摘要:

While measuring egg distribution of the intertidally spawning galaxiid fish,Galaxias maculatus, some noticeably larger eggs (1.86–2.2 mm diam.) were seen. In common with the smallerG. maculatuseggs (1.18–1.5 mm diam.), these eggs peaked in abundance at 300 mm above normal water level. The two sizes of eggs were distributed differently along a 1 m length of stream bank. A sample of the larger eggs was hatched and reared in the laboratory. They proved to be the eggs ofGalaxias fasciatus, a forest‐stream dwelling species not normally found as adults in the intertidal zone.

ISSN:0028-8330    

DOI:10.1080/00288330.1991.9516471

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Literature pertaining to sediment in stream ecosystems is reviewed. Suspended sediment can alter the water chemistry, and cause temperature decreases and turbidity increases. Deposition of sediment may change the character of the substrate, block interstices, and reduce interstitial volume. Turbidity levels as low as 5 NTU can decrease primary productivity by 3–13%. An increase of suspended sediment levels increases the drift fauna and may reduce benthic densities as well as alter community structure. Fish are not so obviously affected, although death resulting from clogging of the gills may occur in sensitive species. Suspended and deposited sediment may alter fish community composition, both by interference with nin‐riffle‐pool sequences and by favouring olfactory feeders over visual feeders. In many situations aesthetic reactions to suspended sediment may be of more concern than biological ones. In already turbid water, a 20–50% reduction in clarity may not be detectable whereas in normally clear water a clarity reduction of 10–15% is distinguishable. Recovery from the effects of suspended sediment and sediment deposition is usually rapid, once the source of contamination is removed and as long as the stream is prone to regular spates; the aesthetic recovery may only take days whereas biological recovery may take months.

ISSN:0028-8330    

DOI:10.1080/00288330.1991.9516472

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:0028-8330    

DOI:10.1080/00288330.1991.9516473

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor