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1.
We quantified temporal and spatial variability in diets of 950 juvenile (age-0) striped bass in the Hudson River estuary.
We used canonical correspondence analysis to assess the roles of temporal and spatial habitat variability in juvenile diet
variation. We found that juvenile striped bass diets in the Hudson River were only modestly comparable to diets in other east
coast estuaries. Among-year differences (51.4%) and spatial differences (41.9%) were substantially associated with juvenile
striped bass diet. We found ontogeny (2.8%) and within-season variation (9.5%) to only weakly associate with diet variation.
Our results indicate that an understanding of the temporal and spatial variation within the Hudson River estuary is vital
in understanding variation in feeding by resident juvenile fish. 相似文献
2.
Large, recreationally or commercially important populations of Atlantic sturgeon (Acipenser oxyrinchus), American shad (Alosa sapidissima), and striped bass (Morone saxatilis) occur in the Hudson River. Members of the Hudson River populations of these fishes also occur over a broad range along the Atlantic coast where they mix with conspecifics from other anadromous populations. For management purposes, it is imperative to be able to discriminate among individual stocks so that weak stocks may be protected and harvest may be allocated equitably. Because of their sensitivity and resistance to environmentally-induced temporal variation, molecular approaches have been increasingly employed in stock identification studies. However, post-Pleistocene recolonization of the Hudson River must have occurred less than 10,000 years ago—a relatively brief period for genetic divergence among populations. We tested whether various measures of DNA variation between Hudson River populations and adjacent populations of Atlantic sturgeon, American shad, and striped bass were sufficient to discriminate among their conspecific populations. American shad populations surveyed for mtDNA variation were highly diverse genotypically, but genotypic frequencies among the populations of the Connecticut, Hudson, and Delaware rivers were statistically homogenous (p>0.05). In contrast, Atlantic sturgeon (surveyed for mtDNA variation) and striped bass (surveyed for mtDNA and nuclear DNA variation) populations of the Hudson River were not genotypically diverse, but they were differentiated from northern and southern populations. Our results suggest higher gene flow (and lesser homing fidelity) among American shad populations in comparison with the two other species. 相似文献
3.
Gillnet surveys from 1990 to 1992 and from 1996 to 1999 indicated a two-fold decrease in native striped bass (Morone saxatilis) populations and a concomitant two-fold increase in hybrid striped bass (Morone saxatilis × M. americana) in the Cape Fear River estuary, North Carolina. Gut content analysis indicated high diet overlap, and tagrecapture data
suggested that hybrid striped bass participate in spawning migrations. These data provide circumstantial evidence that hybrid
striped bass compete with striped bass for food and that they may compete for mates or habitat on the spawning grounds. Increasing
abundance of adult hybrid striped bass in this system elevates the likelihood of hybrid introgression. We recommend that stocking
of hybrid striped bass be terminated to preserve native striped bass populations. 相似文献
4.
J. P. Van Eenennaam S. I. Doroshov G. P. Moberg J. G. Watson D. S. Moore J. Linares 《Estuaries and Coasts》1996,19(4):769-777
Ninety-four prespawning adult Atlantic sturgeon (Acipenser oxyrinchus) were sampled in the Hudson River for age, sex, body size, gonad weight, fecundity, mature oocyte size, and plasma concentrations of gonadotropins, sex steroids, and vitellogenin during the spring spawning migrations in 1992 and 1993. In males, the age and total length ranged from 12 yr to 19 yr and from 133 cm to 204 cm and in females from 14 yr to 36 yr and from 197 cm to 254 cm. The majority of males were 13–16 yr old, and females were 16–20 yr old. Some females had residual atretic ovarian bodies, presumably remaining from a previous spawning and indicating iteroparity. Pre-ovulatory condition was recognized by migration of the germinal vesicle or by germinal vesicle breakdown and by significantly elevated plasma gonadotropins, progesterone, and vitellogenin. All pre-ovulatory females were captured upriver from Hudson River kilometer 136. Individual fecundity ranged from 0.4 million to 2.0 million eggs and oocyte diameter from 2.4 mm to 2.9 mm, and both characters exhibited a significant (p<0.05) positive relationship with female body size. Iteroparous females, tentatively identified by the presence of atretic bodies remaining in the ovary from a previous spawning, had significantly (p<0.05) higher fecundity and produced larger eggs, compared with females spawning presumably for the first time. 相似文献
5.
Dennis T. Logan 《Estuaries and Coasts》1985,8(1):28-38
Although density-dependent growth and mortality are understood to play a large role in regulating populations of some young fish, many investigators report associations between striped bass population fluctuations and environmental variation, not density. One explanation is that mortality is primarily determined by size, which responds through growth to environmental conditions. Mathematically relating mortality to inverse size explains several aspects of striped bass biology. Numerical decline of the 1975 Hudson River cohort is well predicted. Simulated year-class strength responds more strongly to changes in growth and length at hatch than to direct mortality of eggs. The effect of changes in length at hatch and growth, rate on subsequent population size decreases as fish grow. Small changes in temperature or food density early in life could cause the reported association of year-class strength and environmental variation. Disappearance of larvae from an early spawning in the Hudson River in 1976 is attributed to decreasing water temperature, which decreased growth rate. Increased mortality of young striped bass may also result from sublethal exposure to toxicants that decrease growth rate and size at hatch. The approach to modeling population dynamics developed here should be valid for other estuarine and marine species. 相似文献
6.
The tolerance of post yolk-sac American shad Alosa sapidissima larvae to salinities typically seen in estuaries was assessed experimentally. Sixteen-day-old Hudson River (experiment I) and 35-d-old Delaware River (experiment II) larvae were held for 8 d and 9 d respectively in low (0–1‰), medium (9–11‰), and highly (19–20‰) brackish water, and mortality and growth rates were measured. Growth rates did not vary significantly among salinity treatments. Mortality in experiment I did not vary significantly among salinity treatments however, in experiment II, mortality was zero at 10‰ but higher and statistically indistinguishable between 0‰ and 20‰ In experiment II relative condition increased with salinity. These results imply that estuarine salinities neither depress growth rates nor elevate mortality rates of larval American shad when compared with freshwater conditions. We conclude that ecological factors other than the physiological effects of salinity have played more important roles in the evolution of the upriver spawning and nursery preference shown by this species. 相似文献
7.
Physical and biological properties of the Chesapeake Bay estuarine turbidity maximum (ETM) region may influence retention and survival of anadromous white perch (Morone americana) and striped bass larvae (Morone saxatilis). To evaluate this hypothesis we collected data in five cruises, three during May 1998 and two during May 1999, in upper Chesapeake Bay. Time series of freshwater discharge, water temperature, wind, and water level explain differences in ETM location and properties between cruises and years. During high flows in 1998, a two-layer response to wind forcing shifted the ETM up-estuary, while a high discharge event resulted in a down-estuary shift in the salt front and ETM location. In 1999, extremely low discharge rates shifted the salt front 15 km up-estuary of its position in 1998. During 1999, the ETM was less intense and apparently topographically fixed. Gradients in depth-specific abundance of ichthyoplankton were compared with salinity and TSS concentrations along the channel axis of the upper Bay. During 1998, the high flow year, most striped bass eggs (75%) and most early-stage white perch larvae (80%) were located up-estuary of the salt front. In addition, most striped bass (91%) and white perch (67%) post-yolk-sac larvae were located within 10 km of maximum turbidity readings. Total abundance of white perch larvae was lower in 1999, a low freshwater flow year, than in 1998, a high flow year. In 1999, striped bass larvae were virtually absent. White perch (1977–1999) and striped bass (1968–1999) juvenile abundances were positively correlated with spring Susquehanna River discharge. The ETM regions is an important nursery area for white perch and striped bass larvae and life-history strategies of these species appear to insure transport to and within the ETM. We hypothesize that episodic wind and discharge events may modulate larval survival within years. Between years, differences in freshwater flow may influence striped bass and white perch survival and recruitment by controlling retention of egg and early-stage in the ETM region and by affecting the overlap of temperature/salinity zones preferred by later-stage larvae with elevated productivity in the ETM. 相似文献
8.
Each winter, populations of striped bass (Morone saxatilis) migrate north from the coastal mid-Atlantic region of the US to the coastal waters of New England. During this migration, striped bass spend significant time in estuaries and saltmarshes, presumably to forage. However, the extent to which saltmarsh productivity supports striped bass remains unresolved. We used a three-isotope Bayesian mixing model to determine the relative contribution of three primary producers [C4 saltmarsh cordgrass (Spartina spp.), phytoplankton, and benthic diatoms] to striped bass tissue. Phytoplankton (51 % contribution) and Spartina-derived sources (44 % contribution) are the primary sources of production to striped bass, while benthic diatoms made a relatively small contribution (5 %). Our results highlight the importance of saltmarshes to striped bass by showing that primary producers unique to saltmarsh ecosystems support a large proportion of striped bass production. 相似文献
9.
Oxygen consumption rates were measured individually for mixed groups of male, female, and immature striped bass,Morone saxatilis, in filtered Patuxent River, Maryland, water and in filtered water containing suspensions of either fuller’s earth or Patuxent River sediment. Oxygen consumption was determined at fixed swimming speeds at two temperatures, 15 and 22.5°C. Oxygen consumption of striped bass in filtered 15°C water increased as swimming speed increased. At 22.5°C, the same range of swimming speeds had no effect on rates of oxygen consumption. Similar data were obtained with fish swimming at the same speeds in water containing 0.79 g per liter fuller’s earth particles (15°C), and among those swimming at 31.7 and 49.0 cm per s in water containing 1.32 g per 1 Patuxent River sediment (22.5°C). Male and female striped bass respiration rates were similar under all test conditions. At 15°C, striped bass oxygen consumption rates during exposure to fuller’s earth while swimming at 8.6 and 31.7 cm per s did not differ from rates of fish swimming at the same speeds in filtered water. At 49.0 cm per s, rates were significantly depressed. Respiration rates of fish exposed to Patuxent River sediment at 22.5°C while swimming at 31.7 and 49.0 cm per s were significantly lower than those of fish in filtered water. Respiratory response of striped bass to suspended particle stress was manifested by depressed oxygen consumption. This is considered a short-term response to an acute stress. This response and the potential for hematological response to chronic suspended particle stress are discussed. 相似文献
10.
We developed categorical time-series regression models to evaluate the roles of lagged stock abundance history, hydrographic variability, and anthropogenic factors in controlling the variation in abundance of striped bass and American shad in the Potomac, Delaware, and Hudson rivers. These models can be used to evaluate directly the role of interactions of variates to produce greater than average recruitment to commercial fish stocks. Whereas hydrographic factors dominate striped bass dynamics in all three estuaries for the period 1929–1976 compared to the pollution variables tested (i.e., sewage loading, dissolved oxygen, and biological oxygen demand), American shad shows strong dependence on the anthropogenic factors compared to hydrographic variates in all three estuaries. 相似文献
11.
The estuarine turbidity maximum (ETM) is an important nursery area for anadromous fish where early-life stages can be retained
in high prey concentrations and favorable salinities. Episodic freshwater flow and wind events could influence the transport
of striped bass (Morone saxatilis) eggs to the ETM. This hypothesis was evaluated with regression analysis of observational data and with a coupled biological-physical
model of a semi-idealized upper Chesapeake Bay driven by observed wind and freshwater flow. A particle-tracking model was
constructed within a numerical circulation model (Princeton Ocean Model) to simulate the transport of fish eggs in a 3-dimensional
flow field. Particles with the sinking speed of striped bass eggs were released up-estuary of the salt front in both 2-d event-scale
and 60-d seasonal-scale scenarios. In event scenarios, egg-like particles with observed specific gravities (densities) of
striped bass eggs were transported to the optimum ETM nursery area after 2 d, the striped bass egg-stage duration. Wind events
and pulses in river discharge decreased the number of egg-like particles transported to the ETM area by 20.9% and 13.2%, respectively,
compared to nonevent conditions. In seasonal scenarios, particle delivery to the ETM depended upon the timing of the release
of egg-like particles. The number of particles transported to the ETM area decreased when particles were released before and
during wind and river pulse events. Particle delivery to the ETM area was enhanced when the salt front was moving up-estuary
after river pulse events and as base river flow receded over the spawning season. Model results suggest that the timing of
striped bass spawning in relation to pulsed events may have a negative (before or during events) or positive (after river
flow events) effect on egg transport. Spawning after river flow events may promote early-stage survival by taking advantage
of improved transport, enhanced turbidity refuge, and elevated prey production that may occur after river pulse events. In
multiple regression analysis of observed data, mean spring freshwater flow rates and the number of pulsed freshwater flow
events during the striped bass spawning season explained 71% of the variability in striped bass juvenile abundance in upper
Chesapeake Bay from 1986 to 2002. Positive parameter estimates for these effects support the hypothesis that pulsed freshwater
flow events, coupled with spawning after the events, may enhance striped bass early-stage survival. Results suggest that episodic
events may have an important role in controlling fish recruitment. 相似文献
12.
Alexandra Cartaxana 《Estuaries and Coasts》1994,17(3):685-694
Palaemon longirostris was sampled monthly at 12 sites in the Mira River estuary (southwest Portugal) from October 1990 to September 1991. Animals were counted, measured, and sexed. The estuarine distribution of prawns appeared to follow the salinity displacement, the animals being found at river stations during summer and autumn when saline encroachment up the estuary was greater. During winter and spring when freshwater input from the river was greatest, and thus moving the salinity gradient toward the mouth, the prawns migrated downstream to brackish areas. Ovigerous females were collected only from estuarine areas (January to August), suggesting that reproduction does not take place in freshwater habitats. Higher percentages of females than males were generally observed. Females, particularly ovigerous ones, were larger than males. 相似文献
13.
Deborah T. Westin 《Estuaries and Coasts》1978,1(2):126-128
Results of blood and serum analyses on striped bass,Morone saxatilis (Walbaum), adults taken during the 1975 spawning season on the Nanticoke River, Maryland, are reported. The range in values found were 16–70% for hematocrit, 4.0–12.3 g/100 ml for hemoglobin, 2.86–4.49×106/cc for erythrocyte count, 4.5–18.8 mg% for serum calcium, and 6.1–13.0 g/100 ml for plasma protein. These values are compared with others previously reported for adult bass. Serum chloride and serum protein values, ranging from 80 to 186 mEq/l and 3.92 to 8.32 g%, respectively, are reported for the first time for this species. Hemoglobin and hematocrit values for non-spawning, mature striped bass held in ambient sea water for a year fall within the reported ranges. Serum total protein values ranged from 2.36 to 6.14 g% and serum calcium values varied between 8.1 and 14.9 mg% from migratory adult striped bass. The possibility of sexing striped bass using serum calcium levels is discussed. Hematological values reported will help in defining the range encountered in healthy adults of this species. 相似文献
14.
John E. Cooper Roger A. Rulifson J. Jeffrey Isely Sara E. Winslow 《Estuaries and Coasts》1998,21(2):307-317
Juvenile striped bass,Morone saxatilis, collected in Albemarle Sound, North Carolina, during 1988–1992 were examined for food habits and growth. Ages estimated from otoliths collected in 1990–1992 were used to determine individual spawning dates and growth in total length and weight. The majority of striped bass examined had been spawned in mid-May 1990, mid-May to early June 1991, and June to early July 1992. Mysid shrimp was the dominant prey taxon and was consumed in all size classes examined. Mysid shrimp were consumed at twice the rate of copepods and 10 times more frequently than cladocerans. Fishes were a minor prey taxon. The number of mysid shrimp consumed increased with increasing length of striped bass. A higher percentage of mysid shrimp were consumed in the more saline waters of the central sound than in the less saline western sound. The opposite trend was found for consumed fishes. Increases in total length were linear from July to October, but increases in weight were not. Weight increased less rapidly in younger striped bass and more rapidly in older striped bass than either length or age. Quadratic and logarithmic equations accurately predicted weight from measures of total length but weight could not be predicted from age nor could age be predicted from total length. Estimating growth from total length at time of capture may be comparing fish of different ages. Age estimation from otoliths allowed us to determine that growth rates were similar among years and that differences in observed total length over time were due to different spawning times and not growth rates. 相似文献
15.
Five stations on the lower Saint John River, a complex multibasin estuary, were sampled semiquantitatively for zooplankton at biweekly intervals for one year, and qualitatively over a 4-year period. Planktonic Crustacea were dominated by the true estuarine copepods,Acartia tonsa andEurytemora affinis and the euryhaline marine copepodsOithona similis andPseudocalanus minutus. Atypical estuarine forms, confined to a lower fiord-like basin with salinity of 20‰, were the amphipod,Parathemisto abyssorum and the mysidErythrops erythrophthalma. River flows were highly variable from year to year. Certain basins function as lakes in some years and estuaries in other years, causing extreme zooplankton community fluctuations, and succession patterns dependent on salinity rather than season. On occasion freshwater zooplankters maintained viable populations at unusually high salinities (ca. 5‰). Vertical and horizontal distributions of zooplankters indicate that the estuary in fact comprises two systems: a true estuary in the upper reaches and the surface waters at the lower end, and a fiord in a subsidiary basin in the lower end. 相似文献
16.
While many studies of non-native species have examined either soft-bottom or hard-bottom marine communities, including artificial structures at docks and marinas, formal comparisons across these habitat types are rare. The number of non-indigenous species (NIS) may differ among habitats, due to differences in species delivery (trade history) and susceptibility to invasions. In this study, we quantitatively compared NIS to native species richness and distribution and examined community similarity across hard-bottom and soft-sediment habitats in San Francisco Bay, California (USA). Benthic invertebrates were sampled using settlement panels (hard-bottom habitats) and sediment grabs (soft-bottom habitats) in 13 paired sites, including eight in higher salinity areas and five in lower salinity areas during 2 years. Mean NIS richness was greatest in hard-bottom habitat at high salinity, being significantly higher than each (a) native species at high salinity and (b) NIS richness at low salinity. In contrast, mean NIS richness in soft-bottom communities was not significantly different from native species richness in either high- or low-salinity waters, nor was there a difference in NIS richness between salinities. For hard-bottom communities, NIS represented an average of 79% of total species richness per sample at high salinity and 78% at low salinity, whereas the comparable values for soft bottom were 46 and 60%, respectively. On average, NIS occurred at a significantly higher frequency (percent of samples) than native species for hard-bottom habitats at both salinities, but this was not the case for soft-bottom habitats. Finally, NIS contributed significantly to the existing community structure (dissimilarity) across habitat types and salinities. Our results show that NIS richness and occurrence frequency is highest in hard-bottom and high-salinity habitat for this Bay but also that NIS contribute strongly to species richness and community structure across each habitat evaluated. 相似文献
17.
Variable recruitments of striped bass were hypothesized to be caused by factors influencing growth and survival of larvae. Eggs and larvae were collected in the Potomac River from 1987 to 1989 and in the Upper Chesapeake Bay in 1988 and 1989 to estimate abundances, larval growth and survival rates, and environmental variability. Larval batch dates, ages, and growth and mortality rates were estimated from analysis of otolith daily increments. A retrospective analysis of Potomae River ichthyoplankton data from 1974–1977 and 1980–1982 provided additional estimates of larval abundances and vital rates for comparative purposes. Significant correlations betweens vital rates (growth and mortality) and abundances of striped bass larvae, and the Maryland juvenile recruitment index indicated that recruitment level may be fixed during the larval stage. The ratio of mean daily growth and mortality rates (G:Z) of larvae in the Potomac River for 1987–1989 was highest in 1987 when the juvenile index was relatively high, and was lower in 1988 and 1989 when juvenile indices were low. In the Upper Bay, mean larval growth rate, survival rate, and the G:Z ratio were highest in 1989 when the juvenile index also was high. In both tributaries, abundances of late-stage larvae (8 mm SL) were correlated with juvenile-stage recruitment indices. The retrospective analysis provided additional evidence that Potomac River larval abundances and G:Z ratios were positively correlated with juvenile recruitment indices in the 1974–1977 and 1980–1982 periods. Conditions favoring striped bass larval abundance and potential recruitment differed between the Potomac River and the Upper Bay. In the Potomac, late-stage larval abundances coincided with late-season water temperatures that were relatively warm, low river discharges and high, late-season densities of zooplankton prey, which favored larval growth. In the Upper Bay, the high abundance of late-stage larvae in 1989 relative to 1988 was attributed to a higher egg production that was coincident with high zooplankton abundances. 相似文献
18.
Salinity is an important determinant of estuarine faunal composition; previous studies, however, have indicated conflicting accounts of continuous vs. relatively rapid change in community structure at certain salinities from geographically distinct estuaries. This study uses a large fisheries monitoring database (n?>?5,000 samples) to explore evidence for estuarine salinity zonation by nekton in the lower St. Johns River estuary (LSJR). There was little evidence to support the presence of estuarine salinity zones except at the extremes of the salinity gradient (i.e., 0.1?C1.0 and 34?C39). The LSJR estuarine nekton community exhibits progressively slow ecological change throughout most of the salinity gradient with rapid change at the interfaces with fresh and marine waters??an ecoline bounded by ecotones. This study affirms the rapid change that occurs at the extremes of the salinity spectrum in certain estuaries and is relevant to efforts to manage surface water resources and estuarine ecosystems. Given the disparity in the results of the studies examining biological salinity zones in estuaries, it would be wise to have, at minimum, a regional understanding of how communities are structured along the gradient from freshwater to marine. 相似文献
19.
Xueyan Jiang Zhigang Yu Teh-Lung Ku Xinglun Kang Wei Wei Hongtao Chen 《Estuaries and Coasts》2007,30(6):919-926
The Yellow River (Huanghe) is the second largest river in China and is known for its high turbidity. It also has remarkably
high levels of dissolved uranium (U) concentrations (up to 38 nmol 1-1). To examine the mixing behavior of dissolved U between river water and seawater, surface water samples were collected along
a salinity gradient from the Yellow River plume during September 2004 and were measured for dissolved U concentration,234U:238U activity ratio, phosphate (PO4
3–), and suspended particulate matter. Laboratory experiments were also conducted to simulate the mixing process in the Yellow
River plume using unfiltered Yellow River water and filtered seawater. The results showed a nonconservative behavior for dissolved
U at salinities < 20 with an addition of U to the plume waters estimated at about 1.4 X 105 mol yr–1. A similarity between variations in dissolved U and PO4
3– with salinity was also found. There are two major mechanisms, desorption from suspended sediments and diffusion from interstitial
waters of bottom sediments, that may cause the elevated concentrations of dissolved U and PO4
3– in mid-salinity waters. Mixing experiments indicate that desorption seems more responsible for the elevated dissolved U concentrations,
whereas diffusion influences more the enrichment of PO4
3–. 相似文献
20.
Paul R. Jivoff Jennifer M. Smith Valerie L. Sodi Stacy M. VanMorter Kathryn M. Faugno Amy L. Werda Margaret J. Shaw 《Estuaries and Coasts》2017,40(1):235-250
Blue crabs (Callinectes sapidus) are an important species in coastal or lagoonal estuaries where adult population characteristics may differ as compared to drowned-river estuaries. Barnegat Bay, in southern New Jersey, is composed of two large embayments: one without and one with a salinity gradient. We tested the influence of physical characteristics on the abundance, sex ratio, and size of adult blue crabs and examined variation in measures of reproductive potential (e.g., sperm stores) in both sexes in Barnegat Bay from June to September, 2008–2009. Population structure was distinct between the embayments due to sex-specific responses to salinity: male abundance was negatively correlated with salinity whereas adult females were more abundant in high salinity because of proximity to Barnegat Inlet. This produced high sex ratios in low salinity areas and low sex ratios in high salinity areas. Summer was a growing season for adult males while in late summer-early fall, juvenile males recruited to the adult size class. The spawning season lasted from May to August and ovigerous females were concentrated near the inlets. Information on female sperm stores and ovarian development identified two cohorts of adult females: females that will spawn in the current summer and females that will not spawn until the following summer. Thus, not all adult females near the spawning grounds were members of the current spawning stock. This suggests that annual estimates of spawning stock size which overlook the proximity of females to spawning are overestimating the current spawning stock in Barnegat Bay and other estuaries. 相似文献