Citation:

Paul, J., J. Nestlerode, B. Jarvis, AND G. Cicchetti. Monitoring habitat condition with marine benthic indices: M-AMBI and Sediment Profile Imaging in the Gulf of Mexico. Research Area Coordination Team (RACT)--SSWR.401. Watershed Assessment meeting, virtual, FL, April 15, 2024.

Impact/Purpose:

We present an overview of the application and interpretation of sediment profile imagery (SPI) across the Pensacola Bay estuary in areas experiencing varying degrees of low dissolved oxygen stress. We evaluate the time scales over which SPI endpoints and the BHQ index respond to DO in the days and weeks prior to sampling and compare to the M-AMBI calculated from abundance data. We also discuss ecological considerations for the components of SPI endpoints based on the benthic community composition and how those may influence the observed index scores. This presentation should be of interest to SSWR RACT members concerned with monitoring and management of estuarine habitats as it may inform the future use and application of taxonomic-based benthic indicators and water quality monitoring tools for describing ecosystem condition and impacts of aquatic stressors. This invited talk was presented by JSP to an internal (EPA-only) audience at the Spring 2024 Research Area Coordination Team (RACT)-SSWR.401. Watershed Assessment meeting.

Description:

Benthic rapid assessment tools are needed to close the gap between sample collection and analysis so managers can better evaluate ecological response to management actions and environmental conditions. Sediment profile imaging (SPI) captures the top centimeters of sediment in cross-section images which are scored for benthic faunal and biogeochemical features. Although SPI does not allow for species-level identifications, it gives an estimate of benthic ecological status and reduces the time and cost of surveys. Use is impeded by limited information on how SPI image features relate to benthic fauna of the Gulf of Mexico and response to low dissolved oxygen conditions compared to traditional metrics. Using Pensacola Bay, FL as a case study, we evaluate the time scales over which SPI endpoints and BHQ index respond to DO in the days and weeks prior to sampling and compare to the M-AMBI calculated from abundance data. We identified periods of 7 to 31 days as critical windows of exposure prior to a measurable benthic response, and that duration and exposure to low DO as well as recovery periods above 2 mg L-1 as important to benthic habitat condition. The number of burrows and presence of fecal pellets and feeding structures were positively correlated with M-AMBI and exhibited significant relationships to low DO. The BHQ was not a good predictor of hypoxia and not well correlated to M-AMBI indicating the index may need calibration before application in the Gulf of Mexico as epifaunal features are less common in Pensacola Bay than where it was developed. Overall, SPI exhibited agreement with traditional assessment tools and demonstrated value as a rapid assessment technique; yet further research is needed to standardize methods before wide application in the Gulf of Mexico.  

Record Details: