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211.
Influence of dissolved organic matter on copper binding, and calcium on cadmium binding, by gills of rainbow trout 总被引:3,自引:0,他引:3
Complexation of Cu by 5 mg Cl−1 dissolved organic matter (DOM) from a marsh kept Cu from binding to gills of small rainbow trout Oncorhynchus mykiss in 9-day exposures to 0.5 μM Cu in soft water. The protective effect of DOM occurs because the formation of Cu-DOM complexes reduces the amount of free Cu in the water, so the disruptive effects of Cu on ionoregulation, such as inhibited Na uptake, cannot develop. The Cu-DOM complexes themselves do not bind to the gills. Calcium (1100 μm) reduced the accumulation of Cd by trout gills in short, 2-h exposures through competition for gill binding sites but not over longer, 7-day exposures to 0–14 μM Cd. However, the protective effect of Ca against Cd toxicity persisted throughout the longer experiment, likely due to the decrease in the electrochemical gradient for diffusive loss of Ca from the fish to the water. Rainbow trout and fathead minnows Pimephales promelas accumulated Cu and Cd on their gills in a similar manner; thus, binding constants for metal-gill interactions determined for one species of fish can be generalized to other fish species. When literature binding constants determined for fathead minnows were applied to our studies with rainbow trout, computer modelling of Cu-gill and Cu-DOM interactions simulated our results well. In contrast Cd-gill and Ca-gill modelling predicted the initial competitive effect of Ca against Cd accumulation by trout gills, but did not predict the longer-term accumulation of Cd by trout gills. 相似文献
212.
Interindividual variations in feed intake and growth were studied in Baltic salmon Salmo salar and brown trout S. trutta , held under constant low temperatures of 2, 4 or 6° C and continuous light for 2 months. Rates of feed intake and growth were dependent upon rearing temperature, being lowest at 2° C and highest at 6° C. Further, feed intake and growth were initially low, but increased during the course of the experiment in both species and at all temperatures. These results suggest that acclimatization to the rearing conditions may have required several weeks. The increase in group mean feed intake with time was the result of both an increase in the proportions of fish that fed and an increase in feed intake amongst feeding fish. At the same time as feeding and growth rates increased, interindividual variations in feed intake and growth tended to decrease, suggesting that individual fish were acclimatizing to the new rearing conditions at different rates. Thus, the differences in group mean feed intake and growth rates observed at a given temperature reflected interindividual variations among fish making up the groups. This suggests that group rates of feed intake and growth are not only temperature- dependent, but that they are also highly influenced by variability among fish making up the group. 相似文献
213.
Physiological stress effects of continuous- and pulsed-DC electroshock on juvenile bull trout 总被引:1,自引:0,他引:1
Juvenile bull trout Salvelinus confluentus exposed to continuous- or pulsed-DC electroshock exhibited rapid elevations in plasma cortisol and glucose, but plasma chloride did not change. In a 1-h experiment using 240 V at 1·4 A of 60-Hz pulsed DC (voltage gradient 0·81 V cm−1 ), which proved lethal, plasma cortisol and glucose rose significantly within 15 min of a 10-s electroshock. Plasma cortisol reached a peak level of 156 ± 18 ng ml−1 at 45 min and then decreased, whereas plasma glucose reached its highest level of 179 ± 7·5mg dl−1 at 1 h. In a 24-h experiment using lower dosages, plasma cortisol increased from 6·1-16 ng ml−1 to peak levels of 155–161 ng ml−1 in 1 h in response to a 10-s electroshock of continuous (130 V, 0·5 A, 1·45 V cm−1 ) or pulsed (120 V, 0·5 A, 60 Hz, 0·55 V cm−1 ) DC. Although plasma concentrations declined thereafter, levels remained above control values at 24 h. Plasma glucose was elevated from 60–65 to 120–134 mg dl−1 after 1h by both electroshock treatments and remained near or above those levels for the 24-h duration. Plasma cortisol and glucose levels were much higher in electroshocked bull trout at 1 h compared with those in fish 1 h after receiving a 30-s handling stressor (cortisol, 90 ± 12 ng ml−1 ; glucose, 82 ± 6·1 mg dl−1 ). The results indicate that both continuous and pulsed DC were more stressful to juvenile bull trout than handling and that recovery, at least for pulsed DC, may take longer than 24 h. 相似文献
214.
Exposure to 1,500 μg/ml of hydrogen peroxide (H2O2) for 60 min at 13°C was found to be injurious to rainbow trout eggs. On the other hand, the concentration which effectively
inhibited pathogenic fungi in vitro was substantially less than this toxic dosage; specifically, 500 μg/ml for 60 min at 20°C
to inhibit the zoosporic stage and 1,000 μg/ml for 60 min at 20°C to inhibit the vegetative stage. From in vivo tests, treatment
with 1,000 μg/ml of H2O2 for 60 min at 13°C was found to be the most effective procedure to control fungal infection and increase the hatching rate
of rainbow trout eggs. 相似文献
215.
Aluminium (1–100 μM) reduced in vitro calcium deposition on otoliths concentration-dependently in rainbow trout, but cortisol (1 and 10 μg ml−1 ) had no effect. 相似文献
216.
Wet mass and water content of four lots of whole eggs did not change throughout embryonic development of rainbow trout Oncorhynchus mykiss. Eggs in all four lots accumulated Na+ . Eggs in lots 2 and 4 also accumulated Ca2+ and Cl- , whereas eggs in lot 1 showed no significant change in Ca2+ or Cl- and eggs in lot 3 showed no change in Cl- and a small loss of Ca2+ . Although the Na+ content of embryonic tissues increases in the later stages of development, the yolk sac content remained constant, indicating uptake of Na+ from the environment. Na+ uptake by whole eggs was non-saturable, consistent with diffusion of Na+ across the chorion into the perivitelline fluid. Na+ uptake in dechorionated embryos was saturable, as was Ca2+ uptake by both whole eggs and dechorionated embryos, consistent with active uptake or facilitated diffusion mechanisms at the surface of embryos. Very low Ca2+ uptake rates in dechorionated embryos suggest that the Ca2+ uptake mechanism is not fully developed until after hatching. 相似文献
217.
R. I. Figueroa R. Rodríguez-Sabarís M. Aldegunde J. L. Soengas 《Journal of fish biology》2000,57(3):631-646
Plasma glucose, lactate and acetoacetate, brain glycogen and acetoacetate, and liver acetoacetate, glycogen and lactate in fed rainbow trout exhibited daily changes. However, no daily changes were observed in the activities of the brain enzymes glycogen synthetase, 6-phosphofructo 1-kinase, and lactate dehydrogenase. Depending on the length of the previous fasting period most daily changes observed in the metabolic parameters of fed fish disappeared, except for liver acetoacetate levels, which displayed daily changes in both fed and fasted fish. These results suggest that feeding is an important factor regulating most daily changes in the brain and liver carbohydrate and ketone body metabolism of rainbow trout. 相似文献
218.
From 1968–1984 (period I), a brown trout Salmo trutta , population in a 70-ha oligotrophic lake in central Norway was exploited using larger mesh gill-nets selectively removing the larger fish. From 1985–1994 (period II), intermediate sized fish were removed using smaller-mesh sizes gill-nets. Fishing mortality and CPUE were correlated positively with effort and numbers of fish >3 years old for period II. The gill-net catchability was correlated negatively with spawner biomass and number of trout >3 years old. The significant positive correlation between natural mortality and stock biomass and spawning stock biomass indicated density-dependent mortality. The significant correlation between spawning stock and recruitment described by the Ricker model, indicated density-dependent recruitment of 1-year-old trout. The fishing regimes in the two periods affected the population dynamics and density differently. Selective removal of smaller fish permitted the larger fish to survive, and was beneficial in reducing fish density and maintaining stocks at low levels, consequently, achieving the expected increase in fish growth rates. 相似文献
219.
In February to March, wild brown trout Salmo trutta were captured by electrofishing in a natural watercourse (tributaries of the River Lille Aa, Denmark), individually tagged (Passive Integrated Transponders), and released. Representatives of the tagged brown trout were recaptured on the release sites in April by electrofishing and eventually caught in downstream smolt traps ('migrants') placed in the main river or by electrofishing ('residents') on the initial sites in June. Upon each capture, smolt appearance and body size were evaluated, and a non‐lethal gill biopsy was taken and used for Na+ ,K+ ‐ATPase analysis. Based on repetitive gill enzyme analysis in individual fish, a retrospective analysis of the rate of development in individual brown trout ultimately classified as migrants or residents was performed. Two months prior to migration, a bimodal morphological and physiological (gill Na+ ,K+ ‐ATPase) development concurred and was related to the subsequent differentiation into resident and migratory fractions of each population. This differentiation was unrelated to growth rate and body size of individual fish but skewed in favour of migratory females. Individuals destined to become migrants developed a smolt‐like appearance before the onset of migration and had higher rate of change of gill Na+ ,K+ ‐ATPase activity than fish remaining residents. The rate of change of gill Na+ ,K+ ‐ATPase activity was independent of the distance migrated to the trap (3–28 km). Thus in bimodal wild brown trout populations a major increase in enzyme activity takes place before migration is initiated and is a characteristic of migratory individuals only. 相似文献
220.
The seasonal diet of a predator, brown trout Salmo trutta [total length ( L T ) 17–69 cm] and simultaneous density and size‐structure of prey populations, vendace Coregonus albula and smelt Osmerus eperlanus (4–16 cm L T ), in a large boreal lake were analysed and compared in 2001 and 2002. The upper L T limit for consumed prey was c . 40% of the predator L T . All brown trout, however, preferred small (<10 cm L T ) and avoided large (≥10 cm L T ) prey. The results also suggested that equal densities of similar‐sized (4–10 cm L T ) fish of the two prey species led to random foraging on these species by brown trout, but if either one of the prey species predominated (>50%) in the lake, brown trout shifted to foraging on this species almost exclusively. Brown trout diets thus reflected the density dynamics of the two alternative prey species. 相似文献