Coprophagy in Caribbean parrotfishes

Parrotfishes are widely considered to be important grazers on coral reefs that remove autotrophic biomass from the reef substrate and create bare space that is conducive to larval coral settlement and recruitment (Bonaldo et al., 2014). Another aspect of parrotfish foraging and trophic ecology that has received very little attention is coprophagy. Coprophagy, the consumption of fecal matter, occurs in many animal taxa and may be an important means of subsidizing nutritional requirements (i.e., micro- and macronutrients) not met through foraging on preferred resources alone (Bailey & Robertson, 1982; Johannes & Satomi, 1966; Negro et al., 2002; Robertson, 1982).

The feces of planktivorous fishes, including Chromis spp., have been identified as important sources of nutrients and trace elements to tropical and temperate reef ecosystems (Geesey et al., 1984; Hamner et al., 1988; Pinnegar & Polunin, 2006). Their feces are readily consumed by a variety of fishes, including parrotfishes (Pinnegar & Polunin, 2006; Robertson, 1982). Although parrotfish coprophagy has been observed in prior studies (Motta & Overholtzer, 1999; Robertson, 1982), its frequency has not yet been quantified.

In May–July 2019, we conducted video-recorded foraging observations of 162 parrotfishes across five fringing coral reef sites in Bonaire, NL to quantify benthic foraging targets for the five most common species on those reefs