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Bioassessment of a Northwest Florida Estuary Using Benthic Macroinvertebrates
Citation:
Nestlerode, J., M. Murrell, Jim Hagy, L. Harwell, AND J. Lisa. Bioassessment of a Northwest Florida Estuary Using Benthic Macroinvertebrates. Integrated Environmental Assessment and Management. Allen Press, Inc., Lawrence, KS, 16(2):245-256, (2020). https://doi.org/10.1002/ieam.4209
Impact/Purpose:
The objective of this study was to survey benthic communities in Pensacola Bay, describe the current status, and evaluate benthic condition using the a benthic index approach developed for Gulf estuaries (GOM B-IBI). We sampled benthic macrofauna along a transect of Pensacola Bay estuary spanning the salinity gradient and across sites known to experience density stratification and seasonal hypoxia in the bottom layer. We also measured sediment metal concentrations to evaluate possible toxicity based on ER-L and ER-M threshold values. In addition to applying the GOM B-IBI, we also applied the EMAP-E index to our data, an index which has been used to characterize Pensacola Bay in the past, to qualify our results, evaluate the benthic faunal community, and explore factors contributing to the current status. This study provides a valuable update to the literature (e.g., Olinger et al., 1975) describing benthic communities in Escambia and Pensacola Bay, spanning a gradient of both salinity and average exposure to seasonal hypoxia.
Description:
Benthic invertebrate community composition was surveyed across the salinity gradient of the Pensacola Bay Estuary in Florida during summer 2016. Macrofauna densities ranged from 1000 to 9300 individuals m−2, with highest densities occurring at the upper estuary and the lowest in the mid‐ and lower estuary. Taxonomic richness and Shannon diversity were lowest in the upper estuary and increased along the salinity gradient. Small‐bodied, near‐surface infaunal polychaete species (e.g., Mediomastus ambiseta and Paraprionospio alata) dominated the macrofaunal community in fine sediment areas. We calculated the Gulf of Mexico Benthic Index of Biological Integrity for each site and compared the index scores with those from Environmental Monitoring and Assessment Program ‐ Estuaries, an earlier benthic assessment model. Condition evaluations by the different models did not match across all sites in this study; however, scores consistently indicated that most sites were at or near degraded levels, implying that Pensacola Bay represents a marginal habitat for a “healthy” benthic macrofauna community. This study provided new information about the benthic communities and sediments in the Pensacola Bay estuary.
