Dr. Wade H Jeffrey

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.

While microorganisms are rather small, they encompass a large percentage of the biomass and diversity seen in marine environments. They are the building blocks that makeup the foundations of critical marine food webs. Cataloging and monitoring these organisms is important to understand their vital roles in food webs and nutrient cycling (Azam et al. 1983). It is crucial to establish baseline community dynamics in an aquatic system over an extended period. Once a baseline has been established. we can explore how or why microbial communities change. Through the continuation of this seasona study, we have collected water samples from the Pensacola Beach Pier for over six years, providing a wealth of experience and many molecular diversity samples to be processed.

Various petroleum products leak into the environment through different mechanisms, and may include crude oil or refined motor oil. These compounds and their accompanying weathered by-products can be damaging to the environment. To help assess the impact of weathered petroleum products on the environment. this study investigates the formation of reactive oxygen species, such as hydroxy radical. Water accommodated fractions (WAFs) are samples of water mixed with either crude or moto, on and are used to mimic environmental conditions. Over time water soluble components of the oil separate into the water layer of the WAF. The water layer is mixed with a chemical probe (i.e. benzoic acid) and then irradiated using a solar simulator. The amount of p-hydroxybenzoic acid (formed from hydroxy radicals and benzoic acid) is measured by UV detection-HPLC to determine hydroxyl radical
production rates.

While much recent attention has been paid to the Deepwater Horizon oil spill in the Gulf of Mexico and biodegradation by microbial communities, it is important to remember that numerous factors may determine the types of environmental effects that may result from oil spills. Not all oil spills (e.g., crude, refined, weathered, fuels, use of dispersants) are created equal, and it is likely that the characteristics of different environments will affect ecosystem response to oil. Temperature, salinity, and solar radiation are three potentially important factors related to location and seasonality. The effects of some of these environmental factors on the formation of Water Accommodated Fractions (WAFs) developed from Deepwater Horizon oils and the subsequent effects on microbial growth is being investigated. WAFs were generated under varying solar but controlled temperature conditions, various temperatures and salinities, as well as from burned and weathered oil. After all WAFs were collected, each was added to a coastal seawater sample and their effects on bacterial production or phytoplankton photosynthesis determined. Results from both assays demonstrated that WAFs produced in the dark had minimal effects on growth while inhibition was proportional to the amount of solar exposure. Burning oil prior to formation of WAFs increased inhibition of production independent of subsequent solar treatment. Preliminary data suggests that temperature plays a minimal role. The results imply that the ecological effects caused by oil spills are very light dependent and thus could vary by season, location, and may occur to significant depths in the ocean.