Consumption of benthic cyanobacterial mats on a Caribbean coral reef

Abstract

Herbivory is an important process in the general structuring of coral reef benthic communities. However, evidence of its ability to control coral reef benthic cyanobacterial mats, which have recently proliferated on reefs worldwide, remains ambivalent. Here, we report that the French Angelfish ( Pomacanthus paru ), Striped Parrotfish ( Scarus iseri ), Rock Beauty ( Holacanthus tricolor ), Ocean Surgeonfish ( Acanthurus bahianus ), Blue Parrotfish ( Scarus coeruleus ), and Atlantic Blue Tang ( Acanthurus coeruleus ) consume benthic cyanobacterial mats on coral reefs in Bonaire, Netherlands. We documented the foraging patterns of P . paru and S . iseri , and found that benthic cyanobacterial mats comprised 36.7% ± 5.8% and 15.0% ± 1.53% (mean ± standard error) of the total bites taken by P . paru and S . iseri respectively. This magnitude of consumption suggests that grazing by reef fishes may represent a potentially important, but previously undocumented, top-down control on benthic cyanobacterial mats on Caribbean reefs.

First insights into the impacts of benthic cyanobacterial mats on fish herbivory functions on a nearshore coral reef

“…As such we could have expected some species to opportunistically make use of the new dominant resource. These results also contrast to those of Cissell et al 32 who identified several species to be consuming mats in the Caribbean. Reasons for these differences could include the presence of different herbivorous fish species, because of difficulties in visually determining what fish are feeding on, or differences in mat composition and chemistry.…”

“…It’s likely that differences in the metabolites produced by different BCMs, along with variation in tolerance to the metabolites by different fish species, can in part explain discrepancies in observations of grazing on BCMs between this study and others (e.g. Cissell et al 32 ).…”

“…Nonetheless, two recent observational studies have yielded some interesting insights into mat consumption. One study on Australia’s Great Barrier Reef observed Bolbometapon muricatum feeding on mats 31 , and another on the Caribbean island of Bonaire observed some species of angelfish ( Holacanthus tricolor, Pomacanthus paru ), parrotfish ( Scarus coeruleus, Scarus iseri ), and surgeonfish ( Acanthurus bahianus, Acanthurus coeruleus ), appearing to take bites from mats 32 ; though notably, ascertaining whether fish consume the cyanobacteria themselves, or are rather targeting trapped detritus, sediment, or other associated fauna is impossible through observations alone.…”

11-yr of coral community dynamics in reefs around Dahab (Gulf of Aqaba, Red Sea): the collapse of urchins and rise of macroalgae and cyanobacterial mats

“…Previous studies have shown that larger herbivorous species such as acanthurids are the main contributors to macroalgal control (Ceccarelli et al 2006;Rasher et al 2013). Although cyanobacterial top-down control is less understood, partly due to the fact cyanobacteria have been considered largely unpalatable to many broad consumers, recent studies suggest an important role of top-down control on cyanobacterial mats (Capper et al 2016;Cissell et al 2019). Previous studies have reported cyanobacteria as an important ingredient in several damselfish species diets (Lassuy 1984;Feitosa et al 2012).…”

Fine‐scale foraging behavior reveals differences in the functional roles of herbivorous reef fishes

“…vulpinus may need to supplement its diet with other food sources that, while less preferred, produce less toxin. For instance, dense, mat-forming species of cyanobacteria (e.g., genus Lyngbya) are expected to produce more toxins than their sparser counterparts (Cissell et al, 2019). Consequently, short patch residence times and wide movements for Si.…”