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Using benthic assessment tools to evaluate ecological impacts of seasonal hypoxia in the Northern Gulf of Mexico
Citation:
Paul, J., M. Duvall, B. Jarvis, AND J. Nestlerode. Using benthic assessment tools to evaluate ecological impacts of seasonal hypoxia in the Northern Gulf of Mexico. 2022 Joint Aquatic Sciences Meeting (JASM), Grand Rapids, MI, May 14 - 20, 2022.
Impact/Purpose:
This presentation will be given by Dr. Jenny Paul (ORISE) to the 2022 Joint Aquatic Sciences Meeting (JASM) under the theme "Rapid Changes ¿ Collaborative Solutions" and describes the application of the US M-AMBI (multivariate AZTI marine biotic index, derived from macrobenthic community measures) and the BHQ (Benthic Habitat Quality index, derived from sediment profile images), in Pensacola Bay (Florida), to evaluate impacts of intermittent hypoxia on benthic habitat condition. This conference will highlight collaborative research to address common aquatic environmental problems from an ecosystem perspective that delivers actionable results which support science-based solutions. The audience that is expected to be interested in this presentation will include conference attendees (scientists and managers) from across the spectrum of the Consortium of Aquatic Science Societies (CASS), which includes nine international society members. The conference content will be made available both in-person and on-demand (virtually) to registered conference attendees. https://jasm2022.aquaticsocieties.org/call-for-abstracts/
Description:
Seasonal hypoxia (DO < 2 mg L-1) is a leading water quality concern for estuaries and coastal ecosystems. It occurs when stratification of freshwater over saltwater limits oxygen availability to the bottom layer. Benthic assessment tools that detect the impacts of oxygen stress are important for managers and decision makers. Thus, our objectives were to evaluate two distinct indices in the northern Gulf of Mexico: the US M-AMBI (multivariate AZTI marine biotic index, derived from macrobenthic community measures) and the BHQ (Benthic Habitat Quality index, derived from sediment profile images); assessing their sensitivity to intermittent hypoxia. A transect comprised of eight stations was established in Pensacola Bay, FL across the salinity gradient between the river and the Gulf. We sampled monthly May to November in 2016 and 2017 for water, sediment, and macroinvertebrates. We observed near-bottom hypoxia at every station and was most pronounced near the middle of the salinity gradient, while the highest and most stable DO was observed near the Gulf. Generally, index scores trended toward better habitat condition with increasing salinity, with the lowest scores observed near the river where hypoxia was. The BHQ index was the most sensitive to changes in dissolved oxygen compared to M-AMBI, however both indices suggest the most degraded benthic habitat is not necessarily where hypoxia was the most severe. These results are a step toward validating the use of these assessment tools in a northern Gulf coast estuary.
