Not all depths are created equal: Deep water algae layers influence zoobenthos in stratified lakes

We investigated the depth distribution of zoobenthos in relation to both abiotic conditions (pH, available light or photosynthetically active radiation, dissolved oxygen, temperature, and conductivity) and biotic factors (turbidity and phytoplankton, estimated fluorometrically) in a small, dimictic mesotrophic reservoir located at the border of the tall grass prairie and eastern deciduous forest ecoregions of the USA. In addition to the expected influence of physiochemical depth gradients, zoobenthos density within the hypolimnion was highly correlated with the presence of a deep chlorophyll maximum (DCM) produced by phytoplankton, primarily the chrysophytic algal Cryptomonas spp. Our results suggest that the DCM enhances hypolimnetic diversity of both benthic and planktonic invertebrates, thereby increasing overall lentic diversity and secondary productivity.