摘要:

Acute exposure ofOreochromis aureusto cadmium or lead resulted in different tissue accumulation profiles. Trunk kidney accumulated the highest lead concentrations of all tissues analysed after 24‐h or 1‐week exposure to 0.1 mg l–1lead as PbCl2while exposure to 0.1 mg l–1cadmium as CdCl2for 24 h or 1 week resulted in the highest accumulations of cadmium in the intestine. Caudal muscle consistently accumulated the lowest levels of lead or cadmium after a 1‐week exposu

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb01922.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The age and growth of two endemic Lake Tanganyikan clupeid fishes,Stolothrissa tanganicaeandLimnothrissa miodon, were estimated from analysis of otolith microstructure in specimens collected in Zambian waters from October to December 1990. Both species had relatively clear, concentric otolith increments which were believed to represent daily increments based on their similarity to daily increments found in some marine clupeid species. The growth rates estimated from length‐at‐age data were: forS. tanganicae, Lt= 104·0 (1 – exp (– 0.00512 (t– 5·8))); forL. miodon, Lt= 155.4 (1 – exp (– 0.00236 (t+8.1))). In most cases, the growth parameters obtained from otolith analyses generally agreed with those previously estimated from analyses of length‐freque

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb01923.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Over the last decade, goldfishCarassius auratusL., have been introduced into lakes and ponds in the Montreal region. Controlled experiments compared the impact of goldfish in both mud‐and gravel‐bottomed outdoor pools, with either caged or non‐caged vegetation. High levels of turbidity were generated by foraging goldfish in mud pools (P<0.01). All non‐caged submersed plants (Potamogeton) showed extensive grazing damage and all of the unprotected submersed and emergent forms were uprooted. Data from Stoneycroft pond where a feral goldfish population reached 15–17 000 individuals ha‐1, confirmed the experimental findings showing goldfish to be benthic herbivores, causing a visible increase in turbidity and decrease in aquatic vegetation. Gut analysis revealed goldfish to have little diet overlap with native amphibians. High turbidity should reduce the success of predators feeding on goldfish, and may decrease the foraging success of other competitors. The sporadic distribution of goldfish in Canada may be linked to site characteristics, specifically the susceptibility of the area to turbidity

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb01924.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Immature 1‐year‐old Atlantic salmonSalmo salarparr were implanted with Silastic capsules of different sizes filled with testosterone (T). Testosterone had both positive and negative effects on testicular weights, spermatogenesis and steroidogenesis. The positive effects: higher incidence of males with enlarged gonads, spermiation, and high plasma levels of 11‐ketotestosterone (11‐KT) and 17,20β‐dihydroxy‐4‐pregnen‐3‐one (17,20β‐P), were most pronounced in males treated with small T capsules. The negative effects: suppression of gonadal development and depressed plasma levels of 11‐KT and 17,20β‐P compared with mature controls, were most evident in fish tre

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb01925.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Hagfish species of the generaMyxine, EptatretusandParamyxinewere analysed for genetic variation by allozyme electrophoresis and isoelectric focusing of general proteins. Large genetic differences were observed between samples of supposed conspecifics ofMyxine circifronsfrom off the Californian coast, and also within one sample ofParamyxinesp. from Sagami Bay, Japan. The results are convincing evidence of the existence of additional sympatric species in these two areas. In general, the highest genetic identities were found between species within the subfamilies Myxininae and Eptatretinae. Within Eptatretinae, the Japanese speciesEptatretus burgeriwas genetically more similar to Japanese species ofParamyxinethan to American species ofEptatretus. Thus, our data indicate that the generic status ofParamyxineshould be reconsidered.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb01926.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

In this study the first experimental trials of acclimation to salinities of the Italian sturgeonAcipenser naccariiare described. Preliminary observations regarding some morphological features of the gut, kidney and gills following exposure to 20 and 30% salinity are reported, and compared with those displayed by many teleosts in hyper‐ and hypoosmoregulation. Results are discussed with regard to the osmoregulatory mechanisms and to the physiological limits of adaptability of this species in the second year of its life cycle. Within the Acipenseridae,Acipenser naccariiis generally considered a euryhaline species, but nothing is known about its mechanisms of osmotic homeostasis. This species could be a good candidate for aquaculture in fresh and brackish waters owing to the recent success obtained in artificial reproductio

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb01927.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Cytogenetic analyses were performed on a triploid hybrid individual produced in the laboratory by matingPoecilia formosa, an all‐female gynogenetic diploid species, with a normal male of melanistic ornamentalPoecilia sphenops(black molly). Direct chromosome preparations revealed 69 (3n) chromosomes in the somatic complement. This cytogenetic observation in conjunction with the pigmentation phenotype leads us to conclude that occasional failure of sperm exclusion may result in the presence of triploid hybrids even in the natural habitat

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb01928.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Body water content was determined on groups ofCyprinodon variegatusafter sequential acclimation to ambient salinities in the range from fresh water to 100%. A multiple linear regression model applied to the data included body mass (M) of individuals and acclimation salinity (S) as independent variables, and body water content (W) as the dependent variable. The model that described the relationship wasW(g) = 0·059 + 0·723M(g)–0001S(%). Converting values of body water content to percent of wet body mass produced a range of values from 74·5% in fresh water to 72·0% at 100%, only a 2·5% difference in body water content over this wide range of ambient sali

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb01929.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The histochemical profile of calcium activated acid stable myofibrillar ATPase (mATPase) activity in developing larval and juvenile carp was investigated. In the larval fish, differentiation of pink muscle fibres occurred after metamorphosis which was delayed by a week at 17° C compared to larvae grown at 27° C. After metamorphosis the 27° C group exhibited some small myofibres with acid stable mATPase activity in the deep white muscle. This was similar for the juvenile carp which were acclimated for more than a month at 25° C. In contrast, the cold (12° C) acclimated juvenile fish, contained very few small white muscle fibres with acid stable mATPase activity. It was also noted that the cold acclimated fish had lower background acid stable mATPase activity than the warm acclimated fish. Results indicate that after metamorphosis and more evidently in juveniles, temperature can influence the rate of myofibre hyperpl

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb01930.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Primary cultures of gill cells were initiated from gill filament explants of rainbow trout,Oncorhynchus mykiss. The explants were cultured in Leibovitzl‐15 medium with 5, 10 or 20% foetal calf serum (FCS) andl‐glutamine. The attachment efficiency was serum‐dependent though increased FCS concentration did not stimulate further outgrowth of cells. The explants produced cell outgrowth 24 h after attachment as a sheet of cells which exhibited characteristics of gill pavement epithelial cells as indicated by surface microridges revealed by scanning electron micrographs. There was high proliferation for the first 14 days then a stable plateau for 30 days followed by a decline phase from 45 days. Following removal of cells, the explants produced further cell outgrowth which was especially active at the proliferation phase (14 days). Removal of these cells caused the explants to produce a further proliferation of cells reaching confluence in 10–14 days. After the third cell removal cell outgrowth from explants showed migratory activity but did not develop to resemble gill epithelial cells. The use of gill explants to establish primary cultures of fish gill cells has advantages which include longevity of the culture and successive proliferations from explants which could provide a useful tool for the investigation of long‐term processes in cellular biology and reduce the number of culture pre

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1995.tb01931.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY