Fig. 1: Three possible pathways controlling macroinvertebrate biodiversity in Dongting Lake and temporal dynamics of the ecological status of Dongting Lake.

a Three possible pathways. Solid and dashed lines represent direct and indirect effects, respectively. b Six major environmental parameters: human land-use intensity, mean annual temperature, input charge from the Yangtze River, total nitrogen, total phosphorus, and algal bloom intensity. The arrows to the left of the panel represent the important events that might have influenced the ecological status of Dongting Lake. c Annual variation in the species richness of macroinvertebrates. d Annual variation in the functional redundancy. e Annual variation in the taxonomic dissimilarity. f Annual variation in the functional dissimilarity. The dashed lines in (c) and (d) show the gamma diversity for each year. Taxonomic and functional dissimilarity was represented by Bray‒Curtis distances between different sampling sites. The colored envelope surrounding each line represents 95% of generalized additive models.