摘要:

Nitrite, an intermediate in the oxidation of ammonium to nitrate, changes hemoglobin to methemoglobin, which does not carry oxygen; nitrite may thus cause anoxia in fish and other aquatic organisms. The published literature on nitrite toxicity to fish, which consists of about 40 papers, shows that the ratio of the 24-h LC50 (concentration lethal to half of the test organisms in 24 h) to the 96-h LC50 has a median value of 2.0 and is fairly uniform across species; toxicity tests of differing duration can therefore be standardized to a common duration. In general, chronic effects are difficult to detect at concentrations below one-fifth of the 96-h LC50. Most fish concentrate nitrite in fresh water; chloride in the external environment offsets the toxicity of nitrite by competing with nitrite for uptake through the chloride cells of the gills. The strength of the chloride effect is greatest for the least-sensitive species and smallest for the most-sensitive species. The addition of 1 mg/L chloride increases the 96-h LC50 by 0.29 to 2.0 mg/L nitrite-N, depending on the species. Bicarbonate also reduces the toxicity of nitrite, but it is less than 1% as effective as chloride. Calcium reduces the toxicity of nitrite, but much less than chloride; the effects of other metal cations have not been studied. Hydrogen ion concentration of the medium has not been shown to have a discrete effect on the toxicity of nitrite except at extreme concentrations uncharacteristic of the environments in which fish ordinarily live. Nitrite toxicity is exacerbated by low oxygen concentrations because nitrite reduces the oxygen-carrying capacity of the blood. The effects of temperature have not been adequately studied. Very small fish seem less sensitive to nitrite than fish of intermediate or large size. Present evidence suggests that salmonids are among the fishes most sensitive to nitrite; channel catfish Ictalurus punctatus, blue tilapia Tilapia aurea, logperch Percina caprodes, and brook stickleback Culaea inconstans are equally sensitive or slightly less sensitive. The fathead minnow Pimephales promelas, other cyprinids, catostomids, the mottled sculpin Cottus bairdi, and the black bullhead Ictalurus melas are considerably less sensitive. The least-sensitive species tested thus far are the largemouth bass Micropterus salmoides and bluegill Lepomis macrochirus; the largemouth bass does not concentrate nitrite.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1986)115<183:TONTF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Chronic effects of ammonia on the fathead minnow Pimephales promelas were studied in the laboratory in two flow-through tests, each test lasting approximately 1 year. Fish were exposed to five test concentrations over the range 0.07–0.96 mg/L un-ionized ammonia (NH3); the mean pH of the test water was 8.0, and the mean temperature was 24.2°C. The tests started with 3- to 5-d-old larvae that were reared to sexual maturity; progeny of these fish (F1were reared until they were 60 d old. The 5% probability level was chosen to indicate significance. No effects were observed on growth or survival of parental fish at 0.44 mg/L NH3, or on egg production or viability at 0.37 mg/L, but effects on all of these were observed at 0.91 mg/L. Growth and survival of F1larvae were not affected at 0.36 mg/L NH3, which was the highest concentration at which these were tested. Egg hatching success was not affected at 0.19 mg/L NH3, but was at 0.37 mg/L. Brain lesions were common in parental fish at all stages of development at exposure concentrations of 0.21 mg/L NH3and higher, but not at 0.11 mg/L; no other histopathologic effects were observed at any of the test concentrations. The chronic-effects threshold concentration, based on survival, growth, and reproductive success, is estimated to be 0.27 mg/L NH3for the conditions of these tests. Based on histological damage, however, this concentration is estimated to be 0.15 mg/L NH3.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1986)115<196:CTOATF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Recent studies have associated high body concentrations of selenium with declines in fish populations inhabiting cooling reservoirs of coal-fired electric power plants. Because some evidence indicated that these declines resulted from reduced reproduction, we made a series of 18 artificial crosses of bluegills Lepomis macrochirus possessing high and low body concentrations of Se to determine whether elevated Se in parents reduced viability of gametes or increased mortality of embryos and larvae. Bluegills with high body concentrations of Se were obtained from Hyco Reservoir (cooling water source of a coal-fired power plant) and those with low body concentrations were obtained from nearby Roxboro City Lake, North Carolina. Neither percent fertilization nor percent hatch of eggs differed significantly among the parent combinations. However, all crosses (8) that included females with high Se body concentrations resulted in larvae with edema; such larvae did not survive to the swim-up stage. Only one of these crosses produced some normal larvae (35%). Mean Se concentrations in the gonads and carcass (body minus gonad) were more than 20 times higher in bluegills from Hyco Reservoir (average = 7.94 mg/kg) than in those from Roxboro City Lake (average = 0.38 mg/kg). The high Se concentrations in ovaries of Hyco Reservoir bluegills and in their progeny suggested that Se was transferred from females to offspring and caused edema in larvae. This abnormality resulted in mortality of affected larval bluegills–and consequently may have caused reductions in the bluegill populations of selenium-enriched reservoirs.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1986)115<208:EOHTCO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The tissue distribution of rotenoid residues was determined in tissues of common carp Cyprinus carpio (88.2 g), bluegills Lepomis macrochirus (47.9 g), and yellow perch Perca flavescens (67.7 g) after the fish were exposed to 50 μg/L of rotenone-6a-14C (15.9 × 104Bq/μM). Exposures were terminated 1 h after the fish were moribund and failed to respond to gentle prodding. The fish were dissected, and various tissues were oxidized to determine14C-rotenone accumulation and distribution. Major rotenone metabolites were identified by gradient-elution high performance liquid chromatography. The exposure time required for fish to reach total incapacitation was 3 h for bluegills and yellow perch, and 11.25 h for common carp. The mean rotenoid concentrations (μg/100 g fish) in the whole body were 22.4 in yellow perch, 39.7 in bluegills, and 107.8 in common carp. The percentage of rotenone-derived14C activity was higher in the carcass components than in the head or viscera; the skin and bone contained about 60% of the carcass activity. The highest relative rotenoid concentrations were found in the liver, bile, gills, brain, and heart. Percentages of total rotenoid material as parent rotenone were highest in yellow perch (70.0 in the viscera and 84.4 in the fillet), followed by those for bluegills (22.7 and 27.8) and common carp (9.7 and 48.5).

ISSN:0002-8487    

DOI:10.1577/1548-8659(1986)115<214:DAAORI>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Budgets of Ca++, Mg++, Na+, and K+were determined for alevins of Atlantic salmon Salmo salar incubated at pH 6.8, 5.1, or 4.5. Accumulation of Ca++, K+, and Na+by larvae was reduced at pH 4.5 whereas Mg++accumulation was unaffected. The extrapolated dry weight of larvae at terminal yolk resorption was reduced from 27 mg at pH 6.8 and 5.1 to 20 mg at pH 4.5. The findings support the hypothesis that high acidity affects ion uptake from the ambient water more than yolk-to-larva transfer of cations.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1986)115<220:GAMICB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Exposure of young striped bass Morone saxatilis (weight, 8.5–34 g) to a mixture of arsenic, cadmium, copper, lead, and selenium at 4 and 10 times the average environmental concentrations of 1–3 μg/L protected the fish from experimental infection with Flexibacter columnaris, the causal organism of columnaris disease. In four trials, all striped bass died within 7 d after a 2-min exposure to 5 × 106F. columnaris cells in untreated water. In contrast, no fish died after a single day's exposure to the metal mixture followed by infection with F. columnaris and a second exposure to the metals for seven more days. When striped bass were exposed 5 d to individual metals, copper protected against infection and cadmium offered marginal protection but was slightly toxic after 2 d exposure. Arsenic increased susceptibility to infection, and lead and selenium were without an apparent effect.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1986)115<227:EOFMOS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Edwardsiella tarda was isolated from moribund age-0 hatchery-reared striped bass Morone saxatilis for the first time. Pathogenicity was confirmed by contact infection. Characteristic histopathology consisted of epithelial hyperplasia and necrosis associated with the lateral line canals, and abscess formation in the anterior kidney and other internal organs.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1986)115<232:PCBTBE>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A static seawater challenge test was successfully developed and used to establish a profile of the relative stress levels of spring chinook salmon smolts Oncorhynchus tshawytscha within the smolt collection and transport system at Lower Granite Dam on the Snake River. A major feature of the test was the development of water-to-water transfer techniques designed to assure minimal stress interference associated with sampling and transferring test fish from the freshwater sample sites to the seawater test chambers. The test was used to isolate stresses associated with movement of smolts through the system, with handling and marking procedures, and with holding spring chinook salmon smolts in the presence of predominately hatchery-reared steelhead Salmo gairdneri smolts. The test results clearly indicated a pattern of increasing stress levels as smolts moved through the system. The bypass system, the fish and debris separator complex, and transport by truck were areas where stress levels increased. Dipnetting smolts with a standard dip net was implicated as the major contributor to the overall stress associated with our handling and marking procedures. The stress level of spring chinook salmon smolts appeared to be influenced by the presence of high populations of hatchery-reared steelhead smolts. Procedures used in the test provided reliable but somewhat variable results. Changes recommended for reducing the variability include a shorter test time and a different method of replication.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1986)115<236:SSCTTM>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The corticosteroid and hyperglycemic stress responses to multiple acute disturbances were cumulative in juvenile chinook salmon Oncorhynchus tshawytscha. This was demonstrated by the stepwise pattern of increased plasma cortisol and glucose concentrations in fish subjected to a 30-s handling stress applied repeatedly at 3-h intervals over 6 h. The accumulation of physiological stress responses was substantiated by the resultant combined effects of these repeated disturbances on changes in concentrations of plasma lactate and of ionic sodium and potassium, and on the rate of decline of hepatic glycogen concentrations, all of which were greater than those that followed a single handling. Healthy fish appeared more able than diseased fish to elevate plasma cortisol after each of the three successive disturbances, but plasma glucose concentrations following the repeated handlings were higher in the unhealthy fish. As judged from plasma cortisol and glucose responses in fish subjected to a single 30-s stress at four different times in the day, there was little diurnal difference in sensitivity or responsiveness to handling.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1986)115<245:MADECP>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The rhizocephalan barnacle Briarosaccas callosus causes sterilization and reduced growth of red Paralithodes camtschatica, blue P. platypus, and golden Lithodes aequispina king crabs, commercially important species in southeastern Alaska. The prevalence of the parasite (percentage of king crabs infected) was monitored from 1979 through 1985 within a 115-km radius of Juneau. Prevalences were typically less than 1% in commercial landings of legal red and golden king crabs (males only; minimum carapace width 179 mm), but reached 12% in landings of blue king crabs (males of 165 mm minimum carapace width). Annual surveys of commercial red king crab pots, which contain females and sublegal males, usually indicated prevalences of less than 1%, though 50% was reached in exceptional cases. On-board samples from commercial boats that included females and sublegal males confirmed low prevalences (<1%) for red king crabs, but 20% of golden king crabs and 76% of the blue king crabs were parasitized. Within broad temporal and geographic variation, blue king crabs were the most, and red king crabs were the least, heavily parasitized by barnacles of the three host species considered. Prevalences tended to be greater for smaller than for larger hosts, for females than for males among blue and red king crabs, and in turbid than in clear water.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1986)115<252:POTPBB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor