Meeting Abstract
According to NOAA, the highest temperature in the US was recorded in 2016, followed by the third highest in 2017. Rising temperatures and increasing drought frequency could affect marsh health, though in the presence of ribbed mussels, Geukensia demissa, marsh recovery can take as little as 10 years versus 100 years without them. Mussels are usually found on mounds (raised portions of the substrate), at the base of cordgrass, Spartina alterniflora stems. These two species, along with others, work together to maintain the health and biodiversity of the marsh. But as temperatures rise they may be undergoing considerable stress. This study will examine whether cordgrass provides enough shade to decrease stress and enable increase in mussel abundance despite the increase in temperatures in the salt marsh. Eight large mussel mounds (198-243 cm in diameter) with similar cordgrass densities were flagged in the mid-zone of a local saltmarsh at Tybee Island, Georgia. Four of these mounds were tagged as short cordgrass mounds (cordgrass ≤ 40cm, less shade) and the other four as tall cordgrass mounds (cordgrass ≥ 60cm, shaded). During the Spring and Fall of 2018, temperature, sediment organic content, mussel abundance, cordgrass density and height were recorded. In September, three mussels/mound were collected. In the lab, mussel tissue was lysed, and the supernatant was stored at -80°C. Ten microliters of the sample were used to determine total protein concentration. Our results revealed significantly higher sediment organic content and mussel abundance on mounds with tall cordgrass (100-173 mussels/mound) than on mounds with short cordgrass (51-132 mussels/mound). These results further indicate the importance of the interaction between these two species in maintaining salt marsh health.
