摘要:

CO2accumulation is greater than O2removal in the hypolimnion of Dunham Pond (zmax = 4.5 m) during the summer, and in the whole lake during winter stratification. During much of stratification no free oxygen and less than 1% surface light exist below 2.5 m. Despite low light and on-going accumulation of CO2during stratification, CO2uptake is found in situ in sediment surface incubations at 3.5 m. The CO2uptake is associated with an epipelic mat of blue-green algae apparently undergoing anaerobic photosynthesis. Thus, anaerobic photosynthesis and anaerobic respiration appear to be going on simultaneously in the hypolimnion. Respiratory quotients are conventionally thought of as a characteristic of metabolism imparted by the nature of the biochemical substrate being oxidized by an organism. Respiratory quotients of mixed communities of aerobes and anaerobes depend more upon the nature of the oxidizing agent being reduced. The degree to which a community RQ is greater than expected (about 0.85) describes the amount of metabolism for which oxygen is not (yet) the terminal electron acceptor. Excess oxidation of carbon creates ambient reducing power potentially available for bacterial (anaerobic) photosynthesis and chemolithotrophy.Key words: lake, respiratory quotient, oxygen deficit, carbon cycle, benthic respiration, eddy diffusion, heat budget, soft-water, detritus, ecosystem energetics

ISSN:0706-652X    

DOI:10.1139/f79-197

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

A previously unreported virus disease of cultured golden shiners (Notemigonus crysoleucas) is described. The condition is called golden shiner virus (GSV) disease. The virus is icosahedral, measures approximately 70 nm, is ether and heat resistant, stable at pH 3, 7, and 10, and appears to have a double stranded RNA core. It was not neutralized by infectious pancreatic necrosis virus specific antiserum. GSV causes syncytial like cytopathic effect in fathead minnow cells but not brown bullhead, rainbow trout gonad (RTG-2) or channel catfish ovary cells. Severe mortalities in golden shiner culture ponds do not appear to be associated with GSV infections.Key words: fish viruses, RNA virus, fish pathology, fish cell cultures, Cyprinidae, golden shiner

ISSN:0706-652X    

DOI:10.1139/f79-198

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

A comparison of ages determined from surfaces of otoliths and from sections of otoliths showed that ages were similar up to a section age of 22–24 yr. The growth pattern observed on thin sections of otoliths and from broken and burned otoliths from the region of the nucleus was interpreted to indicate that Pacific ocean perch probably live much longer than previously thought. Because the criteria used to identify annuli from otoliths sections appeared valid for younger fish, there was no justification to reject the application of these criteria for estimating ages of older fish and thus no reason to reject the possibility that Pacific ocean perch might live to be older than 70 yr. Ages determined from sections of otoliths from other rockfish species found off the west coast of Canada such asSebastes fiavidusandSebastes brevispinishave ranged from 30 to 60 yr indicating that many species of rockfish may live longer than previously thought.Key words: age determination, otolith, maximum age, age determination errors, Pacific ocean perch, otolith sections

ISSN:0706-652X    

DOI:10.1139/f79-199

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Treatment ofFundulus heteroclitusacclimated to 6.5 °C with benzo(a)pyrene did not elicit any change in the levels of hepatic microsomal NADH- or NADPH-cytochrome c reductase activity, nor in the levels of cytochrome P-450 or its catalytic activities. However, the same treatment offish at 16 5 °C resulted in a marked induction of benzo(a)pyrene hydroxylase and NADPH-cytochrome c reductase. Cytochrome P-450 content was also higher in the warm, treated fish and the Soret maximum of reduced, CO-treated microsomes was shifted to the violet. Levels of aminopyrine demethylase and NADH-cytochrome c reductase activities did not show a significant treatment effect. At neither temperature could treated and control fish be distinguished on the basis of in vitro inhibition of benzo(a)pyrene hydroxylase activity by 7,8-benzoflavone. Levels of NADPH-cytochrome c reductase and benzo(a)pyrene hydroxylase activities were greater in controlFundulusacclimated to 6.5 °C than to 16.5 °C, when normalized to microsomal protein, but not when based on body weight. The results indicate that habitat temperature alone may not affect the capacity for initial hydrocarbon metabolism in fish, but that it can strongly influence the induction of cytochrome P-450.Key words: temperature, cytochrome P-450, hydrocarbon metabolism, mixed-function oxygenase,Fundulus heteroclitus

ISSN:0706-652X    

DOI:10.1139/f79-200

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Infectious pancreatic necrosis (IPN) virus was concentrated from water by a polymer two-phase method using polyethylene glycol and dextran sulfate. A concentration of over 100-fold was attained. By this method as little as one infectious virus particle per litre of water can be detected.Key words: infectious pancreatic necrosis virus, virus concentration, diplornavirus, salmonids, polyethylene glycol

ISSN:0706-652X    

DOI:10.1139/f79-201

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Hatchery-reared Atlantic salmon (Salmo salar) parr were captured 1–3 mo after release in streams, along with wild parr from the same streams. Identification of their stomach contents showed total number of organisms and number of taxa per stomach were greater and there was a higher index of stomach fullness in wild than in hatchery parr resident ≤ 2 mo in a stream. Wild parr consumed more Brachycentridae, Hydroptilidae, Diptera, and Plecoptera than did hatchery parr, but sometimes less Odontoceridae and Heptageniidae. These differences may have arisen from size-dependent food selection, the effects of feeding experience, or possible microhabitat differences between wild and hatchery parr.Key words: salmon parr, hatchery-reared, wild, feeding

ISSN:0706-652X    

DOI:10.1139/f79-202

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

More tainting was found on the left than on the right side of rainbow trout (Salmo gairdneri) that were exposed to a kraft pulp mill "foul condensate." This sidedness was deduced from the results of the triangle taste test used to detect differences between exposed and control fish, and was observed when the tainting was moderate, in the range of effluent concentrations of 0.015–0.046% by volume.Key words: fish, tainting, taste, rainbow trout.

ISSN:0706-652X    

DOI:10.1139/f79-203

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Samples of Antarctic krill (Euphausia superba) and Atlantic krill (Meganyctiphanes norvegica) were analysed for fluoride using a selective fluoride electrode method. Both species showed very high concentrations, a total of 1330–2400 mg F−/kg on fat free dry weight basis in raw samples whereas deep sea prawns (Pandalus borealis) showed a total of 18–91 and red feed (Calanus finmarchicus) 10–37 mg F−/kg. Sections of Antarctic krill were analyzed, and the highest concentration was found in the carapace, 4260 mg F−/kg fat free dry matter, compared with 570 and 750 mg F−/kg in raw and boiled muscle. Biological availability was measured in a chick assay, and showed fluoride in krill to be equally utilized as sodium fluoride added to the diet.Key words: krill, red feed, deep sea prawn, fluoride

ISSN:0706-652X    

DOI:10.1139/f79-204

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f79-205

出版商:NRC Research Press    

年代:1979

数据来源: NRC