The Experts below are selected from a list of 168 Experts worldwide ranked by ideXlab platform
Alan G. Heath - One of the best experts on this subject based on the ideXlab platform.
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An in situ study of rock bass (Ambloplites rupestris) physiology: effect of season and mercury contamination
Hydrobiologia, 1993Co-Authors: Joseph R. Bidwell, Alan G. HeathAbstract:Selected physiological and biochemical variables were examined in rock bass, Ambloplites rupestris, which were collected on five different sampling dates from an area of chronic mercury contamination and a reference site on the South River, Virginia.
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An in situ study of rock bass (Ambloplites rupestris) physiology: effect of season and mercury contamination
Hydrobiologia, 1993Co-Authors: Joseph R. Bidwell, Alan G. HeathAbstract:Selected physiological and biochemical variables were examined in rock bass, Ambloplites rupestris , which were collected on five different sampling dates from an area of chronic mercury contamination and a reference site on the South River, Virginia. The onset of spawning represented the most significant seasonal influence in the physiological profile of the fish, with elevations in hematocrit, hemoglobin, plasma protein, and plasma glucose. Sex-related differences in plasma calcium, liver glycogen and liver ascorbic acid were also unique to the period. Female rock bass had significantly higher levels of liver glutathione than did males on all but one of the sampling dates, although the cause of this difference is not clear. Rock bass from the mercury contaminated site had an average muscle mercury concentration of 1.37 mg Hg g^−1, and an average liver mercury concentration of 2.86 mg Hg g^−1. These levels were approximately an order of magnitude greater than those found in the tissues of the reference fish which averaged 0.165 and 0.101 mg Hg g^−1 in muscle and liver respectively. In July 1987, mercury concentrations in the liver of both reference and contaminated fish increased significantly, possibly the result of greater uptake of the metal through increased feeding or changes in the mercury level of selected prey items. Rock bass collected from the two sites in July also had significantly different levels of liver glutathione: reference fish exhibited an elevation and contaminated fish a depression. When fish from the two sampling stations received a 96-hr exposure to 150 µg HgCl_2 in the laboratory, both groups exhibited elevated liver mercury and decreased liver glutathione. Mercury levels in the gall bladders of the exposed fish were also elevated, suggesting that glutathione may have been lost through excretion with the metal in the bile. On the whole, physiological differences between the two groups of rock bass were limited, indicating that exposure to the mercury is not having a significant impact on the rock bass from the contaminated area. This is further supported by field examination of the fish and comparison of condition indices from rock bass previously taken from the same two stations. Those factors which significantly altered the physiology of the rock bass were unique to certain times of the year, indicating that the most appropriate sampling approach in future studies is one which examines a number of variables over a range of environmental conditions.
Joseph R. Bidwell - One of the best experts on this subject based on the ideXlab platform.
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An in situ study of rock bass (Ambloplites rupestris) physiology: effect of season and mercury contamination
Hydrobiologia, 1993Co-Authors: Joseph R. Bidwell, Alan G. HeathAbstract:Selected physiological and biochemical variables were examined in rock bass, Ambloplites rupestris, which were collected on five different sampling dates from an area of chronic mercury contamination and a reference site on the South River, Virginia.
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An in situ study of rock bass (Ambloplites rupestris) physiology: effect of season and mercury contamination
Hydrobiologia, 1993Co-Authors: Joseph R. Bidwell, Alan G. HeathAbstract:Selected physiological and biochemical variables were examined in rock bass, Ambloplites rupestris , which were collected on five different sampling dates from an area of chronic mercury contamination and a reference site on the South River, Virginia. The onset of spawning represented the most significant seasonal influence in the physiological profile of the fish, with elevations in hematocrit, hemoglobin, plasma protein, and plasma glucose. Sex-related differences in plasma calcium, liver glycogen and liver ascorbic acid were also unique to the period. Female rock bass had significantly higher levels of liver glutathione than did males on all but one of the sampling dates, although the cause of this difference is not clear. Rock bass from the mercury contaminated site had an average muscle mercury concentration of 1.37 mg Hg g^−1, and an average liver mercury concentration of 2.86 mg Hg g^−1. These levels were approximately an order of magnitude greater than those found in the tissues of the reference fish which averaged 0.165 and 0.101 mg Hg g^−1 in muscle and liver respectively. In July 1987, mercury concentrations in the liver of both reference and contaminated fish increased significantly, possibly the result of greater uptake of the metal through increased feeding or changes in the mercury level of selected prey items. Rock bass collected from the two sites in July also had significantly different levels of liver glutathione: reference fish exhibited an elevation and contaminated fish a depression. When fish from the two sampling stations received a 96-hr exposure to 150 µg HgCl_2 in the laboratory, both groups exhibited elevated liver mercury and decreased liver glutathione. Mercury levels in the gall bladders of the exposed fish were also elevated, suggesting that glutathione may have been lost through excretion with the metal in the bile. On the whole, physiological differences between the two groups of rock bass were limited, indicating that exposure to the mercury is not having a significant impact on the rock bass from the contaminated area. This is further supported by field examination of the fish and comparison of condition indices from rock bass previously taken from the same two stations. Those factors which significantly altered the physiology of the rock bass were unique to certain times of the year, indicating that the most appropriate sampling approach in future studies is one which examines a number of variables over a range of environmental conditions.
Cohen, Bryan J. - One of the best experts on this subject based on the ideXlab platform.
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Helminths in Yellow Perch (Perca flavescens) and Rock Bass (Ambloplites rupestris) in Northern Michigan: A comparative study.
2006Co-Authors: Cohen, Bryan J.Abstract:In 1940 at the University of Michigan Biological Station, records began for specimens that had been dissected in the lab, reporting helminths that were found in each specimen. In this study, we compare helmints of yellow perch (Perca flavescens) and rock bass (Ambloplites rupestris) from 2006 to helminths of the same species from 1940-1942. Specimens from 2006 were compared to determine how length and weight of host affect level of parasitism in these species. Parasites of Perca flavescens were significant for length (p0.05). Parasites of Ambloplites rupestris were not significant for length, weight, life stage, or sex of the host (p>0.05). Perca flavescens had significantly more helminths than A. rupestris (p
Michael G. Fox - One of the best experts on this subject based on the ideXlab platform.
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Morphological change and phenotypic plasticity in response to water velocity in three species of Centrarchidae
Canadian Journal of Zoology, 2015Co-Authors: Ashley E. Istead, Stan Yavno, Michael G. FoxAbstract:Morphological responses to flowing water have been documented in many fishes, but rarely reported in species with gibbose body types, despite their use of riffles in rivers and streams. In this study, we compared morphological responses to water flow in three gibbose centrarchids: bluegill (Lepomis macrochirus Rafinesque, 1819), pumpkinseed (Lepomis gibbosus (L., 1758)), and rock bass (Ambloplites rupestris (Rafinesque, 1817)). Flow-through plexiglass units, set to either a sustained flow or static conditions, were used to rear juveniles from each species for an 80-day period. All three species developed more streamlined body forms, longer and thinner caudal peduncles, and longer pectoral fins when reared in sustained current. Pumpkinseed exhibited the highest level of phenotypic plasticity in response to water flow, followed closely by bluegill; rock bass was the least plastic species. Rock bass developed longer predorsal and prepectoral lengths, which differ from the morphological changes observed in bl...
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Morphological variation between lake‐ and stream‐dwelling rock bass and pumpkinseed populations
Journal of Fish Biology, 2002Co-Authors: J. Brinsmead, Michael G. FoxAbstract:Pumpkinseed Lepomis gibbosus and rock bass Ambloplites rupestris stream populations of both sexes were significantly different in external morphology from lake populations in a central Ontario, Canada, watershed. The predictions that stream fishes would be more slender-bodied, and have a more anterior placement of lateral fins than lake fishes were generally supported. The prediction that stream fishes would have a more robust caudal peduncle was partially supported. The prediction that fin size would be larger in stream fishes was not supported, as lake rock bass generally had longer and wider fins than those from stream sites. The results suggest that in some species, smaller fins may be favoured in stream-dwelling individuals because the reduction of drag during swimming more than compensates for their reduced power and propulsion efficiency in a current. Smaller fin size in stream-dwelling centrarchids may be related to their body shape, or to their low usage of fast-moving water within the streams they inhabit.
Charles F. Rabeni - One of the best experts on this subject based on the ideXlab platform.
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Distinguishing centrarchid genera by use of lateral line scales
North American Journal of Fisheries Management, 2007Co-Authors: Nathan M. Roberts, Charles F. Rabeni, John S. StanovickAbstract:Abstract Predator–prey relations involving fishes are often evaluated using scales remaining in gut contents or feces. While several reliable keys help identify North American freshwater fish scales to the family level, none attempt to separate the family Centrarchidae to the genus level. Centrarchidae is of particular concern in the midwestern United States because it contains several popular sport fishes, such as smallmouth bass Micropterus dolomieu, largemouth bass M. salmoides, and rock bass Ambloplites rupestris, as well as less-sought-after species of sunfishes Lepomis spp. and crappies Pomoxis spp. Differentiating sport fish from non-sport fish has important management implications. Morphological characteristics of lateral line scales (n = 1,581) from known centrarchid fishes were analyzed. The variability of measurements within and between genera was examined to select variables that were the most useful in further classifying unknown centrarchid scales. A linear discriminant analysis model was de...
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Climate response among growth increments of fish and trees
Oecologia, 1995Co-Authors: Richard P. Guyette, Charles F. RabeniAbstract:Significant correlations were found among the annual growth increments of stream fish, trees, and climate variables in the Ozark region of the United States. The variation in annual growth increments of rock bass ( Ambloplites rupestris ) from the Jacks Fork River was significantly correlated over 22 years with the ring width of four tree species: white oak ( Quercus alba ), post oak ( Quercus stellata ), shortleaf pine ( Pinus echinata ) and eastern red cedar ( Juniperus virginiana ). Rock bass growth and tree growth were both significantly correlated with July rainfall and stream discharge. Variations in annual growth of smallmouth bass ( Micropterus dolomieu ) from four streams were significantly correlated over 29 years (1939–1968) with mean May maximum air temperature but not with tree growth. The magnitude and significance of correlations among growth increments from fish and trees imply that conditions such as topography, stream gradient, organism age, and the distribution of a population relative to its geographic range can influence the climatic response of an organism. The timing and intensity of climatic variables may produce different responses among closely related species.