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903R85003
841 Chestnut
Philadelphia,
ro
225
C54
984-5
1984
1985
-------
CONTENTS
Executive Summary 1
The Water Quality Base 3
Sediment & Toxics 8
Centerfold Map 12
Plankton & the Food Chain 14
Citizen Monitoring 17
SAV: Habitat & Nursery 18
The Harvest: Finfish 20
The Harvest: Shellfish 22
Case Study: The Patuxent 24
ACKNOWLEDGEMENTS
Executive Editor/Designer: B.G. Bandler
Designer/Production Coordinator/Illustrator:
Karen L Teramura
Editorial Assistants: Elizabeth C. Krome,
Catherine L. Leger.
Production Assistant: Karen L. McDonald
Illustration Assistant: Steven L. Coon.
Photos Skip Brown
CBP Monitoring Subcommittee Representative:
Bert Brun.
EPA Monitoring Coordinator 1984-1985:
Kent Mountford.
Chairman, CBP Monitoring Subcommittee:
William M. Eichbaum.
SYMBOLS
cfs cubic feet per second
DO dissolved oxygen
mgd million gallons per day
mg/l milligrams per liter (=ppm)
N nitrogen
P phosphorus
PAHs polynuclear aromatic
hydrocarbons
PCBs polychlorinated biphenyls
ppb parts per billion
ppm parts per million
ppt parts per thousand
SAV submerged aquatic vegetation
STP sewage treatment plant
TN total nitrogen
TP total phosphorus
TSS total suspended solids
u.g/1 micrograms per liter (=ppb)
u.m micrometer (=micron)
> more than
< less than
Monitoring is a key element in restoring the Chesapeake Bay. Monitoring
keeps managers, researchers, and citizens current on the health of the
Bay, and measures the progress of control strategies. Under the Chesapeake
Bay Agreement of 1983, the implementation Committee established a Monitoring
Subcommittee to develop and Implement a Bay-wide coordinated monitoring
program. The EPA/state cooperative program began in May, 1884 and afull
sampling network was in place on the mainstem Chesapeake by July.
The Chesapeake Bay Monitoring Network is a complex arrangement involving
the federal government, three states (Virginia, Maryland, and Pennsylvania) plus
the District of Columbia, three universities, seven private research institutions,
and more than 125 individuals. The network is comprised of 167 stations that
cover not only the mainstem Bay, but key portions of its 150 tributaries.
Nineteen physical, chemical, and biological parameters are being monitored 20
times a year.
Monitoring data can provide a sound scientific basis for making important
Bay program decisions. Monitoring data can serve environmental managers in a
wide variety of Bay restoration programs-living resources, soil and land
conservation, wastewater treatment, computer modeling-and in the legislative
process.
GLOSSARY
Algae
Bacteria
Baseline
Benthos
Biomass
Estuary
Fall line
Simplest of all aquatic plants.
Most important Bay algae are the
microscopic phytoplankton.
Single-celled micro- organisms
that usually lack chlorophyll.
In reference to data, the initial
measurements against which
later data are compared.
Plant and animal life whose
habitat is the bottom of a sea,
lake, or river.
Quantity (weight) of living matter
Highly productive bay and river
ecosystems where fresh water
meets salt water.
Nonpoint
Nutrient
pH
Zone where a major river changes
from free-flowing (inland
freshwater) to tidally affected
(coastal).
Food chain Feeding sequence from plankton
through higher predator
organisms
Inorganic Combinations of elements (such
as metals) that do not include
organic carbon; generally non-
volatile, not combustible, and not
biodegradable.
Monitoring Observing, tracking, or
measuring for a special purpose.
Nitrogen Essential nutrient; several forms
organic and inorganic (ammonia,
nitrate, nitrite); also atmospheric
gas. Expressed in mg/l
Applied to pollution source'
diffuse rather than point (pipe)
discharge, i.e. farm runoff
Primary element necessary for
the growth of living organisms,
generally applied to nitrogen and
phosphorus, but also carbon and
silicon. Excessive nutrient loads
result in eutrophication.
Measure of acidity or alkalinity
On a 0-14 scale, 7.0 denotes
neutrality, less than 7 acidity and
over 7 alkalinity.
Phosphorus Essential nutrient that occurs in
various forms: inorganic
(orthophosphate, pyrophosphate,
tripoly- phosphate), and organic
Minute plants and animals that
passively float or weakly swim in
water.
The total amount of dissolved
salts per 1,000 units of water
(PPt).
Newly attached juvenile oysters
Reproductive process in fish and
other aquatic animals.
Tidal river River under tidal
influence with a low saline and
upper freshwater reach.
MARCH 1987
Plankton
Salinity
Spat
Spawning
-------
903R85003
This second report from the Chesapeake Bay Program Monitoring Subcommittee
summarizes data collected at over 165 stations Bay-wide for the new coordinated
monitoring program from June 1984 through September 1985. This initial effort
represents the groundwork of a large, complex, and rapidly growing store of
information.
The challenge of the monitoring process should not be over simplified. Because
the Bay is so large and complex, it will take an estimated three to five years to sift out
the natural variability within a given year and between years in order to achieve a base-
line characterization of the Bay, and to understand the slow and subtle changes
resulting from management actions. Time and a consistent sampling program are
essential to meet monitoring objectives. The major objectives are to determine long-
term trends and the driving forces behind them, and to establish the link between water
quality and the health of the Bay's living resources. The monitoring program should
help to distinguish the effects on the Bay from natural events (like flows and salinities)
from man-induced pollutants (such as excessive nutrients). Management actions will
become increasingly focused as a result of this knowledge. The new program's
comprehensive, in-depth information on Bay processes is already being used to design
two water-quality models for the purpose of projecting how restoration programs can
achieve improvements in the Bay.
The first part of this report focuses on the physical-chemical characteristics of the
Bay: flows, salinity, dissolved oxygen, chlorophyll a, and nutrients (the water-quality
base) plus sediments and toxics. The centerfold offers a broad capsulated picture of the
monitoring network and the 1984-1985 Chesapeake. The second half of the
publication covers the Chesapeake's living resources, from plankton, the important
first link in the food chain, through submerged aquatic vegetation (SAV), and the Bay's
finfish and shellfish harvests. The 1984-1985 data summary concludes with the early
results of the citizen monitoring program and a look at the Patuxent River.
Background boxes to help define and put the summary observations in context have
been provided in each section. We suggest you read the boxes before the main text.
Please note that in addition to this 28-page summary report, a more detailed
compendium, composed of 19 chapters that focus on different aspects of the
monitoring program, is available.
The 1984-1985 monitoring period comprised two very different years, and the Bay
responded accordingly. Generally, 1984 was a wet year and 1985 a dry year.
Streamflow in 1984 was 23% above average, while in 1985 it was substantially below
average for the better part of the year. In November 1985, however, dry conditions
were punctuated by tropical storm Juan. Juan's effects were confined, for the most
part, to the lower Bay and had less impact than did "Agnes" in 1972. Flooding and
sediment loadings were extensive in Virginia's major tributaries. The data indicate that
there is some good news to report for SAV, waterfowl, and striped bass. SAV is one
of the bellwethers that led to the conclusion that the Bay was in decline. A 26%
increase in total SAV acreage from 1984 to 1985 is cause for optimism. This is a
hopeful sign for living resources, including the many Bay waterfowl that use SAV as
U.S. lid-, oii.nsntal Protection Agency
Region 111 Information Resource
Center (3PM52)
841 Chestnut Street
Philadelphia, PA 19107
-------
food and habitat. Many waterfowl species remain in trouble, but the populations of a
few species (mallard, bufflehead, and the Canada goose) have increased, presumably
due to their finding food sources other than SAV. The Maryland striped bass ban and
stringent harvest restrictions in Virginia, the Potomac River, and most coastal Atlantic
states appear to be protecting the relatively strong 1982 "rockfish" year-class. When
members of this year-class are adults and spawn (in 1988), it is hoped they will have
better water quality and that healthier year-classes will result. Generally, during 1984
and 1985 shellfish were still under stress. While higher oyster spatfalls were observed
in 1985, survival rates remained low. Harvests of the pugnacious blue-crab were gooc
in both years. While mainstem benthic animals suffer as the number of areas with
low summer oxygen levels increases, it is possible that wastewater treatment
improvements are helping some tributary clams to have more stable populations.
The monitoring results underscore the uniqueness of patterns within each Bay sub-
basin, and the importance of Bay-wide inter-relationships. Higher streamflows in 198<
brought large pulses of nutrients, which triggered heavy plankton growth, particularly
in the upper tidal-fresh reaches of the Potomac and Patuxent rivers. Dry 1985 broughi
higher salinities and, therefore, less clearly defined surface-to-bottom salinity
differences and some improvement in deep-water oxygen conditions. High salinity,
while conducive to better oyster spat production, encourages intrusion up-Bay of oyste
diseases, MSX and Dermo, and the predatory oyster drill. Higher than usual plankton
concentrations were noted during the monitoring period. High productivity appears to
result in high levels of unconsumed plankton, which die and settle in deep water wher
decomposition processes deplete oxygen. Both summers had periods of low oxygen
and anoxia, but the severity and duration of these periods were substantially greater in
1984 than in 1985. Surveys in 1984 found oxygen-poor waters extending further into
Virginia's Chesapeake than had been previously documented. Monitoring in both
summers revealed that hypoxia and deep-water dissolved oxygen (DO) concentrations
are more dynamic than previously expected, a finding that makes trend analysis of DC
very difficult. Toxicants data contribute to our understanding of what toxic substance;
are where, and the relationship among toxicants, fine-grained sediments, and the
benthic community. While there have been overall increases in toxics levels since
1979, there is less DDT. Future reports will benefit from a developing toxics strategy
and ongoing work to monitor organics and metals.
Has progress been made? While it is still too early to document that our control
programs are saving the Bay, it can be said that the 1984-1985 observations are
valuable and represent a solid start toward establishing a base-line characterization.
The first Bay-wide monitoring network, including nearly every tributary, is in place
and is designed to link water-quality monitoring with important habitat and living
resource monitoring. Communication and coordination now exist and have improved
within and among agencies at all levels. So, while the Bay's problems are still with
us, there is cause for modest optimism. Most important, there is a commitment to
the Bay-wide goal of restoring the Chesapeake.
-------
The Water Quality Base
quality because they influence
"" "
crtherpollutants tothe Bay. River
lighter (fresher) water flowing on top of
the h0avfcr$M$MQ wWer. fhtse
difference in salinity, or a stratification
increased:vertical mixing, which
and can i
of«teteS
'Pt0wa*e>$'ate^rAeii^r% Eastern
shore are saltier than western shore
waters because of both the greater
increases in freshwater flows.
organisms for their basic metabolic
processes. It enters the water from
organisms are stressed. Severe
'' ' "" '
); anoxia
Flows of the major tributaries into
the Bay have been monitored for many
years by the U.S. Geological Survey. As
an indication of the freshwater flow
conditions during the first 15 months of
the water quality monitoring program, the
1984-1985 flows can be compared to the
long-term average flow for the
Susquehanna River, which contributes
50% of the fresh water entering the
Chesapeake Bay.
Over the past 18 years, the average
flow of the Susquehanna River at
Conowingo Dam has been 41,950 cfs.
The average flows of the Susquehanna in
1984 were 19% above normal; in 1985
they were 27% below normal. There
were major seasonal differences between
these two years: the 1984 summer flows
were much higher than those in 1985.
The monthly average flows for the six
largest Bay tributaries during 1984 and
1985 are shown below.
River flow patterns in each Bay
tributary are unique because rainfall,
topography, land use, and other factors
differ between basins. For example,
Patuxent River 1984 and 1985 flows
differed from those of the Susquehanna.
Patuxent River flows in 1984 were close
to the long-term average as of that year
(421 cfs), whereas 1985 flows were 50%
below average. The James and
Rappahannock rivers, however,
experienced higher than normal flows
during 1984 (34% and 54%, respectively)
because of above-average winter and
summer discharge. Between the fall of
1984 and the fall of 1985, the James and
Rappahannock rivers experienced dry
conditions, with flows 20% and 35%
below normal, respectively. In
November 1985, tropical storm Juan
produced heavy rainfall in western and
southern Bay watersheds. While the
storm did not have much impact on the
Susquehanna, the Potomac and James
river basins were profoundly affected by
major floods. Because the Bay is so
large, a single broad characterization
cannot describe the response of an
individual sub-basin.
Mean monthly flows
o
• Potomac
A James
O
PamunHey
Mattaponi -•
J FMAMJJASONDJ FMAMJj A ^ C3 N tt
19S4 1985
Freshwater flows into the Bay from these six rivers represent about 90% of all tributary inputs. Flows in 1984
were substantially higher than in 1985. (Source: Maryland Office of Environmental Programs [MDOEP] and
Virginia State Water Control Board[VA SWCB]) Pamunkey and Mattaponi are tributaries to the York River
-------
Depth
I I
Dissolved
oxygen
(mg/l)
1984
39°
38°
37" Latitude
Dissolved
oxygen
(mg/l)
1985
Susquehanna Bay
River Bridge
Potomac
River
Mouth of
the Bay
Susquehanna Bay
River Bridge
Potomac
River
Mouth of
the Bay
t t
t t
Salinity and DO patterns differ from year to year. The bold line represents the bottom of the mainstem, the thin lines represent either averaged salinity (ppt) or DO
(mg/l) values at various depths. Salinity: the lower numbers in high-How 1984 reveal that much of the Bay experienced lower salinities in 1984 than in 1985.
Dissolved oxygen: low DO values were more extensive in high-flow 1984 and were further down-Bay. {Source: MD OEP and VA SWCB)
Salinities were higher and the
vertical salinity gradient was less
pronounced in the lower-flow summer of
1985. In the deep-trough region of the
mainstem, salinities were higher in 1985
than in 1984: surface salinities were
approximately 6 ppt higher and bottom
salinities were about 3 ppt higher.
Similarly, in the Patuxent estuary,
salinities were 4 to 7 ppt higher and
stratification was reduced in 1985
compared to 1984. In the Rappahannock
River, the same pattern of increased
salinity and decreased stratification can be
observed for 1985 relative to 1984.
Stratification differences between the two
summers are reflected in bottom-water
oxygen concentrations.
Dissolved oxygen levels are high
throughout much of the year, in months
when water temperatures are low and the
water column is well mixed. In the late
spring and summer, however, high
oxygen demand in the sediment and the
rain of organics into the lower water
column, coupled with limited downward
Stratification is the layering of the estuary
waters: freshwater stream/lows andseawater
intrusion form two wedges of water going in
opposite directions. The lighter (fresher) water
flows on top of the heavier (saltier) water. These
wedges create surface-to-bottom differences in
salinity that significantly influence life and
conditions in the Bay.
Stratification is strongest where the two
wedges meet, and when river Hows are high.
When stratification is strong, there is little mixing
between surface and bottom waters.
Stratification is weakest at the sources of the
wedges—the rivers and the ocean—and when
flows are low. When stratification is weak,
vertical mixing in the water column increases.
The maximum turbidity zone is an area where
resuspension of bottom sediments is high. It is
located at the upstream boundary of the saltwater
wedge. (Source: MD OEP and VA SWCB)
Maximum turbidity
zone
Fresh water.
river runoff
e ™*»»* '***** * •v V* *," *.4 ?*'
mixing of oxygen, cause the depletion of
oxygen in deeper waters.
Much has been written about the
phenomenon of low dissolved oxygen in
the Bay's deep waters. Recent research
efforts by numerous investigators are
likely to shed additional light on the
complex processes that cause, sustain,
and interrupt anoxic and hypoxic
conditions in this region. The increased
temporal and spatial sampling in the
current monitoring program is making
major contributions to understanding the
Bay's oxygen.
Strongly defined layers of water
(stratification) have a significant influenc
on the DO characteristics of the estuary.
Stratification inhibits the mixing of
surface and bottom waters, and permits
high oxygen demands from sediment anc
the water column to deplete oxygen in th
isolated, deeper water. Higher than
average flows resulted in more
pronounced vertical salinity gradients in
the mainstem in the summer of 1984
than in the summer of 1985.
-------
Averaged longitudinal DO profiles for
the summers of 1984 and 1985 (shown
on page 4) demonstrate that high flow
permits more extensive regions of low
DO. Oxygen conditions for comparable
salinity regions in the Bay's mainstem
and its major tributaries were similar.
Mainstem
In the mainstem there were several
differences between the two years,
especially in the spatial extent of hypoxic
waters (DO of <1.0 mg/1). In 1984
hypoxic water extended well into
Virginia's portion of the Bay, reaching as
far south as the mouth of the
Rappahannock River. This did not
happen in 1985, when winds and tides
caused more frequent re-oxygenation
events and reduced the duration of anoxic
conditions that summer.
The summer 1984-1985 monitoring
results have shown that mainstem deep-
water dissolved oxygen concentrations are
more dynamic than previously expected.
Even during the summer of 1984, when
density stratification was unusually
strong, two major re-aeration events were
documented in the deep-trough region,
one in early July and one in early August.
At least two re-aeration events were also
documented during the summer of 1985.
This means caution must be used when
comparing current data with data from
cruises in past years.
Tributaries
In the Rappahannock River the clearly
defined stratification in the summer of
1984 appeared to have effects on bottom-
water dissolved oxygen concentrations
similar to those observed in the
mainstem: summer DO depletion was
severe and prolonged. In the Patuxent
River, on the other hand, the effects on
dissolved oxygen levels from the
difference in stratification between the
summers of 1984 and 1985 were not as
clearcut as the effects on the mainstem.
The observed differences between oxygen
behavior of the Patuxent and that of the
Bay indicate that factors other than
salinity stratification influence DO
conditions. Topography, localized storm
events, periodic exchanges with mainstem
waters, and the biological impacts of
nutrient loadings—conditions unique to
each basin-can also affect dissolved
oxygen concentrations.
Chlorophylls are a group of green photosynthetic pigments that occur
primarily within plant cells. Chlorophyll-a is the most important of the principal
photosynthetic pigments. It is responsible for the green color in plants.
Chlorophyll-a provides a measure of phytoplankton biomass levels, and is
expressed in micrograms per liter (^g/l). Plankton and chlorophyll levels vary
in the mainstem and tributaries; levels depend on season, nutrient availability,
salinity range, and depth, and are influenced by external physical conditions
such as river flow, sediment load, sunlight, and grazing of phytoplankton by
zooplankton. As yet, there is no general agreement among scientists on
target levels for chlorophyll-a. A chlorophyll-a level of 100 |j.g/l is usually
cause for concern, however.
Latitude •% 37WIWtcf;so''5
Susqueharma River 39°35' Potomac River 38° J «a
198*
Bay Bridge
Patuxent River
39°
38°18'
Mouth of
the Bay
37°
Chlorophyll-a (chl-a ) levels indicate phytoplankton concentrations. These graphics show surface water chl-a
peaks near the Bay Bridge and just below the Potomac's mouth during summer 1984 and February-May 1985. In
bottom waters, chl-a levels were low in summer, but peaked in the winter/spring of 1985. (Source: MD OEP and
VA SWCB)
Chlorophyll is found at the highest
levels in the tidal-fresh portions of the
tributaries from spring to early fall.
Plankton growth follows tributary
enrichment by nutrient-laden spring
flows. The mainstem's higher
concentrations occur in the late winter and
spring. The die-off and settling of this
large pool of organic matter probably
contributes to the spring oxygen demand
in both the water column and sediments;
this demand leads to the development of
summer deep-trough hypoxia/anoxia in
the mainstem.
Tributaries
Chlorophyll patterns in the tributaries
were similar in 1984-1985. The highest
chlorophyll levels in the tributaries were
observed in the warmer seasons above the
maximum turbidity zones; in the cooler
months the higher chlorophyll levels
were found below the maximum turbidity
zone. Generally, the nutrient-rich upper
reaches of the Patuxent and Potomac had
higher chlorophyll concentrations than
those of the James or Rappahannock.
The Patuxent had the highest chlorophyll
levels of all the major tributaries.
The lower Potomac estuary
experienced average chlorophyll values of
40 mg/1 during spring 1985, with a peak
in May of over 90 u:g/l. Summer 1985
chlorophyll levels peaked at unwelcome
levels of 100 (ig/1 in the tidal-fresh
reaches of both the Patuxent and Potomac
rivers.
The peak chlorophyll concentrations
in the tidal-fresh regions of the James and
-------
Rappahannock were 20-50 |ig/l and 20-40
|4.g/l, respectively, with levels decreasing
downstream to below 10 (J.g/1 near the
river mouths.
Mainstem
In general, the upper Bay mainstem
had higher chlorophyll levels than those
found in the central and lower Bay
mainstem; the lowest levels were found at
the Bay's mouth. The higher upper
mainstem levels are largely the result of
the greater availability of nutrients from
the Susquehanna River and other upper
Bay loadings.
Chlorophyll levels had strong
seasonal patterns with pronounced
differences between mainstem surface and
Q bottom waters. During the late winter of
1984-1985 and the spring of 1985, a large
region of high chlorophyll (30-40 u,g/l)
was observed in bottom waters. During
summer hypoxia, bottom chlorophyll
was very low (under 5 fig/1). During
summer sporadic peaks of surface
phytoplankton growth (30-50 u.g/1) could
be seen, chiefly in the central and upper
Bay. In the lower Bay toward the York
River generally surface phytoplankton
chlorophyll was low (5-15 Mg/1).
Nutrients are a major focus of the
Bay restoration program. While light,
temperature, plankton grazing, and
Nitrogen (N) and phosphorus (P)
are essential to plant photosynthesis
and growth. These nutrients are
supplied to the Bay from land runoff,
the atmosphere, fertilizers and STP
discharges. Nonpoint sources supply
significant amounts of N (and in some
tributaries, P); point sources are the
major sources of P.
The Bay and its living resources
once assimilated additional nutrients
from man's activities, but we have
exceeded the Bay's capacity and now
have undesirable phytoplankton levels
in some areas. The death and
decomposition of these algal plants
contributes to dissolved-oxygen
depletion. Over the last several
decades, nutrient levels have
increased in many parts of the Bay,
particularly in the upper, low-salinity
reaches of almost all western
tributaries.
Sediment plays a significant role in
nutrient transport and deposition,
adsorbing both N and P, but primarily
P. It is believed that there are large N
and P reserves in bottom sediments
and that, especially during the warmer
months, substantial amounts of these
nutrients are released from the
sediments back into the water column.
Such releases can contribute to algal
growth.
mixing in the water column play roles in
plant productivity, the levels of nitrogen
(N) and phosphorus (P) are the key
elements in the undesirable Bay over-
enrichment.
Nitrogen: Between July 1984 and
September 1985, levels of total nitrogen
(TN) in mainstem surface waters ranged
between 1 and 2 mg/1 at the head of the
Bay, and from 0.4 to 0.7 mg/1 in the
lower Bay. The higher upper Bay levels
reflect the strong influence of
Susquehanna River inputs. In summer
months, bottom-water concentrations of
inorganic N (and P) are high but surface-
water concentrations are generally low.
Values of TN were higher (generally
at or above 2 mg/1) in the tidal-fresh
regions of the Patuxent and Potomac
rivers than in the upper Bay mainstem. In
the tidal-fresh portions of the
Rappahannock and James, however, TN
levels were comparable to those found at
the mainstem head. In all the tributaries,
TN declined somewhat in the salinity
transition zones, and declined further in
the lower estuaries to levels around
0.5-1.0 mg/1.
The nitrogen enrichment found in the
tidal-fresh regions of the tributaries is the
result of both nonpoint and point-source
impacts. Peaks in N during winter and
Total nitrogen
(mg/1)
2.00
1.33
Nitrates
(mg/1)
Latitude
Susquehanna River Mouth C39°35'), Bay Bridge C39°), Patuxent River Mouth C38°18'), Potomac River Mouth (38°) Mouth of the Bay (37°)
Nutrient levels in the mainstem Bay in 1984-1985 are shown in these three graphics. The first two graphics look different, but are similar: the nitrate values shown in
the middle make up a large portion of the total nitrogen values shown on the left. Highest nitrogen levels are up-Bay. Phosphate levels on the bottom of the Bay are
generally low except during the warm months, when bottom waters become low in oxygen and phosphate is released from the sediments. (Source: MD OEPand VA
SWCB)
-------
spring high-flow periods can be attributed
primarily to high nonpoint source loads.
Phosphorus: The pattern of total
phosphorus (TP) concentrations is similar
to that for nitrogen, but not quite as
clearly defined. In mainstem surface
waters, TP peaked in the turbidity
maximum region at about 0.05 to 0.08
mg/1 and declined down-Bay to levels
generally less than 0.04 mg/1.
During summer hypoxia in the deep-
trough region, P fluxes from the
sediments into the overlying waters (see
pg. 18). As with the bottom-water
accumulation of inorganic N, these higher
P levels may nourish summer algal
populations when and where vertical
mixing occurs.
Tributary TP levels in 1984-1985
reveal differences between rivers. The
Patuxent River had the highest TP levels
of the four major tributaries, with levels
in the tidal-fresh, transition, and lower
estuarine zones approximately 0.30-0.35,
0.25, and 0.1 mg/1, respectively. The
Potomac and James rivers had similar TP
levels of approximately 0.15, 0.1-0.2,
and 0.05-0.010 mg/1 in tidal-fresh,
transition, and lower estuarine reaches,
respectively. The lowest TP values were
found in the Rappahannock River, and
were approximately 0.05-0.10, 0.05-0.10
and 0.03-0.05 mg/1 in the tidal-fresh,
transition, and lower estuarine zones,
respectively. TP showed surprisingly
little seasonal variation.
2.0
Mean total nitrogen (mg/1)
25
Mean total phosphorus (mg/1)
32
CD Tidal fresh
Patuxent Potomac
River River
Average total nitrogen and phosphorus
concentrations in lour important Bay tributaries,
July 1984-September 1985. (Source: MDOEP
andVASWCB)
The Susquehanna, Potomac and James
rivers are the three largest rivers
discharging to the Bay. Together these
three rivers represent 84% of the
freshwater flow. The exact proportion of
the total river input load represented by
these three rivers must be determined by
extrapolation of the monitoring data to
cover unmonitored portions of the
Chesapeake Bay watershed. Methods of
extrapolation range from simple flow-
base techniques to sophisticated watershed
computer models.
Based on the monitoring data, it is
apparent that a simple flow-based
extrapolation would not be very accurate.
Considering only the flow and nutrient
loads for 1984 and 1985 it is clear that, of
these three rivers, the Susquehanna was
the major contributor of flow and
nutrients to the Bay. However, during
the monitoring period, the Susquehanna's
nutrient loadings (66% TN and 42% TP)
were not in proportion to its flow (63%).
If a simple flow-based extrapolation were
used as an estimate for TP loads for the
Susquehanna, a 21% over-estimate would
result. Important factors unique to each
watershed (topography, soils, land use,
population density, etc.) also influence
the magnitude of the loads delivered to the
estuary and must be taken into account in
order to produce an accurate estimate of
nutrient loads.
Nevertheless, the strong influence of
changing river flows on nutrient loads is
clearly evident in both the long-term
record of annual loads and in the seasonal
loads calculated from the 1984-1985
monitoring data. In years and seasons
when river flow is high, nutrient loads are
also high. For example, approximately
80% of the flow and nutrient loads
delivered to the estuary by the
Susquehanna and Potomac in 1984 came
in the winter and spring. D
Mean annual flow
Annual load of total nitrogen
Annual load of total phosphorus
thousands of kilograms per day
60
thousands of kilograms per day
400
thousands of cubic feet per second
1978 79 80 81 82 83 84 85
1978 79 80 81 82 83 84 85
1978 79 80 81 82 83 84 85
Annual flows and nutrient loadings for the Susquehanna and Potomac rivers between 1978-1985 are compared above. The Susquehanna is the largest Bay tributary.
In 1984-1985, it contributed 63% of the freshwater flows to the Bay, and 66% of TN and 42% of TP. The Potomac's nutrient contributions are proportionately higher
than its Hows. Approximately 80% of the flows and nutrient loadings delivered to the Bay's mainstem by the Susquehanna and the Potomac in high-How 1984 were
delivered in the spring. (Source: MDOEP andVASWCB)
-------
Sediments & Toxics
8
Measuring Turbidity, or determining
the amount of suspended solids in the
Bay's water column, is important.
Turbidity can indicate conditions
detrimental to aquatic life. Two
methods used to measure turbidity
are: (1) visibility measurement with a
Secchi disk; (2) measurement of total
suspended solids (TSS). Higher
Secchi depth readings mean lower
turbidity; higher TSS values mean
higher turbidity. Measurements by
Secchi disk are made by simply
lowering the disk into the water and
recording the limit of visibility. Bay
Secchi depths generally range from
over 3 meters (clearer waters in the
winter) down to less than 1 meter (over-
enriched waters, usually in the
summer). In the tributaries and
mainstem, Secchi readings can drop
to as low as 0.1 meter following
storms. TSS is determined by
weighing the material filtered from a
known volume of water. The American
Fisheries Society has recommended a
TSS criterion of 100 mg/l (maximum)
for the prevention of mortality to fish,
zooplankton, and benthic animals.
SEDIMENTS
Mainstem
Monitoring in 1984-1985 confirmed a
strong north-to-south turbidity gradient in
the mainstem. Generally, turbidity is
high in the upper Bay because of the
Susquehanna's heavy flows and the
turbidity maximum zone; it decreases
gradually toward the Potomac's mouth.
The maximum turbidity zone in the
Bay proper occurs up-Bay of Baltimore
near Aberdeen, Md. Monitoring of this
area revealed typically low Secchi depths
(between 0.2 and 0.5 meters) and high
TSS values (between 15 and 25 mg/l).
Turbidity decreases gradually down-Bay,
to a point just above the Potomac's
mouth. Here the Secchi depths were
higher (from 1 to 3 meters) and the TSS
values lower (from 5 to 10 mg/l).
In the central Bay, from the Potomac's
mouth to that of the Rappahannock, there
is sometimes an increase in turbidity.
Here the Secchi depths in 1984-1985 were
between 0.9 and 2.9, and the TSS values
ranged from 10 to 40 mg/l.
From the Rappahannock to the Bay's
mouth the waters again become clearer.
Here Secchi disk readings ranged from 1
to 3 meters, and TSS values ranged from
5 to 15 mg/l. At the Bay's mouth
turbidity is lowest.
Lower Bay western shore waters are
generally more turbid than those along
the eastern shore: the earth's rotation
causes relatively clear oceanic water to be
deflected eastward as tidal currents move
up-Bay, and substantial quantities of more
turbid water are added by the discharges
from western Bay tributaries. These
show up as localized peaks in the lower
Buy in the Secchi depth graphic.
Tributaries
Between their turbidity maximum
zones and their confluence with the Bay,
the tributaries have turbidity and TSS
patterns comparable to those in the Bay
proper. Unlike the main Bay, however,
tributaries like the Patuxent, Potomac,
and James have large stretches of tidal
freshwater, where extensive high-turbidity
areas can result not only from re-
suspended sediment but also from algal
blooms.
The Susquehanna's sediment loadings
(an average of 1.8 million tons annually)
strongly track with river flow and are
delivered directly into the mainstem. In
wetter periods, typically winter and
spring, sediment loads are much higher
than in the summer and fall, when flows
are generally lower. The Susquehanna is
unusual because several reservoirs trap
sediment, at least temporarily, and
moderate loadings. The result is that the
sediment contribution of the Susquehanna
River to the Bay is often proportionately
lower than its flows.
The Patuxent contributes only 0.5%
of the Bay's freshwater flows, but its
sediment loadings are proportionately
higher than its flows. In the Patuxent's
maximum turbidity zone (in the vicinity
of Lower Marlboro), spring TSS peaks
exceeded 80 mg/l. This high turbidity
results not only from loadings, but also
from the natural bottom-to-surface
mixing in the water column. Secchi
depths of 0.2 meters and less were
observed in the 1984-85 monitoring
period. In the lower Patuxent the waters
become comparable to those of the
mainstem at its confluence.
The Potomac is the second largest
contributor of freshwater to the Bay but
contributes proportionately the most
sediment to the Chesapeake system. An
estimated 1.5 million tons are discharged
at the fall line in an average year. Most
of this sediment remains in the upper and
mid-estuary (there is a small net transport
of 1% from the main Bay into the lower
Potomac).
The Potomac's sediment loadings in
1984 and 1985 were 22% and 126%
higher than average. The higher figure
for 1985 reflects the effect of tropical
storm Juan: approximately 1,134,000
tons of sediment was discharged from the
upper Potomac basin in November alone.
The average Secchi disk readings for
the Potomac in Washington, D.C. (where
algal blooms also contribute to the river's
turbidity), ranged from just over 1.1
meters down to 0.6 meters in 1985.
Most of the heavily sediment-laden
Anacostia within the District of
Columbia had Secchi depth readings less
than 0.3 meters.
The share of the total sediment
loadings into the Bay from Virginia's
James River is 16%. The upper reaches
of both the James and the Rappahannock
have comparable Secchi depths (0.6 m),
and both show a steady decrease in
turbidity from their tidal freshwater
portions to their mouths. Their lower
estuarine zones show a marked difference
however. The James carries a heavier
load of TSS than the Rappahannock (13.3
mg/l and 5.5 mg/l at the fall line,
respectively), and tends to remain turbid
longer. The average Secchi reading in the
lower James ranges from 0.9 to 1.4
meters, while the readings in the lower
Rappahannock generally range from 1.4
to 1.8 meters.
The James and the Rappahannock
experienced higher than normal flows in
1984: 34% and 54%, respectively.
Between the fall of 1984 and October
1985 both rivers experienced dry
conditions. The flow of the James was
20% below normal; the Rappahannock
flows were 35% below normal. The
James was significantly affected by
tropical storm Juan.
-------
Turbidity
Secchi
depth (m
4.5
Latitude
Susquehanna River 39°35'
Bay Bridge 39°
Patuxent River 38° 18'
Potomac River 38
37°
Mouth of
the Bay
Secchi depth readings can be converted to a relative
measure of turbidity, or a picture of the lack of water
clarity in the Bay. Turbidity can indicate conditions
detrimental to aquatic life. This graphic shows the
turbidity profile in the Bay's mainstem in 1984 and
1985. The higher values in the graphic indicate higher
turbidity (and lower Secchi depths). Shown is how
spring high flows affect turbidity, especially in the
upper mainstem. Most of the turbid water is near the
Bay Bridge in the area of heavy inflows from the
Susquehanna and other upper Bay tributaries. The
highest turbidity was in the upper Bay during the
summer of 1984 and the winter/spring of 1985 during
periods of Susquehanna River high flows. (Source:
MDOEPandVASWCB)
|flth^flew-*rwlfl'i§nwd*Q :: .§ ThaarrniwI^etffnffrtiisontiiH^ns
. reach the sea, the Bay's rivers (at the fall line) from the Susquehanna,
^.-^•^f'ii^a^^f'. Those*
after these waters have left the Bay, toadings reveal that the sediment
the fine-grained, mostly inorganic _ X: contributions of the three rivers are .
that they have transported remain, '"^£ flows. For example, while the Potomac
suspended in the Chesapeake's water contributes W*£(tftim annual f tow to '
or^W Bay d^nrtfi we «HW roi^Ni , The flow p«it^^«aiehi-B^
for photosynthesis, changes the
and carries unwelcome trave
as excess nutrients and toxic
largest contributor of freshwater (50%) estuary was 238 t
' year of 1930, whereas 4,160,000 tons
~' '
Nonpoint sources
farm & urban runoff
groundwater runoff
(S+N+T)
Atmosphere (N+T)
Lighter freshwater
- Point sources
sewage treatement
plants (N+T)
Fresh-saltwater transition
[maximum turbidity zone)
The complex relationship between sediment, nutrients, and toxics and their pathways is simplified in this illustration. The atmosphere contributes toxics to the Bay, but
the majority of toxics are introduced into the Bay system along with nutrients from both point and nonpoint sources. Sediments, particularly fine-grained sediments, can
adsorb, transport, store, and release both toxics and nutrients. Toxics and nutrients can pass up the food chain, be held in suspension, or be stored in bottom sediments
for later release. (Source: NOAA/National Status and Trends, MD OEP, VA SWCB and Virginia Institute of Marine Science [VIMS])
-------
Some 66,000 chemicals are being
used in t» O.S, of which 60,000
have been classified by EPA as potentially
if not definitely hazardous. It is not
surprising , therefore, that toxic substances
are found in Bay water and sediments. The
Chesapeake Bay Program found the levels
of both organic compounds and heavy
metals to be unnaturally, sometimes
atermfagly l»igh»'parleulaity aiound urban
areas such as Baltimore and
NorfolWHamplon Roads. In Patapseo River
(BafflmoreJ stdhnenfe. metal
concentrations as high as 140 times natural
background levels have been found.
Wh i le not cu rren By a serious th real,
toxicants are being found in the tissue of
the Chesapeake's living resources. The
compounds of greatest concern are metals
such as cadmtott, chromium, copper, zinc,
lead, nickel ; complex organic chemicals
such as polphfcwtRated Mphanyls (PC Be),
chlordane, Kepone, polyaromatic
hydrocarbons {PAHs), arid DDT; and other
chemicals such as chlorine. Limited
studies of ambient levels of highly toxic
tributyltin (used in boat anti-fouling paint)
began In HiSat several harbor sites Bay-
wide; results are expected fay spring of
Low concentrations of these toxic
compounds imy hawltte immediate
effect on organisms, but long-term low-
dosage exposure is not well understood.
I ncreas ingly higher concentrations of toxic
compounds cause reduced fish
reproduction, deformities, and abnormal
behavior; they nay exacerbate disease
effects and cause eventual mortalities.
Toxicants can cause an imbalance in
species; they can be accumulated by
organisms that reach tie family dinner
To xic materials enter fee Bay system
turner plante), and nonpotat sources (urban
and agricultural runoff, dump sites, and tt»
atmosphere). The major toxicant
TartspotB* Is fte Bay system are the
Ifeabelh Rtorand SaMmere Hartxsr
(PsJapseofliwierj. Theaiajortlbuiarfes
also contribute toxic loadings.
TheOty estimated that over 800,000
metric tons of 13 metals enter the Gay from
The toa
-------
Polynuclear aromatic hydrocarbons
(PAHs): Studies elsewhere have
associated sediment contamination by
PAHs with occurrences of serious
histopathological cancers such as
cancerous lesions in fish. Although
disorders of this kind were not observed in
Bay croaker and spot, occurrences of other
types of lesions were correlated with
concentrations of total PAHs in sediment.
Metals: Sample sites in the upper
Bay yielded consistently higher levels of
metals in oyster tissue man sites in the
central and lower Bay. The relative roles
of contamination and natural processes
(availability of metals increases in fresh
water) have not been determined. D
Sediments bind metals and
organics just as they do nutrients,
transporting them to the Bay system
from the rivers and land runoff, and
then retaining them on the bottom of
the Bay. More than 60% of the total
input into the Bay of iron, manganese,
nickel, lead, and zinc is held in the bed
sediments.
The ability of sediment to bind and
store chemicals is related to the size
of sediment particles. Fine-grained
sediments have a relatively higher
surface area per unit mass than do
more coarse-grained ones. Therefore,
with all other factors being equal,
those chemicals that associate with
surfaces will be more concentrated in
fine-grained sediments. Fine-grained
sediments usually contain a higher
proportion of naturally occurring
organic matter. Thus, chemicals that
combine with these natural organics
are more abundant in fine-grained
sediments. Also, fine-grained
sediments have higher concentrations
of metals.
The natural variability of the
contaminants in the system, seasonal
cycling of pollutants within sediments,
and the pathways by which these
toxics go from sediment to the Bay's
living resources are processes not
fully understood.
Monitoring lor toxicants has been conducted at 87
stations along the mainstem of the Chesapeake Bay
and in the Maryland tributaries. (Sources: VIMS, MD
OEP, andNOAA)
Chesapeake
Toxicant Monitoring
Stations
11
VIRGINIA
O SetMmentand organic
monitoring stations
MARYLAND
Sediment or§aotes tOKtes
heavy metaf rojnitQrina. stations
Bioaccumulation and sediment
organic toxics ntonitorfnf sfatteftf
National Status'artd Tr«nd& Pteflrurn „ , -
. Chesapeake Bay mussel Watch Stations , ftf
A Chesapeake Bay benthic surveillance stations
-------
-------
-------
Plankton & The Food Chain
14
They form a vast array of several
hyrui red -species with such
unfamiliar names as dinoflagellates,
* pinhead measures 2,000 |j.m across-
and invisible to the unaided eye, or as
large as a jellyfish. Millions of them
can te present In alter of water,
ThtWjaptwaif producers, teonsymers,
,~a«l form the flr# Holt of
and
interdependent food chain, and are
critical in assessing the slate of the
are
photosynthesis: they use sunlight,
carbon dioxide, water, dissolved
produce the carbohydrates on which
all life d epends. ' Most phytoplankton
serve as tin important food source,
take up carbon dioxide, and add
G3«^entoitiawat«ieslymrt Problems
develop when an overabundance erf
dominating, and a depletion of oxygen
as they die and decompose. Minute
phytoplankton tentatively identified as
cyanobacteria appear tjljettie most
Chesapeake Bay.
2o0$sntap ar elbe animal forms
of plankton. Like phytoplankton, they
are generally grouped according to
size, from the smallest to the largest:
m icrozooplankton (smaller than 200
(im), mesozoo plankton, (larger than
200 ^im) and macrozoopiankton (larger
Iftan 500 u,m). They are usually the
prime consumers of phytoplankton.
Zooplankton include certain types
of protozoans, rotifers, crustaceans,
fish and shellfish. These usually
cwerotiaiple tolntafe qre 0ft»cr!iieal
food for larval and juvenile (and some
Many fishes
Plankton and benthic monitoring
for the new cooperative Bay-wide program
was initiated in 1984-1985. This
program is an important advance toward
understanding the Chesapeake Bay.
Plankton were collected at 23 Bay
stations simultaneously with water-
quality data, allowing biological and
water-quality data to be examined
together. Benthic samples are collected at
86 stations.
Phytoplankton
The Bay is one of the most productive
estuaries in the world. It is not
surprising, therefore, that the 1984-1985
sampling revealed a continuous supply of
phytoplankton. Phytoplankton activity
is greater in the freshwater and transition
(0.5-5.0 ppt) zones of the Bay and its
tributaries where there are high nutrient
concentrations.
Maryland's 12-month sampling
revealed high productivity in the upper
freshwater portions of the Potomac and
Patuxent. The upper two freshwater and
transition stations in the mainstem Bay,
however, showed the lowest productivity.
This low production was at the mouth of
the Susquehanna, where high potential
productivity is inhibited by high
turbidity. The highest productivity in
Maryland's part of the Bay was found in
the mainstem (mesohaline zone, 5-18
ppt) near the Chesapeake Bay Bridge.
The seasonal pattern of phytoplankton
productivity in 1984-1985 was typical:
high late-summer productivity due to
longer days and warm waters; a fall peak
followed by low winter productivity; a
major spring peak following an influx of
nutrients with the spring freshwater
inflows.
Productivity and seasonal patterns for
the Potomac and Patuxent were similar.
The Patuxent, however, had higher and
more frequent peaks of productivity than
any other area sampled. Patuxent River
carbon fixation rates (a measure of
organic production) were 40% higher than
Bay rates, and chlorophyll-a values (a
measure of biomass) were 50%-200%
higher.
In terms of composition, diatoms
were dominant during the late-
winter/spring and fall blooms. Small
coccoid green cells (possibly
cyanobacteria) were numerically dominani
in the Bay in Maryland the rest of the
year. During 1984-1985, large quantities
of phytoplankton settled into deeper Bay
waters, where their decomposition would
further deplete oxygen in bottom water.
Virginia sampling of the mainstem
was limited to the three-month period
July-September 1985. The data indicate:
diverse population patterns with distinct
differences in phytoplankton composition
and concentrations between the central anc
lower Bay; significantly greater
abundances and diversity in the deeper
water layer; a greater diversity and
concentration of species near the Bay's
mouth.
Zooplankton
During 1984-1985, microzooplankton
were sampled in Maryland's portion of the
Bay, and mesozooplankton were sampled
in both Maryland and Virginia. As with
phytoplankton, higher zooplankton
biomass was found in the upper
freshwater and transition zones. Maryland
sampling revealed nothing surprising in
species composition, abundance, or
distribution: shrimp-like crustacean
copepods, Acartia and Eurytemora, were
the dominant zooplankters. In Virginia's
lower Bay, isolated and unexpected high
concentrations of copepods were found.
Zooplankton seasonal peaks occurred.
Coupled with phytoplankton growth,
there were spring and fall peaks, which
-------
Species of phytoplankton (left border)
and zooplankton (right border)
accompany other Bay inhabitants
(center) whose life cycles include both
benthic and planktonic forms.
Complete life cycles are shown for the
blue crab (Callinectes sapidus) and
sea nettle (Chrysaora quinquecirrha).
Other species shown include:
Phytoplankton
1 Cyanobacteria
2 Cylindrotheca closterium
3 Cyclotella meneghiana
4 Katodinium rotundatum
5 Ceratium lineatum
6 Skeletonema costatum
7 Rhizosolenia alata
8 Prorocentrum micans
9 Cryptomonas sp
10 Chaetoceros decipiens
11 Rhizosolenia fragilissima
12 Cyclotella striata
Zooplankton
13 Keratella cochlearis
14 Trochophore larva of oyster
15 Daphnia retrocurva (rare)
16 Bosmina longirostris
17 Alona affinis
18 Barnacle nauplius
19 Blue crab zoea
20 Trochophore larva of polychaete
21 Acartia clausi
22 Acartia tonsa
23 Podon polyphemoides
Benthos
24 Nereis succinea
25 Mya arenaria
15
-------
Millions of animals live on or
burrow in the bottom of Chesapeake
Bay. They are known collectively as
the "benthos." Because of their limited
mobility (worms, clams, shrimp, and
snails) or lack of mobility (oysters and
mussels), they are good indicators of
localized water quality. Some, such
as oysters, crabs, and clams, are
commercially valuable. The less
familiar worms, small crustaceans,
snails, and anemones are also
important. Benthic organisms form
one of the major intermediate links
between the primary producers
(phytoplankton) and the higher trophic
levels such as fish and waterfowl.
Their burrowing and feeding activities
are also important in the nutrient
cycles that control the Bay's
productivity. The benthic community
is not uniformly distributed over the
bottom. Salinity, sediment type, and
dissolved oxygen are the major
determinants in their distribution.
Currents, pollutants, diseases, and
predation further shape their
distribution and abundance. The
greatest benthic variety (some 150
species) occurs in the saltier waters of
the lower Bay.
were more pronounced in the less saline
waters. The monitoring results support
the concept of "coupling" between
phytoplankton and zooplankton: the
seasonal microzooplankton peaks
coincided with or followed by one month
the phytoplankton peaks; the
mesozooplankton peaks coincided with
the phytoplankton peaks during the
spring bloom, but at other times tracked
more closely microzooplankton
abundance. This phenomenon also
suggests that microzooplankton is an
important link between phytoplankton
and the larger mesozooplankton in the
food chain for much of the year.
Benthos
Over the last several decades, die
duration aai'extent of tow
-------
Citizen Monitoring
How Citizens Can Get Involved
•Join the annual hunt for submerged
aquatic vegetation;
• Learn how individuals can reduce
their contribution to pollution;
• Participate in activities to restore
and protect the Bay;
• As a member of an organization, set
up a water-quality monitoring project
for a local watershed.
CONTACT: Citizens Program for the Chesapeake
Bay, Inc., 6600 York Road, Baltimore, MD 21212;
or Kathleen Ellett, Citizen Monitoring Coordinator,
Chesapeake Bay Program, 410 Severn Avenue,
Annapolis, MD 21403.
A citizen volunteer monitoring
program was started in the summer of
1985 by the Citizens Program for the
Chesapeake Bay, Inc. (CPCB). The
program monitors the near-shore waters
of two major Chesapeake Bay tributaries,
the Patuxent and the James. The purpose
of this program is to demonstrate that
volunteers can collect reliable water-
quality data that will help managers detect
and assess long-term Bay ecological
trends for the near-shore habitat. This
pilot project will determine the
appropriateness of a larger, permanent
program.
Data are being collected at 19 sites on
the Patuxent and 16 sites on the James,
from the head of tide to the mouth. Five
surface water-quality factors are measured
weekly at each site: water temperature;
pH (using a color comparator kit);
turbidity (using a Secchi disk); dissolved
oxygen (using a micro-Winkler titration),
and salinity (using an hydrometer). In
addition, monitors record weather and
general ecological observations about the
site on the Data Collection Form. They
send this data to the program coordinator
at the Chesapeake Bay Program Liaison
Office for entry into the Bay Program
computer and subsequent periodic
analysis.
There are 37 participants in the
program. Of those who originally started
in the program, 81% are still monitoring.
The citizen monitors come from a variety
of backgrounds and professions-farmers,
students, housewives, teachers, scientists,
bureaucrats, retired military, and medical
professionals are monitors. All
volunteers attend a training session and an
annual workshop; they receive computer
printouts and plots of their data, plus a
newsletter. The newsletter, River Trends,
contains monitoring results, informative
articles, and sampling tips.
Results obtained so far indicate that
trained volunteers can collect quality-
controlled data. A comparison of citizen
data with data collected by the Virginia
Water Control Board on the James River
and by Maryland's Office of
Environmental Programs on the Patuxent
River shows similar results.
The first comparison was made for
four stations on each river where the state
had a station close to a citizen monitoring
site. The results of the comparison
showed that dissolved oxygen and Secchi
disk readings were in close agreement; pH
values were similar. Water temperatures
showed differences only during
extraordinarily hot weather when the
Citizen's Monitoring
Stations
Upper Marlboro1
• Richmond
WlllUmlburg
Citizen's Monitoring
Stations
f
shallower waters of the volunteer
monitoring stations warmed significantly.
Salinity values were comparable,
although the hydrometers consistently
read about 3 ppt higher than the
conductivity meters used by the state
agencies.
Volunteers have demonstrated their
ability and willingness to collect data on
short notice during and after such tropical
storms as Gloria and Juan, when state and
federal programs were less able to respond
quickly. Secchi disk depths recorded by
volunteers along the James River clearly
showed the increased river turbidity
following those two storms. In late
1985, citizens reported hypoxic/anoxic
conditions in the bottom waters of St.
Leonard's Creek, a tributary of the
Patuxent River. The main channel of the
Patuxent is known to have low dissolved-
oxygen levels in late summer, but low
D.O. levels had not been reported
previously in water as shallow as St.
Leonard's Creek (3-4 meters). The extent
and duration of this phenomenon was to
be explored in 1986.
CPCB began sponsoring a similar
program on the Conestoga River in
Lancaster County, Pennsylvania in the
fall of 1986. Similar projects have been
started in Maryland with the help of
CPCB: on Back Creek in Annapolis,
West River in Anne Arundel County, and
on the Choptank River on the Eastern
Shore.
17
-------
SAV
& Nursery
The restoration of submerged
aquatic vegetation {SAV} is a
Bay cleanup priority for mvsral
reasons, One reason is is high
primaiy productivity «*is high rate of
biomassaocwnylation,' in addition,
aquatic plants form an important (ink in
the food chain,, betwwn. nytrterfe In
thewstef eeJittMi and sediment, and
the animals. Many waterfowl are
'
food; Aquatic plants are also
s*aAif^fttWltrtt'fc%jic»s^te« as
species of commercially important fish
'
running" ol;#»
nitrogen and phosphorus. Seasonally,
SAV provides an important source of
' '
of
wry
Jnnmf
£»
Chesapeake Bay
submerged aquatic
vegetation (SAV), in
severe decline from
the late 1960s until
1984, showed an
overall increase of
26% (47,893 acres)
from 1984 to 1985.
The largest increase
was found mid-Bay,
N v along the Eastern
Shore. There was a slight decrease in the
upper Bay, and little change was observed
in the distribution and abundance of SAV
in the lower Bay. There has been some
slight improvement in the declining
numbers of migratory waterfowl,
especially in SAV-resurgent areas.
Upper Bay
There was a slight decrease of 4.5%
(7,472 acres) in the abundance of SAV in
the upper Bay zone, with declines revealed
in three of the four sections studied.
There was a 142% increase (259 acres) in
the sparsely vegetated Eastern Shore
section, principally along the Elk and
Sassafras rivers. More than half (66%) of
this zone's SAV is in the Susquehanna
Rats area, and this zone is dominated by
wildcelery, Eurasian watermilfoil, and
hydrilla. Redhead grass and widgeongrass
dominate in the Eastern Shore area.
Middle Bay
The 1985 SAV "good news" was the
increase in grasses in all sections of the
middle Bay zone over the previous year,
resulting in a 389% increase (12,315
acres) for the entire zone. Even the
Patuxent River, while still sparsely
vegetated, showed a 401% increase (22
acres in 1984 to 109 acres in 1985). In
the Potomac River, increases were seen in
both the upper and lower sections, 140%
(3,557 acres) and 59% (941 acres)
respectively. Ten species of Bay grasses
were found in the upper Potomac section,
with Eurasian watermilfoil and hydrilla
the most prevalent. Widgeongrass was
found to be the dominant aquatic plant in
the mainstem of the middle Bay zone.
Lower Bay
There were no major changes in SAV
in the nine sections of the lower Bay zone
between 1984 and 1985. The largest
change occurred in the Reedville section,
where the 1985 survey revealed a decrease
of 34% (425 acres) in SAV distribution
from 1984. Most of the Bay's grasses
(59%) are in the lower Bay zone, with
68% of this zone's vegetation located
along the Eastern Shore bay side. Bay
grasses are still absent in two of the six
areas of historical abundance in the lower
bay. Widgeongrass and eelgrass are the
dominant SAV in the lower Bay. D
Analysis of surveys of Bay waterfowl over 39 years (1948-1986) by the
U.S. Fish & Wildlife Service reveals that the overall long-term average
population of Bay waterfowl during January is 1 million birds. The average
for the 1980s is also 1 million birds, but the species composition reflects
major changes. Of the thirteen species of waterfowl studied, only three had
higher population averages in the 1980s than in the 1948-1979 period. The
mallard and bufflehead have shown population increases of 16% and 17%,
respectively. Canada goose populations have shown a more dramatic
increase of 75% (apparently due to their finding food sources other than
SAV). All other species, however, have shown significant declines. The
declines in canvasback and redhead duck populations appear to be directly
related to the degradation of waterfowl habitat in the Bay. A balanced mix
of waterfowl species is not likely unless the Bay's SAV beds recover.
-------
77°iOO'
Kilometers
0 10 20 30 40 BALTIMORE
WASHINGTON
^ ' ~*" DC
Chesapeake Bay, '*-
submerged *xS;v£
aquatic
vegetation
monitoring zones
SAV
Thousands
of acres
75
50
25
0
Thousands of acres
150
100
50
*
0~
tf?
55
&
s?
^•tf
£*
1
ft£-
v*-
i*
1950 1985
—
1978 1984 1985
SAV Beds
aerial view
U1985
No growth
in 1984
Barren Island Pt
19
-------
The Harvest: Finfi
20
The esteemed striped bass, or
"rockfish," can live more than 30
years and can grow to a great size While
the usual maximum size has been 60
pounds in recent years, rockfish weighing
over 100 pounds were recorded in the late
1800s, and have been occasionally
reported in recent years.
In its native range along the Atlantic
Coast, the striped bass spawns from
February through July. In the Chesapeake,
spawning generally occurs from late April
through May. Rockfish spawn in fresh or
nearly fresh water, normally in the upper
tidal reaches of all major Bay tributaries.
The Chesapeake is regarded as the center
of abundance for the species, and
historically its migratory stocks have been
considered the major source for the Atlantic
Coast harvests. In the 1970s, when
rockfish stocks were larger, it was
estimated that the Chesapeake stock
contributed 90% to the Atlantic Coast
striped bass harvests. With reduced Bay
stocks, the current contribution would
appear to average between 50% and 70%
Abundance, health, and conditions of
Chesapeake stocks are therefore critical to
the entire Atlantic fishery.
The trend of decreasing numbers of
harvestable anadromous fish (estuarine or
marine fish that spawn in freshwater),
showed no change in 1984-1985.
Anadromous fish spawning results remain
poor, and abundance of juveniles low.
There is some optimism, however: the
most important anadromous fish, the
striped bass, or "rockfish," appears to be
benefiting from recent protective
regulations, and hatchery-release programs
have been initiated. Also, more data
about striped bass are now being collected
in the upper Potomac River, a significant
striped bass spawning ground. An
excellent intermittent data base exists on
striped bass spawning in the upper
Potomac. There has been a lack of
information, however, on juveniles and
adult fish in the river's reach in the
nation's capital. The new data collection
program initiated by the District of
Columbia in 1985 will rectify this.
Also, the states are standardizing the
available Chesapeake Bay commercial
catch information on the most important
Bay fisheries.
The health of the striped bass remains
a high-priority concern. Research efforts
focus on stock assessments, young-of-
year analyses, larval abundance and
transport studies, related habitat
investigations, hatchery restocking
programs, and laboratory toxicity studies.
It appears that the striped bass
harvesting moratorium in Maryland and
the partial ban in Virginia are protecting
the important 1982 year-class as intended.
The marked increase in striped bass
observed in Virginia since 1981, and the
large numbers of young stripers caught in
unregulated D.C. waters in 1985, are
believed to be a result of the bans.
In 1985, Maryland banned harvesting
of striped bass because of the drastic
declines in commercial rockfish landings
since the mid-1970s. Declines in
commercial fishery landings for both the
Chesapeake and the Atlantic reveal poor
recruitment into the fishery since the
1970 "super" year-class. The 1982 year-
class of rockfish, which will not spawn
until 1988, is the object of protection
because its abundance offers considerable
Mean number of striped bass per catch
30 Maryland 1954-1985
25
20
15
10
5
0
1954
n
n
55
—
-
n
—
—
—
—
60 65
—
—
Mean number of striped
5
4 r
3
<
0
i—
'
bass per catch
Virginia 1967-1985
i * No data 1973-1979
,
if
1967 70 72
*
"1
...
\\
fi
- |
80 82 84 85
—i
~
j_|
HBH
70 75
r
hn
80
—
1
41n
84 85
Striped bass young-of-year indices (abundance) show great variability. Due to differences in habitat and capture method, the indices of the two states are similar, but
not identical. The unusually high 1970 index dominates in both states. Virginia's indices increased steadily from 1981 through 1984, butdroppedin 1985. Maryland's
indices have been very low since 1978, with the larger 1982 year-class the object of state protection. (Source: MD Department of Natural Resources [DNR] and VA
Marine Resources Commission)
-------
Commercial striped bass landings in pounds 1970*1985
5000
n Maryland
4000
3000
2000
1000
I Virginia
It
n_nJMn.
1970
72
74
76
78 80
82
84 85
Commercial striped bass landings in Maryland and Virginia 1970-1985. (Source: NOAA/National Marine
Fisheries Service [NMFS])
potential for increasing the spawning
stock.
While Virginia is optimistic about the
number of rockfish in its waters, recent
stock assessment work has confirmed that
the 1982 year-class is the only reasonably
abundant one in Maryland. Data reveal
very few fish older than the 1981 year-
class in the Potomac, and a very low ratio
of females—the egg layers on which good
year-classes depend-to males. The
Potomac pattern appears to be the general
case for Maryland's portion of the Bay.
Maryland striped bass spawning
stocks have been low; they were lowest
in 1982 and 1983, and slightly higher in
1984 and 1985, largely due to the
protected 1982 year-class males. Striper
egg and larval abundance also continues
to be low. Intensive Maryland habitat
studies, which seek to relate water quality
and other habitat factors to larval
abundance, are currently under way. A
combination of low pH, which tends to
mobilize naturally high levels of
aluminum (which impairs larval gill
function), and low hardness found in
some Eastern Shore rivers such as the
Choptank, may be causing significant
larval mortalities.
Fishery biologists recognize that there
is a high mortality rate (over 99%) in
early life history stages of striped bass;
the mortality rate declines considerably,
however, when individuals reach the
juvenile or "fingerling" (2 to 5 months
old) stage. Juvenile or young-of-year
abundance firmly establishes the strength
of the newly recruited year-class, and
allows projections of its contribution to
the commercial fishery in subsequent
years.
Both Maryland and Virginia survey
juvenile striped bass annually. Young
fish are trapped either by seine net (Md.)
or by seining and trawling (Va.). The
young stripers are counted and the totals
averaged. Due to differences in habitat
and capture method, Maryland and
Virginia juvenile indices are similar but
not identical. Maryland's more shallow
shoreline allows for more extensive
seining and higher young-of-year catches
than is possible along Virginia's deeper
shores. The Maryland indices, therefore,
will be higher than those in Virginia.
In Maryland, a juvenile index of 8 has
been considered the minimum desirable
index because historically, year-classes
with an index of 8 or better have
apparently supported a commercial fishery
of 2 million pounds of stripers annually.
Since the 1970 year-class with a very
high index of 30, however, Maryland
juvenile indices have been alarmingly
low. The 1982 index of 8.4 was followed
by low indices of 1.4 (1983), 4.2 (1984),
and 2.9 (1985). In the District of
Columbia, recent young-of-year averages
(not available prior to 1984) were also
low: 2.4 (1984) and 3.9 (1985). The
Virginia young-of-year indices, however,
show a steady increase from 1.6 (1981) to
4.4 (1984). The 1984 index was the
highest number of juveniles recorded in
Virginia since the record 1970 year-class
with an index of 6.4. The 1985 juvenile
year-class index of 2.3 was only average.
Since mortality of striped bass in the
wild is greatest from the fertilized egg
through the fingerling stage, hatchery
rearing may be a bridge to an improved
fishery. Striped bass are now being reared
in U.S. Fish & Wildlife Service and
Maryland hatcheries until the fall, when
they are less vulnerable and big enough to
be tagged and released into selected Bay
areas. Experimental tagging and tag
recovery programs were initiated in both
Maryland and Virginia in late 1985. The
expectation is for a release of 3.5 million
fish in Maryland alone by the end of the
program in 1989. What has been learned:
a large number of striped bass can be
raised in hatcheries, tagged, and released
into Bay tributaries successfully. The
next step is to determine the program's
impact.
Stocks of other anadromous fish such
as shad, river herrings, and yellow perch
remain at all-time lows. White perch
numbers are also low. Abundance
estimates of the harvest-banned shad from
1980 through 1985 indicate a trend of
generally increasing stocks, but numbers
of young-of-year and adults remain
extremely low. Harvests of marine-
spawning fish, dependent on oceanic
rather than Bay conditions, are relatively
good. Ocean-spawning menhaden, sea
trout, spot, and bluefish harvests
remained stable or increased during 1984-
1985.
The first preliminary comprehensive
assessment on thirteen Bay species
(including striped bass) represents
progress in bringing together the
available commercial catch data in a
uniform manner. Assessments of six
additional species are scheduled. While
the assessments are based on those fish
reported (as opposed to those which may
actually have been caught), and while no
complete set of information exists for any
one of the Bay fisheries, the value of this t
preliminary effort is that it will more
clearly reveal important missing
information. HI
-------
The Harvest: Shellfish
With oyster reproduction and
survival declining seriously over the last
decade, the higher spatfall in both
Maryland and Virginia in 1985 was good
news. Over the 1984-1985 monitoring
period, however, spat survival rates
remained low and still unexplained. No
changes were noted in the dismal picture
for soft-shell clams, but the blue crab
fishery remains healthy, if unpredictable.
Rainfall and temperature are key
22 variables that determine oyster harvests.
A strong correlation has been found
between high salinity and good oyster
reproduction. Dry summers, for example,
may provide the oyster with highly saline
waters and good feeding and growing
conditions as a result. This same kind of
weather, however, can encourage oyster
diseases. The significant effect of rainfall
and temperature on the productivity and
health of the Bay's resources is evident
when one examines the condition of the
Bay's shellfish, particularly in 1984 and
1985.
While there has been no long-term
trend in rainfall/salinity, there has been a
distinct trend toward warmer falls and
winters over the last 10 years. The
spring of 1985, with below-normal
rainfall, was followed by one of the three
warmest autumns in 30 years (which
extended into the winter). The drier and
warmer fall of 1985 resulted in a
considerably longer spawning season than
that of 1984; the oyster spawning season
extended beyond the normal June-
September period into late October.
Both Maryland and Virginia had high
spatfall as a result. Virginia's spatfall
was moderate to heavy in the 1984 and
1985 spawning seasons. The heavier spat
sets generally occurred in 1985,
particularly on the James River seed beds.
There was considerable temporal and
spatial variability in the spatfall. The
occurrence of heavy spatfalls, despite low
brood stock, underscored the importance
of local weather and climate in the
determination of year-class strength.
Although its 1984 spatfall (2.4 spat
per bushel) continued a downward trend,
Maryland found high numbers of spat on
its 55 key oyster bars in 1985. The
Maryland spatfall average in 1985
exceeded 100 spat per bushel. The highet
spatfall was welcome, but it was limited
mainly to the mouth of the Potomac
River and Maryland's Eastern Shore
tributaries. This area is greatly reduced
compared with that area where high spat
sets were recorded between 1938 and
1965.
The survival of spat to yearling
continues to be of prime concern. In this
regard, unfortunately, 1984 and 1985 were
not exceptions. In Virginia, the state-
wide poor survival of spat to yearling was
evident in the oyster bar surveys that
250
200
150
100
50
n
Mean number of oyster spatset per shell
~ Virginia 1965-1985
jonfciiij
1965
70
75
80
84 85
Don
n
Mean number of oyster spatset per bushel
Maryland 1944-1985
* No data
nn
Dru J I L
II
1944
50
55
60
65
70
75
8485
Oyster spat set for Maryland (1944-1985) and Virginia's James River (1965-1985). The density of the annual spat set is a measure ol oyster reproductive success.
Spat set is measured annually but with different methods by the two states. Maryland measures the number of spat per bushel; Virginia measures spat per shell.
Shown here is the great variability of spat set in both states. The relatively higher sets for the two states in 1985 was good news. (Source: MDDNRand VIMS)
-------
Commercial oyster harvest in millions of pounds
20
Maryland
10
I
I Virginia
I
1S6S 70
74
78
82
84 85
Commercial oyster harvests. Since the turn of the century, the trend has been one of decreasing harvests of
smaller oysters. Even though management practices such as shell and seed planting have helped to stabilized
the harvests since the 1960s, the current Bay-wide landings average around 2.6 million bushels (U.S.) annually.
It has been estimated that the sustainable yield of Maryland oysters Is 2-3 million bushels annually. Virginia's
oyster industry has not recovered from the disease attack of the late 1950s. (Source: NOAA/NMFS)
followed the heavy 1985 spawning season
(predation by the abundant blue crab may
play an important role). Bay biologists
point out that the success of the oyster
fishery depends on a number of
consecutive years of above-average spat
set, as well as the absence of threats from
harvest pressure, disease, and lack of
dissolved oxygen.
MSX and Dermo can pose serious
disease threats to the oyster industry.
MSX attacks adult oysters (the peak
period of infection is June), flourishing in
the same saline conditions that favor
oyster production. Virginia's oyster
industry has been threatened by MSX
since 1959. The organism has been a
problem in Maryland waters since 1963.
Maryland's high spat sets in the early
1980s were offset by an extensive
outbreak of MSX in the 1982-1983
season.
While conditions in 1984 and 1985
were not conducive to the spread of MSX
in Virginia, Maryland's lower Bay waters
experienced some Dermo mortalities and
conditions conducive to MSX infestation
in 1985. Mortalities resulting from the
latter would be seen in 1986.
The stocks of Maryland's soft-shell
clams continue to be low; 1984 and 1985
harvests were each only about 1 million
pounds. The crab fishery remains the one
source of "good news" for the Bay's
fisheries, however. While historically
crab harvests have fluctuated wildly, the
fishery appears to be unthreatened. Both
1984 and 1985 were good years for crabs.
Bay-wide crab harvests were 59 million
pounds and 46 million pounds in 1984
and 1985 respectively.
One reason for the lack of concern
about this crop (the Bay's second most
valuable), is because crab year-classes are
believed to depend more on the
environmental conditions and
hydrological effects associated with the
Bay's mouth than other factors. The
higher salinity of the Bay's mouth is also
essential for crab spawning and larval
growth. The circulation pattern at and
outside the mouth of the Bay can
transport crab larvae into the up-Bay
water currents of the deeper, saltier water
layers, or can carry them into ocean
currents and permanently offshore. D
The American oyster has been
important to the Bay's economy
since the mid-1880s, when the
average annual yield for Maryland
alone was about 12 million bushels.
Since the turn of the century, the trend
has been decreasing harvests of
smaller oysters. Even though
management practices, such as shell
and seed planting, have helped to
stabilize the harvests since the
1960s, current Bay-wide landings
average around 2.6 million bushels
(U.S.) annually.
The density of the annual oyster
spat set is a measure of oyster
reproduction success. Free-swimming
oyster larvae (2 to 4 weeks old) drop to
the bottom to set; they attach to
suitably clean and firm substrate
(usually oyster shell) in order to grow.
These spatfalls are measured annually
by Virginia and Maryland, and
monitored carefully since, in spite of
improvement in Virginia's spat sets
since 1980, there has been an overall
Bay-wide decline in spatfall for more
than ten years. Setting patterns and
survival rates have varied widely.
Spat set has long been considered a
reasonable indicator of subsequent
harvests, but its predictive value has
been reduced over the last couple of
decades because of poor spat
survival.
In addition to low reproduction and
larval survival rates, increased
demand, and harvesting, oysters have
been affected by weather and
disease. Oysters require a salinity
range of 5-35 ppt. Freshwater inflow,
therefore, is a key variable affecting
reproduction and mortality.
The oyster diseases known as
Dermo (Perkinsus marinus) and MSX
(Haplosporid/um nelsoni) have taken
their periodic tolls on the oyster
fishery. These organisms are
associated with higher salinities
(above 15 ppt), and are far more
regularly a threat in the saltier waters
of Virginia and lower Maryland. Their
attacks on middle and upper Maryland
Bay shellfish are less frequent but can
be devastating.
The naturally fluctuating harvests
of the economically important soft-
shell clam have dwindled. The reason
for the soft-shell clam decline is not
apparent, although low-oxygen areas,
disease, and heavy harvesting are
suspect.
Crab harvests are variable but
high, and the fishery appears
unstressed. The fishery is controlled
primarily by the better environmental
factors near the Bay's mouth, where
crabs spawn.
-------
A Case Study: The Patuxent
The Patuxent River w the longest
Wrastaterlyerinttoiyland, and
its watershed fs the w% fti^or sub*
stale,
, and ftndMng- have
^
gaaHor ft» JWyxtht, fwwww, isle
order tb t ttlftiHQ the good
b«t*4'*l wthh
h^^efiutaBi
to
jri ''
fill tltese
in
land
Tlie teertorllfcft rfthi JPaiu»nt*as
evfcfertt tytttt
wihtnfhe wrta^fwd.ffepp; 2?) has
revealed increased nutrient
n^d tn
. have also been noted, such as drastic
fraction of what ft was in the 1960s.
Citizen monitoring stations
^ OEP water quality stations
Sewage treatment plants
Maximum turbidity zones
The Office of Environmental Programs
of Maryland's Dept. of Health and Mental
Hygiene initiated a $3 million Patuxent
River program in 1982. Known as the
Patuxent Strategy, the program's major
objective is to address the causes of the
observed water quality decline from a
basin-wide perspective. Research,
monitoring, and modeling will provide
managers not only the necessary
information to understand better the
processes affecting water quality, but
also the means to evaluate the
effectiveness of various management
options. (Source: EPA, MD OEP)
The Patuxent is approximately 110 mi
long from its origin on Parris Ridge to its
confluence with the Chesapeake Bay.
The river drains portions of seven
Maryland counties, and an area of
approximately 930 sq. mi. Its average
flow is 396 cfs; its contributes 0.5% of
the Bay's freshwater flows. The
Patuxent estuary is deep: it ranks sixth
in volume and second in average depth
of the Bay's primary tributaries. About
27% of the land is agricultural, 29%
urban, and 44% forested. The upper
25% of the basin lies within the Piedmont
Province; the lower portion is within the
Coastal Plain. High nutrient and
suspended sediment levels are the
primary water-quality problems.
-------
Historical data reveal the long-term undesirable trend of increased
nutrient enrichment and decreased dissolved oxygen levels in the
Patuxent River.
PHOSPHORUS Two types of phosphorus (P) are commonly reported: dissolved
inorganic P (DIP) and total P (TP). The Patuxent's longest nutrient record is that for
DIP. DIP data collected at Broomes Island in 1939, 1963, and 1969 reveal significant
increases in DIP levels. Values of DIP near the mouth of the estuary have also
increased over the years. The estimated annual loadings of TP from upstream sources
to the Patuxent estuary for 1965: 180,779 Ibs; 1970: 341,717 Ibs; 1975: 608,476
Ibs; and 1985: 216,500 Ibs. During the 1984-1985 monitoring period, the Patuxent
River had the highest TP levels of the tributaries monitored. The Patuxent River TP
concentrations in the tidal-fresh, transition, and lower estuarine zones were
approximately 0.30-0.35, 0.25, and 0.1 mg/1, respectively.
NITROGEN Of the nitrogen forms that are routinely measured, only nitrate was
measured in the Patuxent prior to major STP construction. Shown at right is the
profile of nitrate values for Lower Marlboro in the low-salinity reach of the Patuxent.
The data reveal a clear seasonal pattern of nitrate concentration, with high values in
winter throughout the estuary, and low values in the summer and fall. Nitrate values
tend to be strongly correlated with river flows. The graph shows increases in nitrate
levels after winter periods in both 1936 and 1963, with a major increase in the latter.
Lower Marlboro winter values in 1969 were 8 times higher than those reported in
1963, and 20 times higher than those reported in 1936. The estimated annual total
loadings of TN from upstream sources to the Patuxent River estuary for 1965:
509,268 Ibs; 1975: 2,462,563 Ibs; and for 1985: 1,900,000 Ibs. The 1984-1985
values of TN were generally at or above 2 mg/1 in the tidal-fresh river.
CHLOROPHYLL-a Chlorophyll-a values have increased over the years as shown
in the graph. The data collected at Benedict Bridge, Md., at the lower end of the
turbidity maximum region and in the mesohaline segment of the estuary, show that
maximum observed late-winter and spring values increased by over 100% between
1964 and 1969. Excessive phytoplankton growth from the increased levels of
phosphorus and nitrogen was becoming apparent in the early 1970s. In 1984-1985,
the highest concentrations of chlorophyll-a during the warmer seasons were found in
the upper Patuxent estuary. Chlorophyll levels peaked at 100 ug/1 in the tidal-fresh
reach of the Patuxent in the summer of 1985.
DISSOLVED OXYGEN The lowest DO levels generally occur in the deeper
bottom waters during warm seasons. A comparison of the June and August low DO
values in the lower Patuxent estuary's bottom waters in 1938 and 1978 is shown to
the right. The comparison reveals 1978 minimum DO levels substantially lower than
those observed in 1938, beginning at Benedict and continuing downstream. No zero
values were found in 1938, while zero levels were common in 1978. In the summers
of 1984 and 1985, the DO levels ranged between 5.0 and 9.5 mg/1 in surface waters,
and between 0 and 8.0 mg/1 in bottom waters. CPCB monitoring program volunteers
reported hypoxic/anoxic conditions in the bottom waters of shallow St. Leonard's
Creek in the summer of 1985. While the main channel of the Patuxent is known to
have low dissolved oxygen levels in late summer, low DO levels have only
occasionally been reported in water as shallow as St. Leonard's Creek (3-4 meters).
(Source: Chesapeake Biological Laboratory, University of MD)
JFMAMJJASOND
40
*= 30 -
' 20
o 101-
Q
25
JFMAMJJASOND
60r
S O N D
June
RIVER
-•-BAY
-------
CONTRIBUTORS
The coordinated monitoring network, created on behalf
of the Chesapeake Bay Program, has drawn upon
government resources at federal, state, and. local levels,
and their contractors, and major university research
institutions throughout the Chesapeake basin. Their
coordinated efforts and dedication to the common goal
of restoring and protecting the Chesapeake Bay have
made this report possible. This report was assembled
by the Monitoring Subcommittee by authority of the
Chesapeake Bay Executive Council, the Implementation
Committee, the Citizens Advisory Committee, and the
Scientific and Technical Advisory Committee.
FEDERAL GOVERNMENT
National Oceanic and Atmospheric Administration
National Ocean Service, Office of Oceanography and
Marine Assessment, 6001 Executive Blvd.,
RocMlle, MD 20852. 301/443-8501. Charles Ehler,
Director.
David R. Browne, Cart W. Fisher, Bruce Parker.
Rockwall Building, 11400 RockvBe Pike, Rockvilte,
MD 20852.301/443-8655.
John A. Calder, Gary Shigenaka.
Estuarine Programs Office, Universal Bldg. S,, 1825
Connecticut Ave., N.W., Washington, D.C. 20009.
202/673-5243. Virginia Tippie, Director.
David M, Goodrich, Samuel E. McCoy, James P.
Thomas.
US. Environmental Protection Agency, Region ill
Chesapeake Bay Liaison Office, 410 Severn Ave.,
Annapolis, MD 21403.301/266-6873. Charles S.
Spooner, Director.
Richard BaBuk, Patricia Bonner, Nina Fisher,
Catherine L. Leger, Kent Mountford.
Computer Sciences Corporation, 410 Severn Ave., Suite
109, Annapolis, MD 21403. 301/266-6873. Lacy
Nasteff, Director.
Environmental Photographic Interpretation Center, Vint
Hill Farm Station, Box 1S75, Warrenton, VA 22186.
703/347-6348. Sam E. Williams, Acting Chief.
James Simons.
U.S. Fish & Wildlife Service
Annapolis Field Office, Chesapeake Bay Restoration
Program, 1825 B. Virginia Ave., Annapolis, MD
21401. 301/269-6324. Glenn Kinser, Director.
Bert Brun, Charfes M. Wooley.
Patuxent Wildlife Research Center, Laurel, MD 20708.
301/498-0331. David Trauger, Director.
Matthew C. Perry.
REGIONAL
Chesapeake Research Consortium, P.O. Box 1120,
Gloucester Pi, VA 23062. 804/642-7150. Maurice
Lynch, Director.
Ka'en L. McDonald
Interstate Commission on the Potomac River Basin,
Suito 300,6110 Executive Blvd., Rockviile, MD
208!i2-3903. 301/984-1908. L.E. Zeni, Executive
Director.
Beverly Bandler, Mary-Ellen Webster.
Citizens Program for the Chesapeake Bay, Inc., 6600
York Rd., Baltimore, MD21212. 301/377-6270.
Frances H. Fianigan, Director.
Kathleen K. Ellett.
DISTRICT OF COLUMBIA
Department of Consumer and Regulatory Affairs, 614 H
Stre«t, N.W., Washington, D.C. 20001. 201/727-
7170. Donald G.Murray, Director.
Department of Consumer and Regulatory Affairs,
Environmental Control Division, 5010 Overlook Ave.,
S.W , Washington, D.C. 20032. 202/783-3192.
Anantha Padmanabha, Director.
James Collier, James Cummins, Hamid Karimi.
Martin Marietta envinwn&ntal %st*fns;^00 Rums^?
Hd,, Columbia, MJ%04S.
Talb^ Central (Manager. •
A. Frederick Hallaiwi, fm& Jays/toft
University of Maryland; i5hes*pettefitoRigjc«l,
Laboratory, Bo^, Soloirorta,
.
, Fa*%,
'
Walter ft Bayrtefl,
"
Un)vers% of Marytrrt,
' Laboratory, P.O. i*fc775» Carrt«dge,'MD 21 813.' -
'" ! :
Susquehirma
St,,Harfi$
BtefcT,Director,
VIRGIN!*'
MARYLAND
Academy of Natural Sciences, Benedict Estuarine
Research Laboratory, Benedict, MD 20612.
301/274-3134. James G. Sanders, Director.
David C. Brownlee, Kevin G. Sellner.
Department of Health and Mental Hygiene, Office of
Environmental Programs, 201 West Preston Street,
Baltimore, MD 21201.301/225-6316. William M.
Eichbaum, Assistant Secretary.
Michael Haire, Robert Magnien, Robert Summers.
Department of Natural Resources, Tidewater
Adrnnistration, Tawes State Office Building,
Annapolis, MD 21401.301/269-3767. Paul Massicot,
Director.
Stephen J. Jordan, Chris Bonzek, Cynthia
Stonger.
College el WJIiam *t;M*y-r
.• Science, GteadiiJp ioint, y* ;p06fej
7000.' Frantf Oi
Hert»rtAusBqi
Huggett,
CM Dominion Untv*r'%.
Labo«ory,
Raym&nal W.
Arthur J. Butt' ' .
OWDominion University,Oept.
Harold G. Marshall, Cfialrrnaft:
Ray S. Birdsong, Uahiel 0»«
Virginia State WaW Gonttor Bbanf,
St., Richmond, W23238,
Burton, Executive Director. •/
AlanE.PoiloA,BflbertC.-Sieafrl«tf,
Space limitations prevent the full listing of additional institutional and individual nteflies, but lh» Chesapeaks ffaf. • •
Program would like to acknowledge the cooperation of the following: €hesape«t» Bay Foundation, Mtejfopolilarl
Washington Council of Governments, Pennsylvania Department of Environmental ffesonrtes, Patprrw*? HtvW
Fisheries; Commission, U.S. Army Corps of Engineers (Baltimore and Norfolk Districts), U.S. O»pafW»ntotO4f&Js«,
U.S. Geological Survey, Virginia Council on the Environment, Virginia Game & W«nd FiShwSts Coonrtssion,
Virginia Marine Resources Commission.
For furthsr Information, write: the Chesapeake Bay Program, 410 Sewem Aw!,
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