Effects of land use on the β-diversity of fish assemblages in subtropical headwater streams, China

Land use related to human activities poses a serious threat to aquatic ecosystems and biodiversity, especially in headwater streams. However, uncertainty about how land use affects stream fish diversity may be detrimental to practising effective conservation. This study investigated two neighbouring headwater streams of similar size with different surrounding land use intensities (the less-disturbed Shuxi Stream and the heavily disturbed Maxi Stream) of the Qingyi River in China. We assessed the effects of land use on the beta-diversity of stream fishes by comparing the fish assemblages in the two streams. The results showed that the Maxi Stream displayed higher habitat and assemblage structure heterogeneities than the Shuxi Stream. Taxonomic and functional beta-diversities were significantly higher in the Maxi Stream than in the Shuxi Stream, possibly due to the greater spatial autocorrelation and agricultural land use intensity in the Maxi Stream. Neither urban nor garden land use nor habitat conditions were associated with beta-diversity owing to the low corresponding land use intensities and the lack of hydrochemical measurements. Our results suggest that land use types adjacent to streams directly affect habitat conditions and fish diversity. Protection and recovery of riparian zones may mitigate the effects of agriculture on fish assemblage structures in subtropical headwater streams.