state of the Chesapeake Bay ... annual monitoring report

[From the U.S. Government Printing Office, www.gpo.gov]

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CONTENTS

Executive Summary 1 on/oring isa key element in restoring the ChesapeakeBay. Monitoring
keeps managers, researchers, and citizens current on the health of the
The Water Quality Base 3 Bay, and measures the progress of control strategies. Under the Chesapeake
Bay Agreement of 1983, the implementation Committee established a Monitoring
Sediment & Toxics 8 Subcommittee to develop and implement a Bay-wide coordinated monitoring
program. The EPA/state cooperative program began In May, 1984 and a full
Centerfold Map 12 sampling network was in place on the mainstem Chesapeake by July.

Plankton & the Food Chain 14 The Chesapeake Bay Monitoring Network is a complex arrangement involving
the federal government, three states (Virginia, Maryland, and Pennsylvania) plus
Citizen Monitoring 17 the District of Columbia, three universities, seven private research institutions,
and more than 125 ind ividuals. The network is comprised of 167 stations that
SAV: Habitat & Nursery 18 cover not only the mainstem Bay, but key portions of its 150 tributaries.
Nineteen physical, chemical, and biological parameters are being monitored 20
The Harvest: Finfish 20 times a year.

The Harvest: Shellfish 22 Mon itoring data can provide a sound scientific basis for making important
Bay program decisions. Monitoring data can serve environmental managers in a
Case Study: The Patuxent 24 wide variety of Bay restoration programs--living resources, soil and land
conservation, wastewater treatment, computer modeling-and in the legislative
process.
ACKNOWLEDGEMENTS

Execubve Editor/Designer: B.G. Sandler
Designer/Production Coordinatorilliustrator:
Karen L.ireramura GLOSSARY
Editonal Assistants: Elizabeth C. Krome,
Catherine L. Leger.
Production Ass stant: Karen L. McDonald Algae Simplest of all aquatic plants. Nonpoint Applied to pollution source:
I'lustra: on Ass stant: Steven L. Coon Most important Bay algae are the diffuse rather than point (pipe)
Photos' Skip Brown microscopic phytoplankton. discharge. i e farm runoff.
CBP Mon tonng Subcommittee Representarve: Bacteria Single-celled micro- organisms Nutrient Primary element necessary for
Bert Brun. that usually lack chlorophyll. the growth of living organisms,
EPA Mon tonng Coordinator 1984-1985:
Kent MounrtotinglCord. nator1984-1985.Baseline In reference to data, the initial generally applied to nitrogen and
Chai rman, CP Moni to<rng Subcom m tree measurements against which phosphorus, but also carbon and
William M. Eichbaum. later data are compared. silicon. Excessive nutrient loads
Benthos Plant and animal life whose result in eutrophication.
habitat is the bottom of a sea, pH Measure of acidity or alkalinity.
lake, or river. On a 0-14 scale, 7.0 denotes
SYMBOLS Biomass Quantity (weight) of living matter neutrality, less than 7 acidity and
Estuary Highly productive bay and river over 7 alkalinity.
cfs cubic feet per second ecosystems where fresh water Phosphorus Essential nutrient that occurs in
DO dissolved oxygen meets salt water, various forms' inorganic
mgd million gallons per day Fall line Zone where a major rver changes (orthophosphate, pyrophosphate,
mg/I milligrams per liter (=ppm) from free-flowing (inland tripoly- phosphate), and organic
N nitrogen freshwater) to tidally affected Plankton Minute plants and animals that
P phosphorus (coastal). passively float or weakly swim in
PAHs polynuclear aromatic (al
hydrocarbons Food chain Feeding sequence from plankton water.
PCBs polychlorinated biphenyls through higher predator Salinity The total amount of dissolved
pGBs partsh prinater billioeny organisms, salts per 1,000 units of water
ppb parts per billion oa
ppm parts per million Inorganic Combinations of elements (such (pt)
ppt parts per thousand as metals) that do not include Spat Newly attached juvenile oysters
SAV submerged aquatic vegetation organic carbon; generally non Spawning Reproductive process in fish and
STP sewage treatment plant volatile, not combustible, and not other aquatic animals.
TN total nitrogen biodegradable. Tidal river River under tidal
TP total phosphorus Monitoring Observing, tracking. or influence with a low saline and
TSS total suspended solids measuring for a special purpose upper freshwater reach
pgI1 micrograms per liter I =ppb) Nitrogen Essential nutrient; several forms:
urnm micrometer (-micron) organic and inorganic (ammonia,
> more than nitrate, nitrite): also atmospheric
< less than gas. Expressed in mgA. MARCH 1987

Property of CSC Library

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 U S. DEPARTMENT OF COMMERCE NOAA
achieve improvements in the Bay. COASTAL SERVICES CENTER

The first part of this report focuses on the physical-chemical characteristics of the 2234 SOUTH HOBSON AVENUE
Bay: flows, salinity, dissolved oxygen, chlorophyll a, and nutrients (the water-quality CHARLESTON, SC 29405-2413
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.
i, 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
4f 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
id hopeful En for living resources, including the many Bay waterfowl that use SAV as

C . .,
-,, _
_ l

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 good
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 1984
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 brought
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 oyster
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 where
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 DO
very difficult. Toxicants data contribute to our understanding of what toxic substances
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

Flows of the major tributaries into differ between basins. For example,
the Bay have been monitored for many Patuxent River 1984 and 1985 flows
I qu teshbeauter y o s it ernfl ; n years by the U.S. Geological Survey. As differed from those of the Susquehanna.
c~irculation stratification, a ~nd~ : an indication of the freshwater flow Patuxent River flows in 1984 were close
l ading of sediments, nutrients, and conditions during the first 15 months of to the long-term average as of that year
d:herpollutants tothne Bay. River the water quality monitoring program, the (421 cfs), whereas 1985 flows were 50%
flows and stratification in the estuary 1984-1985 flows can be compared to the below average. The James and
have important implicationsfor the long-term average flow for the Rappahannock rivers, however,
habitats of living resources, nutrient Susquehanna River, which contributes experienced higher than normal flows
dynamics, and phytoplankton growth. 50% of the fresh water entering the during 1984 (34% and 54%, respectively)
Freshwater streamflows and Chesapeake Bay. because of above-average winter and
seawater intrusion form two wedges o Over the past 18 years, the average summer discharge. Between the fall of 3
watergong in opposite direons, the flow of the Susquehanna River at 1984 and the fall of 1985, the James and
lighter (fresher) w ater flowing on top of
0 the heavier (saltier) water. Trheyse: i Conowingo Dam has been 41,950 cfs. Rappahannock rivers experienced dry
wedges create a surface-to-bottom The average flows of the Susquehanna in conditions, with flows 20% and 35%
difference in salinity, or a stratification 1984 were 19% above normal; in 1985 below normal, respectively. In
of :the Bay. they were 27% below normal. There November 1985, tropical storm Juan
High river flows increase were major seasonal differences between produced heavy rainfall in western and
: stratification and inhibit mixing within these two years: the 1984 summer flows southern Bay watersheds. While the
the water column. Low river flows were much higher than those in 1985. storm did not have much impact on the
permit higher estuarine salinities as The monthly average flows for the six Susquehanna, the Potomac and James
seawater intrudes further into the Bay largest Bay tributaries during 1984 and river basins were profoundly affected by
ystem and stratification is reduced. 1985 are shown below, major floods. Because the Bay is so
;; Reiducled stratification results in; gS 0 a; f ;- large, a single broad characterization
increased vertical mixing, which River flow patterns in each Bay cannot describe the response of an
reoxygenates the water. tributary are unique because rainfall, individual sub-basin
- he Bo y's living resources have topography, land use, and other factors

levels vary vertically and horizontally,
and can range from 0ppt atthe head 140 - Mean monthly flows
of tide to 25-30 ppt at the Bay's mouth. o usquehanna
The waters along the Bay's eastern � 120 -
shore are saltier than western shore � Potomac
waters because of both the greater I) A James
tributary flows on the western shore 100 -
and the effect from the earth's Rappahannock
rotation. Salinity generally reaches a - - c80- A Pamunkey
yearly low in the spring when rainfall, a c Mattaponi
groundwater, and melting snow cause o
increases in freshwater flows. 60 -
Oxygen is required by most living
organisms for their basic metabolic
processes. It enters the water from r
the atmosphere, and is also added as 20 -
a byproduct of plankton and SAV 0
photosynthesis. When dissolved LL
oxygen (DO) levels in waterfall below I
3-5mg/l, fish and many other J F M AM J J A S ON D J F M A M J J A SON D
organisms are stressed. Severe
oxygen loss will cause mortalities.
Hypoxia denotes low DO; anoxia Freshwater flows into the Bay from these six rivers represent about 90% of all tributary inputs. Flows in 1984
denotes the total absence of DO. were substantially higher than in 1985. (Source: Maryland Office of Environmental Programs [MD OEP] and
Virginia State Water Control Board[VA SWCB]) Pamunkey and Mattaponi are tributaries to the York River

Depth
o : I I I I I
1 4 2/

0 390 38� 370 39� 38� 370 Latitude
10
20
Dissolved
30 Salinity oxygen
(ppt)
40 1984 1984 ,

Saliniti 39 38w 37h 39i 38a 37t Latitude

alinity thaDigniicantlyinfluence and the Bay's deep waters. Recent research
than30 1984: surface saloxygen
40 1985 1985 II

Susqueha nna Bay Potomac M outh of usisst uehan a Bay POtomac hetwof
River Bridge River the Bay River Bridge River the Bay
tI t t t t t t

salinit and DO patterns differ from year t o year. Th e bold line represent tandhe b m the manste; e in ines represent either averaged sadditional inigh(ppt or D
(mg/) values at various depths. Salinity: the lower numbers in high-flow 1984 reveal that much of the Bay experienced lower salinities in 1984 thatn in 1985.
Dissolv ed o xygen: low DO values were more ext ensiv e in high-flow 1984 and inerwn-Bay. (Source: MD OEP and VA SWCB)

Salinities were higher an d the Stratification is the layerng of the sdepletion of
vertical salinity gradient wa s less waters: fres hwaterstrandtheocean-mfows and seawater oxygen in d eThe increased
Wheintrusion form two wedges of water going in
pronounced to 1984. In the lower-flow summ er of opposite directions. Thelighter(freshe water column increasesMu ch h as been written about the
1985. In the deep-trough region of the flows on top of the heavier (saltier) water. These phenomenon of low dissolved oxygen in

River, the same pattern of increased Themaximumturbidityzone isanareawhere
mainstem salinities were higher in 1985 wed ges create surface-ontrbutons to-bottom differences in
salinity and decreased strathat signiicantly influence life a nd the Bay's deep waters. Recent research
than in 1984: su rfac e salinities were conditions ineBay. efforts by numerous investigators ware
approximately 6 ppt hi gher an d b ottom Stratification is strongest where the two
salinitieummers were a bou t 3 ppt higher. wedr t ad rtification) have a sign a l light on the
When stratification iis strong, there is little mixing complex processes that cause, sustain,
S imilarly, in the Patuxent estuary, betwee n surface and bottom waters and errupt anoxic and hypoxic
salinities were 4 to 7 ppt higher and Stratifcationis weakestatthe sourcesofthe
stratification was reduced in 1985 wedges--the rivers and he ocean--and when conditions in this region. The increased
flows are low. When str atifiver rcation is weak, te mpora l and spatial sampling in the
compared to 1984. In the Rappahannock vertical mixing in the water column increases. current monitoring program is making
River, the same pattern of increased The maximum turbidityzone is an area where
resuspension of bottom sediments is high. t is major contributions to understanding the
rainityof rgand decreased stratification can bthe locatedr at the upstream boundaryof the saltwater Bay's oxygen.
observ edwithlimied for 19wnward5 relative to 1984. wedge. (Source: thanin MDthesummer anof 198VASWCB5.
Stratification differences between the two
summers are reflected in bottom-water (stratification) have a significant influence
oxygen concentrations. on the DO characteristics of the estuary.
Maximum tteurbidity Stratification inhibits the mixing of
Dissolved oxygen levels are high surface and bottom waters, and permits
throughout much of the year, in months Fresh water., high oxygen demands from sediment and
when water temperatures are low and the river r u noff the water column to deplete oxygen in the
water column is well mixed. In the late ~ . ~: ~ isolated, deeper water. Higher than
spring and summer, however, high ~~410,f I ~iN~ average flows resulted in more
oxygen demand in the sediment and the d 1 pronounced vertical salinity gradients in
rain of organics into the lower water ~ Sedii the mainstem in the summer of 1984
column, coupled with limited downward than in the summer of 1985.

Averaged longitudinal DO profiles for
the summers of 1984 and 1985 (shown Chlorophylls are a group of green photosynthetic pigments that occur
on page 4) demonstrate that high flow primarily within plant cells. Chlorophyll-a is the most important of the principal
permits more extensive regions of low photosynthetic pigments. It is responsible for the green color in plants.
DO. Oxygen conditions for comparable Chlorophyll-a provides a measure of phytoplankton biomass levels, and is
salinity regions in the Bay's mainstem expressed in micrograms per liter (plg/l). Plankton and chlorophyll levels vary
and its major tributaries were similar, in the mainstem and tributaries; levels depend on season, nutrient availability,
Mainstem salinity range, and depth, and are influenced by external physical conditions
In the mainstem there were several such as river flow, sediment load, sunlight, and grazing of phytoplankton by
differences between the two years, zooplankton. As yet, there is no general agreement among scientists on
especially in the spatial extent of hypoxic target levels for chlorophyll-a. A chlorophyll-a level of 100 gg/l is usually
waters (DO of <1.0 mg/l). In 1984 cause for concern, however.
hypoxic water extended well into
Virginia's portion of the Bay, reaching as
far south as the mouth of the o 5 let
Rappahannock River. This did not 50-a (L/"\
happen in 1985, when winds and tides oto
caused more frequent re-oxygenation 3 3 _\
events and reduced the duration of anoxic
conditions that summer.
The summer 1984-1985 monitoring 6
results have shown that mainstem deep-
water dissolved oxygen concentrations are
more dynamic than previously expected.
Even during the summer of 1984, when 39
density stratification was unusually
strong, two major re-aeration events were 'S',. 380
documented in the deep-trough region, 7
one in early July and one in early August. In
At least two re-aeration events were also Latitude 0s 37 s985
documented during the summer of 1985. Susquehanna River 39:35' Potomac River 38' 3798
This means caution must be used when Bay Bridge 390 Mouth of 37
comparing current data with data from Patuxent River 3818 the Bay
cruises in past years. Chlorophyll-a (chl-a) levels indicatephytoplankton concentrations. These graphics show surface water chl-a
peaks near the Bay Bridge andjust below the Potomac's mouth during summer 1984 and February-May 1985. In
Tributaries bottom waters, chl-a levels were low in summer, but peaked in the winter/spring of 1985. (Source: MD OEP and
In the Rappahannock River the clearly VA SWCB)
defined stratification in the summer of
1984 appeared to have effects on bottom- Chlorophyll is found at the highest maximum turbidity zones; in the cooler
water dissolved oxygen concentrations levels in the tidal-fresh portions of the months the higher chlorophyll levels
similar to those observed in the tributaries from spring to early fall. were found below the maximum turbidity
mainstem: summer DO depletion was Plankton growth follows tributary zone. Generally, the nutrient-rich upper
severe and prolonged. In the Patuxent enrichment by nutrient-laden spring reaches of the Patuxent and Potomac had
River, on the other hand, the effects on flows. The mainstem's higher higher chlorophyll concentrations than
dissolved oxygen levels from the concentrations occur in the late winter and those of the James or Rappahannock.
difference in stratification between the spring. The die-off and settling of this The Patuxent had the highest chlorophyll
summers of 1984 and 1985 were not as large pool of organic matter probably levels of all the major tributaries.
clearcut as the effects on the mainstem. contributes to the spring oxygen demand The lower Potomac estuary
The observed differences between oxygen in both the water column and sediments; experienced average chlorophyll values of
behavior of the Patuxent and that of the this demand leads to the development of 40 mg/l during spring 1985, with a peak
Bay indicate that factors other than summer deep-trough hypoxia/anoxia in in May of over 90 .g/l. Summer 1985
salinity stratification influence DO the mainstem. chlorophyll levels peaked at unwelcome
conditions. Topography, localized storm Tributaries levels of 100 ig/l in the tidal-fresh
events, periodic exchanges with mainstem Chlorophyll patterns in the tributaries reaches of both the Patuxent and Potomac
Chlorophyll patterns in the tributaries
waters, and the biological impacts of were similar in 1984-1985. The highest rivers.
were similar in 1984-1985. The highest
nutrient loadings--conditions unique to
nutrient loadings--conditions unique to chlorophyll levels in the tributaries were The peak chlorophyll concentrations
e ach basin--can also affect dissolved observed in the warmer seasons above the in the tidal-fresh regions of the James and
oxygen concentrations.

Rappahannock were 20-50 Ag/1 and 20-40 mixing in the water column play roles in
ig/i, respectively, with levels decreasing Nitrogen (N) and phosphorus (P) plant productivity, the levels of nitrogen
downstream to below 10 pg/1 near the are essential to plant photosynthesis (N) and phosphorus (P) are the key
river mouths. and growth. These nutrients are elements in the undesirable Bay over-
supplied to the Bay from land runoff, enrichment.
~Mai~nstem ~the atmosphere, fertilizers and STP
In general, the upper Bay mainstem discharges. Nonpoint sources supply Nitrogen: Between July 1984 and
had higher chlorophyll levels than those significant amounts of N (and in some September 1985, levels of total nitrogen
found in the central and lower Bay tributaries, P); point sources are the (TN) in mainstem surface waters ranged
mainstem; the lowest levels were found at major sources of P. between 1 and 2 mg/I at the head of the
the Bay's mouth. The higher upper The Bay and its living resources Bay, and from 0.4 to 0.7 mg/l in the
mainstem levels are largely the result of once assimilated additional nutrients lower Bay. The higher upper Bay levels
the greater availability of nutrients from from man's activities, but we have reflect the strong influence of
the Susquehanna River and other upper exceeded the Bay's capacity and now Susquehanna River inputs. In summer
Bay loadings. have undesirable phytoplankton levels months, bottom-water concentrations of
* in some areas. The death and inorganic N (and P) are high but surface-
Chlorophyll levels had strong decomposition of these algal plants water concentrations are generally low.
seasonal patterns with pronounced contributes to dissolved-oxygen
differences between mainstem surface and depletion. Over the last several Values of TN were higher (generally
6 bottom waters. During the late winter of decades, nutrient levels have at or above 2 mg/l) in the tidal-fresh
1984-1985 and the spring of 1985, a large increased in many parts of the Bay, regions of the Patuxent and Potomac
region of high chlorophyll (30-40 ig/l) particularly in the upper, low-salinity rivers than in the upper Bay mainstem. In
was obse rved in bottom waters. Du-3 Cring reaches of almost all western the tidal-fresh portions of the
was observed in bottom waters. During tributaries.
summer hypoxia, bottom chlorophyll tributaries. Rappahannock and James, however, TN
was very low (under 5 b tg/l). During Sediment plays a significant role in levels were comparable to those found at
was very low (under 5 sig/l). During nutrient transport and deposition, the mainstem head. In all the tributaries,
summer sporadic peaks of surface adsorbing both N and P, but primarily TN declined somewhat in the salinity
phytoplankton growth (30-50 jIg/l) could P. It is believed that there are large N
be seen, chiefly in the central and upper and P reserves in bottom sediments transition zones, and declined further in
Bay. In the lower Bay toward the York and that, especially during the warmer the lower estuaries to levels around
River generally surface phytoplankton months, substantial amounts of these 0.5-1.0 mg/l.
chlorophyll was low (5-15 Mig/l). nutrients are released from the The nitrogen enrichment found in the
Nutrients are a major focus of the sediments back into the water column. tidal-fresh regions of the tributaries is the
Bay restoration program. While light, Such releases can contribute to algal result of both nonpoint and point-source
temperature, plankton grazing, and impacts. Peaks in N during winter and

Total nitrogen Nitrates Orthophosphorus
(mg/l) / ' (mg/l) _(mg/1)
2.00C / 0.5 Meters ~ 2.00 / 0.5 Meters 0.15/ Bottom

1.33 I\V\(III1.33 0. 10

0.67 1 I h\\V~Qh\~i~f~K )C~tZ~i~i~i~ 0.67 0.05

0.00[1! 0,00 CR~~~U\SS\S 0.00 _ 0

Latitude 380 F s Latitude 380 AS0 1985 Latitude 38j 1985
1984 1984 37 1984

Latitude
Susquehanna River Mouth (39035'), Bay Bridge (390), Patuxent River Mouth (38�18t1, Potomac River Mouth (38]) Mouth of the Bay (37�)

Nutrlient 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 OEP and VA
SWCB)

spring high-flow periods can be attributed Mean total nitrogen (mg/I) extrapolation range from simple flow-
primarily to high nonpoint source loads. 2.5 base techniques to sophisticated watershed
Phosphorus: The pattern of total 2.0 computer models.
2.0 -
phosphorus (TP) concentrations is similar Based on the monitoring data, it is
to that for nitrogen, but not quite as 1.5 apparent that a simple flow-based
clearly defined. In mainstem surface X extrapolation would not be very accurate.
waters, TP peaked in the turbidity 1.0 IConsidering only the flow and nutrient
maximum region at about 0.05 to 0.08 05 loads for 1984 and 1985 it is clear that, of
mg/I and declined down-Bay to levels these three rivers, the Susquehanna was
generally less than 0.04 mg/l. 0 Iij , l*|the major contributor of flow and
During summer hypoxia in the deep- Mean total phosphorus (mg/I) nutrients to the Bay. However, during
trough region, P fluxes from the .32 - - Tidal fresh the monitoring period, the Susquehanna's
sediments into the overlying waters (see _ Salt transition nutrient loadings (66% TN and 42% TP)
pg. 18). As with the bottom-water .24 Estuary were not in proportion to its flow (63%).
accumulation of inorganic N, these higher If a simple flow-based extrapolation were
P levels may nourish summer algal , used as an estimate for TP loads for the
populations when and where vertical 1i-6 ESusquehanna, a 21% over-estimate would
mixing occurs. I result. Important factors unique to each
~~.08 g | _ g L, | Aiwatershed (topography, soils, land use,
Tributary TP levels in 1984-1985 l 1l population density, etc.) also influence
reveal differences between rivers. The 0
reveal differences between rivers. The 0 [ T i t the magnitude of the loads delivered to the
Patuxent River had the highest TP levels Patuxent Potomac Rapp Jam es
River River River River estuary and must be taken into account in
of the four major tributaries, with levels Averagetotalnitrogenandphosphorus order to produce an accurate estimate of
in the tidal-fresh, transition, and lower concentrationsinfourimportant Baytributaries nutrient loads.
estuarine zones approximately 0.30-0.35, July 1984-September 1985. (Source: MD OEP
0.25, and 0.1 mg/l, respectively. The andVA SWCB) Nevertheless, the strong influence of
Potomac and James rivers had similar TP changing river flows on nutrient loads is
levels of approximately 0.15, 0.1-0.2, The Susquehanna, Potomac and James clearly evident in both the long-term
and 0.05-0.010 mg/l in tidal-fresh, rivers are the three largest rivers record of annual loads and in the seasonal
transition, and lower estuarine reaches, discharging to the Bay. Together these loads calculated from the 1984-1985
respectively. The lowest TP values were three rivers represent 84% of the monitoring data. In years and seasons
found in the Rappahannock River, and freshwater flow. The exact proportion of when river flow is high, nutrient loads are
were approximately 0.05-0.10, 0.05-0.10 the total river input load represented by also high. For example, approximately
and 0.03-0.05 mg/l in the tidal-fresh, these three rivers must be determined by 80% of the flow and nutrient loads
transition, and lower estuarine zones, extrapolation of the monitoring data to delivered to the estuary by the
respectively. TP showed surprisingly cover unmonitored portions of the Susquehanna and Potomac in 1984 came
little seasonal variation. Chesapeake Bay watershed. Methods of in the winter and spring. E]

Mean annual flow Annual load of total nitrogen Annual load of total phosphorus
thousands of kilograms per day thousands of kilograms per day thousands of cubic feet per second
60 400 20 _-
50 aE Susquehanna
300 El Potomac 16
40 * No data
12 _ _ _ _
30 _200 __ _a-
20 _a
100
~~~~~~~~~~1 4
t~~~~~~~~~~~~~~~~~o

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 comparedabove. The Susquehanna is the largest Bay tributary.
In 1984-1985, it contributed 63% of the freshwater flows to the Bay, and 668% of TN and 42% of TP. The Potomac's nutrient contributions are proportionately higher
than its flows. Approximately 80% of the flows and nutrient loadings delivered to the Bay's mainstem by the Susquehanna and the Potomac in high-flow 1984 were
deliveredin thespring. (Source: MDOEPandVASWCB)

Sediments & Toxics

between 0.9 and 2.9, and the TSS values period. In the lower Patuxent the waters
Measuring Turbidity, or determining ranged from 10 to 40 mg/l. become comparable to those of the
the amount of suspended solids in the From the Rappahannock to the Bay's mainstem at its confluence.
Bay's water column, is important. mouth the waters again become clearer. The Potomac is the second largest
Turbidity can indicate conditions Here Secchi disk readings ranged from 1 contributor of freshwater to the Bay but
detrimental to aquatic life. Two to 3 meters, and TSS values ranged from contributes proportionately the most
methods used to measure turbidity 5 to 15 mg/l. At the Bay's mouth sediment to the Chesapeake system. An
are: (1) visibility measurement with a turbidity is lowest. estimated 1.5 million tons are discharged
Secchi disk; (2) measurement of total Lower Bay western shore waters are at the fall line in an average year. Most
suspended solids (TSS). Higher generally more turbid than those along of this sediment remains in the upper and
Secchi depth readings mean lower the eastern shore: the earth's rotation mid-estuary (there is a small net transport
turbidity; higher TSS values mean causes relatively clear oceanic water to be of 1% from the main Bay into the lower
higher turbidity. Measurements by deflected eastward as tidal currents move Potomac).
8 Secchi disk are made by simply up-Bay, and substantial quantities of more The Potomac's sediment loadings in
lowering the disk into the water and turbid water are added by the discharges 1984 and 1985 were 22% and 126%
recording the limit of visibility. Bay from western Bay tributaries. These higher than average. The higher figure
Secchi depths generally range from show up as localized peaks in the lower for 1985 reflects the effect of tropical
over 3 meters (clearer waters in the Bay in the Secchi depth graphic. storm Juan: approximately 1,134,000
winter) down to less than 1 meter (over- Tributaries tons of sediment was discharged from the
enriched waters, usually in the upper Potomac basin in November alone.
summer). In the tributaries and Between their turbidity maximum The average Secchi disk readings for
mainstem, Secchi readings can drop zones and their confluence with the Bay, the Potomac in Washington, D.C. (where
to as low as 0.1 meter following the tributaries have turbidity and TSS algal blooms also contribute to the river's
storms. TSS is determined by patterns comparable to those in the Bay turbidity), ranged from just over 1.1
weighing the material filtered from a proper. Unlike the main Bay, however, meters down to 0.6 meters in 1985.
known volume of water. The American tributaries like the Patuxent, Potomac, Most of the heavily sediment-laden
Fisheries Society has recommended a and James have large stretches of tidal Anacostia within the District of
TSS criterion of 100 mg/l (maximum) freshwater, where extensive high-turbidity Columbia had Secchi depth readings less
for the prevention of mortality to fish, areas can result not only from re- than 0.3 meters.
zooplankton, and benthic animals. suspended sediment but also from algal The share of the total sediment
blooms. loadings into the Bay from Virginia's
The Susquehanna's sediment loadings James River is 16%. The upper reaches
SEDIMENTS (an average of 1.8 million tons annually) of both the James and the Rappahannock
strongly track with river flow and are have comparable Secchi depths (0.6 m),
Mainstem delivered directly into the mainstem. In and both show a steady decrease in
Monitoring in 1984-1985 confirmed a wetter periods, typically winter and turbidity from their tidal freshwater
strong north-to-south turbidity gradient in spring, sediment loads are much higher portions to their mouths. Their lower
the mainstem. Generally, turbidity is than in the summer and fall, when flows estuarine zones show a marked difference,
high in the upper Bay because of the are generally lower. The Susquehanna is however. The James carries a heavier
Susquehanna's heavy flows and the unusual because several reservoirs trap load of TSS than the Rappahannock (13.3
turbidity maximum zone; it decreases sediment, at least temporarily, and mg/l and 5.5 mg/l at the fall line,
gradually toward the Potomac's mouth. moderate loadings. The result is that the respectively), and tends to remain turbid
The maximum turbidity zone in the sediment contribution of the Susquehanna longer. The average Secchi reading in the
Bay proper occurs up-Bay of Baltimore River to the Bay is often proportionately lower James ranges from 0.9 to 1.4
near Aberdeen, Md. Monitoring of this lower than its flows. meters, while the readings in the lower
area revealed typically low Secchi depths The Patuxent contributes only 0.5% Rappahannock generally range from 1.4
(between 0.2 and 0.5 meters) and high of the Bay's freshwater flows, but its to 1.8 meters.
TSS values (between 15 and 25 mg/l). sediment loadings are proportionately The James and the Rappahannock
Turbidity decreases gradually down-Bay, higher than its flows. In the Patuxent's experienced higher than normal flows in
to a point just above the Potomac's maximum turbidity zone (in the vicinity 1984: 34% and 54%, respectively.
mouth. Here the Secchi depths were of Lower Marlboro), spring TSS peaks Between the fall of 1984 and October
higher (from 1 to 3 meters) and the TSS exceeded 80 mg/l. This high turbidity 1985 both rivers experienced dry
values lower (from 5 to 10 mg/l). results not only from loadings, but also conditions. The flow of the James was
In the central Bay, from the Potomac's from the natural bottom-to-surface 20% below normal; the Rappahannock
mouth to that of the Rappahannock, there mixing in the water column. Secchi flows were 35% below normal. The
is sometimes an increase in turbidity. depths of 0.2 meters and less were James was significantly affected by
Here the Secchi depths in 1984-1985 were observed in the 1984-85 monitoring tropical storm Juan.

Iurbidity
Secchi
dep th( mX j ~ I ntheirnever-ending need to The annual sediment contributions
0. 3 reach the sea, the Bay's rivers (at the fall line) from the Susquehanna,
discharge an average of 2,000 cubic Potomac, and James rivers are 40%,
meters of water every second. Long 33%, and 16%, respectively. These
0.7 " y afterthese waters have left the Bay, loadings reveal that the sediment
the fine-grained, mostly inorganic contributions of the three rivers are
sediment particles (sand, silt, clay) not in the same proportion as their
t1 8 l 9 t / ( > Ad that they have transported remain, flows. For example, while the Potomac
suspended in the Chesapeake's water contributes 20% of the annual flow to
column or settled on the bottom. The the Bay, its sediment loading is 33%.
4.5l 51 1 I lilkmlllll original Bay channels are now roughly The flow pattern of each Bay
39� A half-filled with sediment. Erosion and tributary is unique; the sediment
Latitde 3 II FM 1985 sedimentation are natural processes, loadings of the tributaries vary due to
Li 38� AL 1ll D Nbut they have been accelerated by differences in rainfall, topography,
370J J A 1984 man's activities and now significantly land use, and other factors.
Latitude affect the entire food chain. Sediment deliveries to the Bay
Susquehanna River 39035' Potomac River 380 Sediment blocks the light needed system are highly seasonal in nature.
Bay Bridge 39 Mouth of 3 for photosynthesis, changes the Most of the contributions are
Patuxent River 38� 18' the Bay 37 character of the bottom of the Bay, transported during high spring flows or
Secchi depth readings can be converted to a relative and carries unwelcome travelers such tropical storm events. In 1t 984, for 9
measure of turbidity, or a picture of the lack of water as excess nutrients and toxic example, the Potomac's riverine
clarity in the Bay. Turbidity can indicate conditions materials. sediment loadings were 85% higher
detrimental to aquatic life. This graphic shows the As mentioned earlier, three from February through May than they
turbidity profile in the Bays mainstem in 1984 and tributaries, the Susquehanna, the were during the following four months.
1985. The higher values in the graphic indicate higher
turbidity(andlower Secchi depths). Shown is how Potomac, and the James, drain 84% of Sediment loadings are also episodic.
spring high flows affect turbidity, especially in the the total Chesapeake Bay drainage The lowest recorded monthly sediment
uppermainstem. Mostoftheturbidwaterisnearthe basin. The Susquehanna is the load discharged to the Potomac's
Bay Bridge in the area of heavy inflows from the largest contributor of freshwater (50%) estuary was 238 tons in the drought
Susquehanna and other upperBay tributaries. The to the Bay; the Potomac is the second year of 1930, whereas 4,160,000 tons
highest turbidity was in the upper Bay during the
summer of 1984 and the winter/spring of 1985 during largest contributor (20%), followed by were discharged in one month during
periods of Susquehanna River high flows. (Source: Virginia's James River (14%). the 1936 flood.
MD OEP and VA SWCB)

/smophere

Fresh- saltwater transition
-mON Atmosphere (N+T) (maximum turbidity zone) . /N+T
Lighter freshwater l Plankton 0Ocean
W=0000. Point sources � .�, Oca
sewage treatement
plants (N+T) r altwate
r~i 'i,' tj~e'tood .. _..~
-e Nonpoint sources it
farm & urban runoff
groundwater runoff
(S+N+T) Die off
(-S^<t4/ + lo A S+++T A \ Man

in suspension /

Sediment absorbtion a D�O' .*�in
Sediment (S) & transport � S'di int0 / e
Nutrients (N) emical
Toxicants (T) n-en //
eUtake

The complexrelationship between sediment, nutrients, and toxics and theirpathways is simplifiedin 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 andnonpoint sources. Sediments, particularly fine-grained sediments, can
adsorb, transport, store, and release both toxics andnutrients. 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])

1985 benthic monitoring contributed 1985 period. Virginia's approach is to
ome 66,000 chemicalsare being significantly toward that understanding. scan for a wide range of possible
used in the U.S., of which B60,000 - hyrocarbon toxicants. Hundreds of
have been classified by EPA'as potent a y Upper Bay Sampling compounds were detected in some of the
if notdefinitelyhazardous. It isnot A total of 26 organic pollutants were samples. As in the upper Bay, the most
rprising, therefore, that toxic substances detected in sediments and biota (clams and abundant toxic compounds found were
aire found in Bay, water and sediments. The
found in B er and seiments, The worms) in 1985. Polynuclear aromatic PAHs, but the total PAH concentrations
Chspeake BayProgram on h v~
Chesaeae ay gam dthl � hydrocarbons (PAHs) were the most were not excessively high.
p~hpth organic, copudsadbay
of bothorgaic cornouprominent organic contaminants detected The spatial distribution of
ymetl r os The spatial distribution of
alarmingly high, particularly aroundurban ranging from 10,000 ppb in Baltimore concentrations appears to reflect both the
areas such as Baltimore and Harbor to less than 1 ppb at the mouth of particle size distribution in the sediments
Norfolk/Hampton Roads. In Patapsco River the PotQmac. The majority of these and input from rivers. Coarse-grained
(Baltimore) sediments metal PAHs were produced by the combustion sediments found near the mouth of the
concentrations as high as 140 times natural of carbonaceous fuels. Pesticides were Bay (CB7.3E, CB8.E on map) contained
Bay (CB7.3E, CB8.1E on map) contained
background levels have been found, detected in sediments and biota at four of low PA4 levels. The PA1
While not currently a serious threate , ' the eight stations sampled. PCBs were concentrations were generally higher near
toxicants are being found in the tissue of ; detected only in the sediments of river mouths than in the mainstem.
the Chesapeake's living resourcs. The f Baltimore Harbor.
compounds of greatest concern are metals Drawing conclusions for the lower
such as cadmium, chromium, copper, zinc, The average concentrations of the four Bay based on a comparison of 1979 and
lead, nickel; complex organic chemicals most abundant trace metals (zinc, 1984-85 sampling is difficult (1) the
10 such as polychlorinated biphenyls (PCBs), chromium copper, and lead) in sediments sampling stations, while comparable, are
chlordane, Kepone, polyaromatic and clams in 1985 (and 1986) were not identical; (2) there are too few
hydrocarbons (PAHs), and DDT; and other analyzed. The analysis revealed that, stations for an area the size of the lower
stations for an area the size of the lower
chemicals such as chlorine. Limited although high metal concentrations were Bay. However, at this point we can say:
studies of ambient levels of highly toxic seen in sediments associated with
tributyltin (used in boat anti-foulingpin Baltimore's industrial area, the � The 1984-1985 samples show
AiWBaltimore's industrial area, the
began in 1985 at several harbor sites Bay- relationships between sediment/metal and increases in overall toxics concentrations
wide; results are expected by spring ofta/metal concentrations were not when compared to 1979 samples
biota/metal concentrations were not
19 consistent. The results showed that in (detection methods have improved also).
consistent. The results showed that in
Low-s: concentratinsof these toxtic
compounds mayhavelittle immediae clams some metals varied considerably � There is a slight but statistically
over the course of the year. Metals such insignificant decrease in total
d:osage exposure is notwel understood as zinc and copper tended to be higher in concentrations in 1985 from 1984
Increasingly higherconcentrations of toxic clams than in sediments. On the other (inferences are guarded since transport of
compounds cause rededud fish hand, lead and chromium were higher in sediment and associated pollutants is
reproduction, deformities, and abnormal sediments than in tissue. dependent upon several variables).
bhavPior;l theyM mayexacrbate d'isea-s Both clams and worms living in � At Hampton Roads, total PAHs
effectsandcause evental malities, j relatively sandy sediments (with low increased about four-fold from 1984 to
Toxicants can cause an imbalance in
organic carbon) had lower body burdens of 1985, a change possibly due to a decrease
�species; they can e accumulated by
organic chemicals than those animals in sediment size that would increase
tabile. living in sediments low in sand (and high toxicant adsorption.
Toximaterials enterthe Basystem in organic carbon). Since the latter T NOAA Status & Trends
from a variet�y of soure-point source~ sediments had higher toxicant
(idutilfiite ewaetratet a'd (NS&T) Program
(industrial falies sewage concentrations, especially in areas near (NS&T) Program
power plants), and nonpointsouces (urban heavy industrial activity, it appears that The National Oceanic & Atmospheric
and agricultural runoffidumpsites, and the bioaccumulation depends on both the Administration (NOAA) studies the
atmosphere). The majortoxicant organic content in sediment and the grain bioaccumulation of toxics in coastal
hotspots'inthe B yser the size. regions nationwide. In the Bay, NOAA
Eliz~~~~~~~~Abt Rivreliminalt icture Hrofro mc
focuses on contaminants in sediments and
(Patapsco Rver). The maor tributaries A preliminary picture of how mucha
in Atlantic croaker livers and oysters.
also contribute toxic ladings, toxic material exists in the Bay was i Atlantic croaker livers and oysters.
TeBeitd e000 obtained during the Bay Program's Preliminary observations follow.
me~tricdtons oflf 1mtalls enterh Bay fro research phase. The new sampling efforts DDT: General use of DDT declined
the major tributaries in an average year. will expand this picture. The ability to significantly during the late 1960s and
The loadings oforganic compounds have- interpret long-term trends, and the reason was ultimately banned in 1972. Analysis
not been quantified as yet, butover30 for the deposition of Bay toxicants at of historical data reflects this decline;
organic compounds have been foundin the; various levels, will require understanding oyster body burdens of DDT and DDT
mainstemn Bay, All but a few of these amre
mainstem Bay. All buta f of ese a of all the other variables that affect levels metabolites declined steadily from 1965
toxic in some concentration.
of pollutants, particularly seasonal and to 1977. In fish, it is known that many
localized variability. environmental and physiological factors
TOXICS can affect bioaccumulation of DDT.
Progress has been made in our Lower Bay Results NS&T results indicate sediment DDT
understanding of the broad distribution of Virginia sampled and examined concentrations are highly correlated with
toxic contaminants in the Bay system. sediments for organic chemicals at eight liver concentrations for Bay Atlantic
The following results from the 1984- stations in the lower Bay in the 1984 and croaker, which eat benthic animals.

Polynuclear aromatic hydrocarbons MM
(PAils): Studies elsewhere have
associated sediment contamination by :
PAHs with occurrences of serious ,
histopathological cancers such as R
cancerous lesions in fish. Although
disorders of this kind were not observed in Y
Bay croaker and spot, occurrences of other R
types of lesions were correlated with .Z~ ; ~
concentrations of total PAHs in sediment. ;
Metals: Sample sites in the upper
Bay yielded consistently higher levels of
metals in oyster tissue than 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. [] ,

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 y ~i- - ~ ~ '
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 ! ii
contaminants in the system, seasonal ..
cycling of pollutants within sediments,
and the pathways by which these .A
toxics go from sediment to the Bay's .
living resources are processes not
fully understood.

Monitoring for toxicants has been conducted at 87
stations along the mainstem of the Chesapeake Bay :at f i th : a
and in te Maryland tributaries. (Sources: VIMS, MD u
OEP, an Nd NOAA)aeiisuWa[rl:

Reinren-Insert Do Not Scan
AL ALA
Document Here

I)ocument ID:.- 0)~,iz~h )b

Page#(
~3~DXO \j~o-J~K\4H~oc�,

Plankton & The Food Chain

f Plankton and benthic monitoring any other area sampled. Patuxent River
for the new cooperative Bay-wide program carbon fixation rates (a measure of
@g~~~~; was initiated in 1984-1985. This organic production) were 40% higher than
:* program is an important advance toward Bay rates, and chlorophyll-a values (a
~, i f f XMXunderstanding the Chesapeake Bay. measure of biomass) were 50%-200%
Plankton were collected at 23 Bay higher.
_ _~~ stations s iutnosywth wtr
m__ mstations simultaneously with water- In terms of composition, diatoms
t d biological and were dominant during the late-
water-quality data to be examined
g .| g g atrsal atobe examined winter/spring and fall blooms. Small
together. Benthic samples are collected at coccoid green cells (possibly
86 stations. ~~~~~coccoid green cells (possibly
~~~~~86 stations.~~ ,cyanobacteria) were numerically dominant
rniQua~~~~~~~~~ estuariesin the Bay in Ma ryl and the re st of the
~~~~~~14 ~gX~~~~ year. During 1984-1985, large quantities

f ~ .. . . ~~~~~of phytoplankton settled into deep er Bay
~ ~ waters, where their decomposition would
P:yto further deplete oxygen in bottom water.
: The Bay is one of the most productive Virginia s ampling of the ainste
t estuaries in th e wo rld. It is no t wa s lim ited to the thr ee-month period
gi;~ = concent~~surprising, therefore, that the 1984-1985 July-September 1985. The data indicate:
a sampling revealed a con tinuous supply of diverse population patterns with distinct
rephytoplanktoled activity
phy tn. Phytoplankton a ctiitydifferences in phytoplankton composition
jis greater in the freshwater and trans ition
tr 3tj P-and concentrations between the central and
(0.5-5.0 ppt) zone s of the Bay and t lower Bay; significantly greater
tributaries where there are high nutrient abundances and diversity in the deeper
-~ ~. a~- concentrations. water layer; a greater diversity and
Maryland's 12-month sampling concentration of species near the Bay's
r evealed high productivity in the uppe r mouth.
freshwater portions of the Potoma c a nd
d:i nl rdc ivPa tuxent. The upper two freshwater and taio zn
h transition stations in the mainstem Bay, , A
f.Ihhowever, showed the low est productivity. d cua
A Th is low production was a t the mouth ofw
ntin the Su squehanna, wh er e high potential Zooplankton ...
3~a~1-~ finflows.$ -productivity is inhibited by high During 1984-1985, icrozooplankton
-ntl turbidity. Th e highest productivity i n were sampled in Maryland's portion of the

~~~~~ th:PtoacanPtu:n were sampdinar. y ooland' otion saofa pheakcurd
~ Maryland's part of the Bay was found in Bay, and mesozooplankton were sampled
�~ the mainstem (mesohaline zone, 5-18- in both Maryland and Virginia. As with
ppt) near the Chesapeake Bay Bridge. phytoplankton, higher zooplankton
The seasonal pat t ern of phytoplankton biomass was found in the upper
productivity in 1984-1985 was typical: freshwater and transition zones. Maryland
:~~~ g = A~ morehigh late-summer productivity due to sampling revealed nothing surprising in
longer days and warm waters; a fall peak species composition, abundance, or
followed by low winter productivity; a distribution: shrimp-like crustacean
major spring peak following an influx of copepods, Acartia and Eurytemora, were
~z V~v~ nutrients with the spring freshwater the dominant zooplankters. In Virginia's
inflows. lower Bay, isolated and unexpected high
Productivity and seasonal patterns for concentrations of copepods were found.
for:f i t..... ~the Potomac and Patuxent were similar. Zooplankton seasonal peaks occurred.
.and p~eda~ion influe~~e zo~ptankt~n The Patuxent, however, had higher and Coupled with phytoplankton growth,
ttuij db die 'more frequent peaks of productivity than 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).10 EE
Other species shown include:

Phytoplankton

I Cyanobacteria
2 Cylindrotheca closterium
3 Cyclotella meneghiana
4 Katodinium rotundatum
5 Ceratium lineatum
6 Skeletonemna costatumr1
7 Rhizosolenia alata 1
8 Prorocentrumn micans
9 Cryptomonas sp
1 0 Chaetoceros decipiens
1 1 Rhizosolenia fragilissima
1 2 Cyclotella striata E

Zooplankton

13 Keratella cochlearis I
1 4 Trochophore larva of oyster
1 5 Daphnia retrocurva (rare)
1 6 Bosmina Ion girostris
17 Alona affinis
18 Barnacle nauplius
1 9 Blue crab zoea
20 Trochophore larva of polychaete
21 Acartia clausi
22 Acartia tonsa )
23 Podfon polyphemnoides

34
Bent hos

24 Nereis succinea
25 Mya arenaria

35~~~~~~~~~~~~~~~~~

were more pronounced in the less saline biomass were found in the deepwater mud
waters. The monitoring results support habitats where summer hypoxia/anoxia
Millions of animals live on or
the concept of "coupling" between (low/no dissolved oxygen) occurs.
burrow in the bottom of Chesapeake
Bay. They ar e known collectively as phytoplankton and zooplankton: the The deep central portion of the Bay in
Bay. They are known collectively as
the benthos." Because of their limited cseasonal microzooplankton peaks Maryland, the lower half of the Potomac
mobility (worms, clams, shrimp, anded with or followed by one month River, and the upper Bay in Virginia
snails) or lack of mobility (oysters and the phytoplankton peaks; the support the lowest benthic biomass; the
mussels), they are good indicators of esozooplankton peaks coincided with greatest benthic biomass is in the
localized water quality. Some, such the phytoplankton peaks during the brackish and low-salinity habitats.
as o r rspring bloom, but at other times tracked
as oysters, crabs, and clams, are more closely microzooplankton A summary of the more notable
commercially valuable. The less abundance. This phenomenon also findings from 1984-1985 benthic
familiar worms, small crustaceans, suggests that microzooplampling:
' suggests that microzooplankton is ang
snails, and anemones are also
snaimporantd anemonth areganmsfom important link between phytoplankton * Effects of anoxia are most apparent
and the larger mesozooplankton in the in deep waters just downstream of the Bay
one of the major intermediate links food chain for much of the year. Bridge where anoxia is generally most
between the primary producers
(phytoplankton) and the hig her trophic severe and of the greatest duration. Stress
levels such as fish and waterfowl. Aft 0 -add i; from hypoxia/anoxia events also appears
16 Their burrowing and feeding activities to have affected benthic communities at
are also important in the nutrient a; C-, two Virginia stations--in the deepwater
cycles that control the Bay's ei mainstem Bay and in the lower
productivity. The benthic community Rappahannock.
is not uniformly distributed over the Overdthe last sever ades, the * Areas not experiencing anoxia
bottom. Salinity, sediment type, and ext ow confirmthatyear-to-yearfluctuationsin
oxygeniepisodes i Bat y bottom waters
dissolved oxygen are the major .oxygen epist a bottom waters , salinity are a major factor influencing
determinants in their distribution. during summer onths have increased. long-term benthic trends.
Currents, pollutants, diseases, and With decreasing oxygen levels, the
predation further shape their abundance of short-lived benthic species * In the Patuxent River, populations
distribution and abundance. The that are less suitable prey for finfish and of a clam (Macoma balthica) dependent on
greatest benthic variety (some 150 crabs has increased, while the availability organic-rich sediment deposits have
species) occurs in the saltier waters of of preferred longer-lived benthic prey for declined since 1980. This suggests that
the lower Bay. fish and crabs has decreased. The lowest secondary sewage treatment and sediment
standing stocks and abundance of benthic controls are having a beneficial effect. []

Nutrients are used and re-used in along with sediment in the high spring plants die, they sink to the bottom and
the Bay. Nutrients such as nitrogen (N) flows (sediments adsorb both decompose (using oxygen in the
and phosphorus (P) are the essential nutrients, but primarily P). The major process) in the sediments.
building blocks needed for growth in the use of these fertilizers is by Nutrients are released back into
elaborate Bay food chain that begins phytoplankton in surface waters where the water column under a variety of
with phytoplankton (microscopic algae). there is enough light to support plant physical and chemical conditions not
Generally, plants use the two nutrients growth. When Bay waters are over- completely understood. Nutrient
in a ratio of 16 parts N to 1 part P. enriched by nutrients, growth release occurs particularly in areas
Nutrients "fertilize" Chesapeake explosions or "blooms" result. with low oxygen levels. Higher water
phytoplankton and the larger aquatic In land ecosystems nutrients tend temperatures and alkalinity, along with
plants just as they do crops and to be washed away, never to return. In physical perturbation of the sediments
gardens on land. estuaries such as the Chesapeake, (due to water turbulence or movement
In order to conduct photosynthesis, however, nutrients tend to be retained of benthic organisms) can also
phytoplankton depend on several forms because of the unique patterns of increase release rates. Overturn
of inorganic N and P: ammonia (N), water movement (circulation) and used mixing events transfer nutrients into
nitrate (N), and phosphate (P). These again and again because of recycling upper waters where they can be re-
nutrients enterthe Bay's estuaries from (similarto processes occurring in a used by new algal generations. This
many different sources: agricultural and compost pile) in both Bay waters and recycling process implies that some
urban runoff, sewage treatment plants, sediments. The algae flow toward the portion of the nutrients stored in
and rainfall. A large portion of these ocean in the lighter (and fresher) sediments will get back into the
dissolved nutrients are transported waters. When these microscopic system.

Citizen Monitoring

program. Of those who originally started
in the program, 81% are still monitoring. Richmond
How Citizens Can Get Involved The citizen monitors come from a variety
* Join the annual hunt for submerged of backgrounds and professions--farmers,
aquatic vegetation; students, housewives, teachers, scientists,
* Learn how individuals can reduce bureaucrats, retired military, and medical Williamsburg
their contribution to pollution; professionals are monitors. All
Participate in activities to restore volunteers attend a training session and an
� Participate in activities to restore
and protect the Bay; annual workshop; they receive computer
printouts and plots of their data, plus a Citizen's Monitoring
� As a member of an organization, set ~ , ,
monitoring project newsletter. The newsletter, River Trends, Stations
up a water-quality monitong projectd.
for a local watershed. contains monitoring results, informative
articles, and sampling tips.
CONTACT: Citzens Program for the Chesapeake Results obtained so far indicate that
Bay, Inc., 6600 York Road, Baltimore, MD 21212; trained volunteers can collect quality-
or Kathleen Ellett, Citizen Monitoring Coordinator, controlled data. A comparison of citizen
Chesapeake Bay Program, 410 Severn Avenue,
Annapolis, MD 21403. data with data collected by the Virginia shallower waters of the volunteer 17
Water Control Board on the James River monitoring stations warmed significantly.
A citizen volunteer monitoring and by Maryland's Office of Salinity values were comparable,
program was started in the summer of Environmental Programs on the Patuxent although the hydrometers consistently
1985 by the Citizens Program for the River shows similar results. read about 3 ppt higher than the
Chesapeake Bay, Inc. (CPCB). The The first comparison was made for conductivity meters used by the state
program monitors the near-shore waters four stations on each river where the state agencies.
of two major Chesapeake Bay tributaries, had a station close to a citizen monitoring Volunteers have demonstrated their
the Patuxent and the James. The purpose site. The results of the comparison ability and willingness to collect data on
of this program is to demonstrate that showed that dissolved oxygen and Secchi short notice during and after such tropical
volunteers can collect reliable water- disk readings were in close agreement; pH storms as Gloria and Juan, when state and
quality data that will help managers detect values were similar. Water temperatures federal programs were less able to respond
and assess long-term Bay ecological showed differences only during quickly. Secchi disk depths recorded by
trends for the near-shore habitat. This extraordinarily hot weather when the volunteers along the James River clearly
pilot project will determine the showed the increased river turbidity
appropriateness of a larger, permanent following those two storms. In late
program. Bowie 1985, citizens reported hypoxic/anoxic
Data are being collected at 19 sites on Citizen's Monitoring conditions in the bottom waters of St.
the Patuxent and 16 sites on the James, Stations Leonard's Creek, a tributary of the
from the head of tide to the mouth. Five Patuxent River. The main channel of the
surface water-quality factors are measured Patuxent is known to have low dissolved-
weekly at each site: water temperature; perat Mrlboro oxygen levels in late summer, but low
pH (using a color comparator kit); D.O. levels had not been reported
turbidity (using a Secchi disk); dissolved previously in water as shallow as St.
oxygen (using a micro-Winkler titration), Leonard's Creek (3-4 meters). The extent
and salinity (using an hydrometer). In and duration of this phenomenon was to
addition, monitors record weather and be explored in 1986.
general ecological observations about the CPCB began sponsoring a similar
site on the Data Collection Form. They program on the Conestoga River in
send this data to the program coordinator Lancaster County, Pennsylvania in the
at the Chesapeake Bay Program Liaison fall of 1986. Similar projects have been
Office for entry into the Bay Program started in Maryland with the help of
computer and subsequent periodic H t/ CPCB: on Back Creek in Annapolis,
analysis. West River in Anne Arundel County, and
There are 37 participants in the Lexington Park on the Choptank River on the Eastern
Shore.

SAV Habitat & Nursery

Chesapeake Bay Middle Bay
submerged aquatic The 1985 SAV "good news" was the
he restoration of submergede vegetation (SAV), in increase in grasses in all sections of the
Taquatic v a A X a severe decline from middle Bay zone over the previous year,
Bay cleanup priority for several
Bayclreasons. One reasonyis its hi ; the late 1960s until resulting in a 389% increase (12,315
priimary productivity te t of X 1984, showed an acres) for the entire zone. Even the
biomass accumulation. In addition, overall increase of Patuxent River, while still sparsely
aquatic plants form an impo0 rant link.i 26% (47,893 acres) vegetated, showed a 401% increase (22
the food chain, between nutrients in from 1984 to 1985. acres in 1984 to 109 acres in 1985). In
the water column and sediment, and The largest increase the Potomac River, increases were seen in
the animals. Many waterfowl are 7 was found mid-Bay, both the upper and lower sections, 140%
particularly dependent on SAVfor ;:;i X along the Eastern (3,557 acres) and 59% (941 acres)
food. Aquatic plants are alsod Shore. There was a slight decrease in the respectively. Ten species of Bay grasses
significant in the Bay's ecosystem as upper Bay, and little change was observed were found in the upper Potomac section,
habitat and nursery areas for many in the distribution and abundance of SAV with Eurasian watermilfoil and hydrilla
species of commerially improtant fish in the lower Bay. There has been some the most prevalent. Widgeongrass was
d f eti1ver s pas " slight improvement in the declining found to be the dominant aquatic plant in
efectively aiderosioncontro athey
dampen wave action and trap light- numbers of migratory waterfowl, the mainstem of the middle Bay zone.
reducing sedirnnt running off the especially in SAV-resurgent areas.
Lower Bay
land. SAJ ac anutrientbufferbyUpper Bay There were no major changes in SAV
nitrogeen and phospfious[ Seaso ally, There was a slight decrease of 4.5% in the nine sections of the lower Bay zone
SAV provides anrimpOtant s'ouree Of; (7,472 acres) in the abundance of SAV in between 1984 and 1985. The largest
dissolved oxygen for th'eB - the upper Bay zone, with declines revealed change occurred in the Reedville section,
The Chesapeake Bay, with its in three of the four sections studied. where the 1985 survey revealed a decrease
broad salinity range,supporits There was a 142% increase (259 acres) in of 34% (425 acres) in SAV distribution
approximately 20species of SAV, 10 the sparsely vegetated Eastern Shore from 1984. Most of the Bay's grasses
of which historically have been section, principally along the Elk and (59%) are in the lower Bay zone, with
abundant. These Bay "grasses" ivary Sassafras rivers. More than half (66%) of 68% of this zone's vegetation located
in their salinitytolerance. this zone's SAV is in the Susquehanna along the Eastern Shore bayside. Bay
The recent precipitous decline in Flats area, and this zone is dominated by grasses are still absent in two of the six
submerged aquatic plants, beginning wildcelery, Eurasian watermilfoil, and areas of historical abundance in the lower
in the 1960s, is believedito be related hydrilla. Redhead grass and widgeongrass bay. Widgeongrass and eelgrass are the
to man's activities. SAV Ilosswasfirt; dominate in the Eastern Shore area. dominant SAV in the lower Bay. D

Analysis of surveys of Bay waterfowl over 39 years (1948-1986) by the
obt 3 1 f 9 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
W hilthes in TheeaSe;sinfo St i d nAtine A increase of 75% (apparently due to their finding food sources other than
th- fin1 av be.ltr sin 9 X puaio SAV). All othe r species, however, have shown significant declines. The
forh declines in canvasback and redhead duck populations appear to be directly
caopefulses. Storm age and grazigi 'I3 n git . ma 3j3orelated 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.

770 00' SUSQUEHANNAR. SA
Thousands Thousands of acres
(0 of acres 150

Kilometers 100

ib1 210 310 40 BALTIMOR J750

- ~~~~~~~~~~~~~~ ~ ~~~~~1978 98 1985 1
1.0

C\J
CHOPTANI(_
WAHNT2

m Lil~~~~~198
LOrwt
iN18
PTN R

PATLJXE0 1

Bare Islan Pt

monito~~~~~~~~~~~~~~~~arial zonew

The Harvest: Finfish

The trend of decreasing numbers of The health of the striped bass remains
T he esteemed striped bass, or harvestable anadromous fish (estuarine or a high-priority concern. Research efforts
rockfish," can live moare than 30 marine fish that spawn in freshwater), focus on stock assessments, young-of-
thyears and can grow to a greatximum size has been 60 showed no change in 1984-1985. year analyses, larval abundance and
the usual maximum size has been 60
pounds in recent years, rockfish weighing Anadromous fish spawning results remain transport studies, related habitat
over 100 pounds were recorded in the late poor, and abundance of juveniles low. investigations, hatchery restocking
1800s, and have been occasionally There is some optimism, however: the programs, and laboratory toxicity studies.
reported in recent years. most important anadromous fish, the It appears that the striped bass
In its native range along the Atlantic striped bass, or "rockfish," appears to be harvesting moratorium in Maryland and
Coast, the striped bass spawns from benefiting from recent protective the partial ban in Virginia are protecting
February through July. In the Chesapeake, regulations, and hatchery-release programs the important 1982 year-class as intended.
spawning generally occurs from late April have been initiated. Also, more data The marked increase in striped bass
through May. Rockfish spawn in fresh or about striped bass are now being collected observed in Virginia since 1981, and the
nearly freh wafter, all major Bay tributaries in the upper Potomac River, a significant large numbers of young stripers caught in
20 The Chesapeake is regarded as the center striped bass spawning ground. An unregulated D.C. waters in 1985, are
of abundance for the species, and excellent intermittent data base exists on believed to be a result of the bans.
historically its migratory stocks have been striped bass spawning in the upper
considered the major source for the Atlantic Potomac. There has been a lack of In 1985, Maryland banned harvestig
Coast harvests. In the 1970s, when information, however, on juveniles and o f striped bass because of the drastic
rockfish stocks were larger, it was adult fish in the river's reach in theinin
estimated that the Chesapeake stock nation's capital. The new data collection commercial fishery landings for both the
contributed 90% to the Atlantic Coast program initiated by the District of Chesapeake and the Atlantic reveal poor
striped bass harvests. With reduced Bay Columbia in 1985 will rectify this.antic reveal poor
stocks, the current contribution would Also, the states are standardizing the recruitment into the fishery since the
appear to average between 50% and 70%. available Chesapeake Bay commercial 1970 "super" year-class. The 1982 year-
Abundance, health, and conditions of catch information on the most important class of rockfish, which will not spawn
Chesapeake stocks are therefore critical to a ri heuntil 1988, is the object of protection
the entire Atlantic fishery. Bay because its abundance offers considerable

Mean number of striped bass per catch
Mean number of striped bass per catch
30 Maryland 1954-1985 Virginia 1967-1985

5
?5 * No data 1973-1979
25 _ 4 __
3

2 %
20 _______ 2___3-0
_15 ' 1967 70 72 80 82 8485

A10 --1 l _____

1954 55 60 65 70 75 80 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 unusuallyhigh 1970 indexdominates in both states. Virginia's indices increasedsteadily from 1981 through 1984, butdroppedin 1985. Maryland's
indices have been verylowsince 1978, with the larger 1982year-class the object of state protection. (Source: MD Department of Natural Resources [DNR] and VA
Marine Resources Commission)

Maryland hatcheries until the fall, when
Commercial striped bass landings in pounds 1970-1985 they are less vulnerable and big enough to
be tagged and released into selected Bay
areas. Experimental tagging and tag
5000 l Maryland recovery programs were initiated in both
l;l Virginia Maryland and Virginia in late 1985. The
4000 expectation is for a release of 3.5 million
fish in Maryland alone by the end of the
3000 _ program in 1989. What has been learned:
a large number of striped bass can be
2000 [_ a X 0 lraised in hatcheries, tagged, and released
into Bay tributaries successfully. The
1000 II- next step is to determine the program's
impact.
10 _ L - Stocks of other anadromous fish such
1970 72 74 76 78 so80 82 84 85 as shad, river herrings, and yellow perch
remain at all-time lows. White perch
numbers are also low. Abundance
Commercialstriped bass landings in Maryland and Virginia 1970-1985. (Source: NOAA/Naional Marine estimates of the harvest-banned shad from
Fisheries Service [NMFS]) 1980 through 1985 indicate a trend of
generally increasing stocks, but numbers 21
potential for increasing the spawning Both Maryland and Virginia survey of young-of-year and adults remain
stock. juvenile striped bass annually. Young extremely low. Harvests of marine-
While Virginia is optimistic about the fish are trapped either by seine net (Md.) spawning fish, dependent on oceanic
number of rockfish in its waters, recent or by seining and trawling (Va.). The rather than Bay conditions, are relatively
stock assessment work has confirmed that young stripers are counted and the totals good. Ocean-spawning menhaden, sea
the 1982 year-class is the only reasonably averaged. Due to differences in habitat trout, spot, and bluefish harvests
abundant one in Maryland. Data reveal and capture method, Maryland and remained stable or increased during 1984-
very few fish older than the 1981 year- Virginia juvenile indices are similar but 1985.
class in the Potomac, and a very low ratio not identical. Maryland's more shallow The first preliminary comprehensive
of females--the egg layers on which good shoreline allows for more extensive assessment on thirteen Bay species
year-classes depend--to males. The seining and higher young-of-year catches (including striped bass) represents
Potomac pattern appears to be the general than is possible along Virginias deeper progress in bringing together the
case for Maryland's portion of the Bay. shores. The Maryland indices, therefore, available commercial catch data in a
Maryland striped bass spawning will be higher than those in Virginia. uniform manner. Assessments of six
stocks have been low; they were lowest In Maryland, a juvenile index of 8 has additional species are scheduled. While
in 1982 and 1983, and slightly higher in been considered the minimum desirable the assessments are based on those fish
1984 and 1985, largely due to the index because historically, year-classes reported (as opposed to those which may
protected 1982 year-class males. Striper with an index of 8 or better have actually have been caught), and while no
egg and larval abundance also continues apparently supported a commercial fishery complete set of information exists for any
to be low. Intensive Maryland habitat of 2 million pounds of stripers annually. one of the Bay fisheries, the value of this
studies, which seek to relate water quality Since the 1970 year-class with a very preliminary effort is that it will more
and other habitat factors to larval high index of 30, however, Maryland clearly reveal important missing
abundance, are currently under way. A juvenile indices have been alarmingly information. []
combination of low pH, which tends to low. The 1982 index of 8.4 was followed
mobilize naturally high levels of by low indices of 1.4 (1983), 4.2 (1984),
aluminum (which impairs larval gill and 2.9 (1985). In the District of
function), and low hardness found in Columbia, recent young-of-year averages
some Eastern Shore rivers such as the (not available prior to 1984) were also
Choptank, may be causing significant low: 2.4 (1984) and 3.9 (1985). The
larval mortalities. Virginia young-of-year indices, however,
Fishery biologists recognize that there 4s4 (1984)a The 1984 index was the
is a high mortality rate (over 99%) in highest number of juveniles recorded in
early life history stages of striped bass; Virginia since the record 1970 year-class
the mortality rate declines considerably, with an index of 6.4. The 1985 juvenile
however, when individuals reach the index of ve
juvenile or "fingerling" (2 to 5 months year-class index of 2.3 was only average.
old) stage. Juvenile or young-of-year Since mortality of striped bass in the
abundance firmly establishes the strength wild is greatest from the fertilized egg _////
of the newly recruited year-class, and through the fingerling stage, hatchery
allows projections of its contribution to rearing may be a bridge to an improved
the commercial fishery in subsequent fishery. Striped bass are now being reared
years. in U.S. Fish & Wildlife Service and
year./y

The Harvest: Shellfish

With oyster reproduction and Bay's shellfish, particularly in 1984 and occurrence of heavy spatfalls, despite low
survival declining seriously over the last 1985. brood stock, underscored the importance
decade, the higher spatfall in both While there has been no long-term of local weather and climate in the
Maryland and Virginia in 1985 was good trend in rainfall/salinity, there has been a determination of year-class strength.
news. Over the 1984-1985 monitoring distinct trend toward warmer falls and Although its 1984 spatfall (2.4 spat
period, however, spat survival rates winters over the last 10 years. The per bushel) continued a downward trend,
remained low and still unexplained. No spring of 1985, with below-normal Maryland found high numbers of spat on
changes were noted in the dismal picture rainfall, was followed by one of the three its 55 key oyster bars in 1985. The
for soft-shell clams, but the blue crab warmest autumns in 30 years (which Maryland spatfall average in 1985
fishery remains healthy, if unpredictable. extended into the winter). The drier and exceeded 100 spat per bushel. The higher
Rainfall and temperature are key warmer fall of 1985 resulted in a spatfall was welcome, but it was limited
22 variables that determine oyster harvests. considerably longer spawning season than mainly to the mouth of the Potomac
A strong correlation has been found that of 1984; the oyster spawning season River and Maryland's Eastern Shore
between high salinity and good oyster extended beyond the normal June- tributaries. This area is greatly reduced
reproduction. Dry summers, for example, September period into late October. compared with that area where high spat
may provide the oyster with highly saline Both Maryland and Virginia had high sets were recorded between 1938 and
waters and good feeding and growing spatfall as a result. Virginia's spatfall 1965.
conditions as a result. This same kind of was moderate to heavy in the 1984 and The survival of spat to yearling
weather, however, can encourage oyster 1985 spawning seasons. The heavier spat continues to be of prime concern. In this
diseases. The significant effect of rainfall sets generally occurred in 1985, regard, unfortunately, 1984 and 1985 were
and temperature on the productivity and particularly on the James River seed beds. not exceptions. In Virginia, the state-
health of the Bay's resources is evident There was considerable temporal and wide poor survival of spat to yearling was
when one examines the condition of the spatial variability in the spatfall. The evident in the oyster bar surveys that

- Mean number of oyster spatset per bushel
Mean number of oyster spatset per shell Maryland 1944 -1985
~~250 ~ 6 Virginia 1965-1985 A
5
4 1
200 -
2

0
150 1965 70 75 80 84 85 _

* No data
100

50 n

0 11iU 11 11 f11t 1l-Fri fn 0L lr,
1944 50 55 60 65 70 75 80 8485
Oyster spat set forMaryland (1944-1985) and Virginia's James River(1965-1985). The density of the annual spatset is a measure of oyster reproductive success.
Spatset is measured annuallybut with different methods by the two states. Maryland measures the numberof spat per bushel; Virginia measures spat per shell.
Shown here is the great variability of spatsetin both states. The relatively highersets for the two states in 1985 was good news. (Source: MD DNR and VIMS)

Commercial oyster harvest in millions of pounds T he American oyster has been
important to the Bay's economy
since the mid-1i 880s, when the
20 Q Maryland average annual yield for Maryland
alone was about 12 million bushels.
- Virginia Since the turn of the century, the trend
has been decreasing harvests of
smaller oysters. Even though
management practices, such as shell
10 and seed planting, have helped to
stabilize the harvests since the

average around 2.6 million bushels
(U.S.) annually.
The density of the annual oyster
0Oi! ~1 11 a s 1 31 : spat set is a measure of oyster
reproduction success. Free-swimming
1969 70 72 74 76 78 80 82 84 85 oyster larvae (2 to 4 weeks old) drop to
the bottom to set; they attach to
Commercial oyster harvests. Since the turn of the century, the trend has been one of decreasing harvests of suitably clean and firm substrate
smaller oysters. Even though management practices such as shell and seedplanting have helped to stabilized (usu ally oyster shell) in order to grow.
the harvests since the 1960s, the current Bay-wide landings average around2.6 million bushels (U.S.)annually. These spatfalls are measured annually 2
Ithas been estimated that the sustainableyield of Marylandoysters is 2-3 million bushels annually. Virginia's by Virginia and Maryland, and23
oyster industry has notrecovered from the disease attack of the late 1950s. (Source: NOAA/NMFS) monitored carefully since, in spite of
improvement in Virginia's spat sets
since 1 980, there has been an overall
followed the heavy 1985 spawning season The stocks of Maryland's soft-shell Bay-wide decline in spatfall for more
(predation by the abundant blue crab may clams continue to be low; 1984 and 1985 than ten years. Setting patterns and
play an important role). Bay biologists harvests were each only about 1 million survival rates have varied widely.
point out that the success of the oyster pounds. The crab fishery remains the one Spat set has long been considered a
reasonable indicator of subsequent
fishery depends on a number of source of "good news" for the Bay's harvests, but its predictive value has
consecutive years of above-average spat fisheries, however. While historically been reduced over the last couple of
set, as well as the absence of threats from crab harvests have fluctuated wildly, the decades because of poor spat
harvest pressure, disease, and lack of fishery appears to be unthreatened. Both survival.
dissolved oxygen. 1984 and 1985 were good years for crabs. larval survival rat reproduction and
larval survival rates, increased
MSX and Dermo can pose serious Bay-wide crab harvests were 59 million demand, and harvesting, oysters have
disease threats to the oyster industry. pounds and 46 million pounds in 1984 been affected by weather and
MSX attacks adult oysters (the peak and 1985 respectively. disease. Oysters require a salinity
range of 5-35 ppt. Freshwater inflow,
period of infection is June), flourishing in One reason for the lack of concern therefore, is a key variable affecting
the same saline conditions that favor about this crop (the Bay's second most reproduction and mortality.
oyster production. Virginia's oyster valuable), is because crab year-classes are The oyster diseases known as
industry has been threatened by MSX believed to depend more on the Dermo (Perkinsus marinus) and MSX
since 1959. The organism has been a environmental conditions and (Haplosporidium nelsoni) have taken
their periodic tolls on the oyster
problem in Maryland waters since 1963. hydrological effects associated with the fishery. These organisms are
Maryland's high spat sets in the early Bay's mouth than other factors. The associated with higher salinities
1980s were offset by an extensive higher salinity of the Bay's mouth is also (above 15 ppt), and are far more
outbreak of MSX in the 1982-1983 essential for crab spawning and larval regularly a threat in the saltier waters
season. growth. The circulation pattern at and of V irginia and low er Maryland
attacks on middle and upper Maryland
While conditions in 1984 and 1985 outside the mouth of the Bay can Bay shellfish are less frequent but can
were not conducive to the spread of MSX transport crab larvae into the up-Bay be devastating.
in Virginia, Maryland's lower Bay waters water currents of the deeper, saltier water The naturally fluctuating harvests
experienced some Dermo mortalities and layers, or can carry them into ocean of the economically important soft-
conditions conducive to MSX infestation currents and permanently offshore. for ts shell clam decline is not
in 1985. Mortalities resulting from the apparent, although low-oxygen areas,
latter would be seen in 1986. 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

T he Patuxent River is the longnestg MOE
intrastateriver in Maryland, and
its watershed is the only major sub-
basin that drains entirely within the .
state. Five decades of research,
monitoring, and modeling have
adequately addresse locaiized .
environmental concerns. The current ;:
goal for the Patuxent, however, is to -
employ a system-wide approach in
order to achieve a return to the good - :
24 water-quality conditions of the 1950s.
Consistent with Northeast trends t
over the last fewdecades, there has 7 7
been an increase in urbanization within
the, Patuxedr wate'rhd. :The human
popula'tion has increasd from 62,000: The Patuxent is approximately 110 mi
ina1920, to 248,210 in 1970,and to long from its origin on Parris Ridge to its
3 8e60 int 1s980. The arnmountf;e~ o :; f 00 :0 2 g g k confluence with the Chesapeake Bay.
35'2',860 -;~~~in 198. T h e : ;amount ofi~ iThe river drains portions of seven
developed landn increased moe than Maryland counties, and an area of
7% betwveen 1 973 and :981. These/ approximately 930 sq. mi. Its average
flow is 396 cfs; its contributes 0.5% of
la use have coincided with th a the Bay's freshwater flows. The
"gr'eening" (from exess-ive Patuxent estuary is deep: it ranks sixth
phytoplankton) and "'browning' (from i ; in volume and second in average depth
excessive sed'iment)of the estuary. of the Bay's primary tributaries. About
The T deterioration ofthe Patuxent was 27% of the land is agricultural, 29%
;evident by the 1960s. ; Citizen monitoring stations urban, and 44% forested. The upper
25% of the basin lies within the Piedmont
: Reoonstruction: -of 50-year patterns � OEP water quality stations Province; the lower portion is within the
within the Sewage treatment phlants Coastal Plain. High nutrient and
reeae inrae n tSewage treatment plants suspended sediment levels are the
enrichment dueto poc~int source (STP' FP primary water-quality problems.
dig~~ia~~~~~~'~ ~Maximum turbidity zones primay watequaliy pobems

grkhh J~iX~d~edbI~The Office of Environmental Program s
dissolved oxygen len-elsint of Maryland's Dept. of Health and Mental
rwa te ofthe;Patuxti ents tuarithe ;: i: Hygiene initiated a $3 million Patuxent
detromRiver program in 1982. Known as themgin
in creasesthe reandfr;y i Patuxent Strategy,the program'smajor
excesi;nsg M - < : : sobjective is to address the causes of the .t)
growth.AThe over-prduditionof algal

grwth haso been noted tol ered The observedwaterqualitydeclinefntal rograms a
dissolved oxygen levelsintas de r of Mbasin-wide perspective. Research, and Mental
waters of the Patuxent estuary: the Hygiene initiated a $3 million Patuxent

loss of submerged aquatic vegetaionv : monitoring, and modeling will provide
and declines in typical native, managers not only the necessary
estuarine-dependent commercial andi information to understand better the
recreationalfinfish and shellfish. processes affecting water quality, but
Today's Patuxent oyster industry ist a o also the means to evaluate the
fraction of what it was:in the 19s i effectiveness of various management
options. (Source: EPA, MDOEP)

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 4
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 c 3 -
increases in DIP levels. Values of DIP near the mouth of the estuary have also o \1969
increased over the years. The estimated annual loadings of TP from upstream sources , 2 -
to the Patuxent estuary for 1965: 180,779 Ibs; 1970: 341,717 lbs; 1975: 608,476 1963
lbs; and 1985: 216,500 lbs. During the 1984-1985 monitoring period, the Patuxent
River had the highest TP levels of the tributaries monitored. The Patuxent River TP 9C3
concentrations in the tidal-fresh, transition, and lower estuarine zones were J F M A M J J A S O N D
approximately 0.30-0.35, 0.25, and 0.1 mg/l, respectively.

NITROGEN Of the nitrogen forms that are routinely measured, only nitrate was 40
measured in the Patuxent prior to major STP construction. Shown at right is the 2
profile of nitrate values for Lower Marlboro in the low-salinity reach of the Patuxent. 30 -
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 1969
tend to be strongly correlated with river flows. The graph shows increases in nitrate 20
levels after winter periods in both 1936 and 1963, with a major increase in the latter. 3|
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 L 1936
loadings of TN from upstream sources to the Patuxent River estuary for 1965:
509,268 lbs; 1975: 2,462,563 lbs; and for 1985: 1,900,000 lbs. The 1984-1985 M J A
values of TN were generally at or above 2 mg/l in the tidal-fresh river.

CHLOROPHYLL-a Chlorophyll-a values have increased over the years as shown 60 -
in the graph. The data collected at Benedict Bridge, Md., at the lower end of the E
turbidity maximum region and in the mesohaline segment of the estuary, show that o -40 -
maximum observed late-winter and spring values increased by over 100% between /
1964 and 1969. Excessive phytoplankton growth from the increased levels of 2=
phosphorus and nitrogen was becoming apparent in the early 1970s. In 1984-1985, 0 1964
the highest concentrations of chlorophyll-a during the warmer seasons were found in -
the upper Patuxent estuary. Chlorophyll levels peaked at 100 ug/l in the tidal-fresh i , i i . . . i
reach of the Patuxent in the summer of 1985. F M A M A

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 June
values in the lower Patuxent estuary's bottom waters in 1938 and 1978 is shown to 6 193
the right. The comparison reveals 1978 minimum DO levels substantially lower than 4 978
those observed in 1938, beginning at Benedict and continuing downstream. No zero >- 2 -
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/l in surface waters, August
and between 0 and 8.0 mg/l in bottom waters. CPCB monitoring program volunteers 9 3
reported hypoxic/anoxic conditions in the bottom waters of shallow St. Leonard's 2
Creek in the summer of 1985. While the main channel of the Patuxent is known to 197
have low dissolved oxygen levels in late summer, low DO levels have only arloboro Point Island
occasionally been reported in water as shallow as St. Leonard's Creek (3-4 meters). RIVER - BAY
(Source: Chesapeake Biological Laboratory, University of MD)

CONTRIBUTORS REGIONAL

The coordinated monitoring network, created on behalf Chesapeake Research Consortium, P.O. Box 1120, Martin Marietta Environmental Systems, 9200 Rumsey
of the Chesapeake Bay Program, has drawn upon Gloucester Pt., VA 23062. 804/642-7150. Maurice Rd., Columbia, MD 21045. 301/964-9200. Donald
government resources at federal, state, and local levels, Lynch, Director. Talbot, General Manager.
and their contractors, and major university research Karen L. McDonald A. Frederick Holland, Fred Jacobs.
institutions throughout the Chesapeake basin. Their Interstate Commission on the Potomac River Basin, University of Maryland, Chesapeake Biological
coordinated efforts and dedication to the common goal Suite 300, 6110 Executive Blvd., Rockville, MD Laboratory, Box 38, Solomons, MD 20688. 301/326-
of restoring and protecting the Chesapeake Bay have 20852-3903. 301/984-1908. L.E. Zeni, Executive 4281. Kenneth Tenore, Director.
made this report possible. This report was assembled Director. Waiter R. Boynton, Gregory D. Foster, Joseph A.
by the Monitoring Subcommittee by authority of the Beverly Bandler, Mary-Ellen Webster. Mihursky, Cluney Stagg, David A. Wright.
Chesapeake Bay Executive Council, the Implementation Citizens Program for the Chesapeake Bay, Inc., 6600 University of Maryland, Horn Point Environmental
Committee, the Citizens Advisory Committee, and the York Rd., Baltimore, MD 21212. 301/377-6270. Laboratory, P.O. Box 775, Cambridge, MD 21613.
Scientific and Technical Advisory Committee. Frances H. Flanigan, Director. 301/228-8200. Dennis L. Taylor, Director.
Kathleen K. Ellett. William Michael Kemp.

FEDERAL GOVERNMENT

National Oceanic and Atmospheric Administration DISTRIT OF CO PENNSYLVANIA
National Ocean Service, Office of Oceanography and Department of Consumer andRegulatory Affairs, 614 H
Marine Assessment, 6001 Executive Blvd., Street, N.W., Washington, D.C. 20001. 201/727- Susquehanna River Basin Commission, 1721 North Front
Rockville, MD 20852. 301/443-8501. Charles Ehler, 7170. Donald G. Murray, Director. St., Harrisburg, PA 17102. 717/238-0426. Robert J.
Director. Department of Consumer and Regulatory Affairs, Bielo, Director.
David R. Browne, Carl W. Fisher, Bruce Parker. Environmental Control Division, 5010 Overlook Ave., Jerrald R. Hollowell.
Rockwall Building, 11400 Rockville Pike, Rockville, S.W., Washington, D.C. 20032. 202783-3192.
MD 20852. 301/443-8655. Anantha Padmanabha, Director.
John A. Calder, Gary Shigenaka. James Collier, James Cummins, Hamid Karimi.
Estuarine Programs Office, Universal Bldg. S., 1825 VIRGINIA
Connecticut Ave., N.W., Washington, D.C. 20009.
202/673-5243. Virginia Tippie, Director. MARYLAND College of William and Mary, Virginia Institute of Marine
David M. Goodrich, Samuel E. McCoy, James P. Science, Gloucester Point, VA 23062. 804/642-
Thomas. Academy of Natural Sciences, Benedict Estuarine 7000. Frank O. Perkins, Dean/Director.
U.S. Environmental Protection Agency, Region III Research Laboratory, Benedict, MD 20612. Herbert Austin, Paul 0. deFur, Jr., Robert J.
301/274-3134. James G. Sanders, Director. Huggett, Robert Orth, Frank Wojcik.
Chesapeake Bay Liaison Office, 410 Severn Ave., David C. Brownlee, Kevin G. Sellner. Old Dominion University, Applied Marine Research
An n apols, MD 21403. 30 1/266-6873. Charles S. Department of Health and Mental Hygiene, Office of Laboratory, Norfolk, VA 23508.804/440-3595.
Spooner, Director. Environmental Programs, 201 West Preston Street, Raymond W. Alden ill, Director.
Richard Batiuk, PatnL cia Bonner, Nina Fisher, Baltimore, MD 21201.301/225-6316. William M. Arthur J. Butt.
Catherine L Leger, Kent Mountord Eichbaum, Assistant Secretary. Old Dominion University, Dept. of Biological Sciences,
Computer Sciences Corporation, 410 Severn Ave., Suite
Computer Sciences Corporation, 410 Severn Ave., Suite Michael Haire, Robert Magnien, Robert Summers. Harold G. Marshall, Chairman.
109, Annapolis, MD 21403. 301/266-6873. Lacy Department of Natural Resources, Tidewater Ray S. Birdsong, Daniel Dauer.
Nasteff, Director.
Environmental Photographic Interpretation Center, Vint Administration, Tawes State Office Building, Virginia State Water Control Board, 2111 North Hamilton
Hill Farm Station, Box 1575, Warrenton, VA 22186. Annapolis, MD 21401. 301/269-3767. Paul Massicot, St., Richmond, VA 23230. 804/257-6683. Richard N.
703/347-6348. Sam E. Williams, Acting Chief. Director. Burton, Executive Director.
James Simons. Stephen J. Jordan, Chris Bonzek, Cynthia Alan E. Pollock, Robert C. Siegfried
Stenger.
U.S. Fish & Wildlife Service
Annapolis Field Office, Chesapeake Bay Restoration Space limitations prevent the full listing of additional institutional and individual names, but the Chesapeake Bay
Program, 1825 B. Virginia Ave., Annapolis, MD Program would like to acknowledge the cooperation of the following: Chesapeake Bay Foundation, Metropolitan
21401. 301/269-6324. Glenn Kinser, Director. Washington Council of Governments, Pennsylvania Department of Environmental Resources, Potomac River
Bert Brun, Charles M. Wooley. Fisheries Commission, U.S. Army Corps of Engineers (Baltimore and Norfolk Districts), U.S. Department of Defense,
Patuxent Wildlife Research Center, Laurel, MD 20708. U.S. Geological Survey, Virginia Council on the Environment, Virginia Game & Inland Fisheries Commission, and the
301/498-0331. David Trauger, Director. Virginia Marine Resources Commission.
Matthew C. Perry. For further information, write: the Chesapeake Bay Program, 410 Severn Ave., Annapolis, MD 21403. (301) 266-6873.

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