CRD 04-13 Ninth Flatfish Biology Conference, December 1-2, 2004, Water's Edge Resort, Westbrook, Connecticut
Abstracts - Poster Presentations
Winter Flounder, Pseudopleuronectes americanus,
Hatching
Success as a Function of Burial Depth in the Laboratory
Walter J. Berry1, Elizabeth K. Hinchey1,
Norman I. Rubinstein1, and Grace Klein-MacPhee2
1U.S. Environmental Protection Agency, Office
of Research and Development,
National Health and Environmental Effects Research Laboratory,
Atlantic Ecology Division, Narragansett, RI 02882
2University of Rhode Island, Graduate
School of Oceanography, Narragansett, RI 02882
Previous experiments have shown that viable hatch of winter flounder
eggs is reduced when the eggs are buried by as little as one half of
one egg diameter (approximately 0.5 mm of sediment). This sensitivity
to burial has resulted in seasonal banning of dredging in several northeastern
U.S. estuaries. In this study, a series of experiments was performed
to better determine burial effects on hatching success of winter flounder. In
the first experiment, eggs were exposed to clean, fine-grained sediment
with burial depths including a no-sediment control, dusting (< 0.5
mm), and up to 2 egg diameters (2 mm) of sediment. A trend of decreased
hatch success and delayed hatch date with increasing depth of burial
relative to controls was observed: however, differences were not statistically
significant (p>0.05). In a second experiment, treatments included
a no-sediment control, 4 egg diameters (4 mm) of clean, fine grained
sediment, and between 0.5 to 6 diameters (0.5 - 6 mm) of highly contaminated,
fine-grained sediment. Eggs buried in 4 diameters of clean sediment
did not hatch. Hatch from eggs dusted with contaminated sediment was
similar to controls, while eggs buried by 3 diameters of contaminated
sediment had little or no hatching success. There was no evidence of
delayed hatch. The results of the second experiment must be interpreted
with caution, however, due to the low control survival (21%). Overall,
the results of our initial trials indicate that winter flounder eggs
may be more resistant to burial than previously thought.
Effect of Contaminated Sediments on Mortality
and Predation Avoidance
in Winter Flounder
Andrew F. J. Draxler1, Daniel Wieczorek1,
Lori Davias2, Michael Schafer1, Yan
Waguespack3, and Bashir Balogun3
1NMFS/ NEFSC/Howard Marine Laboratory, Highlands, NJ
07732
2North Carolina State University, Raleigh, NC 27695
3University of Maryland Eastern Shore, Department of
Natural Sciences, Princess Anne, MD 21853
Young-of-the-year (YOY) winter
flounder (Pseudopleuronectes americanus) held on sediment from
the south branch of the Elizabeth River, VA, sustained significantly
higher rates of in situ mortality and higher predation by bay
shrimp (Crangon septemspinosa) than did fish held on less contaminated
York River, VA sediment. The mortality pattern paralleled previous toxicity
results for winter flounder on Newark Bay, NJ sediment. We speculate
that observed effects on these juvenile demersal fish were the result
of transdermally absorbed sediment components, most likely PAHs, which
are well documented in the Elizabeth River. Preliminary measurements
show that respiration was lower in fish held on Elizabeth River sediment,
which suggests a mechanism for the observed reduction in escape capability.
A Comparison of the Use of Estuarine Habitats by
Flatfishes in
South Carolina and Georgia
Guy’ DuBeck and Mary Carla
Curran
Savannah State University, Department of Natural
Sciences and Mathematics,
P.O. Box 20600, Savannah, GA 31404
As part of a class project in fall 2004, we began a monitoring program
to assess the abundance of flatfishes in a small tidal creek in South
Carolina and one in Georgia. The purpose of the exercise was to familiarize
a student with various fishing gear in two marsh creeks - one accessible
by boat and the other by foot. In Country Club Creek, GA we conducted
three replicate hauls with a 1-meter beam trawl (3-mm mesh). In Chowan
Creek, SC we conducted 3 replicate hauls with a 3-meter seine net. The
Georgia site was dominated by the blackcheek tonguefish Symphurus
plagiusa, although we also obtained the summer flounder, Paralichthys
dentatus. We caught fewer flatfishes in South Carolina, possibly
due to the gear type, but S. plagiusa and P. dentatus were
present. From historical summer data collected from 1998 –2001, fringed
flounder, Etropus crossotus, and bay whiff, Citharichthys spilopterus, were
also found at this site. Future research will include comparing the
efficiency of the seine and beam trawl in Chowan Creek.
Bay Whiff Distribution and Abundance in Galveston Bay, Texas
Lindsay Ann
Glass
Texas A&M, 5007 Ave U #102, Galveston, TX 77551
Bay whiff (Citharichtys spilopterus) are the numerically dominant
flatfish in the Galveston Bay estuary, yet little is know about the ecological
significance of the species. Our objective was to characterize the distribution
and abundance of bay whiff in Galveston Bay. We used a one-meter beam
trawl to sample three types of habitat (marsh edge, 1m depth water, and
2-to-5m water depth) in three main regions of the bay. Total length ranged
between 20 to 30mm in the February, increasing to 40 to50mm in May. The
highest density (0.618/m2) was measured in deep water habitat
during March, and overall equal densities (0.579/m2) were
measured in both east and west bay regions with lower densities (0.3/m2)
in the central portion of Galveston Bay. Based on preliminary results,
the large numbers of bay whiff in Galveston Bay could represent competition
for resources with other flatfish of the same size range.
The Abundance of Flatfishes in Country Club Creek, GA
Karen Harris and Mary Carla Curran
Savannah State University, Department of Natural
Sciences and Mathematics,
P.O. Box 20600, Savannah, GA 31404
The purpose of this study was to provide a quantitative comparison
of the relative abundance and sizes of the flatfish species occupying
a small estuarine tributary over the course of two seasons (Jan-Apr 2004)
as part of an undergraduate research project. Using three replicate
hauls with a 1-meter beam trawl (3-mm mesh), we noted that the catch
was dominated by the blackcheek tonguefish Symphurus plagiusa and,
towards late spring, summer flounder Paralichthys dentatus. S.
plagiusa ranged from 5-20 individuals per date and lengths varied
from 1.7-7.8 cm TL. P. dentatus ranged from 0-23 individuals
per date and lengths varied from 2.0-7.9 cm TL. The southern flounder, Paralichthys
lethostigma, and oscellated flounder, Ancylopsetta quadrocellata,
were also collected. This project will provide some preliminary data
that may be used as part of a future long-term monitoring study.
Differential Effects of Preservative Methods
on American Plaice and
Atlantic Cod Ovarian Tissue
Nikolai Klibansky and Francis Juanes
University of Massachusetts, Department of Natural
Resources Conservation,
Amherst, MA 01003
Addition of relative fecundity estimates to stock-recruit models can
significantly strengthen recruitment predictions, but confusion in the
literature about the effects of common preservatives on ovarian tissue
hinders the standardization of fecundity methods and comparison of fecundity
data across studies. In this research subsamples (~1.5g) of ovarian
tissue of developing American plaice (Hippoglossoides platessoides)
and Atlantic cod (Gadus morhua) were subjected to four preservative
treatments (10% phosphate buffered formalin, non-toxic Gilsons solution,
70% ETOH, and freezing) to quantify effect on sample weight, and assess
whether the preserved samples were suitable for measurement using digital
image analysis. All treatments preserved eggs well enough to measure
digitally, though only eggs in formalin could be analyzed without first
removing debris. Mean weight of American plaice samples in the ethanol
treatment increased by 25%, samples in 10% formalin increased by 20%,
and samples in non-toxic Gilson’s solution decreased by 21% on average. Samples
that were frozen in distilled water increased by an average of 8%, but
this change was not significantly different from zero. Percent change
in weight due to treatment differed significantly between the two species
for all treatments except formalin. In both species, coefficient of
variation for the change in weight was highest for the frozen samples. Ethanol
altered the weight of the cod samples the least, while freezing altered
the weight of plaice samples least, and formalin was the most stable
treatment overall. This information is useful in planning fecundity
lab methods and comparing data across studies using different preservatives.
Use of Shallow Habitats by
Juvenile Winter Flounder,
Pseudopleuronectes americanus, along
the Maine Coast
Mark A. Lazzari
Maine Department of Marine
Resources, West Boothbay Harbor, ME 04575
Historically, the fisheries in Maine's shallow waters (< 10
m) provided resources of recreational and commercial importance, but
no comprehensive studies of the fishes occupying these habitats along
the entire coast ever occurred. Recent legislation has emphasized the
importance of “essential fish habitat” including “those waters necessary
for spawning, breeding, feeding, or growth” to healthy fisheries.
We divided the entire Maine coast into three zones for sampling
over five consecutive years. In 2000, we sampled the midcoast from Casco
to Penobscot Bay, during 2001 - 2002 along the southern Maine coast to
New Hampshire and along the eastern Maine coast to Canada in 2003 - 2004.
Sampling with a 2.0-meter beam trawl (5 minute tows) provides estimates
of the importance of various shallow water habitats (eelgrass, kelp,
drift algae, sand/mud) to the early life history of fishes.
Winter flounder
were a major component of midcoast estuaries (> 2 fish tow –1),
but much less common to the east and south (< 0.2 tow –1).
All shallow habitats function as nurseries. CPUE was consistent (0.73 – 1.0
tow –1) in the
three major habitats sampled in eelgrass, Zostera marina, kelp, Laminaria
longicruris, and over sand, but much lower in drift algae, Gracilaria sp.
(0.10 tow –1). CPUE increases from 0.01 tow –1 in
April to average about 1 tow –1 during June to September before
dropping by half in October. Winter flounder ranged from one – 42 cm
TL with most between 2 – 10 cm (73%) and few adults greater than 20 cm.
Impacts of Size on Growth and Early Maturity
in Female Yellowtail
Flounder, Limanda ferruginea (Storer)
Anthony J. Manning, Margaret
P.M. Burton and Laurence W. Crim
Ocean Sciences Centre, Memorial
University of Newfoundland, St. John’s,
Newfoundland, A1C 5S7 Canada
Yellowtail flounder is a small, early-maturing flatfish that has been
considered as a candidate species for cold-water aquaculture in Newfoundland.
The experiment examined three size classes of one-year-old, cultured
female fish over a 14-month period. Small, medium and large females were
separated as 0+ and young 1+ year fish. Pubertal development in 1+ fish
was lowest, intermediate and highest for the small, large and medium
size classes, respectively. Growth rates were highest for the small size
class and lowest for the medium size class. Large fish still grew well
but mature individuals of this group grew more slowly than immature individuals.
These results reinforce the negative relationship between maturity and
growth rate in flatfish. However, pubertal onset at one year of age was
not always connected with a larger size in these cultured females.
Real-time PCR Analysis of Steroid Enzyme Gene
Expression During Atlantic Halibut (Hippoglossus hippoglossus)
Development
Makoto Matsuoka1, Solveig van
Nes2, Øivind
Andersen2, Tillmann Benfey3, and
Michael Reith1
1National Research Council of Canada, Institute for
Marine Biosciences,
Halifax, Nova Scotia, Canada B3H 3Z1
2Norwegian Institute of Aquaculture
Research, Aas, Norway
3University
of New Brunswick, Department of Biology, Fredericton, New Brunswick, Canada E3B 6E1
Atlantic halibut aquaculture would benefit from the development of
all female lines, since females grow faster and reach a larger size than
males. Determining the period when gonad development occurs would define
the critical time when hormonal or environmental treatments should be
applied to influence sex ratios. We investigated the transcription levels
of the steroid hormone biosynthetic enzyme genes, aromatase (both brain-
and ovary-type) and 11-beta hydroxylase, which catalyze key steps in
the synthesis of 17 beta-estradiol and 11-ketotestosterone, respectively,
in juveniles (16 - 67 mm in standard length) using real-time PCR. The
results suggest that treatments to manipulate sex ratios should be started
by the time fish reach as small as 16 mm when both of the aromatase genes
showed elevated levels in the brain. For all three genes, elevations
in expression levels were observed in both brain and gonad regions in
fish prior to histological sex differentiation (approximately 32 mm). The
elevations in brain occurred slightly earlier than in gonad, supporting
the idea that steroid hormone expression in the brain is a key determinant
of phenotypic sex in fish. However, we were unable to detect consistent
differences in the expression patterns of these genes that would be diagnostic
of sex.
PLEUROGENE: Genomics for the Enhancement
of Commercial Production
of Atlantic Halibut and Senegal Sole
Makoto Matsuoka1, Michael Reith1,
Joan Cerdà2, Harry M. Murray1,
Debbie
Martin-Robichaud3, Brian Blanchard4,
and Susan E. Douglas1
1Institute for Marine Biosciences, 1411 Oxford Street,
Halifax, Nova Scotia, Canada B3H 3Z1
2Institute de Ciències del Mar, Consejo Superior de
Investigaciones Científicas (CSIC),
Passeig, Marítim 37-49, 08003-Barcelona,
Spain
3Fisheries and Oceans Canada, Biological Station, 531
Brandy Cove Rd., St. Andrews, New Brunswick, Canada E5B 2L9
4Scotian Halibut Limited, P.O. Box 119, Clarks Harbour, Nova Scotia, Canada B0W 1P0
Atlantic halibut (Hippoglossus hippoglossus) and Senegal sole
(Solea senegalensis) are two flatfishes yielding high value market
products with good potential for aquaculture in eastern North America
and Mediterranean Europe, respectively. Production–related problems
in these two evolutionary–related species may be addressed with improved
knowledge of important basic biological processes such as reproduction,
development, nutrition, genetics and immunity. The use of genomic approaches
to thoroughly characterize these processes will translate into knowledge
that can be used to overcome the production obstacles and create (for
PLEUROGENE is a new initiative funded through Genome Canada-Genome Spain
for three years (2004-2007). There are two main goals: (i) the construction
of genetic
linkage maps Atlantic halibut and Senegal sole for use in the
selection of improved broodstock based on molecular markers, and (ii) design,
construction a flatfish microarray studies gene expression
these two species. High-throughput
genome- proteome-based technologies will be used identification,
characterization mapping genes important reproduction, larval
development, immunity nutrition. All the genetic and molecular
information obtained in this project will be integrated into an interactive
bioinformatic platform
specifically developed for the project. The knowledge generated by the PLEUROGENE
project
will ultimately lead to the establishment of new technologies for the control
of reproduction and
optimization of larval health and nutrition in the Senegal sole, Atlantic halibut,
and other related
flatfish species under intensive culture conditions.
Effects of Contaminants on Winter Flounder Living
in a Sewage-Impacted
Estuary-Jamaica Bay, NY
Lourdes Mena1, Lucia Cepriano2,
Nancy Denslow3, Martin Schreibman4, and Anne E. McElroy1
1Stony Brook University/MSRC, Stony Brook, NY 11794
2State University of New York, Farmingdale, NY 11735
3University of Florida, Gainesville, FLA 32611
4Aquatic
Research & Environmental Assessment Center,
Brooklyn, NY 11210
Jamaica Bay, NY is an urban estuary that receives millions of gallons
of sewage effluent daily making sewage effluent its primary source of
freshwater. Extremely high levels environmental estrogen mimics (e.g.,
nonylphenol, estradiol, estrone) observed in sediments led us to postulate
that benthic fish residing in Jamaica Bay, NY are likely targets for
endocrine disruption and, potentially, reproductive impairment. We collected
adult, juvenile and young-of-the-year winter flounder, Pseudopleuronectes
americanus, from multiple sites in Jamaica Bay and a reference site
off the east coast of Long Island, Shinnecock Bay, in the spring of 2002
and 2003. Very few male fish were found at the site with the highest
levels of endocrine disruptors. Levels of circulating 17 beta-estradiol
(E2), vitellogenin (VTG) and 11-Ketotestosterone (11-KT) showed unusual
patterns of endocrine disruption in this species. Females from the most
contaminated site showed significantly higher levels of VTG and males
only showed decreased levels of E2 and 11-KT as compared to reference
fish. Histological analysis of liver and gonad tissue are also ongoing.
Habitat for Flatfish: The Relative Importance of Depth, Temperature
and Substrate
Elizabeth T. Methratta, Brian E. Smith, and Jason S. Link
NMFS/NEFSC/Woods Hole Laboratory,
166 Water Street, Woods Hole, MA 02543
Understanding how flatfish abundance, distribution, and production
are related to habitat factors and how these relationships change across
ontogeny at large spatial scales are key components to the development
of spatial tools for fisheries management. A geographic information
system (GIS) was used to bin USGS substrate grain size data and a 34-year
NEFSC time series of environmental and biological data into 10-minute
squares. Data were averaged over 2 seasons (fall and spring) for each
of 3 time blocks (1968-79, 1980-89 and 1990-02). Multivariate statistical
analyses were then used to examine the relative importance of bottom
temperature, depth, substrate grain size, season, and time block for
individual size classes for four flatfish species: American plaice (Hippoglossoides
platessoides), fourspot flounder (Paralichthys oblongus),
winter flounder (Pseudopleuronectes americanus), and yellowtail
flounder (Limanda ferruginea). Depth explained the largest proportion
of variance in the distribution of size classes for American plaice,
winter flounder, and fourspot flounder with larger individuals more abundant
in deeper waters. This pattern reflects the characteristic onshore-offshore
spawning migration undertaken by adults of these species. For yellowtail
flounder, which inhabits deeper waters, time block was the strongest
explanatory factor, with larger individuals relatively more abundant
later in the time series. This is likely a response to the combined
effects of changing exploitation and subsequent recruitment patterns. In
contrast, larger individuals declined over the time series for the other
three species most likely in response to the preferential exploitation
of bigger fish. Substrate grain size explained 2-13% of the explainable
variance in species size-class distributions. Larger substrates were
associated with shallower depths and smaller individuals for all four
species. Although more refined estimates of essential fish habitat for
marine fishes will continue to be challenging, novel geostatistical approaches
offer strong potential in meeting these challenges.
Development of Digestive Capacity in Larval Atlantic Halibut:
A Preliminary Survey
Harry M. Murray, Jeffrey W. Gallant, Stewart C. Johnson, and Susan
E. Douglas
Institute for Marine Biosciences, National Research Council
of Canada,
1411 Oxford Street, Halifax, Nova Scotia B3H 3Z1
The objectives of the present study were to identify the location
and timing of gene expression of specific digestive enzymes in first-feeding
Atlantic halibut larvae and juveniles. Prior to the start of first feeding,
the gastrointestinal tract (GIT) is divided into anterior, mid and hindgut
regions. The liver is present at this time, as is the pancreas. During
larval development the pancreas changes from a compact organ to a diffuse
tissue interspersed though much of the mesentery surrounding the GIT.
Functional gastric glands are not present until approximately 66 days
post-hatch (dph). Using primers based on winter flounder digestive enzyme
gene sequences for bile salt-activated lipase (BAL), trypsinogen (Trp),
and pepsinogen (Pep), we were able to amplify products from RNA extracted
from whole larvae and juveniles using RT-PCR. These products were sequenced
and the sequences used to design halibut gene-specific primers for the
above enzymes. RT-PCR analysis using halibut-specific primers revealed
that Trp and BAL gene expression was evident at least from the time of
first feeding. Pep gene expression was not detectable until 80 dph. In
situ hybridization with DIG-labeled antisense RNA probes localized
expression of BAL and Trp to the exocrine pancreas. Pep expression was
localized only to the glandular regions of the stomach. These data provide
a first step toward understanding the molecular biology underlying the
ontogeny of digestive capacity in Atlantic halibut.
Fish Community Structure of Intertidal Habitats of the Mount Hope
Bay Estuary with Emphasis on Juvenile Winter Flounder, Pseudopluronectes
americanus
Adrienne Pappal
University of Massachusetts-Dartmouth School for Marine Science
and Technology,
706 Rodney French Blvd, New Bedford, MA 02744
Fish respond to a variety of factors in the selection of habitat,
including prey availability, predator avoidance, and competition. Fish
are able to respond to these cues and alter their distribution to minimize
metabolic cost. Identifying which habitats may be preferred for juvenile
winter flounder is critical in conservation efforts and the definition
of essential fish habitat for this species. My masters research focuses
on the juvenile winter flounder population of Mount Hope Bay, where there
is large areas of intertidal rocky/cobble habitat, with patches of Spartina
patens. Intertidal habitat use of juvenile winter flounder was assessed
using a three-pronged effort of field study, habitat mapping and laboratory
study. Collections of winter flounder on site were attempted using a
50ft beach seine and a blocking tidal trap with mixed results. Intertidal
habitats were quantified using random transects and .5m x .5m quadrats.
Ongoing laboratory study will address in depth the substrate and vegetation
preferences of juvenile winter flounder using habitat types present in
the field. These laboratory studies will mimic the dominant rocky/cobble
substrate and emergent Spartina patens grass present in Mount
Hope Bay to determine use by juvenile winter flounder. These habitats
are not sampled effectively with beach seines commonly used in monitoring
programs, therefore juvenile winter flounder may be under sampled in
Mount Hope Bay. It is generally understood in the literature that coarse/
sandy substrates or organic coves are the preferred habitat for juvenile
winter flounder, but it is yet unclear if juvenile winter flounder utilize
rocky/cobble substrates to any great extent.
Regulation of Carbonic Anhydrase-Dependent Renal Sulfate Secretion
by Cortisol in Winter Flounder, Pseudopleuronectes americanus
Ryan M. Pelis1,2, James E. Goldmeyer1,
Joseph Crivello1, and J. Larry Renfro1,2
1University of Connecticut, Department of Physiology
and Neurobiology,
Storrs, CT 06269-4156
2Mount Desert Island Biological Laboratory, Salisbury
Cove, ME 04672
Sulfate secretion by the marine teleost renal proximal tubule is stimulated
by cortisol and dependent on carbonic anhydrase (CA). Thus, cortisol
modulation of sulfate secretion may be through stimulation of CA. To
study this relationship primary cultures of flounder renal proximal tubule
epithelium (fPTCs) were exposed to elevated hydrocortisone (HC) or reduced
HC for 5 days prior to determination of CA activity, CAII protein abundance
(immunoblotting), and transepithelial transport of sulfate in Ussing
chambers. Degenerate primers and RT-PCR were used to obtain a partial
cDNA clone (327 bp) of fPTC CAII that exhibited high sequence similarity
to CAII from numerous species. CAII was localized to the cytosol and
plasma membranes of intact flounder renal tubules with immunohistochemistry. Treatment
of fPTCs with reduced HC caused reductions in CA activity (28%), CAII
protein abundance (65%), and active sulfate secretion (28%), without
affecting cell differentiation. Treatment of fPTCs with methazolamide
(MTHZ, 0.1 mM), a CA inhibitor, reduced active sulfate secretion 55%. Treatment
with reduced HC and MTHZ together had the same effect as MTHZ alone. These
data demonstrate that the marine teleost proximal tubule contains both
cytosolic and membrane-associated CAII and that cortisol directly stimulates
CA activity, CAII abundance, and a fraction of sulfate secretion that
is CA-dependent. Supported by NSF.
A Flatfish Perspective on Asymmetry:
What Genes Mediate Southern
Flounder Metamorphosis?
Alex M. Schreiber and Yan Tan
Carnegie Institution of Washington, Department of Embryology,
115 West University Pkwy, Baltimore, MD 21210
Metamorphosis in frogs and flatfish is mediated by thyroid hormone
(TH). The craniofacial morphology for both tadpoles and larvae is initially
bilaterally symmetric, but during metamorphosis the skull and jaw undergo
abrupt and extensive remodeling. In contrast to the newly remodeled froglet
head that retains bilateral symmetry, the juvenile flatfish has metamorphosed
into the world’s most asymmetric vertebrate: translocation of one eye
to the opposite side of the head is accompanied by asymmetric skull and
jaw development. What TH-responsive genes mediate flatfish metamorphosis
in general, and craniofacial remodeling in particular? Does asymmetric
gene expression correspond with left and right sidedness within and among
flatfish species? How evolutionarily conserved is metamorphosis among
vertebrates? The first step in addressing these questions is to identify
genes that are differentially expressed during metamorphosis. Premetamorphic
13-day old southern flounder were treated for 3 days with either TH or
an inhibitor of TH production (methimazole). Messenger RNA from each
group was purified, and differentially-expressed genes were enriched
using a PCR-based subtractive hybridization procedure. Though we will
sequence 3,000 differentially-expressed clones, here we describe the
first 300 TH-upregulated and 160 downregulated clones of our screen based
upon sequence homology with known vertebrate genes. Upregulated genes
include several implicated in bone remodeling (periostin, PTH-responsive
osteosarcoma protein, Sox, and alpha-2-HS-glycoprotein), as well as development
of skin, gut, muscle, central nervous system, and cell proliferation.
Downregulated genes were homologous to proteins expressed in skin (keratins),
gut (trypsin, lipid binding protein), blood proteins (parvalbumin) and
many metabolic proteins.
Benthic Food Webs on Georges Bank: Where Do Flatfish
Fit into the Picture?
Brian.
E. Smith, Elizabeth T. Methratta, and Jason S. Link
NMFS/NEFSC/Woods Hole Laboratory,
166 Water Street, Woods Hole, MA 02543
Flatfish are an important component of benthic food webs. These species
provide major links between the benthos and upper trophic level predators
in the northeast US continental shelf ecosystem. We examined more than
30 years of food habits data for seven species of flatfish and their
major predators from Georges Bank to evaluate the temporal variation
in flatfish predator-prey relationships. The morphology of flatfish
(gape width) suggests that most species have a strong preference for
certain prey, adopting either a benthivorous or piscivorous diet after
reaching adulthood. Summer flounder (Paralichthys dentatus) and
fourspot flounder (Paralichthys oblongus) were generally piscivorous,
consuming herring, sand lance, hakes, mackerel, and similar forage fish. American
plaice (Hippoglossoides platessoides) specialized on ophiuroids
and sand dollars (Echinarachniusparma). Yellowtail flounder (Limanda
ferruginea), winter flounder (Pseudopleuronectes americanus),
windowpane (Scophthalmus aquosus), and witch flounder (Glyptocephalus
cynoglossus)ate primarily polychaetes, gammarids and similar benthic
invertebrates. Significant shifts in diet were observed for summer and
fourspot flounder across the time series. In contrast, changes in diet
composition were not apparent for the benthivorous flatfish. The major
predators of flatfish on Georges Bank include spiny dogfish, Atlantic
cod, red hake, white hake, sea raven, goosefish, longhorn sculpin, winter
skate, little skate, and piscivorous flatfish. Our results suggest that
the major predator-prey relationships in the Georges Bank benthic food
web have not fundamentally changed over time, despite changing energy
flows and abundance over the past three decades.
Elemental Fingerprints of Juvenile Winter Flounder Otoliths
from Narragansett
Bay, RI and Surrounding Coastal Ponds
Brian K. Taplin1, Richard J. Pruell1,
John Brazner2, Ross Kean3, and Jennifer Yordy4
1US EPA, ORD, NHEERL, Atlantic Ecology Division,
27
Tarzwell Drive, Narragansett, RI 02882
2US EPA, Mid-Continent Ecology Division,
6201
Congdon Blvd, Duluth, MN 55804
3Research and Productivity Council, 921 College
Hill Road,
Fredericton, New Brunswick, Canada E3B 6Z9
4Medical University of South Carolina,
171
Ashley Avenue, Charleston, SC 29425
Elemental fingerprinting has become a powerful tool in fisheries science
for identifying fish migration patterns, seasonal changes in habitat
use, and for delineating the nursery origins of adult fish populations.
In this study we investigated whether elemental signatures in juvenile
winter flounder (Pseudopleuronectes americanus) otoliths, collected
from different habitat types and locations, could be used as natal fingerprints.
Juvenile flounder were collected from different nearshore habitats
(unvegetated, macroalgae, and eelgrass) and locations (upper, mid, lower)
within Narragansett Bay, RI (USA) and surrounding coastal ponds. Sagittal
otoliths were removed, cleaned under a laminar flow hood and digested
with high purity nitric acid. Elemental analysis was then conducted using
Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and or Inductively
Coupled Plasma Atomic Emission Spectroscopy (ICP-AES).
The concentrations of nine elements (Ca, Sr, K, Na, Ba, Rb, Li, Mg
and Mn) were measured and statistically analyzed using multivariate techniques.
Both canonical discriminant analysis (CDA) and linear discriminate function
analysis (LDFA) showed that otolith chemical fingerprints differed between
fish collected from Narragansett Bay and the coastal ponds. In addition,
significant differences were observed in the otolith chemistry of fish
collected from the three habitat types (unvegetated, macroalgae, and
eelgrass). These differences were more pronounced for comparisons either
within the Bay or the coastal ponds and less pronounced for the combined
data including all stations. In order to enhance our ability to differentiate
among juvenile nursery areas, additional measurements including stable
carbon and oxygen isotopes and rare earth elements will be investigated
in the future.
Fin Rot in Winter Flounder from New Haven Harbor, CT:
The Clinical
Profile of a Wasting Disease
John J. Ziskowski, Jose Pereira,
Renee Mercaldo-Allen, and Catherine Kuropat
NMFS/NEFSC/Milford Laboratory, 212 Rogers Avenue, Milford, CT 06460
Fin
rot is a wasting disease characterized by fin loss and muscular emaciation
often found in winter flounder sampled from urban estuaries. This
condition was observed in nearly 50% of flounder present in trawl catches
from New Haven Harbor, Connecticut during the 1980’s. From 1988 to
1990, 106 fish were processed for blood serum analyses to gain an understanding
of the underlying physiological effects of this disease condition. Initially,
blood was removed from affected fish and controls at sea, soon after
capture. About half-way through the study, it was decided to take advantage
of the wet lab capabilities of the Milford Laboratory and return specimens
to shore, holding them overnight for blood removal and processing the
next day. Fish were identified by sex, measured, fin loss was quantified,
hematocrits determined and blood serum chemistry values measured for:
hemoglobin, calcium, bilirubin, osmolality, phosphate, and total protein. A
categorical database was created using fin rot (1/0) as the outcome variable
and all other clinical parameters as predictor variables. Stepwise Logistic
Regression was used to model the contribution of blood values resulting
in the final fin rot outcome. Statistical analyses were done separately
for each sex and for each mode of sampling. For flounder that were sampled
after an overnight rest period, hematocrit and calcium values were the
primary predictors of fin rot in female fish only. Hematocrits were
depressed and calcium values were elevated in these female fin-rotted
fish. Hemoglobin levels were the only predictors of fin rot on female
flounder sampled at sea; calcium levels were not identified as a contributing
variable in the final Stepwise Regression model. Only 6 male flounder
were available for sampling at sea; an insufficient number for statistical
analysis. Blood parameter values varied for diseased fish, depending
on the magnitude of fin loss. The etiology of fin rot is not known but
could result from toxic chemicals or microbes adversely impacting resident
flounder through the food chain, resulting in anemia and hypercalcemia
in affected individuals.
Axial Skeletal Anomalies in Commercially Important Fish from the North
Atlantic
John Ziskowski
NMFS/NEFSC/Milford Laboratory, Milford, CT 06460
Deformities of the axial skeleton are usually observed in fish in
the form of dwarfism, spinal curvature, and cranial compression. When radiographs
are displayed in fish with these conditions; the following underlying
structural deformities can be seen: fusion of vertebral centra, complexed
vertebrae resulting from incomplete fission during embryonic development,
accessory spinal processes, reduced spinal processes, deformed spinal
processes, reduced centra, and deformed centra. Species displayed include:
winter flounder, American plaice, yellowtail flounder, witch flounder,
Dover sole from the North Sea, Acadian redfish, and alewife. Specimens
were obtained from NMFS research vessels operating in the Gulf of Maine
and Georges Bank, from Boston Harbor during New England Aquarium’s Fish
Days, and from trawling activities conducted by the NMFS Milford Laboratory
in New Haven Harbor, Connecticut. The Dover sole was purchased at a
fish market. Associated with this poster presentation, radiographs of
fish will be displayed. |
