Insights from 15 years of benthic infaunal monitoring in a coastal lagoon system

Abstract

Benthic infaunal communities are important indicators of environmental change because they are comprised of organisms with limited mobility that respond rapidly to stress. As part of the Comprehensive Everglades Restoration Plan to restore natural water flows across the Florida peninsula, infaunal communities have been monitored since 2005 in relation to changing water quality and sediment characteristics at 9 sites in the southern Indian River Lagoon (IRL) and St. Lucie Estuary (SLE). Abiotic and biological differences separated the sites into 3 zones, with salinity and the abundance of fine-grained sediments emerging as major drivers of infaunal abundance, species richness and distribution. Degraded communities in the middle SLE were populated by opportunistic and pollution-tolerant taxa, while communities in the southern IRL were abundant and biodiverse. A total of 76 taxa and one-third of all infauna were lost across the three zones in 2016 and 2017, which was likely caused by harmful algal blooms and discharges of sediment and nutrient laden inland freshwater following an El Nino event and Hurricane Irma. This study highlights the importance of long-term monitoring to inform adaptive management practices and lays the groundwork for further analyses to understand how natural and anthropogenic stressors affect this dynamic system.