Summary:
Given their significance as ecological sentinels, seagrasses are excellent models for quantitatively documenting ecosystem functions that may be disrupted by this oil spill event. Gaining an understanding of their genetic, biochemical and physiological responses to oil contamination and subsequent recovery is essential to assessing resilience of sensitive coastal ecosystems. Samples of seagrass were collected across seasons over a spatial scale relevant to the oil contamination event. Prior to the start of the funding, pre-impact samples from several sites along the Northern Gulf of Mexico were collected. Our study sites were matched with those monitored for seagrass distribution and abundance by Grand Bay NERR researchers. Ruppia maritima and Halodule wrightii are the only two seagrasses that occur at these sites. Our primary focus was on R. maritima, as it is the dominant species at many of the sites. Although there was variation in the percent cover within and among sites across years and season, preliminary analyses indicate that the overall seagrass cover was not impacted by the spill. The physiological, protein level biomarker, and genetic diversity data were consistent with this assessment. Oxygen exchange measurements and pigment analyses indicated that the plants were physiologically competent and doing well. Although, preliminary data indicated variation in stress protein expression across sites and sampling times, this variation did not appear to be directly linked to potential impacts of the spill. Based on differences in Fst values, there was little to no genetic differentiation across years and sites. This project allowed us to obtain baseline information, however, follow-up will be required to assess the long-term impact of the spill on seagrass health.