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| Current fisheries research and future ecosystems science in the Northeast Center: collected
abstracts of the Northeast Fisheries Science Center’s Eighth Science Symposium, Atlantic City, New Jersey,
February 3-5, 2004. Northeast Fish. Sci. Cent. Ref. Doc. 04-01
SESSION III |
| Long-term effects of quahoging and crabbing
gear on the benthic
ecosystem of Raritan Bay |
Session III, Abstract III-1
ORAL
PRESENTATION |
Clyde L. MacKenzie, Jr. Donald G. McMillan,
Robert Pikanowski, John Rosendale, Daniel Wieczorek, John Hilbert, and
Chad Brown
NOAA/NMFS/NEFSC, 74 Magruder Road, Highlands,
NJ 07732 |
The
studies of gear effects in Raritan Bay are relatively long-term. The
objectives are to preserve the on-going fisheries for northern quahogs, Mercenaria mercenaria, and blue
crabs, Callinectes sapidus. The effects of short rakes and
bull rakes when quahogs are harvested and of 2-m-wide dredges when
blue crabs are harvested on the benthic habitat were examined. Harvesting
with short rakes no longer exists in Raritan Bay, but is widespread
from the Canadian Maritimes to Florida. In Raritan Bay, harvesting
with bullrakes is on going year-round, whereas crab dredging occurs
during winter. The effect of harvesting with the short rake was examined
in a sandy sediment. The study lasted only 3 months because no effect
on the invertebrates or on sediment grain sizes was detected. The
effects of harvesting with quahog bull rakes and crab dredges have
been underway since 1999. The bottoms where the bull rakes and crab
dredges are used consist of mud covered with live Ampelisca abdita, that
have densities averaging 23,700/m2, and nearly solid mats
of their tubes in the same densities. The tubes project 2-2.5 cm above
the bottom. The A. abdita are short-lived. They reproduce,
resettle and cover the entire mud bottom of southeastern Raritan Bay
with fresh tubes 2-3 times a year. At least 8 finfish species prey
on the amphipods. The quahogs are abundant in this habitat: about
23/m2 avg. In the fall of each year, blue crabs, mostly
females, migrate from the rivers entering Raritan Bay and settle in
the mud-tube habitat for the winter.
Bull raking has been on
going since the early 1980's and crab dredging for at least 200 years
in Raritan Bay. Natural bottoms
and experimental plots are observed. Since the amphipod tubes are
abundant where no harvesting currently occurs, but are temporarily
scarcer where harvesting does occur, it has been obvious that the harvesting
reduces the numbers of A. abdita and their tubes temporarily,
but the habitat is restored as soon as another generation of A.
abdita settles onto the bottom and constructs its tubes.
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| A system
for simulating the biogeochemical habitats of lobsters, and its use
for determining survival at elevated temperature |
Session III, Abstract III-2
ORAL PRESENTATION
|
Andrew F. J. Draxler1, Richard
A. Robohm2, Daniel Wieczorek1 and Michael Schafer1,
Diane Kapareiko2, Steven Pitchford2
1NOAA/NMFS/NEFSC, 74 Magruder Road, Highlands,
NJ 07732
2NOAA/NMFS/NEFSC, 212 Rogers Ave., Milford, CT 06460-6490 |
The American lobster (Homarus americanus)
in Western Long Island Sound (LIS) began dying in increasing numbers
in 1997 culminating in the death of an estimated 12 million lobsters
in 1999. The scientific consensus is that environmental condition,
such as elevated temperature, reduced dissolved oxygen, and introduced
contaminants were responsible for this mortality. The duration of high
temperature was longer in 1999 then in previous years. High temperature
and a stable water column resulted in hypoxic conditions in bottom
water with the production of sulfide and ammonium.
We simulated western LIS
habitat conditions in our multivariate flow-through exposure system
consisting of eight sealed tanks in which chemical
concentrations are maintained using countercurrent gas exchange and
metering pump introduction of aqueous solutions. The tanks have a
flow rate of 9.5 L/min, volume of 253 L, residence times of 27 minutes,
and have accommodated up to 22 lobsters. Each tank has 28 partitions
for shelter and a clear lid to allow monitoring three times a day for
viability and behavioral response to exposure conditions. Lids can
be opened to remove dead animals and animals to be sampled for pathology. The
smallest available market-size lobsters were procured from commercial
harvesters in eastern LIS and acclimated to temperature and bottom
light conditions of western LIS in September, and to salinity at the
Howard Lab (nominally salinity 26 psu). The approximate controls of
system variables are: temperature (± 1°C), dissolved oxygen (± 8 µM),
sulfide (± 2 µM), and ammonium (± 4 µM).
In experiments on the
physical stress caused by temperature, eastern LIS lobsters survived
at 24°C indefinitely under normoxia. They survived
only 3 days at 95 µM dissolved oxygen, and only one day when 55 µM
dissolved oxygen is combined with 9 µM sulfide and 17 µM ammonium.
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| Effects
of environmental stressors on disease susceptibility in
lobsters: a controlled laboratory study |
Session III, Abstract III-3
ORAL PRESENTATION |
Richard A. Robohm1, Andrew F.
J. Draxler2, Diane Kapareiko1, Steven Pitchford1,
Daniel Wieczorek2 and Lori Davias2
1NOAA/NMFS/NEFSC, 212 Rogers Ave., Milford,
CT 06460-6490
2NOAA/NMFS/NEFSC, 74 Magruder Road, Highlands,
NJ 07732 |
The
cause of unprecedented lobster mortalities in western Long Island Sound
(LIS) in 1998 and 1999 is under investigation
by 50 scientists who are conducting numerous studies on paramoebiasis,
pesticide poisoning, and environmental stressors. The objective of our
contribution to this effort is to determine whether increased (but environmentally
realistic) conditions of temperature, hypoxia, sulfide and ammonia, alone
or in combination, can increase susceptibility to microbial infections. In
conjunction with certain environmental conditions, a parasitic amoeba
found in LIS lobsters may have contributed to deaths, but it has not
been possible to culture under laboratory conditions. In order to test
the lobsters’ susceptibility to disease, a known bacterial lobster pathogen, Aerococcus
viridans, was used as a surrogate organism. Market-size lobsters
from commercial harvesters were acclimated for seven days to temperature
and bottom light conditions that exist in LIS in September, and to salinity
at the Howard Lab. Experimental lobsters were injected with 1x103 or
1x106 A. viridans, or sterile saline for control lobsters. Experimental
conditions for temperature and concentrations of oxygen, sulfide
and ammonium were generated in a flow-through metering system at the
Howard Lab. Lobsters were monitored three times daily for viability,
behavior and death. At appropriate intervals, lobsters were transported
to the Milford Laboratory for enumeration of bacteria in the hepatopancreas
and hemolymph. Given adequate oxygen (200µM), mortality of lobsters exposed
to 6µM sulfide and 24µM ammonium increased 50% (12 days to 6.6 days). Mortalities
were further accelerated to about 3 days when oxygen levels were dropped
to 80 µM. Lower oxygen levels alone were sufficient to accelerate mortalities
regardless of the presence of sulfide or ammonium. Temperature (14.5oC
vs. 19.5oC) and bacterial dose had moderate effects on mortality. Bacterial
levels in the hemolymph and hepatopancreas of non-stressed lobsters reached
1x109 g-1 within 10 days. Counts in dying, stressed
lobsters only reached 1x103 to 1x106 g-1 within
the same time interval, indicating that environmentally stressed lobsters
did not require as many bacteria to cause death. Further studies are
in progress to examine whether the same effects are seen in lobsters
infected
with a second bacterium, Vibrio fluvialis.
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Methods
and importance of analyzing PCB concentrations in
lobster Hepatopancreas tissues |
Session III, Abstract
III-4
ORAL PRESENTATION |
Ashok D. Deshpande, Michael W. Schafer,
A. F. J. Draxler, and Daniel Wieczorek
NOAA/NMFS/NEFSC, 74 Magruder
Road, Highlands, NJ 07732 |
American lobsters, Homarus Americanus,
are commonly found in polluted coastal waters, such as Long Island Sound. Long
Island Sound consists of three distinct basins: Eastern, Central, and
Western. Both the Eastern and Central basins are well mixed with good
water circulation. In contrast, the Western basin is narrow and shallow
so that it retains contaminants, such as, nutrients, heavy metals, and
anthropogenic organic compounds from the New York metropolitan area. Lipophilic
contaminants are extracted into lobsters from the surrounding water during
ventilation and from prey particles in the digestive system. One major
type of organic contaminant lobsters are exposed to in Long Island Sound
is polychlorinated biphenyls (PCB’s). The PCB compounds we are currently
studying are lipophilic and accumulate in fatty tissues, especially the
hepatopancreas. Methods for analyzing PCB concentrations in lobster
tissue include four main parts: (1) grinding of sample in sodium sulfate
and placing tissue in an Organomation instrument to extract analytes
using fresh solvent over an 18 hour period; (2) column chromatography
using glass wool, alumina, florosil, and silica to clean the sample from
natural lipids; (3) high pressure liquid chromatography (HPLC) to further
clean the tissue sample from natural lipids and fatty acids; (4) gas
chromatography/mass spectrometry to identify the PCB and measure their
concentrations. The results of this study will establish PCB uptake
characteristics of lobsters in situ and potentially contribute
to our understanding of the decline of lobster populations in Long Island
Sound.
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| Comparison
of two different methods of lipid analysis in
fish tissue |
Session III, Abstract III-5
ORAL PRESENTATION |
Thomas H. Cleary, Vincent Guida, and Jennifer
C. Samson
NOAA/NMFS/NEFSC, 74 Magruder Road, Highlands,
NJ 07732 |
Lipids
are a diverse group of fatty biological substances that can be polar
or non-polar. The polar lipids usually
make up cellular membranes that form boundaries between cells and within
cells. The non-polar lipids are usually stored in the tissue and used
for energy at a later time. Due to the correlation between polychlorinated
biphenyl (PCBs) and lipids, it is important to conduct lipid analyses
as part of the study of contaminants in fish. PCBs are anthropogenic
compounds used as insulating, hydraulic and dielectric fluids until their
manufacture was banned in 1978 due to environmental and health concerns. PCBs
are very soluble in lipids and tend to bioconcentrate in lipid-rich organs. There
are two different methods for determining lipid concentration in a sample. The
gravimetric procedure provides total lipid content of the sample and
is performed by evaporating a pre-determined amount of the solvent extracted
sample. A second method involves Thin Layer Chromatography/ Flame Ionization
Detection using an Iatroscan®, and provides actual amounts for the
different classes of lipids. We will be running both analyses on the
same sample in order to compare results from the two different methods. We
expect that the gravimetric procedure would result in higher values,
as this method does not include a back extraction to remove lipoproteins
and does
not differentiate between lipids and all other organic material.
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