Consumption of tabular acroporid corals by reef fishes: a comparison with plant–herbivore interactions

Abstract

Summary 1.Interactions between primary producers and consumers (i.e. grazers) are of fundamental importance to the successful functioning of ecological communities. Plant-herbivore interactions have been extensively studied, and herbivory has been accepted as an important process contributing to the structure of terrestrial and aquatic ecosystems. In contrast, the functional importance of the ecologically equivalent interaction between scleractinian reef corals and polyp-feeding fishes is largely untested, but has generally been dismissed as unimportant. 2. This study quantified the amount of tabular acroporid coral tissue biomass consumed at the population level by corallivorous butterflyfishes and determined the proportion of both the standing biomass and productivity that is consumed annually at three exposed reef crest sites at Lizard Island, Great Barrier Reef and Australia. 3. Total daily coral consumption ranged from 18AE6 (±1AE6) to 27AE4 (±1AE5) g 200 m )2 day )1 with 61-68% of this consumption directed towards tabular acroporid corals. This selective feeding resulted in an annual consumption of between 8AE9-13AE5% of the total available tissue biomass and between 52-79% of the annual productivity of these tabular acroporid corals. 4. The proportion of standing coral tissue biomass removed by corallivorous butterflyfishes is similar to that removed from terrestrial plants by herbivores. However, the proportion of primary productivity consumed is considerably greater on coral reefs for both corallivorous and herbivorous fishes compared with terrestrial systems. 5. In terrestrial systems, even relatively low levels of defoliation can have significant effects on plant growth rates, seed production and overall fitness. Considering the high proportion of productivity that is consumed by polyp-feeding fishes, it would seem incongruous that these grazing fishes do not have similar effects on coral community structure and population dynamics. Our findings highlight the need to revisit previously held assumptions regarding the functional importance of corallivorous fishes to coral reef ecosystems.

Abundance, diversity, and feeding behavior of coral reef butterflyfishes at Lord Howe Island

“…At Lord Howe Island, four species of obligate coral‐feeding butterflyfishes ( C. lunulatus , C. plebeius , C. tricinctus , and C. trifascialis ) all consumed tabular Acropora disproportionately to its availability, as shown elsewhere (Berumen and Pratchett ; Cole et al. ; Pratchett et al. 2013a).…”

The corallivorous invertebrate Drupella aids in transmission of brown band disease on the Great Barrier Reef

“…The ecological role of grazers in reducing the fitness of prey and their associated communities has been shown to be important in the dynamics of both terrestrial and marine systems (Ayres and Lombardero 2000;Kujiper and Bakker 2005;Rotjan et al 2006;Cole et al 2012). In terrestrial ecosystems, herbivores can alter the quality and quantity of their food source, which in turn affects the quality of food available to other herbivores (Thelen et al 2005).…”

“…In marine ecosystems, the ongoing loss of coral cover has stimulated research into understanding interactions between corals and their predators (Nyström et al 2000;Bellwood et al 2004;Pratchett et al 2004). Recent studies highlight the detrimental effects of continual removal of coral tissue on coral health, stressing the role of corallivorous species in reducing the distribution, abundance and overall fitness of corals (Rotjan et al 2006;Cole et al 2012). Corallivory causes corals to redirect energy towards healing and defence processes (Gochfeld 2004), which may reduce coral biomass, limit growth and reproduction (Cole et al 2012), decrease competitive abilities (Cox 1986) and increase severity of bleaching events by hindering the recovery of zooxanthellae densities (Rotjan et al 2006).…”

“…Recent studies highlight the detrimental effects of continual removal of coral tissue on coral health, stressing the role of corallivorous species in reducing the distribution, abundance and overall fitness of corals (Rotjan et al 2006;Cole et al 2012). Corallivory causes corals to redirect energy towards healing and defence processes (Gochfeld 2004), which may reduce coral biomass, limit growth and reproduction (Cole et al 2012), decrease competitive abilities (Cox 1986) and increase severity of bleaching events by hindering the recovery of zooxanthellae densities (Rotjan et al 2006). Although corallivory appears to have minimal impact on healthy reefs, when combined with other stressors, corallivores can influence coral mortality rates and alter coral community structure (Cole et al 2008).…”

Foraging plasticity in obligate corallivorous Melon butterflyfish across three recently bleached reefs

“…On undisturbed reefs with extensive coral cover, OCB can devote as much as 90% of their time solely to foraging (Cole, Lawton, Pratchett, & Wilson, ; Cole, Lawton, Wilson, & Pratchett, ; Cole et al., ). However, on reefs with low coral cover, especially ones that have bleached recently, the remnant coral patches are small and distantly located (Brown, ; Van Oppen & Lough, ).…”