Defining the sediment microbiome of the Indian River Lagoon, FL, USA, an Estuary of National Significance

Abstract

AbstractThe Indian River Lagoon, located on the east coast of Florida, USA, is an Estuary of National Significance and an important economic and ecological resource. The Indian River Lagoon faces several environmental pressures, including freshwater discharges through the St. Lucie Estuary; accumulation of a anoxic, fine-grained, organic-rich sediment; and metal contamination from agriculture and marinas. Although the Indian River Lagoon has been well-studied, little is known about its microbial communities; thus, a two-year 16S amplicon sequencing study was conducted to assess the spatiotemporal changes of the sediment microbiome. In general, the Indian River Lagoon exhibited a microbiome that was consistent with other estuarine studies. Statistically different microbiomes were found between the Indian River Lagoon and St. Lucie Estuary due to changes in porewater salinity causing microbes that require salts for growth to be higher in the Indian River Lagoon. The St. Lucie Estuary exhibited more obvious microbial seasonality, such as higher Betaproteobacteriales, a freshwater associated organism, in wet season and higher Flavobacteriales in dry season samples. Distance-based linear models revealed these microbiomes were more affected by changes in total organic matter and copper than changes in temperature. Anaerobic organisms, such as Campylobacterales, were more associated with high total organic matter and copper samples while aerobic organisms, such as Nitrosopumilales, were more associated with low total organic matter and copper samples. This initial study fills the knowledge gap on the Indian River Lagoon microbiome and serves as an important baseline for possible future changes due to human impacts or environmental changes.