黄山陈村水库上游河源溪流的鱼类群落及其纵向梯度格局

确定鱼类群落的分布格局及其对人类活动的响应,是合理保护、恢复和管理鱼类多样性的基础。基于2011年5月和10月自黄山陈村水库上游3条河源溪流共39个样点的调查数据,比较研究了溪流间鱼类群落及其纵向梯度格局的异同,着重探讨了人类活动对溪流鱼类群落纵向梯度格局的影响。研究结果显示,同人为干扰较轻的舒溪相比,人为干扰严重的浦溪和麻溪中水宽、底质和植被覆盖率等局域栖息地条件显著变化,这造成了后者的鱼类多样性显著下降及物种组成的显著变化,主要表现为敏感性的地方物种(如宽鳍鱲、光唇鱼、原缨口鳅等)数量减少、耐受性的广布物种(如泥鳅、麦穗鱼、高体鰟鲏等)数量增多。舒溪的鱼类物种数及其组成均与海拔显著相关,但这种"海拔-鱼类群落"关系在麻溪和浦溪中削弱甚至消失。底质、植被覆盖率对舒溪鱼类群落具有重要影响,但对浦溪和麻溪鱼类群落却无显著影响。研究结果表明,在子流域空间尺度上,诸如城镇化发展、土地利用、河道治理等人类活动可通过对局域栖息地条件的影响,导致溪流鱼类多样性下降及其物种组成的变化,破坏鱼类群落的纵向梯度格局,并改变栖息地与鱼类群落之间的联系。

Fish assemblages and longitudinal patterns in the headwater streams of the Chencun Reservoir in the Huangshan Area

Studying the spatial and temporal patterns of stream fish assemblages and identifying how human land-use activities impact these patterns are crucial for fish species conservation, ecosystem restoration and management. The objectives of this study were (1) to examine the influences of human perturbations on the longitudinal patterns of fish species diversity and assemblage structures in headwater streams, (2) to assess the correlations between local habitat factors and fish assemblages, and their longitudinal and temporal patterns. We sampled fish at 39 segments during May and October 2011 from three headwater streams of the Chencun Reservoir in the Huangshan Area, which were influenced by different extents of human activities. A total of 4041 fish were collected, representing four orders, 10 families, and 28 species, among which family Cypriniformes comprised 67.9% of total species richness. 24, 22 and 24 species were sampled from the Shuxi, Puxi and Maxi Streams, respectively. Two-way ANOVA was used to test the influences of streams and seasons on habitat and fish-diversity variables, respectively. Results showed that habitat variables varied significantly across three streams and in different seasons. Results from the Shuxi Stream showed lower numbers in dissolved oxygen and wetted width but higher levels in substrate size and canopy cover than those from the Puxi and Maxi Streams, and May showed lower pH but higher water temperature and discharge than October. However, species richness, fish abundance and the Shannon''s index varied significantly across streams but not between seasons. In overall, fish diversity was higher in the Shuxi Stream than that in the Puxi and Maxi Streams. Results of two-way crossed ANOSIM indicated that fish assemblage structures varied substantially across streams but not between seasons. The assemblage structures in the Puxi and Maxi Streams did not show significant differences, however, they significantly differed from those in the Shuxi Stream. SIMPER analysis indicated that some endemic specialized species (e.g., Zacco platypus, Acrossocheilus fasciatus, Vanmanenia stenosoma) were more abundant in the Shuxi Stream, while those cosmic generalized species (e.g., Misgurnus anguillicaudatus, Pseudorasbora parva, Rhodeus ocellatus) were more in the Puxi and Maxi Streams. The results of Pearson''s correlation and redundancy analysis showed that fish species richness in the Shuxi Stream significantly increased with elevation decreasing in both May and October, respectively. However, this "species richness-elevation" correlation lessened in the Maxi Stream and even disappeared in the Puxi Stream. Similarly, elevation showed significant correlation with assemblage structures in the Shuxi and Maxi Streams but not the Puxi Stream. In addition, the effects of local habitat variables on fish assemblage structures were examined using linear regression model and redundancy analysis, respectively. Results showed that fish assemblages in the Shuxi Stream were significantly affected by substrate and canopy, but those in the Puxi and Maxi Streams were related to water temperature and wetted width. In conclusion, our results suggest that, at the sub-watershed scale, the alteration of local habitat conditions in headwater streams associated with human activities (e.g., urbanization, land-use and river-regulation) may decrease stream fish diversity, modify the correlations between local habitat and fish assemblage, and change the longitudinal pattern of fish assemblages.