At the recent American Elasmobranch Society (AES) Meeting in June, Emily Seubert, a graduate student in the ACER Consumer subgroup, presented her research titled “Species and functional diversity of apex and mesopredators in the northern Gulf of Mexico.”
The data presented was preliminary bottom longline data for years 1 and 2 focusing on the hypothesis that species and functional diversity impact the resiliency of an ecosystem following a natural disaster.
Bottom longline sampling occurs yearly during the spring and fall in inshore and offshore waters around the Chandeleur Islands, Mississippi Sound/ Petit Bois Island and Fort Morgan- across a gradient of oil exposure (from high to low). Year 1 results show offshore the Chandeleur Islands had the highest species diversity while the waters offshore of the Mississippi Sound/Petit Bois Island had the lowest species diversity, but this pattern was not the same during the year 2 spring sampling. During the year 2 spring sampling, the highest species diversity was found in the Fort Morgan offshore waters and lowest diversity in the inshore waters of the Chandeleur Islands. Sampling will continue this fall, allowing ACER researchers to account for annual and seasonal changes so differences due to the location across the oiling gradient can been examined.
What is Emily catching during these bottom longline surveys? Well, it depends on what location is being sampled. The top predators that were caught were Atlantic Sharpnose shark, Blacktip Shark, Blacknose Shark and Red Drum.
Emily has also been collecting tissue samples from her catch for stable isotope analysis, which will give insight to the short term and long term food web dynamics of these predators.
Stay tuned for more ACER research updates in the coming months as we head to Biloxi in November for the 2016 Bays and Bayous Symposium!