Watershed land-use heterogeneity affecting spatial patterns of fish community structure in Han River basin, China

Abstract

Freshwater ecosystems face serious degeneration risks from anthropogenic activities, among which land use heterogeneity transformation is one of the main threats on aquatic biodiversity. However, the mechanisms by which land use heterogeneity affects fish community structure in aquatic ecosystems are still difficult to determine. The results of this study showed that we detected a total of 164 fish species during two seasons, with 97 fish species belonging to 15 orders, 31 families and 74 genera in dry season and 138 fish species belonging to 14 orders, 40 families and 98 genera in wet season. The intergroup differences between the upstream, midstream and downstream of the basin in dry season were smaller than those in wet season, and the species richness in wet season were higher than this in dry season. The values of β-diversity between the upstream and midstream regions was greater than downstream in dry season. The value of β-diversity between upstream and downstream regions was larger than in the midstream in wet season. It concluded that the β-diversity values were generally smaller in wet season than in dry season. Land use types on both sides of the Han River basin are mostly cropland, forest land and man-made surfaces. The results of calculating LUI and fish life history characteristics showed a greater correlation between K and M values in the dry water period and a greater correlation between PD50 and longevity in the rich water period. Moreover, we calculated the correlation between the land use index (LUI) and β-diversity NMDS values, respectively, showed a significant positive correlationship (0.712 in dry season; 0.742 in wet season). This research (a) obtained the spatial and temporal distribution of α-diversity and β-diversity data of fish in the whole basin using eDNA technology; (b) analyzed the relationship of land use heterogeneity on fish life history characteristics; and (c) revealed the correlation between land use index and β-diversity communities. Overall, this study can provide data support and theoretical basis for integrated watershed ecosystem management, and provide suggestions for environmental protection and management around the watershed.