DOC concentrations across a depth gradient on a Caribbean coral reef
- Published
- Accepted
- Subject Areas
- Biochemistry, Biological Oceanography, Ecology, Environmental Sciences, Marine Biology
- Keywords
- Dissolved Organic Carbon, Coral Reef, Depth Gradient, Light, Coral, Algae
- Copyright
- © 2016 Mueller et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2016. DOC concentrations across a depth gradient on a Caribbean coral reef. PeerJ Preprints 4:e2610v1 https://doi.org/10.7287/peerj.preprints.2610v1
Abstract
The dissolved organic carbon (DOC) pool on tropical coral reefs is mainly fueled by photosynthates released from benthic primary producers (BPP), such as reef algae and scleractinian corals. DOC concentrations near BPP have repeatedly been observed to be elevated compared to those in the surrounding water column. As the DOC release of BPP increases with increasing light availability, elevated DOC concentrations near them will, in part, also depend on light availability. Consequently, DOC concentrations are likely to be higher on the shallow, well-lit reef terrace than in deeper sections on the fore reef slope. We measured in situ DOC concentrations and light intensity in close proximity to the reef alga Dictyota sp. and the scleractinian coral Orbicella faveolata along a depth gradient from 5 to 20 m depth and compared these to background concentrations in the water column. DOC concentrations near Dictyota sp. were significantly higher at 10 m than at 5 and 20 m depth. Furthermore, at 10 m DOC concentrations near Dictyota sp. were elevated by 15 µmol C L-1 compared to background concentrations in the water column, but not at 5 and 20 m. DOC concentrations near O. faveolata and in the water column did not differ between depths and concentrations near O. faveolata were not elevated compared to background concentrations at any of the tested depths. Our results indicate that DOC concentrations near Dictyota sp. can differ along a depth gradient from 5 to 20 m. However, the occurrence of elevated DOC concentrations did not follow a natural light gradient across depth. Instead, a combination of light availability (including a restriction by photoinhibition) and water movement are proposed to interactively determine the DOC concentrations in the close vicinity of BPP across the reef slope.
Author Comment
This is a submission to PeerJ for review.