长江中上游干流鱼类多样性与外来种入侵对群落结构的影响

Species diversity of fishes in the middle and upper reaches of the Yangtze River and impact of exotic invasions on fish communities

摘要:

目的 确定长江鱼类多样性变化的驱动因素。方法 通过野外调查结合文献资料，分析长江干流鱼类群落多样性指数和群落结构，比较历史和现今两个时期鱼类群落系统发育的α、β多样性指数的变化。结果 现今长江干流土著鱼类174种，隶属于92属22科9目。现今较历史时期，长江干流土著种减少47种，特有鱼类减少27种，入侵种增加11种。长江中游与上游干流鱼类群落组成具有明显差异性，上游干流鱼类群落生物多样性高于中游，群落分歧主要为43个物种贡献。从历史到现今，所有物种和土著种α水平的平均分类学差异性指数 (∆⁺) 增加，分类学差异性变异指数(⋀⁺)值差异减小，土著种的丢失，造成群落α多样性差异变小。中游与上游干流群落β多样性变化明显，变化过程主要由群落嵌套驱动。中游与上游干流鱼类群落系统发育分类学差异性指数(β_sor.phy)由0.290到0.314的变化，以群落嵌套β_sne.phy由0.054到0.085的变化为主要贡献，土著种变化不明显，外来入侵种的获得，导致群落分类群单元变化，增加了群落系统发育β多样性的差异值。结论 长江干流土著种的丢失和外来种的入侵，改变了鱼类群落的时空格局，人类活动和生境变化显著地影响了长江干流鱼类群落系统发育多样性。

关键词:鱼类;群落结构;生物多样性;物种入侵;长江

Abstract:

Fish species diversity is rich across the Yangtze River basin, but fishery catches are rapidly increasing in the past decades, and declining fish biodiversity poses risks for fishes resources. However, the degree of reduction in fish diversity and the change-drove factors of fish communities in the Yangtze River are still unknown. The data from the investigation and the retrieved literature were analysed the diversity and structure of the fish community to explore the driving factors of fish diversity change and measure the change degree of fish diversity in the Yangtze River. Meanwhile, compared α and β diversity changes of fish communities at species and phylogeny levels during historical and current periods were analyzed. The results showed that 174 species, belonging to 92 genus, 22 families, and 9 orders were found in the main channel of the Yangtze River to date. Compared to the historical period, 47 native species and 27 endemic species decreased, but 11 invasive species increased in the current period. The diversity of fish community in the upper stream was significantly higher than that of the middle (P<0.05), and 43 species contributed to the diversity rates of community construction. All species and native species showed that the average taxonomic distinctness increased from history to the current at the α level, but the taxonomic distinct diversity decreased, and the loss of native species resulted in a decrease in community diversity. The β_sør values of the upper and middle communities showed significant changes at the β level, which was driven by β_sne. The β_sne.phy that changed from 0.054 to 0.085 mainly contributed to the changes of β_sor.phy between the upper and middle communities from 0.290 to 0.314 at the phylogenetic β level. The β_sor.phy for the native species did not change significantly, and the acquisition of exotic invasive species gave rise to changes in community taxonomic units, further resulting in significant changes between communities at the phylogenetic β level. By comparing the changes in fish diversity between historical and current periods, it suggested that the loss of indigenous species and the invasion of alien species had changed the spatial and temporal patterns of fish communities and significantly affected the phylogenetic diversity of fish communities, which was expected to provide theoretical support for ecological restoration in the Yangtze River.

Key words:fish;community structure;biology diversity;invasive species;the Yangtze River