摘要:

The concentration of hydrogen ions which caused 50% mortality of bluegill in 96 h (96 h LC50) was between pH 3.5 and 3.0 for four acids; sulphuric, nitric, phosphoric and hydrochloric. Therefore, it appears that any contribution by the anions of these acids to fish toxicity is similar. This suggests that the quantity rather than the quality of acids is the primary factor in fish toxicity brought about by acid precipitation.At sublethal concentrations of acids, bluegill became hypoactive with respect to their swimming behaviour.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04859.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Prevalence ofLigula intestinalisinCatostomus commersoniwas followed in four lakes near Algonquin Provincial Park, Ontario from 1963 to 1981. Two lakes remained in the natural state, except for regular sampling, and prevalence of the parasite fluctuated from 0.3 to 3.6% and from 1.5 to 13%. Prevalence was higher in fishes from the other two lakes. Fishes in the latter two lakes were removed with ichthyotoxin during the study. Fishes and parasite subsequently recolonized the lakes. Prevalence of the parasite peaked and then declined during recovery in each of the two lakes. Prevalence of the parasite fluctuated around levels which were unique for each of the four lakes. Differences in the level of prevalences among the lakes were probably most dependent on differences in the morphology of the lake basins.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04860.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Experiments were conducted to determine the adaptability of young catfish,Claria lazera, to various saline concentrations. Young catfish, total length 52–88 mm, were subjected to abrupt and gradual changes from fresh water (salinity = 0.14‰) to various salinities. Ninetyfour per cent survival occurred when the fish were transferred from fresh water to 25% sea water (salinity = 9.5‰ No fish survived higher salinities even through gradual c

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04861.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The digestive tract pH values of the teleost fishOreochromis mossambicus, Carassius auratusandIctalurus punctatuswere determined in fish that were (1) starved, (2) fed herbivorous, omnivorous and carnivorous diets and (3) fed altered pH diets. The digestive tract pH profile was determined throughout an 8 h cycle. The herbivorous or carnivorous nature of the diet did not affect the pH values in any of the species. Significant differences in gut pH values were observed when the fish ingested diets with altered pHs. There was a difference between the starved and baseline fed values inCarassius auratuswhich was not observed in the other species. The pH values in the digestive tracts of the three species varied during the digestive cycle.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04862.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Lamellae in the olfactory organ of the channel catfish,Ictalurus punctatus, Rafinesque, possess delicate cilia on surfaces of sensory and non‐sensory epithelia. A technique is presented for examining the olfactory cilia by scanning electron micrograph

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04863.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The depth limits for visual feeding by pollan larvae and fry,Coregonus pollan, were determined in Lough Neagh, Northern Ireland, by combining laboratory estimates of the minimum light threshold for feeding activity with field measurements of spectral, diurnal and seasonal changes in light penetration. Although feeding thresholds were lowest in the blue light (400–490 nm), the rapid attenuation of this region in the lake meant that the depth limits of feedingin situwere determined by response to the green region (490–595 nm). Effects of changes in irradiance and light penetration on the depth of feeding are considered during a seasonal study. Increased sensitivity, as the juvenile stages develop, may be offset by reduced light penetration due to algal growth. Over an annual period the maximum feeding depth for pollan varied between 2.6 and 4.1 m. In the juvenile stages of two other predatory species from the lake, perch,Perca fluviatilis, and pike,Esox lucius, the corresponding ranges were 1.1–1.9 m and 2.7–4.6 m respe

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04864.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The crypsis hypothesis of salmonid parr coloration and behaviour is evaluated in light of the criteria for protective resemblance. A review of the literature indicates that salmonid parr coloration and behaviour correspond to a cryptic interpretation. Experiments on coho salmon,Oncorhynchus kisutch, parr substrate colour preference indicate that the behavioural correlate of appropriate background choice is satisfied. Absorption spectrophotometry of diapositives of fish and experimental substrates suggests that background matching is achieved through achromatic reflectance and absorption of wavelengths by the silvery sides and parr marks, respectively.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04865.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The effects of several factors on the phagocytic activity of cells isolated from the pronephros of striped bass,Morone saxatilis, were measured using a chemiluminescence (CL) assay. The CL responses of phagocytes to varying concentrations of bacteria, phorbol myristate acetate (PMA), and zymosan were shown to be dose‐dependent. Incubation of phagocytes with PMA resulted in a decrease in cell numbers related to the concentration of PMA used in the assay. Opsonization ofAeromonas hydrophilawith normal pooled bass serum decreased the number of colony forming units present in suspension while enhancing the CL response by striped bass phagocytes. Opsonization of zymosan also resulted in an enhanced CL response.Aeromonas hydrophilaandAerococcus viridanskilled by heat treatment, incubation with formalin, or exposure to UV radiation elicited little or no CL when incubated with phagocyte

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04866.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The effect of seasonal changes on the activity of intestinal alkaline phosphatase was evaluated in two types of fish grown in the Kurshskii bay of the Baltic sea. With the pike perch,Lucioperka lucioperka, higher enzyme activity and optimal temperature of activity were observed in the summer compared to winter, whereas with the bream,Abramis brama, essentially no difference in enzyme activity and in optimal temperature of activity was found between the two seasons. In both fish, the thermal stability of the enzyme and the activation energy of enzyme activity decreased in winter. The different biological nature of the two fish appears to be reflected in the response of the intestinal alkaline phosphatase to seasonal changes.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04867.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Annual rings on the vertebral centra were used to determine age in the sand shark,Rhinobatos annulatus. A 6% silver nitrate solution was applied to the concave surfaces of the vertebrae to clarify the rings. The monthly percentage frequency of opaque and hyaline peripheral rings were used to determine the annual nature of the rings. Both sexes can reach a maximum age of 7 years. Conventional growth curves could not be fitted and empirical curves were used to illustrate growth. Total body length at age was calculated from these curves and compared with observed data.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1984.tb04868.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY