溪流鱼类群落对低水头坝的大小及功能的响应——以皖南山区河源溪流为例

以皖南山区的河源溪流为研究区域, 根据2016年7月和11月两次的调查数据, 在区分土著物种和本地入侵物种的基础上, 初步比较研究了低水头坝的坝上蓄水区和冲刷区鱼类群落的季节动态及所受水坝大小和功能的影响。共采集鱼类24种, 隶属4目10科, 其中土著鱼类13种, 本地入侵鱼类11种。尽管坝下冲刷区的鱼类群落无显著季节变化, 但坝上蓄水区的鱼类群落季节动态显著, 其中11月的鱼类个体数显著高于7月。水坝大小对鱼类群落的影响相对较小, 仅冲刷区入侵鱼类群落结构随水坝大小显著变化; 水坝功能对鱼类群落的影响较大, 蓄水区土著鱼类群落及冲刷区入侵鱼类群落等都随水坝功能显著变化——同蓄水坝相比, 引渠坝的蓄水区中宽鳍鱲较少但中华花鳅和吻虾虎鱼较多, 且引渠坝的冲刷区中高体鳑鲏和泥鳅具有更高多度。研究表明, 在研究区域内, 低水头坝对鱼类群落分布的影响视水坝蓄水功能而不同, 而水坝大小的相对重要性较低。研究也进一步证实, 因亲流性土著鱼类与广布性入侵鱼类对低水头坝干扰的响应不同, 在开展有关人类活动对溪流鱼类多样性的影响评价时, 有必要区分土著物种和入侵物种来进行, 以确保研究结论的科学性。

RESPONSE OF STREAM FISH ASSEMBLAGES TO THE SIZE AND FUNCTION OF LOW-HEAD DAMS: A CASE STUDY IN THE HEADWATER STREAMS OF THE WANNAN MOUNTAINS

It has been discovered that low-head dam could impact local habitat conditions, and alter fish assemblages in streams. However, how fish assemblages respond to the size and function of low-head dams is still not clear. Based on the data collected from 15 impounding segments upstream and 15 plunging areas downstream of low-head dams in the Wannan Mountains at July and November 2016, respectively, we examined how habitat factors and fish assemblages varied seasonally, and the differences in their response to dam size and function. Furtherly, after classifying the collected samples into two types (indigenous species and native-invasive species), we determined whether the indigenous fishes and native-invasive fishes were different in their responses to dam disturbance. A total of 24 fish species representing four orders and ten families were collected, including 11 indigenous species and 13 native-invasive species. Although fish assemblages in the plunging areas did not vary seasonally, the assemblages in the impounding areas was significantly different between July and November, where fishes were more abundant in November than in July. Only the assemblage structure of native-invasive fishes in the plunging areas was influenced by dam size. However, both native fish assemblages in the impounding areas and native-invasive fish assemblages in the plunging areas showed difference in their response to the between-dam-function, suggesting that dam function was more important in impacting fish assemblages than dam size. Compared to those associated with the impounding dams, the irrigating dams had less Zacco platypus but more Cobitis sinensis and Ctenogobius spp. in the impounding areas, and more Rhodeus ocellatus and Misgurnus anguillicaudatus in the plunging areas. In addition, the response of the whole fish assemblages (including both indigenous and native-invasive species) to dam disturbance was similar to the indigenous fish assemblages, instead of the native-invasive fish assemblages. Our results suggest that, in this study area, dam function was more important in influencing local fish assemblages than dam size. Due to their potential differences in response to dam disturbance for the indigenous species and native-invasive species, it is necessary for us to distinguish these two types of species when we assess how anthropogenic activities affect fish diversity in streams.