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At least 415 records · Page 23Linked to original sources
USGS1994

Differential predation by northern squawfish Ptychocheilus oregonensis on live and dead juvenile salmonids in the Bonneville Dam tailrace (Columbia River)

Juvenile salmonids ( Oncorhynchus spp.) that have been killed or injured during dam passage may be highly vulnerable or preferred prey of predators that aggregate below dams. Salmonid loss due to predation will be overestimated using gut content analysis if some prey were dead or moribund when consumed. To examine this issue, field experiments were conducted in the Bonneville Dam tailrace (Columbia River) to compare rates of capture of live and dead juvenile salmonids by northern squawfish ( Ptychocheilus oregonensis ). Known numbers of coded-wire-tagged live and dead chinook salmon ( O . tshawytscha ) were released into the tailrace on six nights. Northern squawfish were collected after each release and their gut contents were examined for tags. When 50% of salmon released were dead, northern squawfish consumed 62% dead salmon. When 10% of salmon released were dead, comparable with dam passage mortality, 22% of the tags found in northern squawfish digestive tracts were from dead salmon. These results indicate that predator feeding behavior and prey condition are important considerations when estimating the impact of predation on a prey population.

Oregon, Washington↗
USGS1994

Cadmium, metal-binding proteins, and growth in bluegill ( Lepomis macrochirus</I.) exposed to contaminated sediments from the upper Mississippi River basin

We exposed juvenile bluegill ( Lepomis macrochirus ) to ~1000 mg∙L −1 of continuously suspended river sediment in a 28-d test with six treatments (randomized block with one sediment-free control and five sediments ranging from 1.3 to 21.4 μg Cd∙g dry weight −1 ). Each treatment had three replicates, each with 25 fish. Growth was reduced by exposure to suspended sediment, probably due to physical effects of sediment on feeding and to toxicity in the treatment with the greatest concentrations of metals. Mean whole-body concentrations of cadmium (0.04–0.14 μg∙g wet weight −1 ) were correlated with cadmium concentration in filtered water (8–72 ng∙L −1 ), suspended sediment (0.61–16.8 μg∙L −1 ), and bulk sediment. The concentration of hepatic nonthionein cytosolic cadmium (cadmium not bound by metal-binding proteins, MBP) in fish exposed to the two most contaminated sediments exceeded that in controls. The mean concentration of hepatic MBP was correlated with cadmium concentration in filtered water, suspended sediment, bulk sediment, and whole fish. Whole-body cadmium concentration was the most sensitive indicator of cadmium exposure, with lowest observed effect concentrations of 1.9 μg Cd∙L −1 for suspended sediment and 13 ng Cd∙L −1 for filtered water. Sediment-associated cadmium was less available than waterborne cadmium for uptake by fish.

Mississippi River Basin↗
USGS1994

Dramatic decline of unionid bivalves in offshore waters of western Lake Erie after infestation by the zebra mussel, Dreissena polymorpha

Unionid bivalves and attached epizoic zebra mussels ( Dreissena polymorpha ) were collected at one index station in 1989, 1990, and 1991 and at 17 stations in 1991 in offshore waters of western Lake Erie of the Laurentian Great Lakes. Sampling at the index station revealed that the proportion of live unionids declined from 53% in September 1989 to 17% in May&ndash;June 1990 and to 0% in September 1990: this 100% mortality coincided with heavy infestation by zebra mussels. Quantitative sampling with a Ponar grab at the 17 stations in 1991 revealed a widespread and dramatic reduction in unionid populations. In 1982, five unionid species occurred at 35% of the stations at a density of 4/m 2 , whereas in 1991, no live unionid species were found. Qualitative sampling with an epibenthic sled at the 17 stations in 1991 yielded only 4 live specimens of 2 species ( Amblema plicata plicata and Fusconaia flava ) and 187 dead specimens of 10 species. These and other results indicate that unionid populations are being negatively affected by zebra mussels in the Great Lakes. Similar impacts on unionids are expected to occur where zebra mussels become abundant throughout North America.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1994

Variation in mitochondrial DNA and allozymes discriminates early and late forms of Chinook salmon Oncorhynchus tshawytscha in the Kenai and Kasilof Rivers, AK

Genetic differences between early and late forms of Alaskan chinook salmon ( Oncorhynchus tshawytscha ) were identified using two genetic approaches: mitochondrial DNA (mtDNA) analysis, and protein electrophoresis. Study populations consisted of early and late runs in each of the Kenai and Kasilof rivers in Alaska, and a population from the Minam River, Oregon. Two segments of mtDNA were amplified using the polymerase chain reaction (PCR) and digested with 14–16 restriction enzymes. Results showed that early runs were genetically similar to each other but different from the late runs. The late runs were different from each other based on the frequency of the common haplotypes. Frequency differences in shared haplotypes together with the presence of a unique haplotype separated the Minam River stock from those in Alaska. In the protein analysis, each population was examined at 30 allozyme loci. Based on 14 polymorphic loci, Minam River salmon were genetically distinct from the Alaskan populations. Within the Alaskan populations, early runs were most similar to each other but different from the late runs; the late runs were also genetically most similar to each other. Both mtDNA and allozyme analysis suggest that chinook salmon may segregate into genetically different early and late forms within a drainage.

Alaska↗
USGS1995

Evidence of autumn nitrogen limitation and contribution of picoplankton to carbon fixation in Lake Tahoe

Water samples were collected from Lake Tahoe at midlake and nearshore stations at three depths (25, 50, and 75 m, corresponding to light intensities of approximately 10, 1, and 0.1% of surface light) in May and September. The water samples were evaluated to decide the following: (1) whether carbon fixation was N-limited and whether there were differences between picoplankton and larger phytoplankters and (2) the relative importance of picoplankton carbon fixation and related photosynthetic parameters. Evidence of N-limitation was observed only in September at the midlake station for the populations at 50 and 75 m, and to a lesser extent at the nearshore station at 75 m, but only for the nanoplankton fraction. The contribution of picoplankton to total carbon fixation ranged from 34 to 69% and did not increase with depth. Low values for I k , the photoadaptation parameter, for deep water populations (0.1% light level) in September, but not May, suggested that these populations were adapted to low light in the fall but not the spring.

California, Nevada↗
USGS1995

Removal of algae by the zebra mussel ( Dreissena polymorpha ) population in western Lake Erie: a bioenergetics approach

A bioenergetics model for growth of a zebra mussel ( Dreissena polymorpha ) individual was verified with observations on zebra mussel growth in western Lake Erie. The bioenergetics model was then applied to the zebra mussel population in the western basin of Lake Erie to estimate the removal of phytoplankton by mussels. According to the modeling results, the zebra mussel population consumed 5.0 million tonnes of phytoplankton, while 1.4 million tonnes of phytoplankton was deposited in pseudofeces from the mussels. Thus, a total of 6.4&ensp;&plusmn;&ensp;2.4 million tonnes of phytoplankton was removed from the water column by zebra mussel in western Lake Erie during 1990. Primary production was estimated to be 24.8 million tonnes; therefore, zebra mussel removed the equivalent of 26&ensp;&plusmn;&ensp;10% of the primary production for western Lake Erie.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1995

Planktivory by alewife ( Alosa pseudoharengus ) and rainbow smelt ( Osmerus mordax ) on microcrustacean zooplankton and dreissenid (Bivalvia: Dreissenidae) veligers in southern Lake Ontario

The objective of this study was to describe the diet of young-of-the-year and adult alewife ( Alosa pseudoharengus ) and rainbow smelt ( Osmerus mordax ) in nearshore waters coincident with the colonization of Lake Ontario by Dreissena . Laboratory experiments and field observations indicated that alewife and rainbow smelt consumed dreissenid veligers and that the veligers remained intact and identifiable in the digestive tract for several hours. Dreissenid larvae were found in field-caught alewife and rainbow smelt in August 1992, even though veliger densities were low (<0.1/L). Zooplankton dominated the diet of all fish and veliger larvae were <0.1% of the biomass of prey eaten by these fish. Density of veligers and the distribution of settled dreissenids declined from west to east along the south shore of Lake Ontario. Based on veliger consumption rates we measured and the abundance of veligers and planktivores, we conclude that planktivory by alewife and smelt in the nearshore waters of Lake Ontario did not substantially reduce the number of veligers during 1991&ndash;1993. However, our results indicate that if the density of veligers in Lake Ontario decreases, and if planktivores remain abundant, planktivory on veliger populations could be significant.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1995

Estimating number of species and relative abundances in stream-fish communities: effects of sampling effort and discontinuous spatial distributions

We sampled fishes and measured microhabitat in series of contiguous habitat units (riffles, runs, pools) in three Virginia streams. We used Monte Carlo simulations to construct hypothetical series of habitat units, then examined how number of species, similarity in relative abundances, and number of microhabitats accumulated with increasing number of habitat units (i.e., sampling effort). Proportions of all species and microhabitats represented were relatively low and variable at low sampling effort, but increased asymptotically and became less variable with greater sampling effort. To facilitate comparisons among streams, we fitted simulation results to negative exponential curves. The curves indicated that 90% of the species present were usually found by sampling 5 to 14 habitat units (stream length of 22&ndash;67 stream widths). Estimates of species relative abundances required less sampling effort for a given accuracy than estimates of number of species. Rates of species accumulation (with effort) varied among streams and reflected discontinuity in species distributions among habitat units. Most discontinuity seemed to be due to low population density rather than to habitat selectivity. Results from an Illinois stream corroborated our findings from Virginia, and suggested that greater sampling effort is needed to characterize fish community structure in more homogeneous stream reaches.

Virginia↗
USGS1995

Distribution of phytobenthos in the Yakima River basin, Washington, in relation to geology, land use and other environmental factors

Benthic-algal distributions in the Yakima River, Washington, basin were, examined in relation to geology, land use, water chemistry, and stream habitat using indicator-species classification ( TWINSPAN ) and canonical correspondence analysis (CCA). Algal assemblages identified by TWINSPAN were each associated with a narrow range of water-quality conditions. In the Cascade geologic province, where timber harvest and grazing are the dominant land uses, differences in community structure (CCA site scores) and concentrations of major ions (Ca and Mg) and nutrients (solute P, SiO 2 and inorganic N) varied with dominant rock type of the basin. In agricultural areas of the Columbia Plateau province, differences in phytobenthos structure were based primarily on the degree of enrichment of dissolved solids, inorganic N, and solute P from irrigation-return flows and subsurface drainage. Habitat characteristics strongly correlated with community structure included reach altitude, turbidity, substratum embeddedness (Columbia Plateau), large woody-debris density (Cascade Range), and composition and density of the riparian vegetation. Algal biomass (AFDM) correlated with composition and density of the riparian vegetation but not with measured chemical-constituent concentrations. Nitrogen limitation in streams of the Cascade Range favored nitrogen-fixing blue-green algae and diatoms with endosymbiotic blue-greens, whereas nitrogen heterotrophs were abundant in agricultural areas of the Columbia Plateau.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1995

Population viability of the Snake River chinook salmon (Oncorhynchus tshawytscha)

In the presence of historical data, population viability models of intermediate complexity can be parameterized and utilized to project the consequences of various management actions for endangered species. A general stochastic population dynamics model with density feedback, age structure, and autocorrelated environmental fluctuations was constructed and parameterized for best fit over 36 years of spring chinook salmon ( Oncorhynchus tshawytscha ) redd count data in five Idaho index streams. Simulations indicate that persistence of the Snake River spring chinook salmon population depends primarily on density-independent mortality. Improvement of rearing habitat, predator control, reduced fishing pressure, and improved dam passage all would alleviate density-independent mortality. The current value of the Ricker α should provide for a continuation of the status quo. A recovery of the population to 1957–1961 levels within 100 years would require an approximately 75% increase in survival and (or) fecundity. Manipulations of the Ricker β are likely to have little or no effect on persistence versus extinction, but considerable influence on population size.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1995

Effect of lake-wide planktivory by the pelagic prey fish community in Lakes Michigan and Ontario

We compared predatory demand by pelagic planktivorous prey fish with invertebrate production in Lake Michigan during 1987 and in Lake Ontario during 1990. Predation by the planktivores in Lake Ontario was nearly fourfold higher than in Lake Michigan (approx. 87&ensp;g wet weight∙m &minus;2 ∙year &minus;1 ). Predation rates on Mysis were comparable in Lakes Michigan and Ontario (approx. 21&ensp;g∙m &minus;2 ∙year &minus;1 ), while predation on Diporeia was markedly higher in Lake Michigan than in Lake Ontario (21.3&ensp;vs. 8.5&ensp;g wet weight∙m &minus;2 ∙year &minus;1 ). In Lake Ontario, predatory demand on zooplankton exceeded our best estimate of production by a factor of 1.7. Similarly, predation estimates on Mysis in Lake Ontario were 1.2&ndash;2.0 times the estimated rate of production, depending on the production model used. Lake Michigan planktivores consumed approximately 55% of available zooplankton production in 1987, indicating that competition for prey resources, if operating, was not as intense as that in Lake Ontario in 1990. It is unclear how to resolve the paradox that predation could markedly exceed available prey production in some cases. There could be sources of error in the estimates of both the supply and demand sides of these trophic relationships.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1996

Comparison of mercury concentrations in liver, muscle, whole bodies, and composites of fish from the Red River of the North

Carp ( Cyprinus carpio ) from four sites and channel catfish ( Ictalurus punctatus ) from one site in the Red River of the North in 1994 were analyzed for total mercury content. In carp, mercury concentrations differed among liver, muscle, and whole bodies (0.11, 0.31, and 0.18 &micro;g/g wet weight, respectively), between large and small size groups, but not location. Mercury distribution in channel catfish tissues differed from that in carp. Liver and muscle tissue had similar mean concentrations; each was higher than whole-body concentrations (0.16, 0.18, and 0.11 &micro;g/g, respectively). Mercury concentrations were not significantly different between the two size groups of channel catfish. Weighted-mean mercury concentrations from seven individual fish agreed closely (usually within 10%) with concentrations determined on physical composites of the same fish. The ratio of mercury in whole bodies to mercury in muscle was similar for both carp and channel catfish. Historical data indicate that this ratio may be applicable to other species and locations. The ratio of mercury in livers to whole bodies and muscle differed between carp and channel catfish, which may reflect physiological differences between different trophic groups.

Minnesota, North Dakota, South Dakota↗
USGS1995

Effect of predation by Sacramento squawfish (Ptychocheilus grandis) on habitat choice of California roach (Lavinia symmetricus) and rainbow trout (Oncorhynchus mykiss) in artificial streams

We studied the effects of predatory Sacramento squawfish ( Ptychocheilus grandis ) on habitat choice of juvenile California roach ( Lavinia symmetricus ), adult roach, and juvenile rainbow trout ( Oncorhynchus mykiss ) in artificial streams. In single-prey trials, the proportion of fish found in pool habitat declined in the presence of squawfish for juvenile roach (from 0.55 to 0.00), adult roach (from 0.88 to 0.13), and juvenile rainbow trout (0.70 to 0.15). The presence of squawfish did not affect the use of riffle and edge habitats. Of the fish found in shallow water, the proportion found in edge habitat declined from juvenile roach (0.95) to adult roach (0.80) to juvenile rainbow trout (0.23). We also conducted experiments designed to simulate invasion of an area by squawfish, in which adult roach and juvenile rainbow trout were tested together in the presence and absence of squawfish. The proportion of prey in pool habitat in the presence of squawfish was greater in the two-prey trials than in the single-prey trials for both adult roach (0.31 and 0.13, respectively) and juvenile rainbow trout (0.33 and 0.15, respectively). These results support field evidence that squawfish are an important force in determining the spatial structure of native stream fish assemblages.

California↗
USGS1995

Metals-contaminated benthic invertebrates in the Clark Fork River, Montana: Effects on age-0 brown trout and rainbow trout

Benthic organisms in the upper Clark Fork River have recently been implicated as a dietary source of metals that may be a chronic problem for young-of-the-year rainbow trout ( Oncorhynchus mykiss ). In this present study, early life stage brown trout ( Salmo trutta ) and rainbow trout were exposed for 88&ensp;d to simulated Clark Fork River water and a diet of benthic invertebrates collected from the river. These exposures resulted in reduced growth and elevated levels of metals in the whole body of both species. Concentrations of As, Cd, Cu, and Pb increased in whole brown trout; in rainbow trout, As and Cd increased in whole fish, and As also increased in liver. Brown trout on the metals-contaminated diets exhibited constipation, gut impaction, increased cell membrane damage (lipid peroxidation), decreased digestive enzyme production (zymogen), and a sloughing of intestinal mucosal epithelial cells. Rainbow trout fed the contaminated diets exhibited constipation and reduced feeding activity. We believe that the reduced standing crop of trout in the Clark Fork River results partly from chronic effects of metals contamination in benthic invertebrates that are important as food for young-of-the-year fish.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1995

Brown trout avoidance of metals in water characteristic of the Clark Fork River, Montana

The avoidance response of brown trout ( Salmo trutta ) to mixtures of cadmium, copper, lead, and zinc was determined in water simulating the Clark Fork River, Montana. Effects of acidification on the avoidance response were also evaluated. Tests were conducted in a cylindrical chamber that received reference water at one end and metal-contaminated water at the other; a distinct boundary formed at the center where the chamber drained. A 1 &times; mixture of the four metals (Cd, 1.1&ensp;&mu;g/L; Cu, 12&ensp;&mu;g/L; Pb, 3.2&ensp;&mu;g/L; and Zn, 55&ensp;&mu;g/L) that was representative of the ambient metals concentrations of the Clark Fork River resulted in avoidance by brown trout. Brown trout also avoided 0.5&times;, 2&times;, 4&times;, and 10&times; mixtures but not a 0.1 &times; mixture. A reduction in pH from 8.0 to either 7.0, 6.0, or 5.0 resulted in significant avoidance. Avoidance reactions to metals, similar to those observed in our laboratory experiments, may contribute to the depression of brown trout populations in the Clark Fork River.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1996

Uptake, tissue distribution, and metabolism of malachite green in the channel catfish (Ictalurus punctatus)

The disposition of malachite green was determined in channel catfish ( Ictalurus punctatus ) after intravascular dosing (0.8 mg . Kg -1 ) or waterborne exposure (0.8 mg . L -1 for 1 h). After intravascular dosing, mean plasma concentrations of the parent compound exhibited a triphasic decline with a terminal elimination half-life of 6.2 h. Malachite green was rapidly absorbed and concentrated in the tissues during waterborne exposure. The rate of accumulation was directly related to pH of the exposure water. After waterborne exposure, elimination of the parent compound from plasma also was triphasic with a terminal half-life of 4.7 h. In muscle, the half-life of the parent compound was approximately 67 h. Malachite green and its metabolites were widely distributed in all tissues. In fish exposed to C-14-labeled malachite green, total drug equivalent concentrations were highest in abdominal fat and lowest in plasma. Malachite green was rapidly and extensively metabolized to its reduced form, leucomalachite green, which was slowly eliminated from the tissues. Leucomalachite green is an appropriate target analyte for monitoring exposure of channel catfish to this drug.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1996

Predation by sea lamprey (Petromyzon marinus) on lake trout (Salvelinus namaycush) in southern Lake Ontario, 1982-1992

Dead lake trout ( Salvelinus namaycush ) killed by sea lamprey (P etromyzon marinus ) were collected from the bottom of Lake Ontario using bottom trawls. The number of dead lake trout per hectare could be predicted from the number of type A-1 sea lamprey marks observed on live fish in September gillnet surveys ( r 2 = 0.60, P < 0.01) but not from the sum of marks of types A-1, A-2, and A-3 combined. Sea lamprey selectively attacked and killed the largest lake trout. The lengths and ages of live fish with A-1 marks increased as the population of longer, older lake trout in the lake increased, and the length distributions of fish killed by sea lamprey were not different ( P > 0.05) from those of live fish with A-1 marks in 5 of 6 years where comparisons could be made. Compared with Lake Superior strain lake trout, Seneca Lake strain fish were only 0.41 times as likely to be attacked by sea lamprey and were less likely to die from an attack (both differences P < 0.05). Conservative estimates of the numbers of lake trout killed by sea lamprey in southern Lake Ontario from October to mid-November ranged from 17,000 in 1988 to 121,000 in 1984.

New York, Ontario↗