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Using benthic assessment tools to evaluate ecological impacts of seasonal hypoxia in Pensacola Bay
Citation:
Paul, J., M. Duvall, B. Jarvis, AND J. Nestlerode. Using benthic assessment tools to evaluate ecological impacts of seasonal hypoxia in Pensacola Bay. CERF 2021 Biennial Conference, Virtual, November 01 - 11, 2021.
Impact/Purpose:
This is an invited presentation to the CERF 2021 conference session "Mud, Macrofauna and Microbes: an Ode to Benthos IV", organized to identify and fill knowledge gaps concerning ecology of benthic sediment habitats in coastal and estuarine systems. This session explores benthic interactions through interdisciplinary research and should be of interest to scientists from physical, chemical, biological, and computational disciplines. The audience that would be interested in this presentation will include conference attendees (scientists and managers) from across the nation. This virtual conference content will be available to registered conference attendees for 6 months following the conference (through May 2022).
Description:
Seasonal hypoxia (DO < 2 mg L-1) is among the leading stressors affecting estuaries and coastal ecosystems. Assessment tools that integrate habitat condition over biologically meaningful time periods are valuable to resource managers. Thus, the objectives of this study were to evaluate 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), an estuary along the northern Gulf of Mexico coast, to evaluate impacts of intermittent hypoxia on benthic habitat condition. A transect comprised of eight stations was established across the salinity gradient between the Escambia River to the Gulf. Stations were sampled monthly from May to November in 2016 and 2017 for water quality, sediment, and benthic invertebrates. We observed near-bottom hypoxia at every station at least once between June and August, with the most persistent hypoxia observed near the middle of the estuarine salinity gradient. Substrate in the estuary transitioned from 100% sand to ~75% silt at the middle estuary stations and 100% sand at the station nearest the Gulf. Index scores trended toward better habitat condition with increasing salinity, with the lowest scores observed in the middle of the estuary. However, sensitivity of the US M-AMBI was not adequate for separating sites that experienced intermittent hypoxia. The results of this study are a step toward validating the use of these assessment tools to quantify effect of water quality on benthos in a Gulf coast estuary.
