Dr. Sarah A Tominack

Seagrass beds are important to the health of estuaries around the world, and often these grasses are keystone species for their environments. Water quality conditions controlling light availability such as total suspended solids (TSS), phytoplankton biomass, and the color of the water are important in understanding seagrass health. Six locations from the Pensacola Bay System in Santa Rosa Sound and Big Lagoon with extensive seagrass beds were sampled monthly between May and October 2023. Water quality was measured, and surveys of seagrass beds were conducted at each site. Linear models were developed to attempt to explain K d from water color, phytoplankton biomass, and TSS, as well as their impact on the percent cover of the seagrasses. Seagrass cover increased over the growing season. K d varied between 0.3 /m and 1.8 /m, and across all study sites only color was significantly (p < 0.1) related to light attenuation, although it could not explain much variability (R 2 =0.08). While water depth was significantly related to percent cover of Halodule wrightii and Thalassia testudinum, depth integrated values of light available and factors related to light attenuation explained little variability in percent cover despite significance levels (p < 0.1). Sites in Santa Rosa Sound and Big Lagoon were similar. Larger scale surveys with more opportunistic sampling (e.g. following rain events) in addition to planned collection days, might provide data with clearer relationships to light attenuation and seagrass cover. Surveys that extend to the deepwater edge of the seagrass beds should also be done in the future to provide a clearer picture of the habitat and changes in the beds.

Aquatic sampling methods are commonly used in the field of ecology in standard ways to gather data. These methods are also useful for teaching in K-12 classrooms, but the standard methods can be quite expensive to use and impossible in some cases for teachers to obtain. In this study we wanted to determine cheaper alternatives and how accurate they could be to the industry standard methods.

Benthic marine protists have been well documented from shallow marine benthic habitats but remain understudied in deeper habitats on continental shelves and slopes, particularly in the Northeastern Gulf of Mexico (NEGOM). This region was affected by a deep water oil well failure (BP-Deepwater Horizon, 2010). The combination of a lack of information on deep sea microbenthic communities and the potential for benthic microbial petroleum mineralization prompted this investigation. Water column and nepheloid layer samples were obtained via Niskin bottles and a multicorer respectively at stations across the NEGOM to: (1) determine whether nepheloid and water column communities are distinct and (2) assess benthic species richness relative to sediment PAH contamination. Phylum specific 185 rRNA gene amplification was used to construct clone libraries of ciliate assemblages. BLAST searches in the NCBI database indicated that a majority (similar to 75%) of the clone sequences corresponded (94-100% similarity) with listed, yet unclassified sequences. Several putative species were common at most site locations and depths. Many known benthic ciliates, such as Uronychia transfuga, Uronychia setigera, and Spirotrachelostyla tani, were common in the nepheloid layer samples and not recovered in water column samples. Ciliated protist species richness increased with PAH levels found in surface sediments, suggesting a positive microbial response to petroleum enrichment of the benthos. The presence of previously unknown microbenthic communites in the nephaloid layer over oceanic clay-silt muds alters our view of microbial processes in the deep sea and merits investigation of the microbial processes and rates of microbial mineralization and biomass production important to global biogeochemistry. (C) 2015 Elsevier Ltd. All rights reserved.

The Florida Panhandle continental shelf environment was exposed to oil from the BP oil well failure in the Gulf of Mexico during 2010. Floating mats of oil were documented by satellite, but the distribution of dissolved components of the oil in this region was unknown. Shipek® grab samples of sediments were taken during repeated cruises between June 2010 and June 2012 to test for selected polycyclic aromatic hydrocarbons (PAHs) as indicators of this contamination. Sediments were collected as composite samples, extracted using standard techniques, and PAHs were quantified by GC/MS-SIM. PAHs in samples from the continental slope in May 2011 were highest near to the failed well site and were reduced in samples taken one year later. PAHs from continental shelf sediments during the spill (June 2010) ranged from 10 to 165 ng g(-1). Subsequent cruises yielded variable and reduced amounts of PAHs across the shelf. The data suggest that PAHs were distributed widely across the shelf, and their subsequent loss to background levels suggests these compounds were of oil spill origin. PAH half-life estimates by regression were 70-122 days for slope and 201 days for shelf stations.