Relative sensitivity of brown and rainbow trout to pulsed exposures of an acutely lethal mixture of metals typical of the Clark Fork River, Montana

Brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) fry and juveniles were episodically or continuously exposed to a metals mixture (Zn, Cu, Pb, Cd): the concentrations and ratios of the metals, and variations in water quality (pH, hardness), were selected to represent conditions measured during episodic storm events in the Clark Fork River, Montana. Brown trout fry were more sensitive (lower LC50) than rainbow trout fry to the metals in 8-h exposures with constant hardness and pH, but less sensitive to elevated metal concentrations in conjunction with depressed hardness and pH. Fry were more sensitive than juveniles when exposure was continuous, but neither life stage was clearly more sensitive when exposure was pulsed. Whole-body concentrations of K+ and Ca2+ but not Na+ were significantly depressed in fry exposed to metals. Results support the hypotheses that changes in water quality during thunderstorms are lethal to fry and juvenile life stages of brown and rainbow trouts and that the relative sensitivity of the species to the metals mixture may explain their distributions in the Clark Fork River. Low-frequency extreme conditions may effectively act as a bottleneck on the viability of populations whose relative sensitivities to such extremes may control distributions of species in a system.

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

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f95-791 ◽

1995 ◽

Vol 52 (9) ◽

pp. 1994-2004 ◽

Cited By ~ 80

Author(s):

Daniel F. Woodward ◽

Aïda M. Farag ◽

Harold L. Bergman ◽

Aaron J. DeLonay ◽

Edward E. Little ◽

...

Keyword(s):

Rainbow Trout ◽

Brown Trout ◽

Benthic Invertebrates ◽

Salmo Trutta ◽

Digestive Enzyme ◽

Life Stage ◽

Membrane Damage ◽

Whole Body ◽

Clark Fork River ◽

Young Of The Year

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 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.

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Differences in relative sensitivity of naive and metals-acclimated brown and rainbow trout exposed to metals representative of the Clark Fork River, Montana

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f95-793 ◽

1995 ◽

Vol 52 (9) ◽

pp. 2016-2030 ◽

Cited By ~ 39

Author(s):

J. C. A. Marr ◽

H. L. Bergman ◽

J. Lipton ◽

C. Hogstrand

Keyword(s):

Rainbow Trout ◽

Brown Trout ◽

Salmo Trutta ◽

Relative Sensitivity ◽

Energetic Cost ◽

Time To Death ◽

Clark Fork River ◽

Lead And Cadmium ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Hepatic Metallothionein

Naive and metals-acclimated juvenile brown (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) were exposed to a metals mixture containing zinc, copper, lead, and cadmium, to compare relative sensitivities to metals concentrations typical of the Clark Fork River, Montana. Differences in the survival responses (tolerance versus resistance) measured for naive fish indicated that the rainbow trout are more tolerant (higher 96-h LC50) of the metals mixture, yet the naive rainbow and brown trout showed similarities in resistance (mean time to death). Differences for metals-acclimated fish indicated that brown trout are more resistant. Thus, the relative sensitivity of brown and rainbow trout varies with both the survival response measured and pre-exposure effects of metals on the physiological condition of the animal. Brown trout continued to acquire metals resistance for up to 5 weeks during acclimation to chronic concentrations of the metals mixture. Hepatic metallothionein and copper residue levels were positively correlated in both naive and metals-acclimated trout, and an energetic cost of metals acclimation was evidenced by reduced weight in brown trout acclimated to the metals. In contrast, rainbow trout demonstrated the least degree of acclimation and no significant growth inhibition was observed.

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Early Life Stage Mortality Syndrome in Fishes of the Great Lakes and Baltic Sea

Early Life Stage Mortality Syndrome in Fishes of the Great Lakes and Baltic Sea ◽

10.47886/9781888569087.ch12 ◽

1998 ◽

Keyword(s):

Rainbow Trout ◽

Atlantic Salmon ◽

Brown Trout ◽

Salmo Trutta ◽

Lake Trout ◽

Maternal Diet ◽

Life Stage ◽

Maternal Weight ◽

Thermal Habitat ◽

Finger Lakes

Abstract.—A lethal thiamine deficiency afflicting larval landlocked Atlantic salmon Salmo salar in several of New York’s Finger Lakes has been linked to a maternal diet of the exotic, thiaminase-rich alewife Alosa pseudoharengus. To evaluate why trout and char species in the Finger Lakes are apparently not affected by this “Cayuga syndrome,” levels of thiamine in the whole blood of syndromepositive and syndrome-negative stocks of Atlantic salmon were compared with levels in lake trout Salvelinus namaycush, brown trout Salmo trutta, and rainbow trout Oncorhynchus mykiss from Cayuga and/or Seneca lakes. Thiamine levels did not differ between sexes within any species or stock. Consistent with the hypothesis that thermal habitat partitioning may predispose the salmon to more dietary thiaminase than other Finger Lakes salmonids, thiamine levels in the salmon that produced syndrome-positive sac fry were significantly lower than levels measured in Finger Lakes brown trout and rainbow trout. In contrast, there was no difference between the syndrome-positive salmon and Finger Lakes lake trout, possibly because the male char were in starved (postspawned) condition. Regressions of maternal blood or egg thiamine versus maternal weight and length were not significant for salmon that produced syndrome-positive sac fry; yet, a significant inverse relationship was detected for the syndrome-negative salmon from the Adirondack progenitor stock. These findings may reflect the transition of these reference control salmon from a thiaminase-poor invertebrate diet to a piscivorous diet of thiaminase-active smelt Osmerus mordax.

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