Corallivory in the Anthropocene: Interactive Effects of Anthropogenic Stressors and Corallivory on Coral Reefs

Abstract

Corallivory is the predation of coral mucus, tissue, and skeleton by fishes and invertebrates, and a source of chronic stress for many reef-building coral species. Corallivores often prey on corals repeatedly, and this predation induces wounds that require extensive cellular resources to heal. The effects of corallivory on coral growth, reproduction, and community dynamics are well-documented, and often result in reduced growth rates and fitness. Given the degree of anthropogenic pressures that threaten coral reefs, it is now imperative to focus on understanding how corallivory interacts with anthropogenic forces to alter coral health and community dynamics. For example, coral bleaching events that stem from global climate change often reduce preferred corals species for many corallivorous fishes. These reductions in preferred prey may result in declines in populations of more specialized corallivores while more generalist corallivores may increase. Corallivory may also make corals more susceptible to thermal stress and exacerbate bleaching. At local scales, overfishing depletes corallivorous fish stocks, reducing fish corallivory and bioerosion, whilst removing invertivorous fishes and allowing population increases in invertebrate corallivores (e.g., urchins, Drupella spp.). Interactive effects of local stressors, such as overfishing and nutrient pollution, can alter the effect of corallivory by increasing coral-algal competition and destabilizing the coral microbiome, subsequently leading to coral disease and mortality. Here, we synthesize recent literature of how global climate change and local stressors affect corallivore populations and shape the patterns and effect of corallivory. Our review indicates that the combined effects of corallivory and anthropogenic pressures may be underappreciated and that these interactions often drive changes in coral reefs on scales from ecosystems to microbes. Understanding the ecology of coral reefs in the Anthropocene will require an increased focus on how anthropogenic forcing alters biotic interactions, such as corallivory, and the resulting cascading effects on corals and reef ecosystems.

Different nitrogen sources speed recovery from corallivory and uniquely alter the microbiome of a reef-building coral

“…As anthropogenic perturbations become more common on reefs, it is crucial to understand how these disturbances may change corals’ ability to cope with ongoing biotic processes. Corallivory is a common process on reefs that can exacerbate the response of corals to human impacts (Rice, Ezzat & Burkepile, 2019). The current study suggests that nitrogen source can alter the effects of concurrent seawater warming and corallivory on corals, while nitrogen enrichment can have distinct impacts on microbial community variability.…”

“…Coral predation (i.e., corallivory) is a common biotic process on reefs with many corallivores removing coral mucus, tissue, and skeletal structure. Scraping and excavating corallivory by parrotfishes and pufferfishes removes coral tissue and varying degrees of skeletal structure, which can substantially reduce coral growth rates (Cole, Pratchett & Jones, 2008; Rice, Ezzat & Burkepile, 2019; Rotjan & Lewis, 2008). This impact can exacerbate corals’ response to concurrent stressors and even prevent recovery from anthropogenic perturbations (Rice, Ezzat & Burkepile, 2019).…”

Oxygen‐mediated plasticity confers hypoxia tolerance in a corallivorous polychaete

“…In addition, H. carunculata is on the brink of being considered an invasive pest species with population sizes rapidly increasing in some areas (Williams, 2007;Simonini, Righi, Maletti, Fai, & Prevedelli, 2017). The interactive effects of increased anthropogenic pressures, including deoxygenation, and weakened corals attracting more corallivory have negative ecological implications, and the potential to be realized throughout this fireworm species' circumtropical Atlantic-Mediterranean range (Rice, Ezzat, & Burkepile, 2019;Simonini, Maletti, Righi, Fai, & Prevedelli, 2018).…”

Can Herbivore Management Increase the Persistence of Indo-Pacific Coral Reefs?

“…The relative importance of corallivory is also likely to vary among reefs. For example, although "natural" reefs can have both high coral cover and abundant corallivorous parrotfishes, e.g., Wake Atoll (Muñoz et al, 2012), it may still be the case that certain parrotfish species or size-classes tend to have net negative impacts on corals, and perhaps especially so on degraded reefs where coral cover is lower, and thus corallivory is more concentrated (Rice et al, 2019). Intriguingly, the Fiji MPAs, where herbivore management was highly effective, had few large-bodied parrotfishes, likely in part due to the small size of those protected areas (Bonito et al, 2014;Bonaldo et al, 2017).…”