a March 1&93 _ DRAFT The ehflium fidicinium). an in - ¦ A. Peterson, Technical Director EMAP-Wetlands 200 SW 35th Street Corvallls, OR 97333 ------- EPA ERL-Corvallis Library ^ " iiiiiii linn in mi 00006822 ,< March 1993 Environmental Monitoring and Assessment Program-Wetlands: Estuarine Emergent Conceptual Model by Barry H. Rosen, Louisa Squires and Richard P. Novitzki ManTech Environmental Technology, Inc. USEPA Environmental Research Laboratory 200 SW 35th Street Corvallis, OR 97333 Project Office: Spencer Peterson USEPA Environmental Research Laboratory 200 SW 35th Street Corvallis, OR 97333 U.S. Environmental Protection Agency Environmental Research Laboratory 200 SW 35th Street DRAFT ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands 1.0 EMAP-OVERVIEW 3 1.1 EMAP Rationale 3 1.2 EMAP Objectives 3 1.3 EMAP Approach 5 1.3.1 EMAP Resource and Cross-cutting Groups 5 1.3.2 Probability-Based Sampling Design .5 1.3.3 Indicator and Assessment Concepts 6 Overview 7 Strategy for Selecting and Testing Indicators 7 2.0 CONCEPTUAL ASSESSMENT MODEL 11 2.1 Estuarine Emergent Wetland Ecological Profile 12 2.2.1 Classification 12 2.2.2 Geographical distribution and extent 12 2.2.3 Physical and Chemical Environment 13 Tidal Flooding 13 Salinity 14 Sedimentation 14 2.2.4 Biological Characteristics 15 Vegetation 15 Macroinvertebrates 17 Fish 17 Mammals 17 Birds 18 Reptiles and Amphibians 19 2.2 Environmental Values 19 2.3 Wetland Stressors and Impacts 21 2.3.1 Dredging and excavating 21 2.3.2 Filling 27 2.3.3 Oil and Mineral Extraction 28 2^3.4 Impoundments 29 2.4 Assessment questions 29 2.5 Estuarine Emergent Indicators 31 2.5.1 Measures common to all values 31 Wetland distribution in the landscape 31 Wetland extent.. 32 Vegetation to open water ratio 32 Maxirfium depth/tidal amplitude... 33 2.5.2 Indicators of Productivity 33 Wildlife Production (non-food) 33 Vertebrate Production 33 Shellfish Production 33 Plant Diversity and Abundance 34 Animal Diversity and Abundance 35 2.5.4 Indicators Hydrologic Function 36 Water Regime 37 Shoreline Erosion 38 2.5.5 Indicators of Water Quality Improvement 38 Sediment Accumulation 38 Nutrient Processing 40 3.0 RESEARCH NEEDS 42 4.0 STATUS OF ESTUARINE EMERGENTS INDICATOR TESTING 43 5.0 LITERATURE CITED 47 2 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands CONCEPTUAL ASSESSMENT MODEL OF ESTUARINE EMERGENT WETLAND CONDITION 1.0 EMAP-OVERVIEW This document describes the Environmental Monitoring and Assessment Program's (EMAP) effort to construct approach conceptual assessment models for estuarine emergent, palustrine emergent and forested wetlands. Section I describes EMAP overall and the EMAP-Wetlands rationale and objectives. This section also includes the concept of indicators and risk assessment. Section II describes the EMAP-Wetlands classes and regional components, including ecological profiles, environmental values and stressors to the resource. Section III includes summaries of current models and begins the process of determining current research needs for the development of this program. 1.1 EMAP Rationale The U.S. Environmental Protection Agency's (EPA) Science Advisory Board (SAB) developed risk-based priorities for the EPA (EPA 1990) in its report "Reducing Risk: Setting Priorities and Strategies for Environmental Protection". A recommendation of this report was "...the EPA and the nation must locate and target the most promising opportunities for reducing the most serious risks to human health and welfare and to the environment" (Reilly 1991). Another recommendation was to "improve data and analytical methodologies that support assessment, comparison and reduction of different environmental risks" (EPA 1990). The EMAP is specifically designed to address this need for improved data and assessment capabilities. 1.2 EMAP Objectives EMAP was initiated in 1988 to provide information on the current status and long-term trends in the condition of the Nation's ecological resources. EMAP objectives are: 1. Estimate the current status, trends, and changes in selected indicators of the condition of the Nation's ecological resources on a regional basis with known confidence. 3 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands 2. Estimate the geographic coverage and extent of the Nation's ecological resources with known confidence. 3. Seek associations between selected indicators of natural and anthropogenic stresses and indicators of the condition of ecological resources. 4. Provide annual statistical summaries and periodic assessments of the Nation's ecological resources. To meet the first EMAP objective, EMAP-Wetlands will describe wetland condition in terms of values most important to the wetland resource. This requires identifying and evaluating measurements that can be made for a population of wetlands and that can be used to quantify indicators of the values we are trying to assess. This involves: 1) identifying environmental values attributed to wetland functions 2) developing and testing protocols for measurements and evaluating their usefulness in quantifying indicators of the values, and 3) determining how values can be used to assess the condition of the wetland resource. We will apply these steps to three major wetland classes (described later in section II), which collectively constitute approximately 80% of the resource in the nation. Because the distribution of wetland classes varies geographically, we will also use ecological (e.g., Omernik 1987) or Standard Federal regions to report results. The goal is to implement the program nationally in all regions for these three classes by FY 2003. Therefore, at this point in time, the major objective for EMAP-Wetlands is: To produce annual cumulative distribution functions (CDF's) of indicators of all major wetland values for three nationally dominant wetland classes In all regions of the U.S. The second EMAP objective, regarding the geographic coverage and extent of wetlands, is the responsibility of the US Fish and Wildlife Service (USFWS), National Wetlands Inventory (NWI), according to a June 1992 interagency Memorandum of Understanding. As part of this agreement, NWI is providing EMAP-Wetlands with extent data, associated data bases, aerial photography, and maps. EMAP-Wetlands is currently developing the list of information required for addressing the third EMAP objective, 'seek the association between anthropogenic 4 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands stresses and the changes in indicators of condition'. We will develop a plan that addresses this objective once we know#the population variability of the resource (see Regional Demonstration below). We will assess the utility of existing data, such as the EPA's Toxic Release Inventory, for diagnosing anthropogenic stresses on wetland resources. Information about adjacent resources will be provided by the other EMAP resource groups and EMAP-Landscape Characterization will provide land use/landscape data that correlate with regional wetland condition. The fourth EMAP objective, 'providing annual statistical summaries and periodic assessments', will be satisfied by the CDF's described above. Interpretive reports that describe the condition of the wetland resource will be produced after at least four years of implementation in a region. EMAP has not yet defined the content of these interpretive reports; one approach is to interpret condition and extent in the context of regional anthropogenic stressors (e.g., pesticides) and natural stressors (e.g., climatic variation). 1.3 EMAP Approach 1.3.1 EMAP Resource and Cross-cutting Groups To accomplish EMAP objectives, seven broad resource categories have been defined: Agroecosystems, Arid Lands, Estuaries, Forests, Great Lakes, Surface Waters, and Wetlands. EMAP resource groups use geopolitical boundaries (e.g., Standard Federal Regions) to identify, prioritize, and report the status and trends of environmental resources throughout the Nation. To support issues that cut across resource groups and to ensure their consistency and successful integration, seven coordination and integration groups have been established: statistics-and design, indicators, landscape characterization, quality assurance (QA)/quality control (QC), logistics, information management, and integration and assessment. EMAP-Wetlands receives guidance from and contributes information to these cross-cutting groups. 1.3.2 Probability-Based Sampling Design An unbiased probability-based sampling strategy has been designed to quantify the status and trends in wetland condition with known confidence. A probability sample from a resource population is a means to assure that the data 5 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands collected are free from any selection bias. This is an essential requirement for a program, such as EMAP, that aims to describe the condition of our national ecological resources. The EMAP sample design (described in Overton et al. 1990) achieves comprehensive coverage of wetlands through the use of a grid frame. EMAP uses a uniform triangular grid of points that provides uniform geographic coverage over the entire conterminous United States for selecting sample sites. This grid identifies approximately 12,600 locations for which the major ecological resources will be catalogued and classified. Using existing maps, aerial photography, and satellite imagery, the numbers, classes, and sizes wetlands will be determined for the area included within a 40 km2 hexagon centered on each grid point. The optimal procedures for selecting sampling units are under investigation. However, the basic approach will be to (1) randomly select a subset of the 40-hexes in which wetland classes of interest occur and then (2) randomly select an individual resource unit from each of the selected 40-hexes. The sampling design is flexible and can be adapted for selecting resource units for linear (e.g., Gulf Coast salt marshes) and rare resources by intensifying the grid density. The number of resource units sampled for each geographic region will depend on (1) the precision goals for regional estimates of the resource condition and (2) the expected variability in the measured indicators of resource condition. In most instances, 50-100 sites of the resource in a geographic region annually should allow traditional population parameters (e.g., means, medians, measures of variation) to be calculated. The sites will be sampled on a four-year cycle, with one-fourth of the sites in a region visited each year. By the fifth year, all sites will have been sampled and a second cycle will begin, using the same subsets of resource units. Ideally, each site will be sampled once during a single day every four years. In addition, field measurements will generally be made during a specific portion of the year, termed the index period. Ideally, the index period should be a time when most indicators are relatively stable. Sampling during the index period minimizes the within-resource indicator variability, resulting in more precise regional estimates of wetland status and improved ability to detect trends through time. 1.3.3 Indicator and Assessment Concepts 6 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands Overview EMAP will assess wetland condition, where condition is defined as the state of selected environmental values (e.g., productivity, biological integrity). Assessment questions, which address "how well are the wetlands, in a given region and class, supporting a specific value?", are used to guide the selection of values and policy relevant issues to be addressed by EMAP data. In most cases, values (e.g., wetland productivity) are difficult, if not impossible, to determine directly. Therefore, quantifiable indicators of these values (e.g., waterfowl productivity) that can be calculated from actual field measurements (e.g., number of ducks/area as a measure of waterfowl productivity) are used as surrogates to represent wetland condition (Figure 1). At this time, we are assuming that each value will be assessed independently to determine condition of the resource. There may be interrelationships among values that will require future development of condition models that relate multiple values to condition. Indicators are quantifiable expressions of an environmental value (Olsen 1992) that allow estimation of the condition of ecological resources, magnitude of stress, exposure of a biological component to stress, or the amount of change in a condition (Figure 1). For example, waterfowl production may be the single indicator that is the most meaningful expression of the value "wetland productivity" in the Midwest. Several indicators might be necessary to express a value through the use of a value model. In coastal areas, two indicators, shellfish and plant biomass are needed to express the value "wetland productivity". Single or multiple measurements are used to determine the status, changes and trends in indicators through an indicator model. The relationship between resource condition, values, indicators, and measurements are described in greater detail in the wetlands monitoring strategy in Section II. Strategy for Selecting and Testing Indicators Workshops: To answer the question "How do we describe the condition of wetlands?", workshops involving the scientific community will be conducted for each major wetland class and geopolitical region to develop conceptual models relating wetland condition, wetland values and indicators (Table 1). Preliminary workshops were conducted for 7 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands Resource Condition t Condition Model Wetland Productivity Value Model Indicator(s) Indicator Model Z Number of Ducks/area Measurement(s) Figure 1. Conceptual assessment model illustrating an example the relationships among measurements, indicators, and values associated with resource condition. field studies of estuarine emergent wetlands in Louisiana. In addition to conceptual models, the workshops provide the criteria for defining good and degraded condition for a region and recommend indicator measurement protocols. These criteria and protocols are used as a basis for preparing research plans to evaluate indicators in pilot studies. More extensive workshops will refine conceptual models for estuarine emergent wetlands. Value(s) Waterfowl Production 8 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands Pilot Studies: Pilot studies will be conducted to test the ability of indicators to discriminate between wetlands in good and degraded condition; representative pilot study sites are proposed by local wetland scientists (Table 1). Initially, EMAP- Wetlands will conduct one pilot study for each of the major wetland classes in a selected region. It is anticipated that the development of indicators within this initial pilot study will be sufficient to start at the regional demonstration stage when expanding into new regions. Indicators identified in conceptual models (from the workshops) are reduced to a selected suite of research indicators that are tested on a small geographic-scale, e.g., salt marshes along the Louisiana coast. Pilot studies provide initial estimates of indicator variability components (including index period, field and laboratory measurement and crew variability) and begin to provide data needed to evaluate annual variability. Pilot study data are used to reduce the list of research indicators to those that most effectively discriminate condition, called probationary core indicators. Pilot studies are designed specifically to test and develop indicators of condition and not to assess the condition of the regional population of wetlands. The scientific design, using good and degraded sites, has a long history based on pattern recognition principles (Tau and Gonzales 1974), and is derived on the Bayesian decision rule of optimization. Evaluating indicators in pilot studies provides one means for accepting or rejecting indicators for further evaluation. The good sites identified for pilot studies may be used as candidate wetland reference sites. Reference sites are defined as the least impacted sites for a wetland class in a region, and will provide a statistical characterization (e.g., means, standard deviations) of indicator values (measurements). Regional Demonstration Studies: Regional demonstrations (Table 1) are studies that apply and test probationary core indicators and measurement protocols from pilot studies to the population of wetlands in a region, e.g., the estuarine emergents in the Gulf of Mexico. Regional demonstrations employ the EMAP probability-based sampling approach to select sample sites, thus assuring an appropriate statistical description of the population. Regional demonstration studies provide the first year of data for determining population variability in a region and year to year variability. Data from the demonstration studies will be used to expand the reference site information base and will help to define the reference condition of an entire region. Reference condition, as defined by reference sites, serves as a point of departure when we make 9 ------- Table 1. Strategy for Acheiving National Assessment Mechanism Objectives Indicators Products Workshop Develop a conceptual model linking wetland condition, values and indicators Candidate Criteria for separating extremes of wetland condition in a region Measurement protocols for candidate indicators Pilot study research plan, QA project plan Pilot Study Develop Indicators Select candidate reference sites Research Indicator evaluation report -evaluation of indicator performance -evaluation of index variability: crew, measurement and index period Regional demonstration research plan, QA project plan Regional Demonstration Demonstrate the ability of indicators Probation- to describe condition of one class of ary Core wetlands in a region Determine the logistic issues with with probability-based sampling Sample frame needed for regional implementation Regional reference sites Population variability of indicators Standardized measurement protocols Regional implementation field manual Regional Implementation Assess the condition of each wetland class In a region Core Infrastructure to carry out EMAP in a region Regional reference population Trends in indicator measurements Year-to-year variability Annual statistical summaries Regional assessment protocols Interpretive reports (after 4 years) National Implementation Assess the condition of the Nation's wetlands. Add wetland classes in all regions where they occur as a substantial part of the total wetland resource Add all regions where wetlands occur Core Infrastructure to carry out EMAP in all regions Regional implementation field manuals for all wetland classes and regions Annual statistical summaries National assessment protocols incorporating all regional protocols National assessment (after all wetland classes gave been implemented in all appropriate regions for at least 4 years) D 2 o o 9 O o •o c to a w CO e 3. P o ffl 3 o OQ O D 3 O o. w ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands regional assessments based on probability sampling. It addresses the question, "condition relative to. what?". Information from demonstration studies will also be used to identify issues related to the adequacy of the sample frame needed for regional implementation. Data will also be used to develop indices relating measurements to indicators. Questions related to implementation cost and logistical feasibility will be addressed. Study results are used to select a suite of regional core indicators from the list of probationary core indicators. Protocols used for measuring the core indicators will be compiled into a regional implementation field manual for use during regional implementation. Regional and National Implementation: Regional implementation uses core indicators (Table 1) to monitor the condition of a wetland class in a region, e.g., estuarine emergents in the Gulf of Mexico region, using the EMAR sample frame. Annual statistical summaries and periodic interpretive reports are produced from regional implementation. Over a period of several years, indicator data also are used to establish trends and evaluate the power of the design for detecting trends. Once core indicators are developed for one wetland class in a region, they will be applied in another region where the wetland class occurs, e.g., estuarine emergents along the Atlantic coast. The core indicators will be first applied in a regional demonstration prior to implementing the program in this new region. Once the program has been implemented in a wetland class in all regions where it occurs, EMAP-Wetlands will be able to assess the condition of that class for the Nation by combining regional assessments. The current plan of EMAP-Wetlands is to implement the program for the three priority classes (estuarine emergents, palustrine emergents and palustrine forested) by 2003 in all regions where they occur. National implementation of the program incorporating the remaining wetland classes in all regions will be accomplished in the future. 2.0 CONCEPTUAL ASSESSMENT MODEL This section describes the components of a conceptual model for estuarine emergent wetlands: ecological profile, environmental values, stressors, assessment questions, and indicators. 11 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands 2.1 Estuarine Emergent Wetland Ecological Profile The following review of estuarine emergent wetlands covers the Atlantic, Gulf of Mexico, and Pacific coastal regions. The profile compares the EMAP-Wetlands classification of this wetland resource to the Cowardin classification (1979). The sections that follow include an overview of the extent of and distribution of estuarine emergent wetlands, brief descriptions of the physical and chemical environment, and the biotic attributes. Because of the enormous complexity of these systems and their geographic variation, it was necessary to oversimplify some of the descriptions of ecological processes and interactions. An effort was made, however, to highlight regional similarities and differences in the ecology of this resource class, particularly as they relate to the assessment of estuarine emergent wetland condition. 2.2.1 Classification The EMAP-Wetlands classification of estuarine emergent wetlands is comparable to the system "estuarine", subsystem "intertidal" and class "emergent wetland" of the Cowardin et al. (1979) classification system. These are tidal wetlands adjacent to deepwater tidal habitats (deepwater tidal habitats are monitored by the EMAP-Estuaries, which samples estuarine areas greater than 1 meter water depth) which have salinities ranging from hyperhaline (>40 ppt) to oligohaline (0.5-5 ppt). EMAP-Wetlands will initially develop indicators for the hyperhaline and euhaline wetlands (30 to >40 ppt). Wetlands at these higher salinity levels are referred to as "salt marsh" in this document. The indicator testing program for estuarine emergent wetlands will be expanded to include the mixohaline (0.5-30 ppt), or brackish, component as successful salt marsh indicators are identified. 2.2.2 Geographical distribution and extent In the mid-1980's, there were an estimated 4,074,000 acres of estuarine emergent wetlands nationwide, representing 73% of all coastal wetlands acreage (Dahl et al. 1991). Estuarine emergent wetlands occur extensively along the Atlantic coast and the Gulf of Mexico, and in pockets along the Pacific coast. Comprising 42% of the nation's coastal salt marshes, the Mississippi Delta is the largest continuous wetland system in the United States, having nearly four times more than any other state (Field et al. 1991; Gosselink 1984). On the Atlantic coast; salt marshes are more 12 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands extensive in the South than in the North (Wiegert and Freeman 1990). This is largely a result of development pressure initiated as early as the 19th century in the Northeast. In the southeast, the intertidal salt marshes are extensive and considered to be in relatively good condition (Wiegert and Freeman 1990). Approximately 82% of the Atlantic coast marshes occur in the southeast (between Norfolk south to northern Florida), with 33% of the total area of east coast tidal marshes occurring in Georgia. At approximately 30 N in northern Florida, there is a transition between salt marsh and mangrove marshes. 2.2.3 Physical and Chemical Environment The distinctive physical and chemical environment of estuarine emergent systems have a profound influence on their structure and function. The primary physical and chemical influences that control the biological characteristics of estuarine emergent marshes are tidal flooding, salinity gradient, and sedimentation. Tidal Flooding The most unique and influential physical attribute on the development and function of coastal wetlands is tidal fluctuations. The frequency and duration of salt marsh flooding by tides results from the slope of the land, local land features, such as natural creek bank levees that modify the hydraulic gradient, and the volume of water flow. Water regime changes daily; seasonal, and long-term. Although most tides are periodic and generally predictable, temporal patterns and tidal amplitude also vary geographically. Seasonal effects on tidal cycle are attributed to changes in barometric pressure, seasonal warming and cooling of coastal waters (Gosselink 1984; Smith 1979 as cited in Nixon 1982), and freshwater input (Emery and Uchupi 1972 as cited in Nixon 1982). Bauman (1980) found that the depth and duration of flooding in the Delta marshes of Louisiana peaked in September and October, when the salt marshes are inundated 80% of the time; this is 30% greater than the average over the remainder of the year. Spring tides in the Mississippi Delta are augmented by late spring snowmelt and rain. Similar seasonal patterns are found in coastal wetlands elsewhere (Emery and Uchupi 1972 as cited in Nixon 1982). There is considerable geographic variability in the pattern and amplitude of the short-term tidal cycles. Along the Atlantic coast, tides are relatively low at northern latitudes and increase south to Georgia, where they peak, and then decrease again to 13 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands the latitude where mangroves replace salt marsh in Florida (Wiegert and Freeman 1990). Coastal wetlands in the southeastern United States are subject to semidurnal tidal flooding with a high tide and a low tide (Wiegert and Freeman 1990) that can reach from 1 to 3 m (Nixon 1982). In southern California, wetlands are exposed to two daily high tides and two daily low tides. The daily and seasonal tidal amplitude is different for each of these cycles, but averages about 1.1 m (Zedler 1982). In contrast, the Mississippi Delta wetlands experience diurnal tides that are generally small, averaging about 30 cm at the coast (Gosselink 1984). Meteorological events and upstream runoff may occasionally modify these daily tides substantially. For example, wind generated by frontal systems may increase tidal amplitude by 40-50 cm in delta marshes of Louisiana. Salinity The salinity of estuarine wetlands is dominated by sodium chloride (NaCI; Cowardin et al. 1979). Salinity generally decreases along a gradient from polysaline at the seaward limit to oligohaline at the landward limit (Cowardin et al. 1979). The salinity gradient is influenced by the slope of the land and the source and magnitude of the freshwater relative to the marine water inflow (Gosselink 1984). In addition to the interaction between the sea and the freshwater rivers, many other factors influence the salinity regime of both the tidal water and the interstitial water of the soil (Wiegert and Freeman 1990). While the tidal water salinity generally decreases continuously landward, interstitial soil salinity may actually increase at higher infrequently flooded elevations. Salts concentrate in these soils because evaporation exceeds tidal water exchange and rainfall inputs. Sedimentation The formation and maintenance of tidal marshes is dependent upon the continual input of sediments. The transport and transformation of sediments largely determine their development and geomorphic dynamics. Salt marshes receive the majority of their sediment inputs from rivers. Salt marshes also receive sediments from tidal waters that transfer sediments from nearshore zone and from mud deposits on the continental shelf and deposit them in tidal marshes (Phleger 1971 as cited in Nixon 1982). While fluvial sediments are the primary material responsible for the marshes along the Gulf and Pacific coasts, sediments derived from the continental shelf are particularly important source for many of the coastal marshes along the Northeastern United States that receive little sediment from land (Nixon 1982). Coastal 14 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands submergence, or the rise in sea level relative to the land (Gosselink 1984), is due in part to land subsidence and has been accelerating in the Gulf region in recent times. In the Mississippi delta, the average rate of subsidence is a centimeter per year, twice the rate along the Atlantic coast. The large volumes of sediment delivered by the Mississippi River to the delta has created several major sedimentary basins over a long period of geologic time. The accumulation of heavy sediment loads over several millennia has caused excessive subsidence, which has influenced recent wetland loss. The size class distribution of sediments within the tidal marsh sediments consists largely of clay and silts. In the San Francisco Bay, sediments contain approximately 60% clay and the remaining material is silt (Krone 1962 as cited in Josselyn 1982). Sediments discharged to the Mississippi delta salt marshes consists over 70% clay with some silt and hardly any sand (Gosselink 1984). In Georgia marshes, the soil at the creek bank is approximately 50% clay and 20% sand, while the high marsh is almost entirely sand (Wiegert and Freeman 1990). In contrast, the soils of the northeast marshes contain large amounts of peat. Frey and Basan (1985) attribute these differences to a combination of tidal flushing, more rapid degradation of plant detritus, and slower rate of coastal submergence. 2.2.4 Biological Characteristics The salinity gradient together with the depth and duration of inundation largely determine the types of plant and animal communities that develop in estuarine emergent marshes. Tidal marshes are typically highly productive and support diverse and abundant wildlife and plant species. Animals inhabiting tidal salt marshes must have behaviors that allow them to adjust or avoid wide-ranging levels of salinity, temperature, humidity, desiccation and inundation. Unlike most animals, plants are unable to move to a more favorable location when the environment changes. Thus, plants inhabiting tidal salt marshes have developed structural and physiological modifications to tolerate frequent flooding by saline or brackish water, exposure to higher salinities in the rooting zone, and constant exposure to waterlogged soil (Wiegert and Freeman 1990). Vegetation The distinguishing gestalt of the estuarine emergent wetlands is the zonation of 15 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands plant species corresponding primarily to elevation and salinity (e.g.; Chabreck and Linscombe 1978; Zadler 1982; Josselyn 1982). By far, the dominant plant species in the lower salt mash zones in all estuarine wetlands in the contiguous United States is cordgrass: Spartina alterniflora grows along the Gulf of Mexico and Atlantic coasts (Gosselink 1984; Nixon 1982) and S. foliosa grows along the pacific coast (Zedler 1982; Atwater and Hedel 1976 as cited in Josselyn 1982). At the lowest elevations cordgrass forms virtually monospecific stands. Increasing in elevation, cordgrass grows with other species, which vary by region. In the Gulf of Mexico region, other species include salt grass (Distichlis spicataV black rush (Juncus roemerianus) and to a lesser degree marsh hay cordgrass (Spartina patens) and batis (Batis maritima) (Chabreck 1971). In the tidal salt marshes of the Atlantic coast, the association includes glasswort (Salicornia sp.) as well as Q. spicata and Juncus qerardi (Nixon 1982). There is considerable diversity and variability of salt marsh vegetation along the pacific coast. In the pacific salt marshes in California, the second major plant species found pickleweed (Salicornia virpinica): other species encountered include saltgrass ID. spicatal Jaumea (Jaumea carnosaV and alkali heath (Frankenia qrandifolia) (Zedler 1982; Josselyn 1982). The brackish zone of estuarine emergent marshes are characterized by a large variety of species, which vary by region. In the Gulf of Mexico and the Atlantic coast wetlands the dominant species are Spartina patens. Distichlis sp. and Juncus sp. In southern California, dominant species include Monanthochloe littoralis. Salicornia subterminales and Frankenia palmeri: in northern California, however, the brackish zone is dominated most' by bulrushes (Scirpus olneyi and robustus) and cattails GMlfi spp). Submerged aquatic plants are absent in the salt marsh zone, and only a few grow in the brackish marsh zone (Gosselink 1984). In the Mississippi delta brackish submerged species include widgeongrass (Ruppia maritima). dwarf spikerush (Eleocharis parvula). water hyssop (Bacopa monnierh. and watermill foil (Mvriophvllum soicatum) (Gosselink 19841. The pacific coast salt marshes harbor a number of state rare and endangered plant species. In California, for example, Soft bird's beak (Cordvlanthus mollis spp.. mollis) and Jepson's pea (Lathvrus jepsonin are listed as rare species (Atwater et al. 1977 as cited in Josselyn 1982). 16 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands Macroinvertebrates Macroinvertebrates include the terrestrial animals that are intolerant of submersion and the aquatic migrant and resident animals. The terrestrial macroinvertebrates include primarily arthropods that feed on the macrophytes and seek refuge in the highest part of the plants during high tide (Wiegert and Freeman 1990). The marsh snail (Littorina irrorata^ is an important herbivorous invertebrate in alterniflora marshes in the Mississippi delta. In &. alterniflora marshes of North Carolina, South Carolina and Georgia, 109 herbivorous insects have been identified. Resident aquatic macroinvertebrates include the benthic fauna such as polychaete worms, oysters, mussels, and fiddler crabs. Coastal shrimp are the primary migrant macroinvertebrate species. Although the shrimp inhabit the nearshore zones for most of their life, intertidal marshes and tidal creeks provide food and protection that juveniles require for survival (Vetter 1983 as cited in Wiegert and Freeman 1990; and others). Turner (1977) showed correlations between shrimp yield (kg/ha) and intertidal wetlands areas worldwide, specifically, the area of estuarine wetland vegetation. Fish The tidal marshes surrounding estuaries have long been recognized as playing an important role in enhancing fish productivity (Day et al. 1977). While very few fish species are completely dependent on coastal wetlands throughout their life cycle, these wetlands are used seasonally for spawning, feeding, or as a nursery (Wagner 1973; Chambers 1980 as cited in Conner and Day 1987; Gunter 1967 as cited in Josselyn 1983). From a study in San Francisco Bay, Smith and Kato (1979) concluded that the loss of tidal wetland habitat was partially responsible for the decline of commercial fisheries. Fish are generally excluded from the high marsh areas except during very high tides or in more permanent larger pools, as in the case of mummichogs (Fundulus spp..) and sheepshead fCvprinodon variegatusl in New England salt marshes (Nixon 1982). In the tidal salt marshes of the Atlantic, small killifish are abundant (Wiegert and Freeman 1990). Larger predaceous fish use the salt marsh in the spring to feed on fiddler crabs and other prey. Mammals Many small mammals can be found in estuarine emergent marshes, but the majority of these animals use the marsh simply for foraging. Raccoons (Procvon lotor). 17 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands minks (Mustela vision^, skunks (Mephitis mephitisl weasels (Mustela sp.), and muskrats (Ondatra zibethicus^ can be found in tidal marshes (Gosselink 1984; Josselyn 1983; Nixon 1982). These species use the brackish habitats and, except for the muskrat, feed on shellfish, bird eggs, and mice and generally find lodging in upland areas. Muskrats feed almost entirely on vegetation. In the Mississippi Delta, the dietary and lodging habits of muskrats destroy much of the marsh vegetation and can result in periodic vegetation collapse called "eat-outs" (Gosselink 1984). A variety of smaller mammals can be found in both salt and brackish marshes, but most of these species use the marsh for only a portion of their activities. In California tidal marshes, only two small mammal species are dependent upon tidal wetlands: the Suisaun shrew YSarey sinuosusl and the salt marsh harvest mouse (Reithrodontomys raviventrisl. which is listed as an endangered species (USFWS 1979). In the east coast salt marshes, the only year-round resident mammal is the marsh rice rat (Oryzomys palustris^ (Wiegert and Freeman 1990). Other mammals that use the tidal wetlands include several mice species (e.g., Micfrotus sp.. Zapus sp., Peromvscus sp.), shrews (Sorex sp.) and on the pacific coast, rabbits (Lepus californicus and Svlvilapus bachmaniV In the San Francisco Bay, the salt marshes are also important breeding areas for the harbor seal fPhoca vitulina^ (Josselyn 1983) Birds Estuarine emergent marshes are extremely important to migratory waterfowl species and a variety of wading birds, diving ducks, birds of prey and others. The majority of bird species appear to prefer the high marsh habitat, which has little or no tidal flooding and relatively higher diversity of habitat due to the edge effect of the marsh upland ecotone. These areas are used for feeding, cover, nesting, and brood rearing. Although birds are mobile and are generally found throughout all marsh zones, some preferences are apparent. Wading birds apparently prefer brackish marshes (Sasser et al. 1982 as cited in Gosselink 1984). The majority of waterfowl use the near coastal habitats, their adjacent salt ponds, or the managed impoundments (Gosselink 1984; Gill 1977 as cited in Josselyn 1983). Salt marsh habitats, however, are unpalatable for dabbling ducks, which generally restrict their activities to freshwater ponds (Gosselink 1984). Several species nest in the high marsh habitat, but feed in pools intermixed in the salt marsh zone (e.g., clapper rail, willet, black duck, blue-winged teal, Canada goose, seaside sparrow) (Nixon 198 2). In California, salt and brackish habitats are important to several endangered bird 18 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands species including the light-footed clapper rail (Rallus lonnirostris levipesl (Jorgensen 1975), California clapper rail (R. I. obsoletusl (Jones and Stokes and Assoc. 1979 as cited in Josselyn 1983), and the California black rail (Laterallus jamaicensis coturniculus: other listed species that are not limited to tidal marshes but may use them include the California brown pelican and the American peregrine flacon (Zedler 1982; Josselyn 1983). Reptiles and Amphibians In the Mississippi Delta salt marshes, no amphibians are found and only 4 reptile species. Alligators do occur in some slightly brackish areas. Zedler (1982) noted two factors that limit the occurrence of amphibians and reptiles in salt marshes: amphibian eggs require freshwater to develop and reptiles must restrict the location of subterranean refuge and egg deposition to above the high tide line. Unlike the salt marshes of the Mississippi Delta, Hyes and Guyer (1981 as cited in Zedler 1982) identified a few amphibian species including treefrogs fHyla regillal and gopher snakes (Pituophis melanoleucusl While reptiles and amphibians do not require the salt-marsh environment for their existence the vegetation and fauna provide food and cover, and these animals provide a food source for mammals and birds. 2.2 Environmental Values A conceptual model relates the four values (Figure 2) to indicators of those values, and the measurements employed to quantify each indicator. These four primary wetland values must all be considered together to report overall regional condition of wetlands. For now, we will weigh all values equally. We recognize, however, that there may be socioeconomic tradeoffs in maximizing one at the expense of another. The four primary wetland values upon which EMAP-Wetlands will assess condition are described below: 19 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands Wetland Condition Estuarine Emergent Wildlife Production (non-food: fur, aesthetic) Vertebrate types & number/area Wetland distribution in the Vertebrate Production (fish, waterfowl, mammals, etc.) . Invertebrate types & number/area Vegetation types & number/area Vegetation:open water ratio Maximum depth; tidal amplitude Shellfish Production Salinity regime Vegetatlon:open water ratio Water Regime Tidal amplitude, range Water depth Redox-Eh, sulfides Hydraulic conductivity Soli salinity Carbon/Nitrogen ratio % organic soil Bulk density Shoreline Erosion Vegetation»pen water ratio Sediment characteristics Productivity HydrologicX Function / / BlologicalX \ Integrity / Water / Quality ^Improvement^ Plant Diversity and Abundance Vegetation types & number/area: rare, threatened endangered or nuisance species Biomass; stem size % Cover Spectral reflectance Animal Diversity and Abundance Invertebrate types & number/area Vertebrate types & numbers/area Sediment Accumulation Bulk density Accretion rate % organic soil Vegetation:open water ratio Tissue and soil analysis- contaminants Nutrient Processing Aerial cover-plants Plant spp. (number & diversity) Dead vegetation Plant tissue nutrient analysis Figure 2. Conceptual assessment model showing the relationship of values associated with evaluation of wetland condition (hexagons), selected Indicators of those values (italics headings) and the measurements quantifying each indicator (subheadings). Biological Integrity is defined as the sustainability of a balanced, integrative, adaptive community of organisms having a species composition, diversity, habitat and functional organization comparable to that of natural wetlands in the region (adapted from Karr and Dudley 1981). These characteristics will be related to those found in the 20 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands least impacted wetlands in a given region under the assumption that least impacted wetlands have sustainable biological integrity. EMAP-Wetlands proposes to combine indicators of plant and animal abundance and diversity into indices of biological integrity. Productivity is the quantity and/or quality of any service or product that wetlands provide society (e.g. commercial timber, wildlife, recreation and food production). Management of a wetland for maximum productivity of one service or product may conflict with productivity of other services or products. Hydrologlc function is defined as the natural water-flow patterns necessary for the sustainability of the wetland and its functions (e.g., flood conveyance, water storage capabilities and shoreline protection). During periods of peak flow, wetlands can temporarily store flood waters and then slowly release these waters as flood levels fall. Coastal salt marshes stabilize the shoreline by reducing erosion and siltation and maintain salinity gradients between the upland and the ocean. Water quality improvement is defined as the ability of wetlands to assimilate nutrients, trap sediments or otherwise reduce downstream pollutant loads. Water quality is improved through the assimilation of nutrients by plants and through chemical conversion (e.g., denitrification). The precipitation of sediments and associated materials, such as metals and pesticides, also improves water quality. 2.3 Wetland Stressors and Impacts Human activities have greatly altered the estuarine emergent wetlands on all coasts. In the Gulf of Mexico, hydrology has been severely modified by "both by altering the pathways of water movement and by changing the rate of water exchange in aquatic and wetland areas" (Conner and Day 1987). Our initial attempts at understanding the effects of stressors on each wetland value and its associated indicators are illustrated in Figures 3-6. 2.3.1 Dredging and excavating Dredging and excavating are commonly used for mosquito-control ditching, canal construction, flood control, and to open up and maintain harbors (Office of Technology Assessment 1984; Tiner 1984; Zedler 1982). By removing wetland vegetation and their soils, these activities typically reduce the surface elevation and 21 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands create poor habitat for both flora and fauna. Flooding by deeper water prevents plants from becoming established and the anoxic conditions of the soil prevent macroinvertebrates from colonization. In the Chesapeake watershed, dredging was one of ihe major reasons given for the loss of coastal wetlands to estuarine waters between the mid-1950's and the late 1970's (Tiner 1984). In Louisiana, dredging of canals to access oil and gas development sites has resulted to significant wetland losses. Craig et al. (1980) and Turner et al. (1982) showed positive correlations between canal density and the extent of wetland loss. 22 ------- Est ua rine Emergent Biological Integrity Conceptual Model ro CO Hydrology plant species diversity A saltwater intrusion A vegetation composition Dredging (canals and ditches) water a sediment ' export . Plant abundance A % open water exchange water depth A vegetation composition;.; stabilized water levels ^ % open water submerged Impoundments aquatjc_j)lants water level manipulation emergent vegetation macroinvertebrate diversity nutrients Filling (development) a drainage & ' runoff chemical ^concentration in tissue contaminants extent plant species ^ diversity & abundance ^subsidence A vegetation composition Oil & Mineral Extraction b open water chemical ^ concentration in tissue Contaminants ^hydrocarbons metals and toxics Point Source Pollution plant abundance A nutrients ~ expected* plant species * expected* plant ~ abundance expected* macroinvertebrate species * expected* macroinvertebrate abundance \\f expected* V fish species .1. expected* V fish abundance expected* bird species expected* bird abundance | expected* mammal species A. expected* V mammal abundance 'expected relative to reference condition 9 O. co ------- Estuarine Emergent Productivity Conceptual Model ro a Hydrology plant species A vegetation composition A saltwater 1 intrusion diversity expected . shellfish Y & fish Dredging (canals and ditches) A sediment export water A % open water • plant abundance exchange water depth accretion rate A vegetation composition.• expected ^ waterfowl & mammals stabilized water levels > ^ % open water submerged Impoundments aquatic _pl_ants water level manipulation I emergent macroinvertebrate abundance vegetation expected ^ shellfish & fish ^ nutrients * Filling (development) a drainage & ' runoff expected shellfish chemical ^ concentration in tissue contaminants extent plant species ^ diversity & a water ' depth A vegetation composition open water Extraction waterfowl abundance chemical ^ concentration in tissue Contaminants mammals A hydrocarbons metals and toxics Point Source Pollution A nutrients 'expected relative to reference condition Ml KP'aHn' 1 abundance expected* ^ shellfish & fish § Q. ------- Estuarine Emergent Water Quality Improvement Conceptual Model rvj in Hydrology I plant species A vegetation composition A saltwater intrusion diversity sediment Dredging (canals and ditches) water ^ % open water . Plant abundance export exchange water depth accretion rate • A vegetation composition;!; stabilized water levels > ^ % open water a submerged aquatic, jrt ants Impoundment (lor waterfowl or shoreline protection water level manipulation i emergent * vegetation nutrients Filling (development) a drainage & ' runoff ^ chemical concentration in soil & tissue contaminants extent plant species diversity & abundance a water ' depth A vegetation composition open water Extraction (subsidence ^ chemical concentration in soil & tissue ContamInants . m hydrocarbons metals and toxics A nutrients Point Source Pollution ^ expected* nutrient processing expected* contaminant removal expected* * sediment trapping expected relative to reference condition O O o p o o •o e a w Gft e to 3. O o o o3 o s 3 o s CL M ------- Estuarine Emergent Hydrologic Function Conceptual Model Dredging (canals & ditches) Impoundments^ (for waterfowl or shoreline protection] Filling (development) Sea Level Rise (subsidence) A Water Regime A water 1 exchange A sediment transport open water water exchange water runoff A sediment transport open water a water ' depth water exchange mineral sediment organic sediment mineral sediment organic sediment T hydraulic Y ¦ conductivity J ¦ plant y abundance ¦ hydraulic V conductivity extent ¦ plant y abundance ^ % open water I expected* protection of shoreline J. expected* water storage capacity ^ expected* salinity regime a expected* ' protection of shoreline J. expected* water storage capacity ^ expected* salinity regime ^ expected* » protection of shoreline ^ expected* * water storage capacity * expected* r salinity regime 'expected relative to reference condition ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands Increasing canal density indirectly contributes to the loss of brackish marshes by increasing saltwater intrusion into these areas with the tides. The excess salinity can decrease plant species diversity by killing the less salt tolerant plants and increase the area covered by open water. Furthermore, the resulting increased tidal flows erode canal banks,; thereby exacerbating the conversion of marsh to open water. In California, open water communities have replaced emergent marshes shift in vegetation to eelgrass beds (Bradshaw et al. 1976). Dredged channels are also constructed as flood control measures to route flood waters through and around marshes instead of over them, reducing the delivery of sediments and their nutrients to the marsh (Gosselink 1984). During an experimental ditching program in San Francisco tidal wetlands where ditches were constructed in wetlands to enhance circulation (rather than to drain the wetlands), Balling et al. (1980) found that mosquito fish (Gambusia affinisl migrated to new areas using the ditched channels rather than through submerged vegetation at high tide. They found that these ditched wetlands also had twice as many other fish species as unditched areas. The rate of land loss in Gulf of Mexico appears to be related to the construction of canals and spoil banks (Craig et al. 1980; Scaife et al. 1983; Blackman 1979 as cited in Conner and Day 1987). These activities reduce soil waterlogging and lower the rate of sedimentation, which js important to offset subsidence (Baumann et al. 1984) and provide a source of nutrients (Day et al. 1982 as cited in Conner and Day 1987). Because differential species tolerances to water depth, even slight elevational changes from sediment deficits can shift the plant species composition and increase open water area. Subsidence of sediment is causing the loss of large areas of marsh (Baumann 1980; Baumann et al. 1984 as cited in Conner and Day 1987). 2.3.2 Filling Salt and brackish marshes have been prime locations for urban and industrial development because of their proximity to the ocean and natural harbors (Zedler 1982). Fill activities have resulted in major losses of estuarine wetlands by permanently destroying wetlands by burying vegetation and increasing the elevation of the area to eliminate tidal inundation. In 1975, the California Coastal Zone Conservation Commission reported that 75% of the coastal estuaries and wetlands had been destroyed or severely altered since the turn of the century. They further noted that of the 28 major estuaries in southern California, two-thirds had been 27 ------- Draft 1.0 Conceptual Model, for Estuarine Emergent Wetlands dredged or filled. In Virginia, urban development was the major factor contributing to coastal wetland loss between the mid 1950's and the late 1970's (Tiner 1984). Reduced coastal wetland acreage has direct effects on the local wildlife populations that uso the wetlands (Zedler 1982 and others). Presumably, impacts to migrating waterfowl and other water-dependent birds is particularly severe in arid regions, such as southern California, where adequate stopover habitat is rare. Furthermore, developments pose barriers to both animal movement and plant dispersal. Boland (1981 as cited in Zedler 1982), for example, found that shorebirds require alternate resting and feeding habitats under different tidal conditions. In addition to local direct impacts, filling can have indirect effects of decreasing water quality when the urban runoff increases nutrient and contaminant inputs and when the fill material is contaminated. Highways built through marshes on fill material can cause either flooding if subsurface water is impeded or dewatering of adjacent wetlands, which can either increase or decrease the habitat value. 2.3.3 Oil and Mineral Extraction Direct impacts to estuarine wetlands from oil and mineral extraction activities have included subsidence of the marsh substrate and increased contaminant loading. Indirect effects of these activities result from primarily construction of navigation channels that allow access to gas and oil development sites, and are discussed under the heading "Excavation" above. Impacts resulting from exposure to petroleum hydrocarbons are less clear. The majority of research on the impacts of petroleum hydrocarbons has been done in the southern United States (Nixon 1982; e.g., Mendelssohn et al. 1990; Webb 1981). Research in one area of the Mississippi delta region exposed to chronic, low-level oil spills had fairly high levels of hydrocarbons in the sediments (Bishop et al. 1976 as cited in Gosselink 1984). Milan and Whelan (1979) found that the hydrocarbons concentrate in tissues of benthic organisms including oysters and mussel, free swimming organisms such as grass shrimp and killfish, and emergent grasses. In another study, there was a 50% reduction in amphipods, crustaceans, and benthic organisms compared to non-oil field control areas. From their study on the response of a New England salt marsh community to an oil spill, Hampson and Moul (1978) found differential responses due to life form of the plants: perennial plants such as Spartina sp. and Distichlis sp. were more resistant than annuals like Salicornia sp. Nevertheless, the perennial £. altemiflora showed a decrease in biomass, height, and density in the oiled areas 3 years after the 28 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands spill. The severity of impacts depends on a number of factors including severity of spill, the composition and toxicity of the petroleum compounds, and the temperature and season at the time of the spill (Nixon 1982). 2.3.4 Impoundments Impoundments are constructed primarily to attract waterfowl and, to a lesser extent, prevent marsh loss. Construction of marsh impoundments and levees have been a common practice in the Gulf of Mexico and along the Atlantic to create brackish water impoundments to improve habitat for waterfowl and fur animals (Gosselink 1984; Tiner 1984). Impoundments eliminate the supply of sediments necessary to balance accretion with subsidence. In addition to sediment deficits, completely impounded marshes become fresher in time because of the surplus freshwater input from rainfall. The combination of stabilized or increasing water levels and conversion to fresh water eliminates emergent salt marsh plants and promotes the growth of submerged aquatics, a condition that attracts waterfowl and fur bearing animals, but is apparently unattractive to fish species. Some impoundments are equipped with water level control structures that allow water in and out of the impoundment. These types of impoundments generally provide more favorable habitat for a diversity of wildlife including birds, fur animals, and if the control gates are managed to allow juveniles organisms access during migration, fish and shellfish (Davidson and Chabreck 1983). 2.4 Assessment questions Assessment questions guide the selection of indicators to be used in the monitoring program. We have an initial list of assessment questions (Table 2) that are broad and address issues related to each value. In addition, we list the major indicator category that is related to the value, and some of the potential measurements that will be used to quantify the indicator. 29 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands Table 2. EMAP-Wetlands proposed conceptual finkages of values, indicator categories, and measurements for Estuarine Emergent wetlands. * 'expected" is defined by reference conditions. ASSESSMENT QUESTIONS INDICATOR CATEGORY MEASUREMENTS Biological Integrity What proportion of estuarine emergent wetlands have X% of their expected*: native species rare species threatened species endangered species nuisance species species richness What proportion of estuarine emergent wetlands have X% of their expected*: habitat biomass (plant or animal) Productivity What proportion of estuarine emergent wetlands have X% of their expected*: wildlife production? shellfish production? What proportion of estuarine emergent wetland provide expected habitat for*- breeding waterfowl populations? wetland vegetation? shellfish habitat? Hydrologlc Function What proportion of estuarine emergent wetlands are providing salinity and water regime expected*? depth Plant Diversity-(community composition) Animal Diversity-(oommunity composition) Plant Abundance Animal Abundance Plant Abundance Animal Abundance Plant Abundance Animal Abundance Shoreline Erosion Water Regime Water Quality Improvement What proportion of estuarine emergent wetlands improving water quaity as expected*? Sediment Accumulation Nutrient Processing identification of native species identification of rare species identification of threatened spp. Identification of endangered spp. identification of nuisance spp. total number of species % cover stem height and width index biomass for each species % cover stem height and width index biomass for each species % cover stem height and width index spectral reflectance extent vegetation to open water ratio sediment characteristics tidal amplitude, range, water Redox--Eh, sulfides hydraulic conductivity soil salinity carbon/nitrogen ratio % organic soil bulk density bulk density accretion rate % organic soil vegetation:open water ratio tissue and soil contaminants % cover plant spp. (number and diversity) dead vegetation plant tissue nutrients 30 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands 2.5 Estuarine Emergent Indicators Indicators which quantify an environmental value for estuarine emergents will be used to estimate the condition of the resource as well as the stress on the biological components of the wetland. Indicators are monitored and evaluated to determine condition and changes in condition over time. 2.5.1 Measures common to all values Wetland distribution In the landscape A number of important wetland attributes, useful for assessing wetland condition, can be quantified remotely, using aerial photography and (or) satellite imagery. These indicators are referred to collectively as landscape indicators. Landscape indicators are of particular utility because (1) they may be more cost effective to measure than indicators that require field visits and (2) they generally provide an integrated assessment of wetland condition and stressors, more suitable for the scale of analyses (regional, long-term trends) of interest for EMAP than are many of the more highly variable indicator measurements that can be obtained during field sampling. A wide variety of landscape-level measurements may be potentially useful for EMAP-Wetlands. For example, interpretation of aerial photography (in particular low altitude aerial photography) and satellite imagery could provide information on wetland vegetation community composition, wetland edge patterns (changes over time indicate subsidence), occurrence and area covered by terrestrial vegetation (indicates less frequent flooding); greenness (an indicator of vegetative productivity and/or changes in vegetation community composition); the occurrence and extent of sediment plumes (indicates nonpoint source pollution); and the occurrence and intensity of algal blooms (indicative of excessive nutrients). Many of these landscape indicators, such as vegetation community composition, wetland edge patterns, and greenness, may be particularly useful for providing context for or corroborating data collected during field visits. For example, analyses of vegetation community composition from aerial imagery could be used to explain vegetation data collected on the ground. Changes in emergent plant community structure (as measured by both remote sensing platforms and field measures) generally occur rapidly in response to stress (e.g., eutrophication, 31 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands contamination, subsidence). A decrease in greenness may indicate the onset of a stress response before permanent compositional changes occur. The characterization of spatial patterns, both within and outside of wetland boundaries, provides a measure of habitat and landscape structure, which in turn influences ecological functions, particularly animal diversity and abundance. The availability of habitat patches of sufficient size and the degree of among patches via corridors affect the types of species that can be supported. The importance of habitat fragmentation is well documented for birds (Robbins et al. 1989, Gosselink et al. 1990). Thus, correlation's between vertebrate response indicators and the results of spatial pattern analyses will be particularly relevant. Numerous indicators of spatial patterns have been suggested (O'Neill et al. 1988, Turner 1989) although relatively few have received rigorous empirical scrutiny. Some indicators describe landscape heterogeneity as a function of patch characteristics. Others emphasize the arrangement of patches. However, in all instances, the choice of scale is critical to the measurement and interpretation of pattern indicators. For EMAP-Wetlands, two categories of scale are appropriate. Within individual wetlands selected for monitoring, patch areas will range typically from 0.1 to 10 ha, whereas patches measured in a landscape context will range from 10 to 1,000 ha. Analyses of these two scale categories will remain independent, although scales may occasionally overlap. Wetland extent Many functional attributes of wetlands are related directly to their size (aerial extent). Remote sensing is the most effective way to monitor changes in wetland area over time. Analysis of trends data derived from aerial photography for the NWI has, to a great extent, provided the foundation for current public and private efforts to protect wetlands. Documenting losses and gains in wetland area are critical for understanding regional trends and identifying geographic areas in need of immediate attention. This measurement is of fundamental importance to the monitoring program, as an important indicator of sustainability for all wetland values. Vegetation to open water ratio In salt marshes, evidence of deterioration may exist in tracking the change in the vegetation to open water ratio. The increase in wetland open areas indicates more 32 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands frequent flooding and degradation. Open water in an area of salt marsh corresponds to a loss of vegetation, which provides food and habitat for faunal components of the ecosystem. Maximum depth/tidal amplitude Water levels and the tidal amplitude are used to determine inundation frequency and duration. These characteristics have an influence on most productivity, water quality, biological integrity and productive indicators. 2.5.2 Indicators of Productivity Productivity is the quantity and/or quality of any service or product that wetlands provide society (e.g., recreation and food production). Salt marsh productivity includes wildlife (non-food), vertebrate (fish and waterfowl) and shellfish production. Several measurements have the potential to be useful in the development of models and these are described below. At this point in time, the extent, and wetland distribution in the landscape (described above) will be used to estimate production 'in estuarine emergent wetlands and we are seeking additional input for this value. Wildlife Production (non-foodl Wildlife production includes the use of wetlands for aesthetics and recreation (i.e., bird-watching) and also for products that are not considered as food (i.e., the harvesting of fur-bearing animals). At this point in time, we recognize the importance of coastal wetlands for wildlife production (Turner 1990), however, we have not developed methods or protocols specifically for wildlife production. Vertebrate Production Vertebrate production includes the human consumption of animals such as fish and waterfowl. At this point in time, we recognize the importance of coastal wetlands for vertebrate production (Turner 1990, Turner and Boesch 1987), however, we have not developed methods or protocols specifically for vertebrate production. Shellfish Production Perhaps the most important productivity indicator is the production of shellfish which includes shrimp, crabs, and bivalves. As part of this indicator, plant biomass may be needed to determine the amount of detritus or other fodd materials available to 33 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands these organisms. Turner and Boesch 1987) illustrated the direct relationship between intertidal area and relative density of shrimp yield in disturbed and natural habitat. At this point in time, we recognize the importance of coastal wetlands for shellfish production, however, we have not developed methods or protocols specifically for shellfish production. 2.5.3 Indicators of Biological Integrity Biological integrity is defined as the sustainability of a balanced, integrative, adaptive community of organisms having a species composition, diversity, habitat and functional organization comparable to that of natural wetlands in the region (adapted from Karr and Dudley 1981). These characteristics will be related to those found in the least impacted wetlands in a given region under the assumption that least impacted wetlands have sustainable biological integrity. EMAP-Wetlands proposes to combine indicators of plant and animal abundance and diversity into indices of biological integrity. Plant Diversity and Abundance Plants are the most critical biological element of a wetland and are important in and of themselves in addition to providing food and habitat for animals. Potential analysis of the plants species present include the abundance and diversity of species in an as well as specific information on the rare, threatened, endangered and nuisance species. Recent research on salt marsh plants includes work by Bertness (1991) and Niering and Warren (1980) in New England. In addition to using vegetation as part of biological integrity, vegetation is the primary means by which wetlands are described and classified (Cowardin et al. 1979). Thus, measures of vegetation community composition and abundance are considered high priority indicators for EMAP-Wetlands. Changes in plant communities are intimately tied to all of the proposed EMAP-Wetlands values described in section. Studies of vascular plant communities and their characteristics are abundant in the literature, and sampling methods are well developed (Britton and Greeson 1988, Frederickson and Reid 1988). Wetland plants, because they are immobile, are reliable indicators of certain types of stressors, such hydrologic modification and nutrient/pollutant loadings (Leibowitz and Brown 1990). Changes in the community composition or density of vegetation should coincide with the coarser indicators of 34 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands spatial pattern. Abundance or density of vegetation is important as a food base for the animal community. An estimate of biomass or standing crop would provide useful information. Non-destructive methods (i.e., measuring stem size: length, diameter, % cover, spectral reflectance: (3 bands from videography; satellite imagery) are currently being explored for a variety of reasons. Animal Diversity and Abundance Animals are important biological elements of a wetland. Potential analysis of the animal species present include the abundance and diversity of species as well as specific information on the rare, threatened, endangered and nuisance species. Recent research on salt marsh animals includes work on invertebrates (Livingston 1987, Roberts and Matta 1984, Rountree and Able 1992), fish (Rountree and Able 1992, Shreffler et al. 1992), and birds (Goss-Custard and Yates 1992, Craig and Beal 1992). Invertebrates: Invertebrates are found in all wetland types and are responsive to major stressors (i.e., altered hydrology, excess sediment, changes in nutrient cycling, and contaminants). Benthic/epiphytic macro-crustaceans, such as amphipods, crayfish, and oligochaetes, are examples of invertebrates sensitive to stressors. They are relatively sedentary, and thus may be indicative of chronic stressors affecting the benthos. Larger taxa, such as mollusks, are known to accumulate contaminants. Due to their immobility, they also may be good response indicators of localized pollution problems (Schindler 1987, Simon et al. 1988). Macroinvertebrates typically serve as the primary food resource for both invertebrate and vertebrate predators, and therefore can be used in developing indicators of productivity as well as biological integrity. Unfortunately, the ecology of macroinvertebrates living in the organic substrates found in wetlands is not well known compared to streams. The relationships that work for streams may not hold for wetlands. Also, the numerical and spatial variability of macroinvertebrates in wetlands appears to be much greater than that observed in streams. Detailed studies have been conducted for macroinvertebrates in emergent wetlands in conjunction with waterfowl research. Ross and Murkin (1989) provided a review of sampling techniques and suggested a protocol for long-term studies. At this point in time, we recognize the importance invertebrates in coastal wetlands for, 35 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands however, we have not developed methods or protocols specifically for them. We are seeking additional input for this indicator. Vertebrates: Mammals. Birds and Fish: The types of habitat required to meet the life requisites of vertebrate species have been extensively documented. Thus, vertebrates are often considered to be useful indicators of how environmental conditions are changing within those habitats. Vertebrates can serve as integrators of cumulative impacts, because they are often the trophic end points of a biological continuum that is exposed continuously to a broad range of negative effects. As a result, vertebrates are useful indicators of biodiversity for many faunal taxa. Most vertebrate taxa are of major interest to the public, either because of their commercial value (e.g., hunting and fishing) or because they are readily observable (e.g., birding) (Brooks and Hughes 1988). Therefore, vertebrate species are seen as logical candidates for EMAP's suite of response indicators. Yet, the empirical basis for predicting how vertebrates will respond to environmental impacts in wetlands is weak. Research has shown that monitoring vertebrate species and communities can be an effective way to evaluate changing environments (Karr 1987, Root 1990) if precise definitions and procedures are used to specify the rationale, goals, and context for monitoring a particular taxa (Landres et al. 1988). Vertebrates selected by EMAP-Wetlands should be wetland dependent (at least for a portion of their life cycle), broadly distributed, relatively easy to observe and measure, and sensitive to habitat modifications associated with expected stressors. Unfortunately most vertebrates do not meet these criteria. At this point in time, we recognize the importance vertebrates in coastal wetlands for, however, we have not developed methods or protocols specifically for them. We are seeking additional input for this indicator. 2.5.4 Indicators Hydrologlc Function Hydrologic function is defined as the natural water-flow patterns necessary for the sustainability of the wetland and its functions (e.g., flood conveyance, water storage capabilities and shoreline protection). During periods of peak flow, coastal wetlands can temporarily store flood waters and then slowly release these waters as flood levels fall. Coastal salt marshes stabilize the shoreline by reducing erosion and siltation and maintain salinity gradients between the upland and the ocean. 36 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands Hydrology is the major forcing function regulating wetland health. By definition, the source and periodicity of water determines the structural and functional characteristics of every wetland and, hence, its productivity, and biodiversity (Mitsch and Gosselink 1986, Brinson 1988). When the hydrology is altered, changes in nearly all other abiotic and biotic components of a wetland can be expected. The processes that define a wetland may shift dramatically or imperceptibly. Soil characteristics and nutrient fluxes will be affected. The capacity for a wetland to store water, and to retain sediment and contaminants can be altered. Species composition of floral and faunal communities can be expected to change, as well as wetland productivity. Although hydrology is of recognized intrinsic importance to a wetland, direct measurement can be elusive and indicators of hydrology are needed. Water Regime Water regime is also a major determinant of plant and animal species present (Naidoo et al. 1992), and measurements include both characteristics of the water regime itself, such water depth (Swenson and Turner 1986, Turner 1991, Nyman et al. 1990), tidal amplitude/ range, and sediment characteristics that develop in response to the water regime. Sediment characteristics included redox (Eh and sulfides), % organic material, carbon/nitrogen ratio of sediments, bulk density, and soil salinity. Measures of sediment characteristics, such as a highly reduced environment (measured with redox potential), indicate that waterlogging is common. Highly reduced environments also promote the accumulation of toxic sulfides. Generally, the wetter the area, the higher the organic matter of the soil, because wetness and anoxia inhibits decomposition of plant material. Spartina alterniflora colonization is also inhibited by anoxic soils (Gammill and Hosier 1992; King and Klug 1982). Carbon to nitrogen (C/N) ratios in soils also provide an indirect measure of hydrology, with high ratios being related to wetter conditions. Soil bulk density is a good measure of soil structure (Blake 1965) and measures both inorganic matter and water content (Rainey 1979). In addition, soil organic matter content is directly related to bulk density (Gosselink et al. 1984). Another measure of soil structure is hydraulic conductivity, which may be used to characterize wetland sediments. 37 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands Salinity is a major determinate of plants (Naidoo et al. 1992, Zedler 1983) and animals that will utilize the salt marsh. Water salinity fluctuates with tidal influence and is not suited to the sampling regime proposed for EMAP. The salinity of the pore water is being explored as a more stable measure of the salinity regime that the wetland experiences. Shoreline Erosion Erosion of coastal shorelines is a major problem throughout the United States (Williams et al., 1991a). One of the main functions of a coastal wetland is the prevention of erosion by the plant roots that hold soil. An increase in erosion indicates the instability and deterioration of the wetland, mostly due to the loss of appropriate plant species. Several papers have described shoreline erosion and its importance (Williams et al. 1991b, Turner 1990, Turner and Cahoon 1988). Other measures may relate to shoreline erosion, such as the vegetation to open water ratio. A major effort has utilized aerial imagery of extent over time (Sasser et al. 1986, Turner and Roa 1990, Baumann and Turner 1990, McBride 1989, McBride et al. 1991) and modeling (Costanza et al. 1990 , Cowan and Turner 1988). 2.5.5 Indicators of Water Quality Improvement Water quality improvement is defined as the ability of wetlands to assimilate nutrients, trap sediments or otherwise reduce downstream pollutant loads. Water quality is improved through the assimilation of nutrients by plants and through chemical conversion (e.g., denitrification). The precipitation of sediments and associated materials, such as metals and pesticides, also improves water quality. Sediment Accumulation When viewed from a watershed perspective, wetlands typically function as relatively small pockets of accretion on an otherwise eroding landscape (Brinson 1988). From a geophysical perspective, wetlands are depositional landforms, even though during some seasons certain materials may be exported. If the rate of sediment flux within a wetland can be monitored accurately, then changes in an established trend could be detected and serve as an indicator of disturbance, as well as wetland sustainability and productivity. However, sedimentation in wetlands is relatively modest when compared to landscape-level subsidence rates (Brinson 1988). 38 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands High rates of sedimentation may have adverse effects in some types of wetlands, rapidly decreasing wetland size and condition, but may be beneficial in others. For example, for some coastal marshes, sediment input is required to counter the effects of land subsidence (DeLaune et al. 1983, Hatton et al. 1983, Gammill and Hosier 1992). Changes in sediment and organic matter flux rates may be indicative of a number of wetland stressors. Mulholland and Elwood (1982), for example, found that the accumulation rate of organic carbon was higher in small lakes and culturally eutrophic lakes than in oligotrophy lakes. The interpretation of regional data on sediment and organic matter fluxes must be coordinated carefully with data on changes in the spatial patterns of landscapes and individual wetlands, if the anticipated rate variations and causal factors are to be addressed. Chemical Contaminants in Sediment: Because of their hydrologic position on the landscape, wetlands often receive .water and sediments laden with contaminants from urban and agricultural runoff, and municipal wastewater. Thus, wetlands can serve as significant "sinks" for metals (Millward et ai. 1992), pesticides (Pait et al. 1989), PCB's (Kennish et al. 1992) organic compounds through sediment accretion. Measurements of contaminants in the water column are subject to significant temporal and spatial variation, particularly after extreme rainfall events. Given the infrequent sampling protocol required for EMAP, sampling for contaminants in sediments should provide more consistent results than samples taken from the water column. As an indicator of exposure, the levels of contaminants in sediments would be expected to have both direct and indirect negative effects on two other wetland values: productivity, biological integrity. The discovery of massive die-offs or the absence of a species from a community can suggest that lethal exposure levels of a contaminant have occurred. Bioaccumulation monitoring, however, can identify sub-lethal and chronic, low-level exposure to a source of pollution. Bioaccumulation of contaminants in aquatic organisms has been investigated extensively (e.g., Cairns and Dickson 1980, Biddinger and Gloss 1984, Hellawell 1986, USFWS and USGS data bases). Detection of intermittent pollution sources is strongly dependent on the time and 39 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands place of sampling (Root 1990). Therefore, measuring bioaccumulation can be more informative than water or sediment testing alone, because the amount of exposure received by an organism overtime is reflected in the level of contaminants found in its tissues. The methods for analysis of tissue samples are well developed; however, the choice of an organism and the specific tissues to be monitored is highly dependent on the kinds of pollution expected for a given area. Bioaccumulation offers the advantage of a chemical-by-chemical approach for determining the health of the Nation's wetlands (Brown et al. unpublished). Nutrient Processing High nutrient loadings from urban and agricultural runoff and wastewater inflows are primary stressors of wetland systems and important factors influencing wetland productivity and biological integrity. Monitoring of water quality has focused on large rivers, lakes, and reservoirs rather than wetlands, although this may have led unintentionally to an assessment of nutrients in the fringing wetlands along these waterbodies. Most of the data on wetlands, per se, comes from monitoring studies of wetlands receiving municipal wastewater, with the majority being found in southern states, particularly Florida (Adamus and Brandt 1990). Publications by Nixon and Lee (1985) and Hammer (1989) summarize much of this information. Eutrophication studies by Turner and Rabalais (1991a & b) are pertinent to the salt marshes. Other studies have examined the utilization of nutrients by salt marsh plants (Patrick and DeLaune 1976, DeLaune and Patrick 1980) We anticipate thai other measurements will be used to determine the nutrient processing in salt marshes, such as aerial cover (plants), plant species present and abundance, dead vegetation, and plant tissue nutrient analysis (C/N ratio). Bioaccumulation in Tissues: The discovery of massive die-offs or the absence of a species from a community can suggest that lethal exposure levels of a contaminant have occurred. Bioaccumulation monitoring, however, can identify sub-lethal and chronic, low-level exposure to a source of pollution. Bioaccumulation of contaminants in aquatic organisms has been investigated extensively (e.g., Cairns and Dickson 1980, Biddinger and Gloss 1984, Hellawell 1986, USFWS and USGS data bases). Detection of intermittent pollution sources is strongly dependent on the time and place of sampling (Root 1990). Therefore, measuring bioaccumulation can be more 40 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands informative than water or sediment testing alone, because the amount of exposure received by an organism over time is reflected in the level of contaminants found in its tissues. The methods for analysis of tissue samples are well developed; however, the choice of an organism and the specific tissues to be monitored is highly dependent on the kinds of pollution expected for a given area. Bioaccumulation offers the advantage of a chemical-by-chemical approach for determining the health of the Nation's wetlands (Brown et al. unpublished). Increases in contaminant bioaccumulation may affect wetland productivity, biodiversity, and sustainability. 41 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands 3.0 RESEARCH NEEDS (See proposal by Vallero and Hyatt 1992) SECTION NEEDS REVISION; WILL INCLUDE SUBSTANTIAL INPUT FROM WORKSHOP PARTICIPANTS A. Identify available measurements and models B. Develop and test new measurements and models 1. to evaluate interpretability of indicator data 2r to test/refine quantitative methods/models for summarizing indicator data into multi- metric indices 3. to'evaluate the statistical and ecological advantages, limitations, and assumptions of each method/model. C. Demonstrate/refine the application and utility of the selected methods for index construction and models indicator interpretation for assessment of condition IV. Application of conceptual model A. Indicator selection and testing: good/bad B. Assessment of condition Implementation: regional boundaries, wetland complexes, integration 42 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands 4.0 STATUS OF ESTUARINE EMERGENTS INDICATOR TESTING To develop the program for assessing the condition of estuarine emergent wetlands, we have identified the Gulf of Mexico, the Atlantic and the Pacific coasts. Indicator testing was initiated in the salt marsh component of estuarine emergent wetlands in the Gulf of Mexico region in 1991. Planning for the first pilot study (Phase I) began in October 1990. A workshop involving Gulf Coast wetlands scientists was held in January 1991 in Baton Rouge, Louisiana. The workshop resulted in a conceptual model, which identified values and indicators of salt marsh condition and an approach for selecting good and degraded sample sites. The experts suggested that the pilot study focus on salt marshes as representative of the estuarine emergents; they further defined salt marshes in good condition as those mostly vegetated and those in degraded condition as sparsely vegetated and showing signs of deterioration. Based on workshop results, additional discussions with experts, and literature review, the conceptual model was refined to identify the primary values of estuarine emergent systems as productivity, biological integrity, hydrologic function, and water quality improvement. The primary objectives of the Phase I Pilot Study were to: 1) test the ability of a proposed suite of ecological indicators to detect differences between good and degraded salt marshes; 2) evaluate the spatial variability of indicators at three levels (among hydrologic basins, within good and degraded salt marshes, and within sample sites); 3) evaluate different measurement protocols to develop standard techniques; and 4) identify logistical issues important for future field sampling programs in the Gulf Coast salt marshes. A Cooperative Agreement was established between ERL-C and Louisiana State University (LSU) in June 1991 to design and implement the field sampling activities and conduct data analysis. To select good and degraded salt mash areas to meet objective one, aerial photographs were examined. Good sites were defined as having stable vegetation to open water ratios of at least 50% between 1978 and 1988; degraded sites were those with ratios of vegetation to open water less than 50% and that decreased by about 30% during the ten year period. The sample sites wer6 selected from those that were: (1) classified as salt marshes (i.e., dominated by Spartina afterniflora) by Chabreck and Linscombe (1978) and by US Fish and Wildlife 43 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands Service Habitat maps; (2) sufficiently large to avoid streamside effects (strips of higher productivity along the levee); (3) accessible by boat under normal tide conditions; and (4) geographically distributed over the salt marsh portion of each basin. To meet objective two, a stratified sampling design was used to evaluate spatial variability at three levels: among hydrologic basins, within good and degraded wetland areas, and within sample sites. Forty-eight sample sites were allocated equally among three hydrologic basins of the Mississippi Delta having the greatest percentage of salt marsh area: Barataria, Terrebonne, and St. Bernard. Within each basin-, 16 sites were selected to evaluate the ability of indicators to discriminate condition. At each sample site, data and samples were collected within randomly located, 6-point, fixed-plot clusters. At one good and one bad site in each basin, two additional plot clusters were sampled to assess within-site variability. To meet objective three, several measurements related to each indictor were field tested to identify those that differed most between good and degraded wetlands. As an example, we made several measurements to quantify the amount of plant material present per unit area, which is a component of productivity and biological integrity in our conceptual framework. Plant measurements included stem height and diameter, percent cover, and dry weight. Comparison of these measurements will allow the selection of the most cost-effective (and non-destructive) method for the Phase II Pilot Study. In addition, some of the data will be used to calculate components of variance that are needed for evaluating indicator performance. Field work was conducted in September 1991 and data analysis initiated in FY92 (Phase I). Data collected during the pilot study are currently being analyzed. Results of analyses will be provided in an indicator evaluation report recommending research indicators. The overall research objective for Phase II of the pilot study is to determine which measurements derived from the FY91 salt marsh pilot can be used to quantify indicators of condition. We are attempting to answer the question: What indicators can distinguish good from degraded condition for estuarine emergents in the Gulf of Mexico? The measurements being tested relate to assessment questions, which will guide indicator development and, subsequently, will be used as the basis for assessing wetland condition (Table 2). 44 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands The specific objectives of the Pilot Phase II are to: 1) apply the best of the indicators developed in FY91 pilot to some of the same sites to begin to evaluate year to year variance component; 2) expand beyond the three basins used in the FY91 pilot to include as mubh of the Gulf of Mexico salt marshes as possible ; 3) add new indicators, such as macroinvertebrates (for biological integrity and productivity), that are related to the environmental values; 4) continue developing measurement protocols; 5) develop relationships between aerial imagery and ground-level data; and 6) examine index period variability in salt marshes. Indicators recommended in the Phase I Pilot Study indicator evaluation report and 2-3 additional research indicators selected in cooperation with National Oceanic and Atmospheric Administration (NOAA) and EMAP-Estuaries, will be tested. Research will be conducted along portions of the Gulf of Mexico (Texas to Florida) classified as salt marsh, within the constraints of logistics and funding. Approximately 25 of the FY91 sites that were classified correctly as "good" or "degraded" will be revisited in the same field season to estimate year to year variability. Approximately 50 sites will be selected to collect information from areas outside of the influence of the Mississippi River, and may include salt marshes from Texas to Florida. Some of these sites may be selected as reference sites. Approximately one half of these sites will be revisited once to estimate index period variability. Aerial imagery will be obtained at sample points to correlate landscape measurements with ground-level measurements. Aerial images will be used to determine the vegetation/open water ratio, biomass, and other landscape characteristics such as channelization. New indicators will be tested, including macroinvertebrate diversity and abundance and those Indicators that Integrate over time, such as sediment depth. The Phase II Pilot Study completes the indicator evaluation pilot study for salt marshes in the Gulf of Mexico. Additional sites beyond the influence of the Mississippi River Delta will provide information on population variability of the indicators. This study will also provide a broader understanding of appropriate measurements for salt marshes other than the Spartina alterniflora dominated systems of the Louisiana salt marshes. Through coordination with the NOAA's Coastal Change Analysis Program (C-CAP), the pilot study will develop relationships between EMAP ground-level measurements and satellite imagery. The pilot will also be coordinated with Utah State University and NOAA staff involved with the Videogrcphy Spectral Analysis 45 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands Project described in a later section. The Phase II research will provide probationary core indicators, candidate reference sites, and index variability. Probationary core indicators will provide the basis for a Regional Demonstration Research Plan. A Regional Demonstration Study will be conducted in the Gulf of Mexico region in FY94 using probationary core indicators identified in the Phase II research effort. The objectives of the Regional Demonstration are to demonstrate the ability of the indicators to describe condition of salt marshes in the Gulf of Mexico region and to identify logistic issues that arise using the probability-based sample design. Standardized measurement protocols will be identified for the core indicators that will be implemented in the monitoring program to make regional assessments. Regional Implementation is scheduled to begin in FY95, to allow the first estimates of condition in FY96 for the Gulf of Mexico. We will also begin to examine salt marsh indicators in other tidally influenced wetlands adjacent to salt marshes (e.g., brackish) during the regional implementation phase. The purpose of this effort is to evaluate the feasibility of estimating the condition of the entire estuarine wetland system. After initiating the program in the Gulf of Mexico, we plan to expand first to the Atlantic (FY96) and then to the Pacific (FY98) coasts with national implementation of estuarine emergent monitoring program by FY99. Indicators and measurement protocols that were successful in the Gulf of Mexico region and that are consistent with the conceptual model for a new region will be tested first in a Regional Demonstration. Pilot studies may be conducted in the new region for regionally-specific indicators. 46 ------- Draft 1.0 Conceptual Model for Estuarine Emergent Wetlands 5.0 LITERATURE CITED Adamus, P.R. and K. Brandt. 1990. Impacts on quality of inland wetlands of the United States: A survey of indicators, techniques, and applications of community-level biomonitoring data. U.S. Environmental Protection Agency, Environmental Research Laboratory, Corvallis, OR. Atwater, B.F. and C.W. Hedel. 1976. 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