Herbivory facilitates growth of a key reef‐building Caribbean coral

Abstract

The decline of reef‐building corals in conjunction with shifts to short‐lived opportunistic species has prompted concerns that Caribbean reef framework‐building capacity has substantially diminished. Restoring herbivore populations may be a potential driver of coral recovery; however, the impact of herbivores on coral calcification has been little studied. We performed an exclusion experiment to evaluate the impact of herbivory on Orbicella faveolata coral growth over 14 months. The experiment consisted of three treatments: full exclusion cages; half cage procedural controls; and uncaged control plates, each with small O. faveolata colonies. We found that herbivorous fish exclusion had a substantial impact on both macroalgal cover and coral growth. Fleshy macroalgae reached 50% cover within some exclusion cages, but were almost absent from uncaged control plates. Critically, O. faveolata calcification rates were suppressed by almost half within exclusion cages, with monthly coral growth negatively related to overgrowth by fleshy macroalgae. These findings highlight the importance of herbivorous fishes for coral growth and the detrimental impact of macroalgal proliferation in the Caribbean. Policy makers and local managers should consider measures to protect herbivorous fishes and reduce macroalgal proliferation to enable coral communities to continue to grow and function.

Assessment of Elkhorn Coral Populations and Associated Herbivores in Akumal, Mexico

“…Parrotfish biomass in the Mesoamerican Barrier Reef has been increasing slightly in the past few years, and the populations observed here in Akumal are comparable to country and region-wide parrotfish population sizes (Jackson et al, 2014;McField et al, 2018), indicating that recovering populations may be reaching a threshold in which they can exert effective top down control of algal growth (Williams et al, 2016). Even though total parrotfish biomass was not correlated to lower macroalgal cover, fish grazing activity from non-browser species may have other positive benefits such as contributing to increased coral calcification (Suchley and Alvarez-Filip, 2017) or overall reef accretion (Cramer et al, 2017). Conversely, we found increasing macroalgal cover with increasing browser species density.…”

Adding insult to injury: Ship groundings are associated with coral disease in a pristine reef

“…While we observed recruit mortality from corallivory, we hypothesize a greater positive impact on recovery via herbivory. The link between herbivory and benthic resilience is well-established; herbivory controls algal abundance and protects high quality recruitment substrates, thus facilitating coral growth and recruitment [ 54 , 55 ]. Wilson et al [ 56 ] described a complex relationship between coral decline and fish community change.…”

Native Herbivores Improve Sexual Propagation of Threatened Staghorn Coral Acropora cervicornis

“…Grazing herbivores may help control algae to maintain systems and improve coral development (Serafy et al, 2013;Toh et al, 2013;Villanueva et al, 2013;Craggs et al, 2019). This interaction mirrors natural systems, where herbivores play an important role in controlling benthic algal succession by maintaining small epilithic algae in a grazed state (Lirman, 2001;Suchley and Alvarez-Filip, 2017). By replicating conditions encountered in the wild, rearing juvenile corals with herbivores may reduce the amount of time spent cleaning aquaria.…”