Exploring Great Lakes benthoscapes: can we visually delineate hypoxic habitats?

Benthic macroinvertebrate communities are useful indicators for biological assessment of environmental and anthropogenic stressors, but our ability to quantify benthic populations is constrained by small spatial scales of traditional grab sampling and labor-intensive processing. During the 2019 assessment of Lake Erie’s benthic community we studied lake benthoscapes by enhancing the traditional collection of grabs at 68 stations with underwater imagery, water quality, and sediment nutrients data. Four major habitats were identified from video data including Dreissena aggregations, Hexagenia burrows, and biogenic structures (“chimneys” and “tubes”). All four habitats differed in near-bottom dissolved oxygen (DO) concentration, with the highest DO found above dreissenids and the lowest in chimney habitats. DO, turbidity, and chlorophyll concentration provided the largest contribution to the MaxEnt model and predicted benthoscape distribution. There was a significant separation of benthic species by selected benthoscapes confirmed by independent cluster analysis. Suitable habitat for Dreissena was limited to normoxic areas, and Hexagenia habitats to the western basin. The central basin, subject to summer hypoxia, was mostly characterized by tube and chimney habitats. The agreement among biological, video, and abiotic data confirmed that video analysis can provide a novel, quick, and reliable method to detect benthic habitats affected by periodic hypoxia.