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.