摘要:

Effects of particle size, fish size and temperature on the filtration rate of silver carp were determined. When feeding at 20°C on zooplankton and spherical particles (yeast, micronic beads and pollen), 32‐g silver carp filter particles larger than 70 urn at a maximum rate of 18.251 h−1. For particles smaller than 70 μm, filtration rates decrease with decreasing particle size until there is no measured filtration for particles smaller than 10 μm. Filtering rates (FR) for particles between 10 and 50 μm are described by the equation,FR=−20.8 + 21.7 × log particle diameter. Filtration rates rise as fish size, particle size and temperature increase. Filtration rates per unit biomass, however, fall as fish size increases:FR= 1.54 W0.713, whereFRis the maximum filtration rate in1h1fish1andWis weight of fish in grammes. The results of these trials are consistent with the hypothesis that particle selection by silver carp is a mechanical, passive function of gill raker

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03366.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Danish rainbow trout,Salmo gairdneriRichardson, (40–65 g) were transferred to 28%o sea water at intervals throughout the early spring and summer. Gill Na+/K+‐ATPase of fish kept in fresh water surged distinctly during May. Simultaneously, a body silvering occurred and plasma concentrations of Cl−, Na+and total thyroxine (T4) decreased. The seawater transfer‐induced adaptive response in plasma electrolytes comprised a biphasic change, i.e., an adjustive peak phase and a regulatory phase lasting for 2 days and 1 week after transfer, respectively. Further, gill Na+/K+‐ATPase activity increased to a new level after an initial lag phase of 2–3 days, but electrolyte regulation was mostly initiated prior to the adaptive change in ATPase activity. In spite of increasing pre‐transfer freshwater Na+/K+‐ATPase activity during the spring, the electrolyte peak level, the degree of muscle dehydration and the mortality of fish transferred to sea water increased from April to July. The apparent uncoupling of freshwater Na+/K+‐ATPase activity and plasma electrolyte regulation in sea water is discussed in relation to smelting and prediction of hypo‐osmoreg

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03367.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Eosinophilic granule cells (EGC) are reported among peritoneal exudate cells (PEC) of unstimulated and carrageenan‐, zymosan‐, latex‐ andAeromonas hydrophila‐stimulated eels,Anguilla australis. At the light microscopy level EGC are large (<50 μm diameter) and have strongly to moderately basophilic cytoplasm, eosinophilic granules, and often striated colourless cytoplasmic inclusions. Ultrastructurally, the cytoplasm is rich in ribosomes, and contains characteristic granules, parallel tubular structures 46–50 nm in diameter, and parallel rod‐like arrays (PRLA) 14–15 nm in diameter that are angular or hexagonal in cross section. EGC contain granule‐associated, partially or completely cyanide inhibited, but azide and aminotriazole resistant, peroxidase, acid phosphatase, esterases and weak cytoplasmic periodic acid‐Schiff positivity. PRLA lack enzyme content. A few (<10%) unstimulated and carrageenan‐ and zymosan‐stimulated EGC contain granule‐associated and diffuse β‐galactosidase, and EGC in eels injected i.p. with filtered carrageenan‐stimulated PEC supernatants show heterogenei

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03368.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The potential impact of sibling cannibalism on the size and population structure of captive populations of Koi carp,Cyprinus carpioL., which were fed only dry foods, was determined. The rate of cannibalism was found to be positively density‐dependent, with the highest rate being recorded at initial stocking densities of 40 larvae 1 (33.3% of the fish had been eaten by cannibals by day 52). Two types of cannibalism could be distinguished: type I, where the head of the prey was rejected once the caudal region of the prey had been progressively ingested; type II, where the prey were caught either head‐first or tail‐first and were ingested completely. The first type was limited to the period from the ninth to the 15th day of rearing, and the second type started on the 18th day. Measurement of the mouth, head and tail allowed the calculation of predicted cannibal ‐prey relationships. The consequences and implications of coeval sibling cannibalism in culture systems are di

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03369.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Rainbow trout were exposed to an episode of artificial soft water at pH 5.4 containing 0.95 mg 1 ‐1 of aluminium for 1 h and gill, skin, body mucus and blood aluminium concentrations were determined. Skin and blood showed no significant increase in aluminium content, whereas whole gill tissue and body mucus showed significant increases. The results are discussed in terms of the gill and body mucus being major sites of aluminium absorption, and a tentative mechanism for aluminium absorption is discusse

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03370.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The four paired gill arches of the South American lungfishLepidosiren paradoxacontain single branchial arteries directly connecting dorsal and ventral arteries. In gill arches 3 and 4 the branchial arteries also supply looped arlerioles and capillaries to much‐reduced gill filaments. Regulation of blood between these routes is thought to be by alteration of vascular resistance. Within the filaments, extensive subepithelial capillary networks and numerous small pumps connect lymphatic vessels in the central connective tissue compartment with venules which, in turn, drain to paired branchial veins.The features of the endothelium of many of the filament blood vessels suggest extensive transporting, haematolytic and granulopoeitic functions. Large numbers of macrophages pack the connective tissue. Many contain extensive quantities of haemosideri

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03371.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Factors affecting male reproductive success were investigated in a natural population ofPadogobius martensi, a small freshwater goby showing paternal care. Males were found to be polygynous and their mating success was related both to their body length and to the size of the nest occupied. Body size was a good predictor for the presence of eggs in the nest. The number of egg batches guarded by a male was highly correlated with the area of his nest. Mature males with a total length of 48 mm or less (1‐year‐old individuals) occupied nest sites in breeding areas but were never found with eggs in their nests. The components of sexual selection which may determine the variance in mating success are discus

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03372.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Goldfish acclimated for minimum periods of 3 weeks to 5, 15, 25 and 35°C exhibited significant changes in circulating leucocyte types and numbers. Total leucocyte, lymphocyte, neutrophil and eosinophil levels increased significantly between 5 and 25°C, as did their relative contributions to the total leucocyte population. Thrombocyte and blast cell counts increased non‐significantly, while variations in monocyte and basophil levels were inconsistent. Between 25 and 35° C, lymphocyte numbers fell sharply, while neutrophil concentrations remained essentially constant as did those of thrombocytes. Response to an intraperitoneally administered mitogen, phytohaemagglutinin, was delayed and reduced at 5° C compared with

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03373.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Mortality of 0+ Eurasian perch was measured directly from the decline in catch in a high‐speed plankton sampler and described by a negative exponential model. A mean mortality of 0.063 day1(range=0.020–0.089) was calculated; for 0+ juveniles it was 0.021 day1. Mean larval production was 0.85–1.30 mg dry weight m−2day−1in Loch Kinord and 0.08–0.12 in Loch Davan. Annual production of 0+ juveniles was 1.97–7.55 kg wet weight ha−1at L. Kinord and 1.01 kg at L. Davan. The contribution of 0+ perch, including the egg stages, to total perch production was 88–96%. Availability of food items on transition to exogenous feeding and through the larval period did not limit survival. Cannibalism by adults accounted for most of larval mortality, and predation by pike and adult perch were responsible for the majority of juvenile losses. The population structure of adult perch, for 12 year classes, was stable at L. Kinord, while year classes at L. Davan exhibited fluctuations in abundance and in two sampling years were eliminated in the first summer. Survival in the eleutheroembryonic phase was variable at L. Davan and observed to be low compared with L. Kinord. It is suggested that this was a result of water turbulence on the exposed and shallow spawning

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03374.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The roles of five different dietary fibres (cellulose, agar, guar gum, carrageenan and carboxy‐methylcellulose) each as 10% wt/wt added into the diet, affecting the intestinal sugar absorption, blood sugar level and utilization of dextrin were studied in hybrid tilapia,Oreochromis niloticus × O. aureus; dextrin and glucose were also included in the study as controls for comparison. There were seven dietary groups: each diet was fed to three aquaria each containing 15 fish. The experiment was carried out in a closed circulation, filtered, rearing system for 2 months. The results indicated that the weight gain percentage and food conversion ratio were significantly (P<0.05) lower in tilapia fed fibre‐containing diets than those of tilapia fed dextrin or glucose diet. The intestinal absorption of carbohydrate and the blood sugar content of tilapia were low when diets contained fibre, regardless of the so

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03375.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY