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Algae sediment dynamics are mediated by herbivorous fishes on a nearshore coral reef

McAndrews, Ryan S. and Eich, Andreas and Ford, Amanda K. and Bejarano, Sonia and Lal, Ronal and Ferse, Sebastian C. A. (2019) Algae sediment dynamics are mediated by herbivorous fishes on a nearshore coral reef. Coral Reefs, TBC . pp. 1-11. ISSN 0722-4028

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Epilithic algae are a ubiquitous component of coral reefs. Components of the epilithic algal matrix (EAM) can have a significant influence on coral settlement and benthic feeding by fishes. We employed a herbivore exclusion experiment on a fringing reef in Viti Levu, Fiji, to investigate the functional role of herbivorous fishes in affecting the EAM between different habitat types and levels of community-based fishing restriction. We surveyed the herbivorous fish community and deployed experimental tiles on the reef flat and lagoonal slope and inside and outside of an area where fishing is restricted (tabu). Tiles were deployed for 3 months, half within cages to exclude herbivorous fishes. We then identified algal type and quantified epilithic algal turf height, sediment dry weight, and detritus within the EAM on each tile. EAM that developed under herbivory was remarkably similar, regardless of the differences in habitat or fishing restriction. In contrast, EAM within cages was characterised by longer turf, heavier sediment load, and high variance in turf length and sediment load. Habitat type played a strong role in determining EAM characteristics where herbivores were excluded. Caged EAM on the reef flat was characterised by algal turf and fleshy macroalgae, whereas EAM in cages on the lagoonal slope was overwhelmingly dominated by filamentous and mat-forming cyanobacteria. The results presented here demonstrate the importance of herbivorous fishes in maintaining a benthic environment favourable to coral settlement and survival. Our results suggest that herbivore biomass per se is not a reliable predictor of foraging activity. Moreover, these results show that the absence of herbivore foraging can have different consequences depending on the habitat type, even within the same reef.

Item Type: Journal Article
Additional Information: DOI
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Divisions: Faculty of Science, Technology and Environment (FSTE) > School of Marine Studies
Depositing User: Fulori Nainoca - Waqairagata
Date Deposited: 01 Apr 2019 00:23
Last Modified: 01 Apr 2019 00:25

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