Sediment bacteria in Lugu Lake

Understanding biodiversity patterns and the role of
biotic attributes in governing these patterns remains one of the most important
challenges in ecology. Here, taking water depth in Lake
Lugu as a typical geographical gradient, we
studied how these different taxa, that is bacteria, diatoms and chironomids, respond
to the same depth and environmental gradients using molecular and morphological
methods. We further evaluated the relative importance of water depth, environmental
variables and biotic attributes in explaining biological characteristics, such
as biomass, species richness and community composition. The biomass of
chironomids and the richness of bacteria and chironomids both showed a nonlinearly
decreasing pattern associated with water depth, while biomass and species
richness of diatoms showed U-shaped and hump-shaped patterns, respectively. The
three taxonomic groups all showed increasing dissimilarity with water depth changes,
and there was clear cross-taxon congruence among the variations in community
composition. Abiotic variables were pivotal in structuring biological
characteristics; however, the biotic attributes also explained a unique portion
of their variations. This suggests that biotic interactions significantly
influenced the patterns of biomass, species richness and community compositions
along the water depth gradients for the three taxonomic groups studied. Our
results provide new evidence that biotic attributes could help in predicting the biodiversity
of aquatic communities along geographical gradients, such as water depth gradients.