Indirect effects of overfishing on Caribbean reefs: Sponges overgrow reef-building corals

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1 Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC, United States
2 Department of Biology, Valdosta State University, Valdosta, GA, United States
3 Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, Baltimore, MD, United States
DOI
10.7287/peerj.preprints.836v1
Published
Accepted
Subject Areas
Aquaculture, Fisheries and Fish Science, Conservation Biology, Ecology, Environmental Sciences, Marine Biology
Keywords
food webs, trophic cascades, indirect effects, resource trade-offs, chemical defense, top-down control, spatial competition, coral reefs, MPAs, marine protected areas
Copyright
© 2015 Loh 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
Loh T, McMurray SE, Henkel TP, Vicente J, Pawlik JR. 2015. Indirect effects of overfishing on Caribbean reefs: Sponges overgrow reef-building corals. PeerJ PrePrints 3:e836v1

Abstract

Consumer-mediated indirect effects at the community-level are difficult to demonstrate empirically. Here, we show an explicit indirect effect of overfishing on competition between sponges and reef-building corals from surveys of 69 sites across the Caribbean. Removal of sponge-eating angelfishes and parrotfishes resulted in > 3 fold increase in overgrowth of corals by sponges, with coral-sponge contact increasing from 11.0% to 25.6%, and these sponges were mostly species palatable to sponge predators. Palatable species have faster rates of growth or reproduction than defended sponges, which instead make metabolically expensive chemical defenses. On average, overfished sites had lower macroalgal cover, contrary to prevailing assumptions about seaweed control by herbivorous fishes. Coral-sponge competition provides an additional and unambiguous justification for marine protected areas (MPAs) in the Caribbean, where the conceptual model of sponge community ecology and defense trade-offs is notable for the clarity of top-down control and indirect effects across a broad geographic region.

Author Comment

This is a submission to PeerJ for review.

Supplemental Information

nMDS plot of survey sites by benthic community structure using square-root transformed occurrences of benthic categories

Sites labeled green are less-fished, and sites labeled blue are overfished. The following benthic categories were used: rock, fire coral, rubble, zoanthid, sponges, other benthos, hard coral, gorgonian, silt, sand, turf, macroalgae, and coralline algae. Prefixes of site names denote the following locations: B, Bahamas; C, Cayman Islands; D, Dominican Republic; E, St. Eustatius; F, Key Largo, FL; J, Jamaica; M, Martinique; O, Bonaire; P, Bocas del Toro, Panama; R, Puerto Rico; S, St. Lucia; U, Curaçao; X, Mexico.

DOI: 10.7287/peerj.preprints.836v1/supp-1

Benthic cover data for all survey sites. (Excel spreadsheet)

DOI: 10.7287/peerj.preprints.836v1/supp-2

Correlation of individual variables with axes 1 and 2 of the nMDS ordination of benthic category occurrence across all survey sites (Fig. S1)

DOI: 10.7287/peerj.preprints.836v1/supp-3