Fine grained compositional analysis of Port Everglades Inlet microbiome using high throughput DNA sequencing
Similar to natural rivers, manmade inlets connect inland runoff to the ocean. Port Everglades Inlet (PEI) is a busy cargo and cruise ship port in South Florida, which can act as a source of pollution and nutrients to surrounding beaches and offshore coral reefs. Understanding the composition and fluctuations of bacterioplankton communities ("microbiomes") in major port inlets is important due to their impacts on surrounding marine environments. We hypothesize annual microbial fluctuations based
... fluctuations based on seasons (wet vs dry), assessed by high throughput 16S rRNA amplicon library sequencing. Surface water samples were collected weekly for one year, creating a high sampling frequency and fine sampling scale. Over 1.4 million 16S rRNA V4 reads generated a total of 16,384 Operational Taxonomic Units (OTUs) from the PEI habitat. We observed Proteobacteria, Cyanobacteria, Bacteroidetes, and Actinobacteria as the most dominant phyla. Analysis of potentially pathogenic genera show the presence of Staphylococcus and Bacillus, albeit at lower relative abundances during peak shipping and tourist months (November –April), thus underscoring their relatively low presence. Statistical analyses indicated significant alpha diversity differences when comparing microbial communities with respect to time. This observation probably stems from the low community richness and abundance in August, which had lower than average rainfall levels for Florida's wet season. The lower rainfall levels may have contributed to less runoff, and subsequently fewer bacterial groups being introduced into the port surface waters. Bacterioplankton beta diversity differed significantly by month and season. The 2013-2014 dry season (October-April), was warmer and wetter than historical averages, which may have driven the significant differences in beta diversity. Increased nitrogen and phosphorous concentrations were also observed in these months, possibly creating favorable bacterial growth conditions. To our knowledge, this study represents the first to sample a large port at this fine sampling scale. These data can help establish underlying inlet microbial community baselines, and supplement the vital monitoring of local marine and recreational environments, which appears more poignant in the context of local reef disease outbreaks and worldwide coral reef collapses in the wake of a harsh 2015-16 El Nino event.