Meeting Abstract
To compare seasonal diversity patterns of planktonic eukaryotes, a 2.5 year study sampling surface water in Mobile Bay and along the Alabama coast was conducted. Four locations along a transect were sampled bi-monthly from July 2009 to December 2011. To better understand the variation within these communities, high-throughput Illumina amplicon sequencing targeting the eukaryotic specific hypervariable V9 region of the small subunit ribosomal RNA gene was employed. Prior to sequencing, water samples were prefiltered using a 150 µm nitex screen and planktonic eukaryotes were collected using a 142 mm diameter 0.7 µm glass fiber filter. There was a significant difference in pelagic micro-eukaryote community composition both spatially (Bay vs. Shelf) and temporally. Community composition changed was correlated with DIN, temperature, salinity, DO, and prokaryote abundance. However, OTUs are being replaced with close relatives. The Bay had significantly lower temperature, lower salinity, and higher nutrients within the winter and spring season in comparison to the other seasons. This corresponded with higher abundance of diatoms in the Bay in the winter and spring. The Shelf on the other hand did not show a significant difference in environmental factors in reference to season and was heavily dominated by copepods during late spring to summer. Time points of large copepod abundance appeared to be correlated with lower dinoflagellate abundance. Furthermore, sampling for this project was conducted before, during, and after the Deepwater Horizon oil spill. Unfortunately, no hydrocarbon analyses were conducted, even though oil was reported to have reached both shelf locations, especially in June 2010. However, no visible shifts in community composition were observed when oil sheens were present.
