摘要:

A cadmium-saturation technique for quantifying metallothionein (MT) in mammalian tissues was evaluated for use in fish tissue. We administered 3 mg109cadmium/kg body weight by intraperitoneal injection over a 5-d period to adult brook trout Salvelinus fontinalis to induce MT in liver and kidney tissues. The cadmium-saturation technique was modified so the amount of cadmium bound to unsaturated and cadmium-saturated MT could be measured. The method gave precise measurements of MT concentrations when aliquots of liver supernatant, which were analyzed separately, were quantified by atomic absorption or radiometric measurements. Two to four times more cadmium and MT concentrated in the liver of treated fish than in the kidney. Intraperitoneal administration of cadmium completely displaced copper and zinc from MT in liver of treated fish; cadmium concentrations in liver determined by the quantitation of cadmium-saturated MT and of unsaturated MT were identical. However, exposure of brook trout to cadmium in water did not result in the complete saturation of MT with cadmium. Concentrations of MT and mortality were significantly increased in fish exposed to 5 μg Cd/L or more for 30 d.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1987)116<541:CTFMMI>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A modification of an established technique for quantifying metallothionein (MT) in mammals was used to evaluate the toxicological importance of MT as a biological indicator of stress from chronic cadmium toxicity in brook trout Salvelinus fontinalis. In a 30-d study, fish mortality was significantly increased but growth was not altered by exposure to 3.6 μg Cd/L or more. After chronic exposure to cadmium, both mortality and whole-body residues showed a dose-response relation over the exposure range of 3.6 to 60.6 μg Cd/L. Concentrations of MT were increased significantly in all exposures that resulted in significant mortality; however, they showed no dose-response relation to cadmium exposure, nor were they correlated with mortality or whole-body cadmium residues. Consequently, measurement of MT alone was not a useful indicator of cadmium toxicity in brook trout. A better biological indicator was the amount of free cadmium in liver tissue. Free cadmium (the difference between the amount of cadmium in the supernatant resulting from centrifugation at 100,000 x gravity and the amount bound to MT in an unsaturated condition) showed a dose-dependent increase with increasing cadmium exposure and was highly correlated with mortality and whole-body residues. Free cadmium concentrations were significantly elevated in all exposures to 3.6 μg Cd/L or greater. The presence of free cadmium in tissues of brook trout from all exposures suggests that MT was not saturated with cadmium before the appearance of pathological effects and thus conflicts with the “spillover” hypothesis. As judged by the results of our toxicity studies, the spillover hypothesis should be redefined as a continuum of toxic responses to varying balances between the relative abundance of metals present and their respective binding affinities for MT.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1987)116<551:EOMMAA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

We measured the sensitivity of eggs and yolk-sac larvae of blueback herring Alosa aestivalis to acid and aluminum pulses in moderately soft fresh water (23–25 mg/L, hardness as CaCO3) during 96-h experiments in the laboratory. Over a 3-h period, pH was reduced from 7.4–7.7 to 5.5–5.6, coincident with an increase in aluminum from 0 to 0.10, 0.15, 0.20, or 0.25 mg/L. These pH-aluminum conditions were maintained for five single-pulse durations (0.5, 4, 8, 12, 24 h) and then gradually returned to control conditions within 8–10 h. Relatively mature embryos (20–24 h postfertilization, early tail-bud stage) were more tolerant than larvae to all treatments. Eggs exposed to a 24-h pulse of pH 5.5–5.6 and 0.20 mg/L total aluminum (predicted total monomeric aluminum, 0.09 mg/L) experienced the highest mortality observed for this life stage, 48%. Larvae tolerated single pulses of pH 5.5–5.6 (without aluminum) for up to 12 h, but mortality doubled (25% to 49%) when pulse duration doubled (12 h to 24 h). Pulses of 0.10–0.15 mg/L total aluminum (predicted total monomeric aluminum, 0.05–0.07 mg/L) coincident with acid pulses of pH 5.5–5.6 increased larval mortality from 19% after a 4-h pulse to 66% after an 8-h pulse to 98 and 100% after 12- and 24-h pulses, respectively. Our results suggest that acidic episodes (or spates) and associated mobilization of inorganic aluminum in coastal plain tributaries of Chesapeake Bay during spring rain storms may be an important source of early life stage mortality for blueback herring populations that spawn in these poorly buffered habitats.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1987)116<561:ROBHEA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

This study was conducted in order to determine how various technical and biological factors affect brain cholinesterase (ChE) activity of rainbow trout Salmo gairdneri. Brain ChE activity increased in proportion to increasing temperature to 20°C, but at higher temperatures, the ChE activity increased at a slower rate and was absent at 45°C. Brain ChE activity remained stable for a long time when the rainbow trout were stored at −20°C or lower, and short (2-d) storage at 4°C was not detrimental; dead fish left 1 d at ambient water temperature also did not have lower ChE activities. Habitat temperature did not affect brain ChE activity significantly. Small rainbow trout had markedly higher brain ChE activities than large fish.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1987)116<570:TABCFT>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Stress-induced changes in plasma cortisol, glucose, and chloride were more extreme in wild rainbow trout Salmo gairdneri than in hatchery-reared fish subjected to confinement in a net and to electroshock. During 12 h of net confinement, plasma cortisol increased from resting levels of 10 ng/mL to 480 ng/mL in wild fish, and from 2 ng/mL to 155 ng/mL in hatchery fish. Plasma glucose was also higher in wild fish, increasing from 55 to 284 mg/dL, versus an increase from 58 to 196 mg/dL in hatchery fish. Plasma chloride decreased from resting levels of 132–135 meq/L to 53 meq/L in wild fish (and it continued a decline to 33 meq/L during the first 24 h after confinement), but only to 102 meq/L in hatchery fish. Both wild and hatchery-reared fish required more than 24 h after they were removed from the net to recover resting levels of plasma constituents. Plasma concentrations of cortisol, glucose, and chloride were less altered in response to electroshock than they were in response to net confinement. One hour after galvanonarcosis, plasma cortisol concentrations in wild fish peaked at 234 ng/mL and remained moderately elevated for 4 d; cortisol in hatchery fish peaked at 70 ng/mL within 0.5 h of the electrical stimulus and then returned to resting levels within 1 h. No substantial changes in plasma glucose or plasma chloride occurred in either the wild or the hatchery-reared rainbow trout after galvanonarcosis.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1987)116<574:PSRIWA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

We estimated the amount of genetic divergence among seven cutthroat trout Salmo clarki subspecies and rainbow trout Salmo gairdneri using electrophoretic data from 46 protein loci. There was little genetic divergence among the Colorado River, finespotted, greenback, and Yellowstone subspecies of cutthroat trout, but a large amount existed among the coastal, Lahontan, and westslope subspecies. These latter three subspecies were electrophoretically as similar to rainbow trout—or more so—as they were to the other four subspecies of cutthroat trout examined. Morphologically, in contrast, the cutthroat trout subspecies were all more similar to each other than to rainbow trout. The data, therefore, suggest that morphological and protein evolution have proceeded at different rates among some of these fishes. The presence of fixed or nearly fixed allele-frequency differences between the subspecies of cutthroat trout and rainbow trout and between many pairs of cutthroat trout subspecies provides a powerful means of identifying “genetically pure” populations of these taxa.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1987)116<580:GDAIOS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The stock structure of the exploitable population of striped bass Morone saxatilis in Rhode Island coastal waters was estimated by a quadratic discriminant analysis of nine proteins of eye lenses separated by isoelectric focusing. This technique permitted identification of Hudson River and Chesapeake Bay striped bass with 88.0 and 89.5% correct classification, respectively. Classification of individuals sampled from the Rhode Island commercial trap-net fishery in November 1982 indicated that approximately 54% were from the Chesapeake Bay stock and 46% were from the Hudson River stock. These stock composition estimates apply to age-2–5 striped bass from the exploitable population in Rhode Island. The stock composition of the coastal population is expected to change with time and with relative year-class strengths of the contributing stocks.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1987)116<588:COCBAH>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The differences in concentrations of 10 elements in scales of striped bass Morone saxatilis from several freshwater (<0.1‰), estuarine (0.5–15‰), and saltwater habitats (20–30‰) in the eastern United States were evaluated. Barium, iron, aluminum, calcium, magnesium, manganese, potassium, sodium, strontium, and zinc were measured by flame atomic absorption spectrophotometry. Absorbance values for barium, iron, and aluminum were extremely erratic due to matrix interferences. Discriminant function analysis correctly classified 95% of freshwater and 95% of saltwater fish based on Ca and Mg alone. These two elements were the single best indicator pair. When seven elements were considered, 97 and 95% of fish from fresh water and salt water, respectively, were classified correctly. One-way analysis of variance of individual elemental contents of scales from different salinities consistently distinguished among freshwater, estuarine, and saltwater fish, although not always in a predictable order. Concentration of elements varied with sex, but, when all data were combined, only manganese concentration was significantly affected by sex. Fish size was often negatively correlated with elemental content. The strongest correlations were between magnesium and fork length, weight, and age in all three environments. We concluded that discriminant function analysis, in conjunction with age and growth information for individual striped bass, can provide a useful means for distinguishing between freshwater and saltwater striped bass.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1987)116<594:DOFVSS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

We developed a method for the analysis of observed changes in catch rates of similar species or groups of fish from southeastern Asia and the northwestern Atlantic region. Aggregated time series of catches per standard tow from research vessel surveys were examined as Markov chain models after transition probability matrices were derived from them by quadratic programming. The matrices were projected to provide some insight about stability and changes in the multispecies assemblages. Results from these analyses generally support inferences previously made from the data and provide some additional information regarding stability.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1987)116<601:EATMSA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Some mechanisms hypothesized to cause stunting of northern pike Esox lucius include overpopulation and competition, lack of appropriately sized prey, and lack of thermal refuges in midsummer. The objective of this work was to use an energetics model of northern pike growth over 3 years to test the effects of these mechanisms on stunting. Simulations for females indicated the following: (1) competition-based stunting could occur when food resources were reduced by only 5–10% per individual, such that size at age 3 would be reduced by up to 51%; (2) lack of appropriately sized prey could result in stunting (up to 35% of a northern pike's annual ration often comes from large and rare prey), such that size at age 3 could be reduced 80%; (3) inappropriate thermal regimes could reduce northern pike growth up to 58%, but only under extremely warm conditions.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1987)116<612:SOMCSI>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor