摘要:

Intra‐ and interspecific differences in pigmentation between finfold larvae of the three most abundant cyprinids in Dutch eutrophic waters, bream, white bream and roach, were studied, using laboratory‐raised larvae in the length range 8–11 mm. Because the internal pigmentation of the larvae has been used for identification, some attention is paid to the effects of different ways of fixation and preservation on transparency. The size and the shape of the melanophores, as described in the literature, could not be used as identification characters because of too much intraspecific variation and the effects of light conditions at the moment of fixation. Three characters proved to be significant for the identification of the larvae of the three species. Roach can be distinguished from bream and white bream by the pattern of melanophores on the belly. A second character is the pigmentation of the ventral aorta, which is only found in white bream. Lastly bream shows an irregular pattern of melanophores on the dorsal side, in contrast to roach which has a regular pa

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb02961.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Redds of trout,Salmo truttaL., Atlantic salmon,S. salarL., and rainbow trout,S. gairdneriRichardson, were studied at sites in north‐east England, south‐west Wales and southern England (Dorset). Spawning females preferred gravels of 20–30 mm diameter and water velocities at 0·6 depth of 15 cm s‐1and

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb02962.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

A study was made of the effects of aLigula intestinalisinfestation on the biology and distribution of gudgeon in Lough Neagh, Northern Ireland. During the summer months, when the majority of the gudgeon population was restricted to the inshore areas of the lough,Ligulawas present in all age (size) classes of the host although levels of infestation were highest in the oldest individuals. While there was no significant effect on the length‐weight relationship of the gudgeon, the presence of the parasite did adversely affect gonad size in both sexes.Ligulaalso influenced the distribution of the gudgeon population by decreasing the swimming depth of infested individuals and by delaying their autumnal migration to the deeper offshore parts of the loug

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb02963.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Using a behavioural assay, the palatability of urea, taurine, betaine and the 20 common amino acids (L‐isomers) to rainbow trout was determined. The trout responded positively only to aqueous solutions of leucine, isoleucine, proline, phenylalanine, tryptophan, methionine, glutamate, arginine, taurine and urea. Proline, the most effective compound, was active at 10‐4m but not 10‐5m. Palatibility was not directly related to test solution pH; concentration and molecular structure apparently played a greater role. There is good, though not perfect, agreement between the behavioural results obtained here and published electrophysiological data on the palatal sensitivity of rainbow trout to these subst

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb02964.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb02965.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY