Preliminary investigation of benthic macroinvertebrates as indicators of environmental gradients and land-use influences in a subtropical stream

The spatial and temporal variation patterns of benthic species have received global attention due to their important role in conserving river biodiversity and maintaining environmental sustainability. Upon analyzing 1-year macroinvertebrate data from five sampling sites (A, B, C, D, and Z) along the river, from the upper reaches to the lower reaches, we were able to evaluate the spatial and seasonal variations in the macroinvertebrate community structure and examine the influences of river environmental factors on macroinvertebrate composition within the Lai Chi Wo (LCW) catchment in Hong Kong, China. The results revealed significant seasonal variations in macroinvertebrate richness between the wet season and the dry season. Among different sites, the macroinvertebrate community structures at sites B (middle reach without farming influence) and C (one upstream tributary) were similar, while the structure at site D, affected by seawater intrusion, differed from the others. Moreover, Diptera and Ephemeroptera were found to be the dominant taxa in LCW, and water depth and water conductivity were identified as the most important environmental factors in controlling the distribution of macroinvertebrates. This preliminary study offers valuable baseline insights into the spatial and seasonal variations of macroinvertebrate community structure within the LCW catchment, underscores the role of key environmental factors, and highlights the potential influence of land-use. The findings establish a foundation for future research and could be beneficial for the development of effective management strategies aimed at conserving macroinvertebrate biodiversity in subtropical stream ecosystems.