Transcript Slide 1

nalysis of PCB Accumulations in Chesapeake Bay Striped Bas
William Gardner
University Maryland Eastern Shore, Princess Ann, MD
Department of Natural Science, Living Marine Cooperative Science Center
Introduction
Polychlorinated biphenyls (PCB) threaten the ecological and economic value of Chesapeake Bay striped bass (Morone saxatilis). In terms of the former, PCBs are known
endocrine disruptors and have been linked to declines in wild fish populations. In terms of the latter, the state of Maryland has issued both statewide advisories for striped bass
caught in the Chesapeake Bay and in Maryland’s Atlantic coastal waters. Data used to generate the statewide Chesapeake Bay advisories suggest that striped bass are exposed
to sources both inside and outside the estuary. However, data is lacking for assessing the PCB levels in young striped bass maturing within their natal subestuaries. Furthermore,
the state of Maryland has adopted no consumption advisories for striped bass captured in its coastal waters. This management decision is based predominantly on PCB levels in
striped bass capture in New York Coastal waters, due to insufficient data elsewhere. As of result of these data gaps, the main focus of this research has been to further our
understanding as to when and where striped bass are exposed to quantities of PCBs sufficient enough to cause accumulations to warrant a health advisory.
Striped Bass Fishery
It is estimated that 50 – 90 percent of
the Atlantic coast striped bass
migratory stock are spawned in
tributaries of the Chesapeake Bay (Fig
1). In 2008 recreational and
commercial landings were more than
25.6 million and 7.1 million lbs,
respectively (NOAA 2009).
Susquehanna River
Chester River
Choptank
River
Potomac
River
Patuxent
River
Nanticoke
River
Rappahannock
River
Pocomoke
River
York
River
James River
Figure 1. Chesapeake Bay
spawning rivers
Striped Bass Migrations
Adult striped bass migrate from the
Atlantic Ocean into freshwaters of the
Chesapeake Bay to spawn in the early
spring. After spawning, migratory
striped bass exit the Chesapeake Bay
and generally move northward along
the Atlantic Coast (Fig. 2). They spend
most of the summer and early autumn
in New England shore waters. In late
autumn, striped bass return to the
Chesapeake Bay region. Chesapeake
Bay striped bass generally over-winter
off the coast of North Carolina.
Maryland’s PCB Advisories
Maryland has issued both statewide and
coastal PCB advisories for striped bass
Table 1). Data used to generate these
advisories suggest that striped bass are
being exposed to PCB both inside and
outside of the Chesapeake Bay (J. Beaman,
MDE, 2005). The research proposed here
has evolved from uncertainties regarding
the drivers behind these advisories. The
statewide advisories rely on data collected
from legally harvestable fish. Thus, data is
lacking for accessing PCB levels in young
striped bass maturing within their natal sub
estuaries. Furthermore, the USEPA has
classified several of these areas as having
“insufficient or inconclusive data” (Fig. 3).
Secondly, Maryland’s coastal advisories is
based on limited data, largely from New
York coastal waters (MDE 2007 and
ECASCAW 2008).
Waterbody
Chesapeake
Bay and
Tributaries
Table 1. PCBs (risk driver)
Allowable Meal/Year
Objective
Preliminary Results
The objective of this study will be to
characterize the effects of spatial
variation and life history traits on PCB
accumulations in Chesapeake Bay
striped bass.
Methods
Fifthteen striped bass ages 1 to 3
yrs will be collect from natal
Chesapeake Bay subestuaries and
twenty-five 3 to 5 yrs will be collect in
the Bay’s lower mainstem. Thirty
striped bass > 3 yrs will be collected in
the winter off the coast of North
Carolina deep water trawl nets during
NOAA-funded LMRCSC winter survey
(Fig. 5)
Table 2. Preliminary PCB Data for striped bass
collected in Maryland waters
Location
n
Weight Length
(g)
(cm)
*Upper
Chesapeake
Bay, Rock
Hall
9
146 + 99
**Pocomoke
River,
Bullbegger
10
**Choptank
River,
Tred Avon
9
24 + 6
0.5 + 0.3
7 + 6.7
260 + 172
24 + 9
0.7 + 0.4
8.3 + 2.9
292 + 203
29 + 4
0.5 + 0.3
3.7 + 3.5
* Area Not Characterized due to historically low levels
** Area of Insufficient or Inconclusive Data
4.5
170
4
3
PCB analysis will be carried out at
the NOAA/NMFS) James J. Howard
Marine Sciences Laboratory (Fig. 5)
according to previously described
methods (Dockum 2009, Williams
2006).
2.5
ng/g 2
206
1.5
1
0.5
8
18
195
187
0
PCB Congener BZ#
Figure 6. PCB congener accumulations in
Upper Bay mainstem striped bass
170
1.2
General
Population
8 oz meals
Women
6 oz meals
Children
3 oz meals
< 28” May 16 –
Dec 15
> 28” April 15
– May 15
25
9
6
AVOID
MD Coastal
waters
12
AVOID
AVOID
19
15
The statistical approach undertaken
will follow U.S. EPA recommendation
for testing fish tissue data (U.S. EPA
2000).
1
128
0.8
0.6
118
ng/g
0.4
0.2
8
99
18
110
101
0
PCB Congener BZ#
Figure7. PCB congener accumulations in
Choptank striped bass
206
7
6
5
4
ng/g
3
2
1
44
95
195
180
0
PCB Congeners BZ#
Figure 8. PCB congener accumulations
in Pocomoke River striped bass
Hypotheses
Figure 4
Region of Concern- area with probable adverse effects
Area of Emphasis- area of potential adverse effects
Area of Low Probability for adverse effects
Area with insufficient or Inconclusive Data
Historically Low Levels of Chemical Contamination
Fig 3.
PCBs
(ng/g)
3.5
Figure 5. Sample collection and
analysis utilizing NOAA resources
Figure 2. Striped Bass
Migrations
Lipid
content
(%)
Congener-Specific PCB Data
PCBs are a class of chemical consisting of
209 possible congeners with varying
degrees of chlorination (Fig. 3). Congenerspecific PCB data can lead to the
identification of likely sources through
fingerprinting techniques. This involves
matching the congener pattern present in
biota with known sources in the
environment, while accounting for
environmental weathering and
bioaccumulation processes. The resulting
PCB signature will not be a direct
reflection of the source but rather a
descriptive component. Congener-specific
PCB data in the Chesapeake Bay is
limited (Liebert 2006).
Specifically, we will test several
hypotheses:
1. PCB levels measured in striped bass
(1 to 3 yrs) will not be discernable
between Chesapeake Bay
subestuaries.
2. PCB concentrations in Chesapeake
Bay striped bass collected in the
aforementioned subestuaries will be
similar to published values (> 313
ng/g) of fish taken from known
contaminated areas.
3. Whether PCB accumulations are
occurring mainly within the Bay or in
marine habitats will be accomplished
by comparing PCB concentrations in
out-migrating sub-adults with adults
over-wintering in NC’s coastal waters.
4. Will PCB concentrations measured in
striped bass overwintering (NC) be
similar to published values for fish
taken from NY’s Coastal water (400
ng/g)?
5. We will also test the hypotheses that
fish size, age and lipid content will
influence PCB levels, and we will
asses their relative importance.
Table 3. Preliminary PCB Data for striped bass
collected in North Carolina’s coastal waters
Location
Age
(yrs)
Length
(cm)
Weight
(g)
Lipid
content
(%)
PCBs
(ng/g)
Atlantic
Coast, NC
Cape
Hatteras,
(n=40)
7+2
73.4 +
10.5
4224 +
1857
5+3
145.99
+ 55.10
Conclusions
Preliminary results showed average
PCB concentrations were 7.0, 8.3, and
3.7 (ng/g) for young striped bass
collected in the Upper Bay mainstem,
Pocomoke River and Choptank River,
respectively (Table 2). These levels are
below levels observed in “regions of
concern”. Although PCB levels were
similar in magnitude from all three natal
subestuaries, spatial differences in PCB
congener accumulation patterns were
visually apparent (Fig. 6, 7, & 8)
(suggestive of localized sources).
Striped bass collected from NC’s
coastal waters ranged in age from 3 to
10 (yrs) with a mean PCB concentration
of 145.99 + 55.10 (ng/g) (Table 3),
which is well below level observed in
NY’s coastal water. This may argue for
less-restrictive coastal advisories in
MD’s water.