Title: EVIDENCE OF ADAPTATION IN A CORAL-ALGAL SYMBIOSIS AT MESOPHOTIC DEPTHS IN THE NORTHWEST GULF OF MEXICO

Abstract: Many coral species common in shallow habitats also live in the mesophotic zone (30-150 m). Similar to shallow corals, many mesophotic corals maintain important symbioses with photosynthetic microalgae in the genus Symbiodinium. Despite the importance of the coral-algal symbiosis in corals' ability to thrive in multiple dynamic environments, few studies have focused on symbionts associated with mesophotic corals. This study compares the algal symbiont assemblages in Montastraea cavernosa found at shallow (20-25 m) and mesophotic (45-50 m) sites at the East and West banks of Flower Garden Banks (FGB) National Marine Sanctuary. Symbiont densities per unit area of coral tissue are significantly higher in mesophotic corals at FGB. Additionally, while chlorophyll concentrations are similar between depths, the overall chlorophyll concentrations per unit area of coral tissue are significantly higher in mesophotic corals. These results suggest that increased symbiont densities may be a method of adaptation for zooxanthellate corals in mesophotic reef environments. Symbiont densities and chlorophyll concentrations did not differ between the East and West banks. Next generation sequencing of the ITS2 gene provides a comprehensive assessment of symbiont community structure, including uniformly stable assemblages in M. cavernosa at the shallow sites. This study and additional comparisons between shallow and mesophotic reefs are designed to help inform management strategies for FGB and similar coral reef communities.

Authors: Polinski JM, Voss JD

Presentation: Poster (#331)

Session: 29

Date: 06/21/16

Time: 18:15 - 19:45

Location: Poster/Exhibit Hall

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