Assessing Habitat Quality of Mount Hope Bay and
Narragansett Bay Using Growth, RNA:DNA, and
Feeding Habits of Caged Juvenile Winter Flounder
(Pseudopleuronectes americanus Walbaum)
Lesa Meng, David L. Taylor, Jonathan Serbst,
and J. Christopher Powell
Northeastern Naturalist, Volume 15, Issue 1 (2008): 35–56
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2008 NORTHEASTERN NATURALIST 15(1):35–56
Assessing Habitat Quality of Mount Hope Bay and
Narragansett Bay Using Growth, RNA:DNA, and
Feeding Habits of Caged Juvenile Winter Flounder
(Pseudopleuronectes americanus Walbaum)
Lesa Meng1,2, David L. Taylor3,*, Jonathan Serbst1,
and J. Christopher Powell4
Abstract - Somatic growth rates, RNA:DNA, and feeding habits of juvenile
Pseudopleuronectes americanus (Winter Flounder) were used to asses small-scale
spatio-temporal variations in the habitat quality of Mount Hope Bay and Narragansett
Bay, RI. Three successive caging experiments (14–16 d each) were conducted
with flounder (initial size = 25–35 mm total length) in June and July 2003 in shallow
water habitats (<1 m) of Spar Island, Common Fence Point, and Hog Island; the
first two sites were located in Mount Hope Bay, and the latter in Narragansett Bay.
The average growth rate of flounder ranged between 0.51 and 0.95 mm d-1 and was
inversely related with increased incidences of hypoxic conditions (i.e., amount of
time dissolved oxygen was ≤4.0 mg L-1). RNA:DNA, a surrogate measure of growth
and feeding condition, corroborated somatic growth trends, and therefore exhibited
similar spatio-temporal variability. In contrast to somatic growth, however, water
temperature was the most important factor affecting flounder condition, such that
RNA:DNA was inversely related to the amount of time water temperature was >20
ºC. Benthic core samples indicated that food availability was greatest at Spar Island
and was attributable to the numerical dominance of Crepidula fornicata Linnaeus
(slipper limpet) during the early summer. Moreover, stomach contents of flounder
reflected differences in prey species composition, whereby individuals from Spar
Island consumed a higher percentage of molluscs relative to the other sites, where
the preferred prey items were harpacticoid copepods and small decapods (primarily
brachyuran crabs). Despite the observed discrepancies in feeding habits across sites,
the extent of stomach fullness for flounder did not vary spatially (mean fullness =
44–49% across sites). It is concluded that the somatic growth, RNA:DNA, and feeding
behavior of juvenile flounder in Mount Hope Bay and Narragansett Bay varies
significantly across small spatio-temporal scales in response to changes in dissolved
oxygen and thermal conditions.
The functional significance of estuaries as nursery habitat for youngof-
the-year (YOY) fish is defined by the survival of resident species.
1US Environmental Protection Agency, Office of Research and Development, National
Health and Environmental Effects Laboratory, Atlantic Ecology Division,
27 Tarzwell Drive, Narragansett, RI 02882. 2Deceased. 3Roger Williams University,
Department of Biology and Marine Biology, One Old Ferry Road, Bristol,
RI 02809. 4Division of Fish and Wildlife-Marine Fisheries, Fort Wetherill Marine
Laboratory, 3 Fort Wetherill Drive, Jamestown, RI 02835. *Corresponding author
36 Northeastern Naturalist Vol. 15, No. 1
Moreover, the number of YOY fish surviving to subsequent life-history
stages is affected by individual growth rates (Houde 1987, Pepin 1990,
Rice et al. 1993). For example, rapid growth during ontogeny can increase
the survival of early-stage fish by reducing size-dependent predation (Anderson
1988, Parker 1971, Post and Evans 1989). Fast growth also confers
a survival advantage because fish that attain larger body sizes at the end
of the summer growing season have lower over-wintering mortality (Hurst
and Conover 1998, Schultz et al. 1998, Sogard 1997). To this end, fisheries
scientists frequently evaluate the quality of nursery habitats by measuring
the growth of YOY fish.
High-quality nurseries are those in which the growth of YOY fish is
enhanced because these habitats presumably offer adequate prey resources
and optimal environmental growth conditions. The biological and physical
factors that regulate habitat-specific growth of fish, however, often vary over
small spatial and temporal scales (Manderson et al. 2002). Thus, determining
habitat quality on the basis of growth performance of fish is difficult
because associations between individuals and their habitat are complex.
Nevertheless, evaluating the functional significance of nurseries is necessary
to properly identify and manage areas that are important for fish year-class
formation and recruitment.
Pseudopleuronectes americanus Walbaum (Winter Flounder) is a pleuronectid
flatfish that has traditionally supported valuable commercial and
recreational fisheries. This species is distributed along the northwestern
Atlantic coast extending as far north as Labrador and southward to North
Carolina and Georgia (Pereira et al. 1999). The primary concentration of
Winter Flounder occurs in inshore regions, and early life-history stages are
estuarine-dependent (Able and Fahay 1998). Specifically, Winter Flounder
spawning occurs in estuaries during the winter and early spring (January
to April; Collette and Klein-MacPhee 2002). After hatching, larval Winter
Flounder are pelagic for ≈60 d (Chambers and Leggett 1987), after which
metamorphosis occurs, and the resulting juveniles settle to the benthos during
the spring and early summer (April to June; Collette and Klein-MacPhee
2002). The small size of Winter Flounder at metamorphosis (8 to 9 mm total
length [TL]; Chambers and Leggett 1987) exposes the juveniles to intense
predator-induced mortality during settlement and several months thereafter
(Manderson et al. 1999, 2000; Taylor 2003, 2005). Variation in the growth
rates of juvenile flounder is therefore likely to influence post-settlement
survival by regulating the amount of time fish are susceptible to different
predators (Taylor 2003, Taylor and Collie 2003).
The growth of post-settlement Winter Flounder is responsive to
several habitat-specific characteristics, including prey availability, temperature,
and dissolved oxygen (Manderson et al. 2002, Meise et al. 2003,
Phelan et al. 2000). Previous studies on the growth response of Winter
Flounder to these environmental variables have focused primarily on
2008 L. Meng, D.L. Taylor, J. Serbst, and J.C. Powell 37
main effects over broad spatial scales (Manderson et al. 2002). The habitats
of temperate estuaries of the northeastern United States, however,
are generally heterogeneous at fine spatial scales (<5 km), and seasonal
environmental conditions vary simultaneously over small temporal
scales (weeks). In this study, caging experiments were used to measure
juvenile Winter Flounder somatic growth rates and to assess small-scale
spatio-temporal variability in the habitat quality of Mount Hope Bay and
Narragansett Bay, RI. RNA:DNA and feeding habits of juvenile flounder
were also used as alternative measures of fish condition within specific
habitats. Winter Flounder growth and condition were subsequently
examined relative to habitat-specific environmental variables to ascertain
inter-estuarine dynamics in habitat quality.
Study area and experimental sites
The Narragansett Bay Estuary (≈260 km2 area) is contiguous with
Block Island Sound at its mouth and extends northward into Rhode Island
and Massachusetts (Fig. 1). Mount Hope Bay is a semi-enclosed estuary
(≈35 km2) that adjoins Narragansett Bay at the East Passage and Sakonnet
River (Fig. 1). Both estuaries are relatively shallow (mean depth = 7.8
and 5.7 m for Narragansett Bay and Mount Hope Bay, respectively), and
are characterized by a small salinity range of 24–30 ppt, a large annual
Figure 1. A= the collection site (▲) of Winter Flounder used in the study (Wickford
Habor). B= Experimental caging sites (●) in Mount Hope Bay (Spar Island and Common
Fence Point) and Narragansett Bay (Hog Island).
38 Northeastern Naturalist Vol. 15, No. 1
temperature range from -0.5 to 27 ºC, and weak seasonal stratification
(Oviatt and Nixon 1973).
Three sites were chosen for the caging experiments: (1) Spar Island in
central Mount Hope Bay, (2) Common Fence Point along the southeastern
edge of Mount Hope Bay, and (3) Hog Island in the East Passage of Narragansett
Bay (Fig. 1). To ensure access to experimental cages, sites had water
depths <1 m at mean low tide and were located in areas distant from boating
and other human disturbances. Moreover, sites were chosen based on
consistent substrates, bathymetry, and wind and wave exposure. Sites were
positioned along the northern edge of landmasses to maintain consistency in
physical forcing and substrates of all sites were primarily sand, cobble, and
Juvenile Winter Flounder somatic growth was monitored in 1-m2
cages composed of wooden and welded metal frames. Cages were 70 cm
tall and covered with 3-mm stiff plastic netting on the sides and top. Galvanized
steel edges (5 cm deep) around the bottom of the frame allowed
for burial of cages into the sediment. Cages were further secured into the
sediment by driving 70-cm stakes through fixtures at the lower corners
of the cages. To allow access to the inside of cages, removable tops were
constructed and cages were placed in water that was approximately 60 cm
deep at mean low tide. Four cages were used per experimental site, with
the exception of experiment 2 at Spar Island where one cage was lost.
Three successive experiments were conducted between 10 June and 22
July 2003, each lasting 14 to 16 d.
Juvenile Winter Flounder were collected one day prior to the start of
a caging experiment. Fish were collected from one site outside of Wickford
Harbor, Narragansett Bay (Fig. 1), with seine hauls (61- x 3.05-m
beach-seine set with 0.64-cm mesh size and 0.48-cm bunt). Winter Flounder
from 25 to 35 mm TL were measured to the nearest mm TL and
individually marked with visible implant fluorescent elastomer. To assess
handling mortality, fish were held overnight in the field before placing
them in cages. Dead Winter Flounder (<1% of total) were replaced with
healthy marked fish. Prior to each experiment, cages were cleared of
resident fish and decapods using bar seines and dip nets. Four randomly
chosen fish were placed into each cage, a density comparable to juvenile
Winter Flounder numbers measured in several temperate estuaries of the
northwest Atlantic (Curran and Able 2002, Sogard et al. 2001). Cages
were serviced every 3 d to make repairs and brush the plastic netting to
minimize fouling. At the end of an experiment, flounder were retrieved
from cages using bar seines and dip nets (89% retrieval rate). Retrieved
fish were immediately placed on ice, after which TL (± 0.5 mm) was measured
in the laboratory.
2008 L. Meng, D.L. Taylor, J. Serbst, and J.C. Powell 39
At each caging site, several variables related to habitat quality were
measured. Hydrolabs were deployed at each station that measured water
temperature (°C), dissolved oxygen (mg L-1), and salinity (ppt) at 45-min
intervals. A handheld YSI Model 85 (YSI Incorporated, Yellow Springs, OH)
was used to take similar measurements every 3 d to verify data collected by
the Hydrolabs. Three 1-L samples of water were also collected at each site
at the end of experiments, and subsequently analyzed for chlorophyll-a concentration
using high-performance liquid chromatography.
A stepwise multiple linear regression model was used to examine relationships
between flounder somatic growth, RNA:DNA (see below), and
the following abiotic and biotic variables: average water temperature, maximum
water temperature, proportion of time water temperature was >25 °C,
proportion of time water temperature was >20 °C, average salinity, average
dissolved oxygen, minimum dissolved oxygen, proportion of time dissolved
oxygen was ≤2.0 mg L-1, proportion of time dissolved oxygen was ≤4.0
mg L-1, chlorophyll-a concentration, and initial fish size. Nine observations
were used for the analyses (3 sites x 3 experiments), and data represented
as proportions were arc-sin square-root transformed to meet assumptions
of normality and homogeneity of variance. The effect of caging site (Spar
Island, Common Fence Point, and Hog Island) and experiment (experiments
1–3) on flounder growth (mm d-1) and RNA:DNA were also assessed with
independent, two-way analysis of variance (ANOVA) models. Mean rates
of growth and RNA:DNA across three levels of sites and experiments were
contrasted with a Ryan–Einot–Gabriel–Welsch (Ryan’s Q) multiple comparison
test (Day and Quinn 1989).
Juvenile Winter Flounder RNA:DNA, a surrogate measure of short-term
(1–3 d) instantaneous growth and feeding condition (Kuropat et al. 2002),
was measured using techniques described by Caldarone et al. (2001). Briefly,
this method used N-lauroylsarcosine to dissociate proteins from the nucleic
acids, and the fluorophore ethidium bromide (EB: 3,8-diamino-6-phenyl-5-
ethylphenanthridinium bromide) to measure total nucleic acids. Fluorescence
was detected using a 96-well fluorescence microplate reader (BioTek FL500,
BioTek Instruments, Inc., Winooski, VT). RNase was added to differentiate
RNA from DNA, and when residual fluorescence was significant (>7%),
DNase was also added to determine the true DNA content. Standard curves
were constructed from genomic ultrapure calf thymus DNA, and molecular
grade 18S- and 28S-rRNA.
Prey availability and stomach content analysis
Prey availability at each caging site was measured by four core samples
(6.7 cm diameter by 5 cm deep) taken inside and outside of the cages at the
end of the first and third experiments (16 cores total for each site). Samples
were sieved on 0.25-mm screens, and all prey was identified to the lowest
40 Northeastern Naturalist Vol. 15, No. 1
practical taxonomic level. A three-way ANOVA model was used to compare
mean differences in prey availability between sites, inside and outside of
cages, and at the end of the first and third experiments. Variables used in
the analysis were number of molluscs, polychaetes, copepods, amphipods,
“other” organisms (98% of which were nematodes), total number of organisms,
and number of taxa.
The stomach contents of 118 flounder used in caging experiments were
analyzed and averaged by cage (n = 35). Stomach fullness was estimated visually
by comparing relative amounts of food in the stomachs. Specific prey
items recovered from flounder stomachs were identified to the lowest taxon
possible, and further categorized as molluscs, polychaetes, copepods, amphipods,
and “other” organisms (82% of which were decapods). Moreover,
the amount of each food category was recorded as the percent volume for
each stomach. Independent, two-way ANOVA models were used to examine
differences in stomach fullness and percent volume of each food category
across sites and experiments. Data represented as percentages (proportions)
were arc-sin square-root transformed to meet assumptions of normality and
homogeneity of variance, and mean values of stomach fullness and prey
contents were contrasted with a Ryan’s Q multiple comparison test across
three levels of sites and experiments.
Water temperatures generally increased throughout the duration of the
study and ranged from 14.0 to 26.9 °C, with the lowest temperature at Spar
Island and the highest at Hog Island (Table 1, Fig. 2). Average temperatures
for Common Fence Point, Hog Island, and Spar Island were 20.1,
20.8, and 20.6 °C, respectively. Average salinities were 27.2, 27.2, and
25.8 ppt for Common Fence Point, Hog Island, and Spar Island, respectively
(Table 1). Common Fence Point had the highest average dissolved
oxygen content at 6.01 mg L-1, followed by Spar Island (5.34 mg L-1) and
Hog Island (4.59 mg L-1) (Table 1, Fig. 2). By the third experiment, dissolved
oxygen levels were ≤4.0 mg L-1 60% of the time at Hog Island,
followed by 51% at Spar Island and 32% at Common Fence Point. The
highest chlorophyll-a concentrations were at Common Fence Point during
the first experiment (19.8 μg L-1), followed by Spar Island during the third
experiment with 14.8 μg L-1 (Table 1). All remaining chlorophyll-a concentrations
were <10 μg L-1.
Winter Flounder somatic growth rates differed significantly across experiments
and caging sites (ANOVA: experiment p < 0.0001, site p < 0.05)
(Table 1, Fig. 3a). Specifically, average growth across sites decreased with
each experiment, with the fastest growth occurring during experiment 1
2008 L. Meng, D.L. Taylor, J. Serbst, and J.C. Powell 41
Table 1. Environmental conditions (means and ranges) of the three experimental sites in Mount Hope Bay and Narragansett Bay, and the initial lengths, growth
rates, and RNA:DNA of Winter Flounder used in three caging experiments (experiment 1 = June 10–25; experiment 2 = June 25–July 9, and experiment 3 = July
9–22, 2003). Chlorophyll-a, initial fish length, growth, and RNA:DNA are means per experiment ± 1 SE. Values represent the average of four replicates per site,
with the exception of experiment 2 at Spar Island where one cage was lost.
Common Fence Point Hog Island Spar Island
Envronmental Conditions 1 2 3 1 2 3 1 2 3
Temperature (ºC) 16.8 21.8 21.8 17.2 23.1 22.1 16.9 22.4 22.5
Range 14.3–19.2 18.2–26.0 18.7–25.1 14.4–21.6 20.0–26.9 19.3–25.6 14.0–19.7 18.0–26.0 19.7–24.7
Salinity (ppt) 28.2 25.8 27.6 27.8 25.5 28.3 26.3 24.1 27
Range 23.6–30.5 19.4–28.8 24.8–29.7 23.1–30.1 22.2–27.9 26.4–29.5 23.2–29.6 18.5–27.8 23.9–29.3
Dissolved oxygen (mg L-l) 6.4 6.9 4.8 5.3 4.6 3.9 5.2 6.8 4.1
Range 2.8–11.3 1.2–15.1 1.7–9.1 1.7–9.3 0.1–13.2 0.5–10.1 1.6–9.2 1.9–12.5 0.3–9.1
Chlorophyll-a (μg L-l) 19.8 ± 0.5 3.3 ± 0.1 5.0 ± 0.5 8.9 ± 0.2 2.7 ± 0.04 4.1 ± 0.2 9.3 ± 0.5 8.3 ± 0.03 14.8 ± 0.7
Initial fish length (mm) 29.1 ± 0.4 33.8 ± 0.4 32.3 ± 0.5 27.9 ± 0.7 33.8 ± 0.9 37.4 ± 1.5 29.3 ± 0.8 34.7 ± 1.0 34.7 ± 0.2
Growth (mm d-1) 0.71 ± 0.01 0.86 ± 0.06 0.59 ± 0.05 0.70 ± 0.02 0.61 ± 0.01 0.67 ± 0.04 0.95 ± 0.03 0.79 ± 0.06 0.51 ± 0.05
RNA:DNA 8.0 ± 0.3 7.4 ± 0.3 5.8 ± 0.4 7.8 ± 0.1 6.7 ± 0.1 6.0 ± 0.4 9.1 ± 0.3 6.9 ± 0.4 6.5 ± 0.1
42 Northeastern Naturalist Vol. 15, No. 1
Figure 2. Maximum temperature (ºC) and minimum dissolved oxygen (mg L-1) measured
by Hydrolabs deployed at Common Fence Point, Hog Island, and Spar Island
during the three experiments (experiment 1 = June 10–25; experiment 2 = June
25–July 9, and experiment 3 = July 9–22, 2003).
2008 L. Meng, D.L. Taylor, J. Serbst, and J.C. Powell 43
(0.79 mm d-1), followed by 0.76 and 0.59 mm d-1 for experiments 2 and 3,
respectively. Moreover, average growth across experiments was highest at
Spar Island (0.75 mm d-1), followed by Common Fence Point (0.72 mm d-1)
and Hog Island (0.66 mm d-1).
Figure 3. Juvenile Winter Flounder growth rates (a) and RNA:DNA (b) for three experiments
at Common Fence Point, Hog Island, and Spar Island. Values represent the
average of four replicates (cages) per site (+ 1 SE), with the exception of experiment
2 at Spar Island where one cage was lost.
44 Northeastern Naturalist Vol. 15, No. 1
The interaction effect between experiment and caging site on flounder
growth was significant (ANOVA: experiment x site p < 0.0001), thereby
precluding contrasts across the main effects (Table 1, Fig. 3a). The interaction
effect was attributed to significantly faster growth at Common Fence
Point during experiment 2, relative to experiments 1 and 3. Conversely,
flounder growth did not vary by experiment at Hog Island, and at Spar Island
growth was 54–86% slower during experiment 3 relative to the previous experiments.
Also during experiment 1, growth rates of flounder at Spar Island
were 10–36% faster relative to the other two locations, and conversely during
experiment 2, flounder at Hog Island experienced 30–41% slower growth
when compared to flounder at the alternative sites.
The amount of time dissolved oxygen was ≤4.0 mg L-1 was the only environmental
factor that significantly affected juvenile Winter Flounder growth
(regression: p = 0.05, R2 = 0.432). The estimated coefficient for the dissolved
oxygen variable was negative (-0.436), suggesting an inverse relationship
between hypoxic events and flounder growth.
There was a strong positive correlation between Winter Flounder
RNA:DNA and daily somatic growth rates (regression: p < 0.0001, R2 =
0.471). Correspondingly, trends in Winter Flounder RNA:DNA generally
corroborated observed spatial and temporal patterns of flounder growth,
only differing in two instances (experiments 2 and 3 at Common Fence
Point and Spar Island, respectively) (Table 1, Fig. 3b). RNA:DNA was
significantly different among experiments and caging sites (ANOVA: experiment
p < 0.0001, site p < 0.05), and the experiment-site interaction
effect was not significant (ANOVA: experiment x site p = 0.086). Flounder
RNA:DNA declined significantly at each site from the first to third
experiment, and when averaged across experiments, fish at Spar Island
had significantly higher RNA:DNA relative to conspecifics at Hog Island.
Moreover, the RNA:DNA of Winter Flounder was negatively correlated
with the amount of time water temperature exceeded 20 °C (regression:
p < 0.005), and elevated temperatures accounted for 72% of the variation
observed in flounder condition.
Prey availability and stomach content analysis
The number of benthic organisms in core samples indicated that food
availability varied among experimental sites and inside versus outside of
the cages (i.e., across the cage boundary) (ANOVA: site p < 0.0001, cage
boundary p < 0.05; Fig. 4a). Moreover, the interaction between sites and the
cage boundary was not significant (ANOVA: site x cage boundary p = 0.26).
Relative to the prey measured at Hog Island and Common Fence Point, Spar
Island had significantly more total food items (mean = 1433 individuals m-2
versus 366 and 84 individuals m-2 for Hog Island and Common Fence Point,
respectively) and taxa (mean = 19 taxa m-2 versus 12 and 10 taxa m-2 for Hog
2008 L. Meng, D.L. Taylor, J. Serbst, and J.C. Powell 45
Island and Common Fence Point, respectively) (Table 2, Fig. 4a). All of the
food groups varied significantly among sites (except amphipods; Table 2),
and the greatest discrepancy occurred for molluscs with Crepidula fornicata
Figure 4. Mean number of benthic organisms m-2 collected (a) inside (“In”) and outside
(“Out”) of experimental cages, and (b) at the end of experiment 1 (“Initial”) and
experiment 3 (“Final”). Benthic organisms were collected using a 6.7-cm-diameter
core sampler (5 cm deep) at three locations: Common Fence Point, Hog Island, and
Spar Island. Four core samples were taken inside and outside of the cages at the
end of the first and third experiments (16 cores total for each site; n = 8). Error bars
represent + 1 SE.
46 Northeastern Naturalist Vol. 15, No. 1
Table 2. Stomach fullness and contents of Winter Flounder used in three caging experiments (118 flounder were examined and averaged by cage; n = 35), and
benthic organisms found in 6.7-cm-diameter core samples. Core samples were taken inside and outside of cages after experiment 1 and 3 (n = 48). Values represent
the average (± 1 SE) percent volume of food item eaten per stomach (“Eaten”) and the average number of prey items found m-2 (“Cage”).
Common Fence Point Hog Island Spar Island
Experiment 1 2 3 1 2 3 1 2 3
% Stomach fullness 43.1 ± 3.4 53.0 ± 4.7 40.3 ± 3.3 44.2 ± 6.9 34.4 ± 4.0 55.7 ± 3.8 63.3 ± 4.3 41.7 ± 5.3 36.8 ± 5.1
Eaten 39.0 ± 5.1 20.7 ± 5.8 0.6 ± 0.4 4.7 ± 3.9 0.8 ± 0.4 0.3 ± 0.3 62.1 ± 5.6 7.0 ± 3.6 0.7 ± 0.4
Cage 5.5 ± 0.9 13.9 ± 6.8 3.6 ± 1.2 2.0 ± 1.2 2170.0 ± 750 208.0 ± 146
Eaten 1.8 ± 1.3 2.0 ± 0.9 2.1 ± 1.1 13.8 ± 7.6 22.9 ± 7.3 4.6 ± 2.5 1.0 ± 0.7 3.2 ± 1.8
Cage 7.6 ± 1.5 20.3 ± 5.0 65.8 ± 20.5 52.1 ± 8.8 182.0 ± 35.3 150.0 ± 26.4
Eaten 14.9 ± 3.2 8.7 ± 2.0 30.9 ± 7.3 15.8 ± 6.6 4.3 ± 1.2 5.4 ± 2.4 3.9 ± 0.8 5.4±1.2 14.8 ± 0.7
Cage 1.4 ± 0.4 2.1 ± 1.1 6.3 ± 2.8 2.0 ± 0.9 25.8 ± 6.1 1.1 ± 0.9
Eaten 8.1 ± 3.5 13.3 ± 3.7 4.1 ± 3.1 44.1 ± 9.0 30.4 ± 7.8 51.4 ± 2.4 11.7 ± 4.3 70.2±9.6 58.9 ± 7.7
Cage 0.1 ± 0.1 0.5 ± 0.3 3.6 ± 2.0 24.8 ± 21.2 52.8 ± 19.9 6.5 ± 3.0
Eaten 40.3 ± 5.4 57.6 ± 5.9 61.6 ± 8.8 24.5 ± 7.9 45.9 ± 7.6 39.9 ± 7.3 24.3 ± 4.0 9.6±5.5 39.6 ± 7.3
Cage 96.0 ± 15.8 4.3 ± 1.7 187.0 ± 38.6 316.0 ± 79.0 44.3 ± 15.9 17.9 ± 7.5
2008 L. Meng, D.L. Taylor, J. Serbst, and J.C. Powell 47
Linnaeus (slipper limpet) being the numerically dominant species (mean
number of molluscs = 1189, 10, and 3 individuals m-2 at Spar Island, Common
Fence Point, and Hog Island, respectively). Copepods and the number
of taxa were significantly greater outside the cages, but all other prey categories
were not significantly different across the cage boundary.
Food availability differed significantly as a function of time and caging
site (ANOVA: time p < 0.0001, site p < 0.05), but the interaction effect was
also significant (ANOVA: time x site p < 0.001), precluding contrasts across
the main effects (Fig. 4b). The interaction effect was due to a ten-fold decrease
in molluscs at Spar Island at the end of the third experiment (Table 2).
Otherwise, there was no difference in food availability inside and outside of
the cages when initial and final cores were compared.
The stomach contents of Winter Flounder differed significantly by experiment,
caging site, and the experiment-site interaction effect (ANOVA:
experiment p < 0.0001, site p < 0.0001, experiment x site p < 0.0001; Fig. 5).
Conversely, stomach fullness was similar among sites (mean = 44–49%) and
experiments (mean = 43–52%) (ANOVA: experiment p > 0.05, site p > 0.05).
The interaction effect between experiment and site on stomach fullness was
significant (ANOVA: experiment x site p < 0.001), however, and reflects a
decline in the mean stomach fullness of flounder at Spar Island from 63% in
the first experiment to 37% in the third (Table 2).
Stomach contents of caged Winter Flounder reflected spatial differences
in prey composition, and therefore, patterns of feeding habits
differed considerably across sites (Table 2, Fig. 5). For example, Winter
Flounder at Spar Island consumed significantly more molluscs than
flounder at Common Fence Point and Hog Island (ANOVA: p < 0.0001).
This result indicates opportunistic foraging by flounder on the abundant
slipper limpet, as this mollusc accounted for >83% of the total number
of available prey at Spar Island. Conversely, harpacticoid copepods were
the preferred food resource of flounder at Common Fence Point and Hog
Island, accounting for 52–78% of the total number of prey identified in
stomach contents. The consumption of copepods at Common Fence Point
and Hog Island suggests a selective foraging strategy, considering the
relatively low abundance of this prey item at the respective sites (1–2%
of the total number of available prey).
Notwithstanding the numerical dominance of copepods in the diet of
juvenile Winter Flounder (particularly at Common Fence Point and Hog
Island), this prey category accounted for a relatively low percent volume
of the total stomach contents (8.5–18.2%). In contrast, amphipods were not
regarded as a prominent food resource based on availability or numerical
identification in stomach contents, yet this prey category routinely ranked
among the top items by percent volume of the total diet (8.5–47%). The
availability of polychaetes was consistent across sites (range = 12–18% of
total prey), but this prey item was only consumed by flounder at appreciable
48 Northeastern Naturalist Vol. 15, No. 1
Figure 5. Food items available compared to the prey consumed by juvenile Winter
Flounder in experimental cages at three sites: Common Fence Point, Hog Island, and
Spar Island. For each prey category, values represent the percent of the total number
of food items in core samples (“Available”), percent of total number of prey items
eaten (“Number eaten”), and percent volume of prey items eaten (“Volume eaten”).
2008 L. Meng, D.L. Taylor, J. Serbst, and J.C. Powell 49
levels at Hog Island (ANOVA: p < 0.005). Within the “other” prey category,
nematodes were relatively abundant in the field (accounting for 98% of the
organisms within the category), but this prey item was not consumed by
flounder in high quantities. Conversely, the majority of “other” prey consumed
(based on percent volume of stomach contents) were small decapods
(>82%), and this food resource was eaten in significantly greater quantities
by flounder at Common Fence Point relative to the alternative sites
(ANOVA: p < 0.0001).
Patterns of somatic growth, RNA:DNA, and feeding habits of juvenile
Winter Flounder varied on small spatio-temporal scales in response to
changes in dissolved oxygen, thermal conditions, and prey composition,
respectively. Specifically, the average growth rate of caged Winter Flounder
decreased throughout the duration of this study and was negatively
correlated with the occurrence of hypoxic events (dissolved oxygen ≤4.0
mg L-1). The RNA:DNA of Winter Flounder corroborated somatic growth
trends, which was also reported in similar investigations that compared the
growth and condition of caged juvenile Winter Flounder (Kuropat et al.
2002). In contrast to the growth patterns observed in this study, however,
RNA:DNA were inversely related to elevated water temperatures (>20 ºC).
Diet analysis of Winter Flounder further revealed that differences in feeding
habits across experimental sites reflected habitat-specific variability in
prey composition. The mollusc C. fornicata, for example, was opportunistically
consumed at Spar Island when this species was numerically dominant,
whereas harpacticoid copepods and small decapods (i.e., brachyuran crabs)
were preferentially selected as a food resource at alternative sites (Common
Fence Point and Hog Island). Cumulatively, these results underscore
how biotic and abiotic factors influence the function of habitats at small
spatial and temporal scales, and consequently, the importance of evaluating
biological responses at the appropriate scale.
The somatic growth of post-settlement flatfish, including Winter Flounder,
is responsive to a multitude of biotic and abiotic factors. Temperature,
for example, is one the most significant factors underlying variations in the
growth of early-stage flatfish (Malloy and Targett 1991, Manderson et al.
2002, Meng et al. 2000, Rose et al. 1996). For juvenile Winter Flounder,
growth as a function of temperature exhibits a unimodal response with optimal
growth occurring at ≈15 ºC (Rose et al. 1996). In contrast to similarly
designed experiments (Meng et al. 2000, 2001; Phelan et al. 2000; Sogard
1992), water temperature during this study did not account for a significant
level of variation in observed flounder growth. There was, however, an
inverse relationship between flounder RNA:DNA and the amount of time
water temperature was >20 ºC.
50 Northeastern Naturalist Vol. 15, No. 1
RNA concentration reflects active protein synthesis, and therefore
represents an indirect measurement of short-term (1–3 d) instantaneous
growth (Kuropat et al. 2002). Moreover, RNA content normalized with
DNA concentration (i.e., RNA:DNA) is frequently used as a tool to assess
variability in fish growth and recent feeding history (Buckley et al.
1999). For example, Malloy and Targett (1991) noted increased RNA:
DNA in juvenile Paralichthys dentatus Linnaeus (Summer Flounder)
when temperature and foraging activity increased simultaneously. The opposite
trend was observed in this study, whereby Winter Flounder RNA:
DNA was inversely correlated with periods of elevated water temperature
(>20 ºC). Water temperatures ranging between 20 and 29 °C may inhibit
the feeding of juvenile Winter Flounder (Casterlin and Reynolds 1982).
Results from this investigation, however, do not support this supposition
because flounder stomach fullness remained relatively constant (mean
fullness across experiment = 43–52%) despite changing temperature
conditions. More likely, warmer temperatures depress protein synthesis
in juvenile Winter Flounder because a disproportionate amount of energy
is devoted to increased metabolism, which in turn, leaves less energy for
somatic development (Buckley et al. 1999). This physiological response
also partially explains the general decrease in Winter Flounder somatic
growth rates during the investigation (mean growth = 0.79 and 0.59 mm
d-1 during experiments 1 and 3, respectively).
Concentrations of dissolved oxygen decrease as water temperature increases,
which in turn negatively affects fish growth. In this study, levels
of dissolved oxygen ≤4.0 mg L-1 explained 43% of the variability in Winter
Flounder growth. This is consistent with Bejda et al. (1992), who found
lower growth in Winter Flounder under conditions of fluctuating and low
dissolved oxygen. In a Narragansett Bay caging study, Winter Flounder
growth decreased dramatically as dissolved oxygen fell with increasing
temperatures (Meng et al. 2001). Caging studies in New Jersey showed
growth and survival were depressed in tidal marsh creeks and vegetated
macroalgae habitats where dissolved oxygen was often less than 2 mg L-1, due to
high temperatures and the breakdown of macroalgae (Phelan et al. 2000). In
Long Island Sound, areas with low dissolved oxygen had fewer and smaller
Winter Flounder (Howell and Simpson 1994). Thus, prolonged periods of
low dissolved oxygen can have a distinctly negative affect on Winter Flounder
Chlorophyll-a concentrations may also have indirectly negatively affected
growth during this study by contributing to low dissolved oxygen
concentrations. Chlorophyll-a is a surrogate measurement for nutrient
enrichment that is known to degrade fish habitat by lowering dissolved oxygen,
increasing turbidity, and changing sediment characteristics (Valiela et
al. 1992). Increased nutrients may also benefit fish by producing more food
(Meng et al. 2002, Tsai et al. 1991), but it is unclear how nutrients interact
2008 L. Meng, D.L. Taylor, J. Serbst, and J.C. Powell 51
with other factors, such as temperature. In this study, there was no clear trend
in chlorophyll-a concentrations.
Adequate food resources, which are often associated with substrate
characteristics (Manderson et al. 2002, Phelan et al. 2001), are also necessary
to sustain maximal growth rates of post-settlement flatfish (Gibson
1994 and references therein). Variations in the growth of newly settled
plaice, for example, have been partially attributed to food quality and
quantity (Poxton 1983, Van der Veer and Witte 1993). Similarly, Meise et
al. (2003) observed a positive relationship between juvenile Winter Flounder
growth and benthic food abundance in the Navesink River/Sandy Hook
Bay estuary in New Jersey. In this study, somatic growth of flounder was
fastest at Spar Island during experiment 1 (0.95 mm d-1) and may be related
to the availability and subsequent consumption of the abundant slipper limpets.
This mollusc was also abundant at Common Fence Point and Mount
Hope Bay, albeit at a lesser extent, and was eaten in proportions indicative
of their overall availability. The steady decline in flounder growth at Spar
Island (experiment 3 growth rate = 0.51 mm d-1) may have been related to
lower prey availability and, specifically, the lower abundance of slipper
limpets. Stomach fullness decreased markedly over time at Spar Island
(63% and 37% fullness after experiments 1 and 3, respectively), coinciding
with a ten-fold decrease in prey density during the same time period.
As previously discussed, water temperatures between 20 and 29 °C might
cause feeding inhibition in juvenile flounder (Casterlin and Reynolds
1982), and in this study, may have interacted with lower prey densities to
decrease stomach fullness at Spar Island.
In contrast to Winter Flounder opportunistically foraging on slipper
limpets, the frequency of harpacticoid copepods, amphipods (primarily
Microdeutopus gryllotalpa Costa), and small decapods (brachyuran crabs)
in fish stomach contents was disproportional to the preys’ overall habitatspecific abundance. Harpacticoid copepods were also a major constituent
in the diet of post-settlement Winter Flounder (≈12–36 mm TL) in the
Mystic River, CT (Pearcy 1962) and the Pettaquamscutt River, RI (Mulkana
1966), but not from the Navesink River/Sandy Hook Bay estuary (Stehlik
and Meise 2000). In another study in Narragansett Bay, Polydora cornuta
Bosc (mud polychaete) was a favored food item (Meng et al. 2001). In this
study, however, despite the relatively high abundance of polychaetes such
as P. cornuta, this prey category was eaten less frequently than expected.
Winter Flounder are generally considered opportunistic feeders, foraging on
the most abundant and available prey resource (Carlson et al. 1997, Stehlik
and Meize 2000). Results from this study partially verify this supposition,
most notably through the presence of slipper limpets in the stomach contents
of flounder from Spar Island. However, flounder from alternative sites apparently
exhibit a selective foraging strategy, whereby fish preferentially
consume prey items that were in relatively low abundance.
52 Northeastern Naturalist Vol. 15, No. 1
Somatic growth rates measured in this study are slightly higher than
other northeastern estuaries, but comparable to other studies on Winter
Flounder in this size range. Winter Flounder growth averaged from
0.51 to 0.95 mm d-1 in this study, compared to 0.22 to 0.60 mm d-1 in the
West Passage of Narragansett Bay (Meng et al. 2001) and 0.29 to 0.44
mm d-1 in Rhode Island’s coastal lagoons (Meng et al. 2000). DeLong et
al. (2001) developed a length-based model for Winter Flounder growth
based on data from Narragansett Bay. Using their model for 30-mm fish,
similar in size to those used in our experiments, growth was estimated
at 0.32–0.37 mm d-1. In the Mystic River estuary, growth averaged from
0.28 to 0.35 mm d-1 (Pearcy 1962). Phelan et al. (2000) recorded growth
of -0.3 to 0.69 mm d-1 when they compared Connecticut and New Jersey
estuaries, with higher rates in New Jersey. Growth of caged fish in New
Jersey estuaries ranged from 0 to 1.3 mm d-1 (Sogard 1992), and that of
free-ranging fish was calculated from otoliths at 0.3 to 1.7 mm d-1 (Sogard
and Able 1992). Another caging study in the Navesink River/Sandy
Hook Bay estuary recorded rates of 0 to 0.9 mm d-1 and noted that growth
was most rapid at cool temperatures (<21 °C) (Manderson et al. 2002).
The gradient of growth rates from north to south suggests that warmer
temperatures may be beneficial up to a point, but when temperatures exceed
25 °C, as they did in the Rhode Island coastal lagoon study, Winter
Flounder growth is depressed (Meng et al. 2000). As previously stated,
modeling studies have indicated that the optimum temperature for juvenile
Winter Flounder growth is ≈15 °C (DeLong et al. 2001, Rose et al.
1996), but it is likely that the optimum temperature varies among estuaries
and through the growing season, and is dependent on the variation of
other factors, such as salinity (Manderson et al. 2002).
This study demonstrates that the quality of estuarine nurseries is dynamic
because of variations in habitat-specific environmental factors that regulate
fish growth. Specifically, juvenile Winter Flounder growth and condition
(RNA:DNA and feeding habits) varied considerably over relatively small
spatial scales (<5 km) and temporal scales (weeks) in response to seasonal
changes in dissolved oxygen concentrations, thermal conditions, and prey
species composition. These results underscore the importance of measuring
the biological responses of early-stage fish to dominant controlling factors
at the appropriate scale.
We thank Phil Colarusso of the US Environmental Protection Agency,
Region 1 in Boston, MA, for suggesting this study and guiding us through the
process of acquiring the funds through the Regional Acquired Research Effort
program to conduct the work. Many people helped with the field effort, including
Nora Sturgeon, Adam Frimodig, Steve Raciti, Lee von Kraus, Adam Memon, Sarah
Pierce, Julie St. Andre, and Nicole Calabrese. We also thank Sheldon Pratt for
2008 L. Meng, D.L. Taylor, J. Serbst, and J.C. Powell 53
identifying and enumerating the benthic prey, and Jean St. Onge-Burns and Melissa
Wagner for analyzing RNA:DNA and fish stomach contents. We are grateful
to Saro Jayaraman for analyzing the chlorophyll samples. Jim Heltshe’s suggestions
on the statistics were invaluable. We thank the many people who reviewed
this manuscript, including Marty Chinata, Beth Hinchey, and Walter Berry. Mention
of trade names or commercial products does not constitute endorsement or
recommendation for use. This paper is contribution number AED-05-095 of the
US Environmental Protection Agency, Office of Research and Development, National
Health and Environmental Effects Laboratory’s Atlantic Ecology Division.
Although the research described in this article has been funded by the US Environmental
Protection Agency, it has not been subjected to Agency-level review.
Therefore, it does not necessarily reflect the views of the Agency.
Able, K.W., and M.P. Fahay. 1998. The First Year in the Life of Estuarine Fishes in
the Middle Atlantic Bight. Rutgers University Press, New Brunswick, NJ.
Anderson, J.T. 1988. A review of size-dependent survival during pre-recruit stages
of fishes in relation to recruitment. Journal of Northwest Atlantic Fishery Science
Bejda, A.J., B.A. Phelan, and A.L. Studholme. 1992. The effect of dissolved oxygen
on the growth of young-of-the-year Winter Flounder, Pseudopleuronectes americanus.
Environmental Biology of Fishes 34:321–327.
Buckley, L.J., E. Caldrone, and T.L. Ong. 1999. RNA-DNA ratio and other nucleic
acid-based indicators for growth and condition of marine fishes. Hydrobiologia
Caldarone, E.M., M. Wagner, J. St. Onge-Burns, and L.J. Buckley. 2001. Protocol
and guide for estimating nucleic acids in larval fish using a fluorescence microplate
reader. Northeast Fisheries Science Center Reference Document 01-11. US
Department of Commerce, National Oceanic and Atmospheric Administration,
Northeast Region, Northeast Fisheries Science Center, Woods Hole, MA.
Carlson, J.K., T.A. Randall, and M.E. Mroczka. 1997. Feeding habits of Winter
Flounder (Pleuronectes americanus) in a habitat exposed to anthropogenic disturbance.
Journal of Northwest Atlantic Fishery Science 21:65–73.
Casterlin, M.E., and W.W. Reynolds. 1982. Thermoregulatory behavior and diel activity
of yearling Winter Flounder, Pseudopleuronectes americanus (Walbaum).
Environmental Biology of Fishes 7:177–180.
Chambers, R.C., and W.C. Leggett. 1987. Size and age at metamorphosis in marine
fishes: An analysis of laboratory-reared Winter Flounder (Pseudopleuronectes
americanus) with a review of variation in other species. Canadian Journal of
Fisheries and Aquatic Sciences 44:1936–1947.
Collette, B.B., and G. Klein-MacPhee. 2002. Bigelow and Schroeder’s Fishes of the
Gulf of Maine. 3rd Edition. Smithsonian Institution Press, Washington, DC.
Curran, M.C., and K.W. Able. 2002. Annual stability in the use of coves near inlets
as settlement areas for Winter Flounder (Pseudopleuronectes americanus). Estuaries
Day, R.W., and G.P. Quinn. 1989. Comparisons of treatments after an analysis of
variance in ecology. Ecological Monographs 59:433–463.
54 Northeastern Naturalist Vol. 15, No. 1
DeLong, A.K., J.S. Collie, C.J. Meise, and J.C. Powell. 2001. Estimating growth
and mortality of juvenile Winter Flounder, Pseudopleuronectes americanus, with
a length-based model. Canadian Journal of Fisheries and Aquatic Sciences 58:
Gibson, R.N. 1994. Impact of habitat quality and quantity on the recruitment of juvenile
flatfishes. Netherlands Journal of Sea Research 32(2):191–206.
Howell, P.T., and D. Simpson. 1994. Abundance of marine resources in relation to
dissolved oxygen in Long Island Sound. Estuaries 17:394–402.
Houde, E.D. 1987. Fish life dynamics and recruitment variability. American Fisheries
Society Symposium 2:17–29.
Hurst, T., and D.O. Conover. 1998. Winter mortality of young-of-the-year Hudson
River Striped Bass (Morone saxatilis): Size-dependent patterns and effects
on recruitment. Canadian Journal of Fisheries and Aquatic Sciences 55:
Kuropat, C., R.Mercaldo-Allen, E. Caldarone, R. Goldberg, B. Phelan, F. Thurberg.
2002. Evaluation of RNA concentration as an indicator of growth in young-ofthe-
year Winter Flounder Pseudopleuronectes americanus and Tautog Tautoga
onitis. Marine Ecology Progress Series 230:265–274.
Malloy, K.D., and T.E. Targett. 1991. Feeding, growth, and survival of juvenile
Summer Flounder Paralichthys dentatus: Experimental analysis of the effects of
temperature and salinity. Marine Ecology Progress Series 72:213–223.
Manderson, J.P., B.A. Phelan, A.J. Bejda, L. Stehlik, and A.W. Stoner. 1999. Predation
by Striped Searobin (Prionotus evolans,Triglidae) on young-of-the-year
Winter Flounder (Pseudopleuronectes americanus, Walbaum): Examining prey
size selection and prey choice using field observations and laboratory experiments.
Journal of Experimental Marine Biology and Ecology 242:211–231.
Manderson, J.P., B.A. Phelan, A.W. Stoner, and J. Hilbert. 2000. Predator-prey relations
between age-1+ Summer Flounder (Paralichthys dentatus, Linnaeus) and
age-0 Winter Flounder (Pseudopleuronectes americanus, Walbaum): Predator
diets, prey selection, and effects of sediments and macrophytes. Journal of Experimental
Marine Biology and Ecology 251:17–39.
Manderson, J.P., B.A. Phelan, C. Meise, L.L. Stehlik, A.J. Bejda, J. Pessutti, L. Arlen,
A. Draxler, and A.W. Stoner. 2002. Spatial dynamics of habitat suitability for
the growth of newly settled Winter Flounder Pseudopleuronectes americanus in
an estuarine nursery. Marine Ecology Progress Series 228:227–239.
Meise, C.J., D.L. Johnson, L.L. Stehlik, J. Manderson, and P. Shaheen. 2003. Growth
rates of juvenile Winter Flounder under varying environmental conditions. Transactions
of the American Fisheries Society 132:335–345.
Meng, L., C. Gray, B. Taplin, and E. Kupcha. 2000. Using Winter Flounder growth
rates to assess habitat quality in Rhode Island’s coastal lagoons. Marine Ecology
Progress Series 201:287–299.
Meng, L., J.C. Powell, and B. Taplin. 2001. Using Winter Flounder growth rates
to assess habitat quality across an anthropogenic gradient in Narragansett Bay,
Rhode Island. Estuaries 24:576–584.
Meng, L., C.D. Orphanides, and J.C. Powell. 2002. Use of a fish index to assess
habitat quality in Narragansett Bay, Rhode Island. Transactions of the American
Fisheries Society 131:731–742.
Mulkana, M.S. 1966. The growth and feeding habits of juvenile fishes in two Rhode
Island estuaries. Gulf Research Report 2:97–167.
2008 L. Meng, D.L. Taylor, J. Serbst, and J.C. Powell 55
Oviatt, C.A., and S.W. Nixon. 1973. The demersal fish of Narragansett Bay: An
analysis of community structure, distribution, and abundance. Estuarine and
Coastal Marine Science 1:361–378.
Parker, R.R. 1971. Size-selective predation among juvenile salmonid fishes in
British Columbia inlet. Journal of the Fisheries Research Board of Canada 28:
Pearcy, W.G. 1962. Ecology of an estuarine population of Winter Flounder, Pseudopleuronectes
americanus (Walbaum), Parts I–IV. Bulletin of the Bingham
Oceanographic Collection 18:39–64.
Pepin, P. 1990. Predation and starvation of larval fish: A numerical experiment of
size- and growth-dependent survival. Biological Oceanography 6:23–44.
Pereira, J., R. Goldberg, J.J. Ziskowski, P.L. Berrien, W.W. Morse, and D.L. Johnson.
1999. Essential fish habitat source document: Winter Flounder, Pseudopleuronectes
americanus, life history and habitat characteristics. National Oceanic and
Atmospheric Administration (NOAA) Technical Memorandum, NOAA/National
Marine Fisheries Service-NE-138.
Phelan, B.A., R. Goldberg, A.J. Bejda, J. Pereira, S. Hagan, P. Clark, A.L. Studholme,
A. Calabrese, and K.W. Able. 2000. Habitat-specific growth of young-of-the-year
Winter Flounder (Pseudopleuronectes americanus) and Tautog (Tautoga onitis)
in three northeastern US estuaries. Journal of Experimental Marine Biology and
Phelan, B.A., J.P. Manderson, A.W. Stoner, and A.J. Bejda. 2001. Size-related
shifts in the habitat associations of young-of-the-year Winter Flounder (Pseudopleuronectes
americanus): Field observations and laboratory experiment with
sediments and prey. Journal of Experimental Marine Biology and Ecology 257:
Post, J.R., and D.O. Evans. 1989. Experimental evidence of size-dependent predation
mortality in juvenile Yellow Perch. Canadian Journal of Zoology 67:
Poxton, M.G. 1983. The food and growth of 0-group flatfish on nursery grounds in
the Clyde Sea Area. Estuarine, Coastal and Shelf Science 17:319–337.
Rice, J.A., J.A. Miller, K.A. Rose, L.B. Crowder, E.A. Marshall, A.S. Trebitz, and
D.L. DeAngelis. 1993. Growth-rate variation and larval survival: Inferences
from an individual-based size-dependent predation model. Canadian Journal of
Fisheries and Aquatic Sciences 50:133–142.
Rose, K.A., J.A. Tyler, R.C. Chambers, G. Klein-MacPhee, and D.J. Danila. 1996.
Simulating Winter Flounder population dynamics using coupled individualbased
young-of-the-year and age-structured adult models. Canadian Journal of
Fisheries and Aquatic Sciences 53:1071–1091.
Schultz, E.T., D.O. Conover, and A. Ehtisham. 1998. The dead of winter:
Size-dependent variation and genetic differences in seasonal mortality among
Atlantic Silversides (Atherinidae: Menidia menidia) from different latitudes.
Canadian Journal of Fisheries and Aquatic Sciences 55:1149–1157.
Sogard, S.M. 1992. Variability in growth rates of juvenile fishes in different estuarine
habitats. Marine Ecology Progress Series 85:35–53.
Sogard, S.M. 1997. Size-selected mortality in the juvenile stages of teleost fishes: A
review. Bulletin of Marine Science 60:1129–1157.
56 Northeastern Naturalist Vol. 15, No. 1
Sogard, S.M., and K.W. Able. 1992. Growth variation of newly settled Winter Flounder
(Pseudopleuronectes americanus) in New Jersey estuaries as determined by
otolith microstructure. Netherlands Journal of Sea Research 29:163–172.
Sogard, S.M., K.W. Able, and S.M. Hagan. 2001. Long-term assessment of settlement
and growth of juvenile Winter Flounder (Pseudopleuronectes americanus)
in New Jersey estuaries. Journal of Sea Research 45:189–204.
Stehlik, L.L., and C.J. Meise. 2000. Diet of Winter Flounder in a New Jersey estuary:
Ontogenetic change and spatial variation. Estuaries 23:381–391.
Taylor, D.L. 2003. Size-dependent predation on post-settlement Winter Flounder
Pseudopleuronectes americanus by sand shrimp Crangon septemspinosa. Marine
Ecology Progress Series 263:197–215.
Taylor, D.L. 2005. Predatory impact of the green crab (Carcinus maenas Linnaeus)
on post-settlement Winter Flounder (Pseudopleuronectes americanus Walbaum)
as revealed by immunological dietary analysis. Journal of Experimental Marine
Biology and Ecology 324:112–126.
Taylor, D.L., and J.S. Collie. 2003. A temperature- and size-dependent model of
sand shrimp (Crangon septemspinosa) predation on juvenile Winter Flounder
(Pseudopleuronectes americanus). Canadian Journal of Fisheries and Aquatic
Tsai, C., M. Wiley, and A. Chai. 1991. Rise and fall of Potomac River Striped Bass
stock: A hypothesis of the role of sewage. Transactions of the American Fisheries
Valiela, I., K. Foreman, M. LaMontagne, D. Hersh, J. Costa, P. Peckol, B. DeMeo-
Anderson, C. D’Avanzo, M. Babione, C. Sham, J. Brawley, and K. Lajtha. 1992.
Couplings of watersheds and coastal waters: Sources and consequences of nutrient
enrichment in Waquoit Bay, Massachusetts. Estuaries 15:443–457.
Van der Veer, H.W., and J.I.J. Witte. 1993. The “maximum growth/optimal food condition”
hypothesis: A test for 0-group Plaice Pleuronectes platessa in the Dutch
Wadden Sea. Marine Ecology Progress Series 101:81–90.
Further research on Mount Hope Bay
is available in Special Issue #4 of the
Natural and Anthropogenic Influences on
the Mount Hope Bay Ecosystem. The papers
in this special issue were presented as
part of a day-long symposium to determine
the state of knowledge of the Mount Hope
Bay ecosystem and to examine how natural
and anthropogenic factors affect estuarine
systems. The symposium was convened as
part of a joint meeting of the New England
Estuarine Research Society and the Southern
New England Chapter of the American Fisheries
Society. 204 pp. To order a copy, please
contact Dan MacDonald at: School for Marine
Science and Technology, University of Massachusetts
Dartmouth, New Bedford, MA 02744;