Seasonal shift in boreal riverine fish assemblages and associated bias in bioassessment

详细信息    查看全文

• 作者：Tapio Sutela ; Teppo Vehanen ; Ari Huusko ; Aki Mäki-Petäys
• 关键词：Electrofishing ; Boreal rivers ; Fish assemblages ; Bioassessment ; WFD
• 刊名：Hydrobiologia
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：787
• 期：1
• 页码：193-203
• 全文大小：
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Freshwater & Marine Ecology; Ecology; Zoology;
• 出版者：Springer International Publishing
• ISSN：1573-5117
• 卷排序：787

文摘

Collated electrofishing data from wadeable riffles of boreal rivers in Finland revealed a substantial shift in the fish assemblage composition, accompanied by a decline in total fish density and a reduction in species richness from early summer to late autumn. As the major changes in fish assemblages, the density of cyprinids decreased sharply from June towards autumn, whereas salmonids peaked in September. These shifts were considered to originate mainly from spawning migrations, fish movements to winter refuge habitat and other temperature-related responses of rheophilic versus eurytopic fish species. Temporal change in fish assemblages induced a prominent variation in the monthly fish-based index values used for bioassessment. The proportion of sampled sites classified as high or good in ecological status within the Water Framework Directive (WFD) based on fish increased from 25.9% in July to 68.3% in October. These results, combined with the observed timing of young of the year (0+) fish recruitment to electrofishing catch, suggest that sampling of fish in boreal rivers for WFD monitoring should be restricted to a considerably shorter period than the prevailing practice in order to avoid temporal bias.