the relationships among climate
change stressors, other potentially-interacting local stressors, and determinants of coral reef
resilience. This list is in no way exhaustive, nor are these questions developed fully; this is
because each question requires background research (i.e., re-analysis of existing data) and full
development of experimental hypotheses that build on existing information paralleled by
appropriate experimental design. This level of specificity is beyond the scope of this report;
however, there are tools available to help in designing research projects for gathering climate
change-specific information. For example, A Global Protocol for Assessment and Monitoring of
Coral Bleaching (Oliver et al., 2004) provides several different methods for conducting a coral
bleaching survey, depending on what questions need to be answered. See the Appendix for
additional support materials.
Optimally, this information would be organized into an easily-interpreted format in order
to provide vital baseline and event-specific information. This could help resource managers
prepare for, respond to, and assess ecosystem changes that result from large-scale bleaching
events (Marshall and Schuttenberg, 2006). Organizing data in a Geographic Information System
(GlS)-based electronic database would be ideal. With this basic information, managers could
assess the potential impacts to coral communities, vulnerabilities to combined stressors, and
efficacy of actions to address pollution, location by location. The information could also play an
important role in marine protected area (MPA) planning processes. In the longer term, these
efforts could be supplemented with additional water quality, coral disease, over-fishing, and
MPA planning information along with investigations of other important climate factors such as
local weather variability, ocean carbonate chemistry, sea level rise, and possible changes in UV-
radiation levels.
Several management activities have already been proposed, into which many of the
suggested near-term, hypothesis-driven monitoring and research needs can be integrated. These
suggested integrations are outlined in the third column of Table 5-la and b and are paired with
key projects proposed by the CRAG or by the ASEPA (Buchan and Matatumua, 2004; CRAG,
2004). In addition to monitoring and research, developing public awareness about climate
change and coral bleaching to clarify the need to reduce local anthropogenic stressors is vital.
Both the CRAG and the ASEPA support education and outreach activities. This report
emphasizes the importance of these activities as priority actions, along with the priority research
and monitoring questions that have been outlined.
An example of an opportunity to integrate suggested research questions into already-
proposed management actions exists in the activities supported in the draft American Samoa
Coral Reef Monitoring Program plan (Whaylen and Fenner, 2005). This CRAG-instigated
monitoring plan establishes the annual collection of basic-but important-coral reef monitoring
parameters at several sites around Tutuila Island. Quantification of coral bleaching is included in
the basic monitoring. With a small investment in capacity, data collection could also address
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Table 5-la. Research questions and activities that could be integrated into local management activities
RESEARCH TOPIC AREAS
Climate change stressors
Non-climate interacting stressors
Sustaining resilience
Research
questions or
activities
£
Existing
management
activities into
which research
could be
integrated
Under what conditions does
bleaching occur in American
Samoa?
What is the extent of bleaching
during large-scale events?
What is the extent of recovery and
mortality following a large-scale
bleaching event?
Have extreme rain events become
more intense?
Has precipitation increased on
average?
£
Planned projects in the CRAG
2004-2007 LAS focal area: Climate
change
American Samoa Coral Reef
Monitoring Program
Planned projects in the CRAG
2004-2007 LAS focal area: Land-
based sources of pollution
Coastal Non-point Pollution
Control Program
Are coral communities impacted by
areas of poor water quality?
Is pollution associated with rain
events or other periodic events? If
so, will pollution worsen with
increasing severity of rain events?
How can near-shore monitoring be
expanded to better detect poor water
quality?
Does existing management of
sources of water pollution
adequately protect coral
communities, considering the added
stressors of climate change?

Planned projects in the CRAG 2004-
2007 LAS focal area: Land-based
sources of pollution
Coastal Non-point Pollution Control
Program
American Samoa Coral Reef
Monitoring Program
American Samoa's Marine
Protected Areas Strategy
Are there reef areas that regularly
show less bleaching during large-
scale bleaching events?
Are there reef areas with
characteristics that have been
hypothesized to enhance resilience to
bleaching (see table 5.2 for a list of
factors)? What are the correlations
between bleaching/recovery and
these characteristics?

American Samoa's Marine Protected
Areas Strategy
American Samoa Coral Reef
Monitoring Program
Planned projects in the CRAG 2004-
2007 LAS focal area: Climate
change

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Table 5-lb. Research activities appropriate for external agencies or researchers

RESEARCH TOPIC AREAS

Climate change stressors
Non-climate interacting stressors
Research
questions or
activities
£
Management
projects
benefited
•	Are there areas where local stressors exacerbate
bleaching?
•	Is there variability in bleaching? By species or area?
•	Have cyclones increased in intensity, locally? Is there
evidence that this trend is continuing?
•	Have extreme rain events become more intense?
•	Is local ocean carbonate chemistry changing? If so, is
this change altering coral calcification rates and skeleton
integrity?
•	What are the past and future trends in sea-level rise?
•	What is the current UV stress to corals based on water
attenuation of solar radiation? Does this fluctuate in the
short or long term?
&
•	Planned projects in the CRAG 2004-2007 LAS focal
area: Climate change
•	Planned projects in the CRAG 2004-2007 LAS focal
area: Land-based sources of pollution
•	American Samoa Coral Reef Monitoring Program
•	American Samoa's Marine Protected Areas Strategy
•	Coastal Non-point Pollution Control Program
•	For the establishment of appropriate biocriteria: how
are climate change stressors likely to interact with local
water quality stressors?
•	Is the prevalence of coral diseases increasing? Is it
increasing with average sea surface temperature?
•	Is there a correlation between coral disease and
bleaching events?
£
•	Coastal Non-point Pollution Control Program
•	Planned projects in the CRAG 2004-2007 LAS focal
area: Land-based sources of pollution
•	American Samoa Coral Reef Monitoring Program
•	Planned projects in the CRAG 2004-2007 LAS focal
area: Climate change

-------
more specific climate change questions. A key addition to this project would be an event-
triggered monitoring response to track bleaching extent, mortality, and recovery, as well as local
variability.
Near-term monitoring activities are needed to fill important data gaps and to inform both
immediate and long-term management decisions. This supports taking the following actions in
the near-term:
•	Integrate suggested climate change research questions into existing or proposed local
management actions and
•	Develop the capacity to accomplish increasingly comprehensive monitoring and research
through partnerships with visiting researchers with local and outside funding.
Hypothesis-driven monitoring and research is crucial to successful adaptive management
in response to climate change. A far-reaching benefit of near-term monitoring and research is
additional insight into the usefulness of building long-term resilience. This can then be applied
to the MPA planning processes.
5.3. LONG-TERM TIME FRAME: DESIGN AND IMPLEMENT RESILIENT MPA
NETWORKS
While the first requirement for maximizing resilience to climate change (reducing and
eliminating non-climate stresses) is addressed by immediate actions as described in Section 5.1,
the second requirement (protecting adequate and appropriate habitat) is part of long-term
planning. Effective management actions over the long term will likely include strategies for
monitoring the resilience capacity of coral reef communities and, more importantly, protecting
adequate and appropriate reefs in MP As. The goal of sustaining the resilience of large-scale reef
ecosystems is a complex undertaking. However, the adaptive management approach can support
gradual progress by integrating resilience theories into management strategies at a basic level
and expanding over the long-term as capacity evolves and more information becomes available.
This scientific approach, coupled with enthusiastic village community involvement, could lead to
effective and more resilient MPAs.
Any MPA can provide some resilience by creating a refuge from local stressors, a
managed seascape, and a possible component of a network. However, more can be done to
incorporate resilience theory into the criteria used for the selection of new MPAs and in the
design of MPA networks.
The concept of protecting appropriate reefs involves MPA designation of sites where
overall reef resilience is greatest and, in particular, where factors exist that are thought to
specifically confer resilience to climate change stressors. While some of these factors overlap
with what is already considered in selecting an MPA, other factors are only considered when
climate change is added to the planning matrix. The general characteristics to consider include
46

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ecosystem condition (e.g., coral condition, water quality, fish abundance), local environment
(e.g., reef topography, current speed, light levels), biological diversity (i.e., genetic diversity
within species and species diversity within ecosystem functions), and connectivity (i.e., stable
"seed" sources for repopulation) (Marshall and Schuttenberg, 2006; West et al., 2005). More
specific factors can be indirectly recognized by studying a reef's response to past incidents of
elevated sea surface temperatures or by examining an area for the presence of characteristics that
confer resilience (West et al., 2005). Factors that may confer resilience to climate change stress
include physical features such as sources of cool water provided by upwelling or strong currents,
natural shading by nearby cliffs and screening by light-absorbing matter in the water column; as
well as biological features such as innately-resistant and tolerant coral communities (Marshall
and Schuttenberg, 2006; West and Salm, 2003). General characteristics, such as biological
diversity and connectivity, are also emerging as key factors in the management of coral reefs in
the face of climate change (Ayre and Hughes, 2004).
Table 5-2 proposes some specific characteristics that could be investigated as part of the
MPA planning process. An easily-interpreted presentation of these location-specific
characteristics, once they are determined, could include their incorporation into a GIS-based
"resilience map" for American Samoa.
A variety of tools are available to help managers understand and sustain resilience (see
Appendix for a full listing). These offer guidance on testing for resilience, managing resilience,
and augmenting resilience (Marshall and Schuttenberg, 2006; West et al., 2005; West, 2001).
Early information tools were geared towards coral reef MPA managers and identified the
potential characteristics that would confer resilience (Salm and Coles, 2001; Westmacott et al.,
2000). Subsequently, there have been additional products created to advise reef managers who
work both within and beyond MP As in response to coral bleaching (Marshall and Schuttenberg,
2006; West et al., 2005; The Nature Conservancy and Partners, 2003). Other tools cover the
landscape/seascape beyond the reef and beyond bleaching (Hansen et al., 2003).
Selection and protection of the necessary habitat, even with a climate filter, cannot be a
static or self-contained process if resilience is to be sustained. Continuous management must be
employed in the MPA. This may require flexible zoning schemes or integrated coastal
management actions for specific episodic management. Access to reefs (e.g., by village fishers)
may need to be limited or other local stressors (e.g., sediment runoff from coastal development
projects) reduced during a bleaching event. In American Samoa this would involve the scientific
skills of local resource managers and a continual cooperation from nearby village communities
over the long term. Building and sustaining resilience to climate change in a MPA will
necessitate a holistic coastal zone management approach-from the top of the watershed to the
open ocean-and involvement from all stakeholders, especially local village communities.
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Table 5-2. Factors that may confer resilience to coral bleaching
Resilience factors
General factors
-	effective management regime
Physical factors that reduce temperature stress
-	exchange
-	upwelling
-	areas adjacent to deep water
-	wind-driven mixing
Physical factors that enhance water movement and flush toxins
-	fast currents
-	complex topography
Physical factors that decrease light stress
-	shade
-	incidental angle of sunlight
-	slope
-	turbidity
-	absorption /colored dissolved organic matter (CDOM)
-	cloud cover
Factors that correlate with bleaching tolerance
-	temperature variability
-	emergence at low tide
Indirect indicators of bleaching tolerance
-	broad size and species distributions
-	high genetic diversity
-	areas of greatest remaining coral cover
-	history of corals surviving bleaching events
Factors that enhance repopulation
-	availability and abundance of local larvae
-	connectivity to local and distant larvae sources
-	recruitment success
-	low abundance of disease, bioeroders, corallivores
-	suitable substrate
Source: Adapted from West and Salm (2003).
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The support of communities toward establishing and maintaining MP As is growing in
American Samoa. Additionally, the long-term management approaches described in this section
are highly compatible with the stated commitments of the American Samoa government and the
CRAG with regard to MPAs. In 2000, the late Governor Sunia pledged that the American
Samoa Government would establish no-take MPAs in at least 20% of the surrounding reefs by
2010. In response, the CRAG has drafted American Samoa's Marine Protected Area Strategy
(Oram, 2005). While this plan centers on maintaining ecosystem sendees and meeting village
community needs, it also lists "resilience-building" as one of its core goals. However, this plan
could benefit from the incorporation of specific information on resilience to climate change
stressors in particular, especially given the potential for the increasing vulnerability of American
Samoa's coral reefs to future climate change. Comprehensive MPA planning will require the
development of specific monitoring for the many desirable physical and biological
characteristics that interest stakeholders. This provides an excellent opportunity to test
hypotheses regarding factors that are
believed to confer resilience to climate
change. (See Table 5-2.)
In summary, MPAs can be
powerful conservation tools for
protecting coral resources. A key factor
for establishing resilience is protecting
adequate and appropriate habitat. MPAs
can go beyond traditional concerns to
also incorporate resilience to climate
change. This supports incorporating the
following elements into long-term
planning:
•	Integrate climate change resilience actions in the American Samoa MPA planning
process, including incorporation of factors hypothesized to confer resilience to climate
change into American Samoa's Marine Protected Area Strategy and associated
monitoring.
•	Continue to develop community involvement and a holistic coastal-zone management
approach.
A healthy reef in American Samoa. (Photo by Eric
Mielbrecht.)
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6. CONCLUSIONS
The major goal of this report is to provide some priority adaptation options to be
integrated into existing and future management processes in order to enhance the resilience of
American Samoa's coral reefs to climate change. As is the case for most marine ecosystems
globally, there are limited existing data for and publications on coral reefs that lend themselves
directly to application in management actions. For example, while there are data on water
quality, there is very little research on the causal relationship of reef condition to measured
localized poor water quality in American Samoa. Another limitation in information has been
that while good historical monitoring of coral cover exists, there is a lack of data on community
composition, function, genetic diversity, and connectivity to local and distant larval sources.
Finally, there are a number of on-going research projects in American Samoa that should soon
provide additional useful information and fill some of these gaps. Throughout the report, when
necessary, conclusions are qualified due to these kinds of data limitations.
In some cases, data may actually exist but have not yet been analyzed in terms of the
management questions posed in this report. This lack of data or analysis becomes even more
pronounced for the complex questions stemming from the interactions of climate change and
local stressors. This report highlights recommended, basic research questions that would help
address this lack of information. While suggestions and approaches are presented, detailed
planning for implementation and adoption must be developed at the local level, taking into
account the specifics of local issues and concerns. However, this report makes a first effort at
integrating recommended management actions and research questions into existing management
activities to facilitate progress.
While the report does indicate a need for continued research in American Samoa on
climate change issues, this does not mean that it is impractical to develop an assessment of
climate change and interacting stressors for coral reef management. Also, this report emphasizes
that priority actions on these management approaches can be taken now. It is important to note
that efforts to improve or maintain coral resilience in response to climate change require action
sooner rather than later. Implementation, based on current knowledge using the adaptive
management paradigm, can be undertaken, evaluated, and later modified based on new
information.
Within an adaptive management approach and with the best available information, this
analysis of climate change and interacting stressors in American Samoa supports the
recommendation of the following priority management actions:
1.	immediate time frame - implement water quality improvements
2.	near-term time frame - develop and implement hypothesis-driven monitoring and
research
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3. long-term time frame - design and implement resilient MP A networks, with strong
village community outreach and involvement.
This report provides a systematic approach by which these adaptive management
strategies can be further developed. Ideally, future actions would encompass the priority
management actions developed herein but be progressively customized for American Samoa
based on existing regulatory and political conditions, community involvement, and information
from additional research and analysis.
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APPENDIX
Resources specific to coral reefs
•	A Reef Manager's Guide to Coral Bleaching (Marshall and Schuttenberg, 2006)
•	Coral Bleaching and Marine Protected Areas (Salm and Coles, 2001)
•	R2 Reef Resilience: Building Resilience into Coral Reef Conservation, Additional Tools
for MPA Managers (The Nature Conservancy and Partners, 2003)
•	Resistance and Resilience to Coral Bleaching: Implications for Coral Reef Conservation
and Management (West and Salm, 2003)
•	Great Barrier Reef Coral Bleaching Response Plan Summer 2006-2007 (Great Barrier
Reef Marine Park Authority, 2006)
•	Coral Bleaching: Causes, Consequences and Response (Schuttenberg, 2001)
•	Management of Bleached and Severely Damaged Coral Reefs (Westmacott et al., 2000)
•	How Climate Change Could Affect MP As: What Practitioners Need to Know (MPA
News, 2001)
•	The Implications of Climate Change for Australia's Great Barrier Reef (WWF, 2004)
Resources spanning multiple ecosystems
•	Buying Time: A User's Manual for Building Resistance and Resilience to Climate
Change in Natural Systems (Hansen et al., 2003)
Field methodologies specific to coral monitoring
•	A Global Protocol for Assessment and Monitoring of Coral Bleaching, 1st Edition
(Oliver et al., 2004)
•	Development of benthic sampling methods for the Coral Reef Assessment and
Monitoring Program (CRAMP) (Brown et al., in press)
•	C-NAV Coral Navigator, CD ROM with GCRMN and ReefCheck methods (Available at
the AIMS Bookshop Science Communications, Townsville, Queensland 4810, Australia)
•	Additionally, various Web sites detail different monitoring and assessment methods for
coral reefs:
-	Hawaii Coral Reef Network -
http://www.coralreefnetwork.com/research/methods.htm
-	Australian Institute of Marine Science Monitoring -
http://www.aims.gov.au/pages/research/reef-monitoring/methods.html
-	Australian Government website on monitoring for coral bleaching -
http://www.nrm.gov.au/monitoring/indicators/estuarine/coral-bleaching.html
-	Coral Reef Assessment and Monitoring Program (CRAMP) website -
http://cramp.wcc.hawaii.edu/
-	Atlantic and Gulf Rapid Reef Assessment (AGRRA) - http://www.agrra.org/
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- Reef Check manual - http://www.reefcheck.org/
-	Global Coral Reef Monitoring Network (GCRMN) -
http ://www. coral.noaa. gov/gcrmn/
-	Real-time sea surface temperature monitoring resources
-	US Coral Reef Watch Program and the Coral Reef Early Warning System
(CREWS) - http://coralreefwatch.noaa.gov/
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