| Bacteria are found in all oceans around the globe and dominate marine processes because of their abundance and contribution to biogeochemical cycles. Resource availability and environmental parameters are both key factors in determining bacterioplankton growth and community structure. Understanding temporal changes in the microbial community structure in the Gulf of Mexico has the potential to shed new light on the dynamics of energy transfer and organic processing. A two-year seasonal study was conducted at a station 40 km south of Choctawhatchee Bay on the Florida Shelf in the Northeast Gulf of Mexico. A total of 31 water column samples were collected from surface and bottom waters (~90 m) and mid-water deep chlorophyll maxima, when present, at 12 different time points. In addition to microbial diversity, chemical, physical, and biological environmental parameters such as bacterial production, nutrients, temperature, salinity, chlorophyll a, and bacterial counts were also taken. 16S rRNA clone libraries generated 2,160 high quality clones that were used for community analysis. 535 OTUs were obtained at 97% similarity. Samples were analyzed in three different categorical groupings: all OTUs, all OTUs grouped together at order level, and OTUs without dominant taxa. Environmental patterns were seen to correlate directly with seasonal changes, however community structure was independent of seasonal trends. Depth, nutrients, and salinity were seen to have a slight influence on the community structure. This shows that no single parameter is driving the community structure, but rather the community structure is the result of complex interactions between many factors. |
