Symbiodinium photosynthesis in Caribbean octocorals

PLoS One. 2014 Sep 5;9(9):e106419. doi: 10.1371/journal.pone.0106419. eCollection 2014.

Abstract

Symbioses with the dinoflagellate Symbiodinium form the foundation of tropical coral reef communities. Symbiodinium photosynthesis fuels the growth of an array of marine invertebrates, including cnidarians such as scleractinian corals and octocorals (e.g., gorgonian and soft corals). Studies examining the symbioses between Caribbean gorgonian corals and Symbiodinium are sparse, even though gorgonian corals blanket the landscape of Caribbean coral reefs. The objective of this study was to compare photosynthetic characteristics of Symbiodinium in four common Caribbean gorgonian species: Pterogorgia anceps, Eunicea tourneforti, Pseudoplexaura porosa, and Pseudoplexaura wagenaari. Symbiodinium associated with these four species exhibited differences in Symbiodinium density, chlorophyll a per cell, light absorption by chlorophyll a, and rates of photosynthetic oxygen production. The two Pseudoplexaura species had higher Symbiodinium densities and chlorophyll a per Symbiodinium cell but lower chlorophyll a specific absorption compared to P. anceps and E. tourneforti. Consequently, P. porosa and P. wagenaari had the highest average photosynthetic rates per cm2 but the lowest average photosynthetic rates per Symbiodinium cell or chlorophyll a. With the exception of Symbiodinium from E. tourneforti, isolated Symbiodinium did not photosynthesize at the same rate as Symbiodinium in hospite. Differences in Symbiodinium photosynthetic performance could not be attributed to Symbiodinium type. All P. anceps (n = 9) and P. wagenaari (n = 6) colonies, in addition to one E. tourneforti and three P. porosa colonies, associated with Symbiodinium type B1. The B1 Symbiodinium from these four gorgonian species did not cluster with lineages of B1 Symbiodinium from scleractinian corals. The remaining eight E. tourneforti colonies harbored Symbiodinium type B1L, while six P. porosa colonies harbored type B1i. Understanding the symbioses between gorgonian corals and Symbiodinium will aid in deciphering why gorgonian corals dominate many Caribbean reefs.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Anthozoa / classification
  • Anthozoa / physiology*
  • Biodiversity
  • Caribbean Region
  • Chlorophyll / metabolism
  • Microsatellite Repeats
  • Oxygen / metabolism
  • Photochemical Processes
  • Photosynthesis*
  • Phylogeny
  • Population Density
  • Symbiosis*

Substances

  • Chlorophyll
  • Oxygen

Grants and funding

This material is based upon work supported by the National Science Foundation under Grant No. IOS 0747205 and National Science Foundation Research Experience for Undergraduates (REU) supplements (No. 1038291 and 0936630) to the above grant (TLG). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. The work was also funded by the Explorers Club Exploration Fund, and a University of Mississippi Graduate Student Council Research Grant (BDR). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.