摘要:

Sentinel freshwater mussels(Hydridella menziesi)were immersed in rivers at sites impacted by faecal pollution. The indicator bacterium,Escherichia coli, was recovered from all mussels including those at a forest control site, but concentrations were highest at sites impacted by either treated sewage or treated meat‐processing waste water, or by inputs from dairy farms. The three pathogens sought were recovered from mussels, except those at the forest (control) site:Campylobacter jejuniandCampylobacter coliat treated sewage sites;Salmonella typhimuriumandC. jejuniat treated meat‐processing waste water sites; andC. jejuniandYersinia enterocoliticaat sites impacted only by dairy farms. The FRNA bacteriophage concentration was high in mussels impacted by sewage or sheep‐processing waste water but was low when the input was only from dairy farms. Mussels up to 23 km from a sewage discharge contained a high concentration of FRNA suggesting that there could be a health risk due to viruses, although the water did not exceed recommended guidelines. Pathogens were also sought in untreated waste waters.C. jejuniandC. coliwere recovered from both sheep‐processing and beef‐processing waste waters and the only sewage isolate identified was confirmed asC. coli. Salmonellaspp. were recovered from all waste waters, withS. typhimuriumphage type 135, isolated from a sample of meat‐processing waste water, and from mussels immersed 1 and 5 km down stream of that plant's discharge.Y. enterocoliticawas recovered from most samples of animal waste water. It appears that pathogens are introduced into New Zealand rivers by all major sources of faecal contamination.

ISSN:0028-8330    

DOI:10.1080/00288330.1999.9516862

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Recent studies have led to the recognition ofGalaxias depressicepsand reinstatement ofGalaxias anomalus. The two species maintain near allopatric distributions and it has been suggested that spawning habitat availability, at least partially, controls the distribution of these species. The spawning habitat of each species was determined and an assessment of the influence of spawning habitat availability on the distribution of the two species was carried out. Factors that may have influenced the onset of spawning were also examined. We found thatG. depressicepsselected spawning sites with a high proportion of boulder substrata and nests were found on the underside of or between boulders.G. anomalusspawned within the streambed substrata, under boulders or cobbles, in shallow water and narrow channels relative to the available habitat. Suitable boulder spawning substratum forG. depressicepsin theG. anomalussites was limited and this supports the hypothesis that spawning habitat availability influencesG. depressicepsdistribution. ConverselyG. anomalusspawning habitat was available inG. depressicepsstreams, indicating that spawning habitat limitations are not restrictingG. anomalus. The onset of spawning, for both species, did not appear to be related to daylight, phase of the moon, or stream water level, but all species started spawning as water temperatures rose. The proximity ofG. anomalusspawning sites to the stream edge and their occurrence in poorly consolidated substrata presents two management issues. Water abstraction may expose spawning sites if stream water levels are lowered, and these sites are vulnerable to trampling by stock.

ISSN:0028-8330    

DOI:10.1080/00288330.1999.9516863

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The community structure, density, and biomass of native fish species was determined for first‐ to second‐order streams draining mature pine, native forest, and pasture catchments in seven, North Island, New Zealand, east coast rivers or streams. Multiple‐pass electric fishing was used to determine fish densities, and differences in fish community structure between land uses were detected using non‐metric multi‐dimensional scaling analysis. Species responsible for changes in fish community structure were identified by comparing species densities between land uses. Six fish species occurred commonly within each drainage system and although there was no difference in fish community structure between streams in native or exotic forest, differences occurred between the fish communities of forested and pastoral streams. Pastoral streams contained more shortfinned eels(Anguilla australis), more inanga(Galaxias maculatus), and fewer banded kokopu(Galaxias fasciatus)than forested streams. Fish biomass was also higher in pastoral streams. We concluded that the type of forest (mature exotic pine versus mixed‐species indigenous) had little effect on the native fish populations, but that pasture supported an increased fish density and biomass due mainly to increases in shortfinned eels. There were fewer banded kokopu in pasture than in forested streams, but exotic forest streams contained as many banded kokopu as native forest streams.

ISSN:0028-8330    

DOI:10.1080/00288330.1999.9516864

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor