The Use of Stable Isotopes to Assess Potential Effects of Algal Blooms on Seagrass and Macroalgae Communities in the Indian River Lagoon, Florida

Algal blooms have caused significant losses in seagrass and macroalgae in the Indian River Lagoon, FL. To gain an understanding of these effects, samples of Gracilaria sp., Halodule wrightii, pinfish, and white mullet were taken throughout October and November of 2013. Samples from 2001 of Gracilaria sp., Halodule wrightii, Syringodium filiforme, Thalassia testudinum, pinfish, spotted seatrout, and white mullet were also obtained. Stable isotope data were obtained from these samples and compared by year and species. Halodule wrightii and pinfish had a significantly larger 2013 [delta]C13 values. Halodule wrightii also displayed lower total %C and total %N averages for 2013 when compared to 2001 data. These results may indicate a link between Halodule wrightii and pinfish, with pinfish consuming organisms that use Halodule wrightii as their source of nutrients. The location of collections also seemed to play a role in stable isotope values, as indicated by samples of Halodule wrightii