ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04819.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

An investigation of the reproductive state and gonad development of Gerreidae in Natal showed that the fry ofGerres rappi, G. acinacesandG. filamentosusentered estuaries at 10 mm (s.l.). They stayed in the estuary until attainment of maturity, which was between 70 and 110 mm according to species. Gonad activity was initiated in estuaries but all females left before their eggs were ripe. Testes ripened while the fish were still in the estuary but no ripe running individuals were found. Since few large and no spent individuals occurred in the estuaries sampled, it appears that most fish do not return from the sea. Sequence of oocyte maturation and testes development were determined histologically. The estuarine area may be of importance to the fry as a safe nursery ground and to maturing individuals as an environment in which gonad maturity is reached for the first time.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04820.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

When transferred to sea water the chorion of cod and lumpsucker eggs harden, reaching a resistance of about 150 and 2000 g respectively. In sea water this hardening process is independent of fertilization. Studies of eggs kept in artificial sea water with various ionic compositions indicated, in the lumpsucker eggs, that a cortical reaction seems to be a prerequisite for the hardening process. Calcium is necessary for the reaction both in unfertilized and inseminated eggs, whereas hardening takes place in the absence of potassium, magnesium or sulphate. Addition of barium or strontium as a substitute for calcium only caused hardening in the presence of activating spermatozoa. Activating spermatozoa were also necessary for hardening of lumpsucker eggs kept in ovarian fluid, but such hardening only occurred if calcium and/or magnesium were added. The hardening of lumpsucker eggs was associated with profound changes in the thickness and surface appearance of the chorion.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04821.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Channel catfish,Ictalurus punctatus, were immunized with cilia from three isolates ofTetrahymena pyriformisand challenged withIchthyophthirius multifiliisusing a reproducible quantitative procedure. Two different methods of deciliation were used in antigen preparation. Results indicate thatT. pyriformiscilia elicit an immune response in channel catfish againstI. multifiliis, and that the protective ability of the cilia varies betweenT. pyriformisstrains.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04822.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The activity of chitinolytic enzymes in the stomach or foregut of 29 North European marine and freshwater fish were determined. No correlation with a chitin‐eating feeding habit was observed but species that were able to mechanically disrupt prey had low activity while species that ingest prey whole had high activity. The primary function of gastric chitinase in fish may be to chemically disrupt the chitinous envelope of pre

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04823.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Gravid sandsmelt,Atherina presbyter, were captured from Langstone Harbour, Hampshire, during 1978. They were maintained under laboratory conditions where spawning took place. The egg and its embryonic development are described. From fertilization to hatching took 26–27 days at 15°C and 13–15 days at 20° C. The newly hatched postlarvae were 6.5 to 7.2 mm long. Postlarvae 10.7, 13.4, 15.4 and 19.0 mm taken from the same locality are described and compared with previous descriptions. Their occurrence confirms successful spawning in the central English Ch

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04824.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Rainbow trout were exposed to a model mixture of water‐soluble aromatic hydrocarbons (AH) at concentrations of 0.3–15.2 ppm for periods of 1–72 h. None of the parameters monitored except RBC changed at 0.3 ppm AH, while all constituents, except blood glucose, changed at 7.2 ppm AH. At 15.2 ppm, all fish died within 1 h. Haematological changes included increased haematocrit, haemoglobin concentration, erythrocyte counts, and blood clotting (prothrombin) times. Plasma Cl−concentration decreased significantly. Changes resembled a stress response except for the increased clotting times, which typically decrease, and lack of increase in blood

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04825.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Young of the year striped bass,Morone saxatilis, were exposed to sublethal concentrations of zinc and benzene and infected with larvalAnisakisnematodes to determine the effects of these stressors on various physiological parameters. Results indicated that both pollutants and parasites significantly decreased haematocrit values. Parasites alone increased the liver somatic index, decreased haematocrits and, in the initial phase of the experiment, lowered antibody titres. Pollutants alone did not appear to significantly affect antibody titres, nor was there any difference in zinc and benzene uptake in the livers of infected and non‐infected fis

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04826.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Ranges in the means of blood measurements from 121 Baltic salmon taken on nine occasions spread over an annual cycle were: packed cell volume or haematocrit; blood haemoglobin; red blood cell counts including immature erythrocytes; mean corpuscular haemoglobin concentration; mean cellular haemoglobin content and mean cellular volume. Seasonal changes appeared in all blood variables. Ontogenetic differences occurred in RBC and mean cellular volume when comparing 1 + parr with 2 + smolts in August one year apart, and in haemoglobin, RBC and immature RBC when comparing 1 + parr with adults once in November 1976. This points to greater influence upon haematological variation by season than by age. Significant regressions found within age groups, between pairs of mutually independent blood variables, are presented.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04827.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The effects of an initial infection ofGyrodactylus bullatarudison a challenge infection were investigated using guppies,Poecilia reticulala, by terminating the initial infection after 1 or 2 weeks and immediately reinfecting the fish. Establishment success, mean parasite population size, peak parasite burden, time to peak burden and duration of the infection were all significantly lower in the challenge infections than in the respective initial or control infections. These parameters did not differ significantly between the 1‐ and 2‐week challenge gro

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04828.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY