Re-examining Temporal and Spatial Variation of Benthic Invertebrate Biodiversity in Lake Maurepas, Louisiana, USA, Forty Years Later

Lake Maurepas, an oligohaline embayment in southeastern Louisiana, USA, lies on the westernmost edge of the socio-ecologically important Lake Pontchartrain Basin, a region with a history of hydraulic fossil shell dredging and water pollution. Relative to the nearby Lake Pontchartrain, our knowledge of the invertebrate community in Lake Maurepas is limited. The most recent record of benthic invertebrate community data was collected between 1983 and 1984. We aim to establish an updated baseline dataset on the spatial and temporal variability of the invertebrate community within Lake Maurepas, and compare our findings with those from 1984, using the same petite ponar grab dredging methodology. While species richness is similar between the two sampling projects, we observed higher species abundance and a distinct species composition in 2024 than in 1984. We observe temporal patterns in 2024 invertebrate species abundance and community composition, which are driven by oligochaetes, midge larvae, Helobdella leeches, and Probythinella mud snails, whereas the 1984 study showed no comparable seasonal trends. Contrary to the 1984 study, saltwater species were rarely collected in 2024. Our findings provide baseline information on invertebrate diversity and abundance in Lake Maurepas, describe changes that have occurred over the last 40 years, and identify potential bioindicator species, which is important considering anthropogenic impacts on the lake.