Fish Feces as Fish Food on a Pacific Coral Reef

The fates of 5,975 feces produced by 88 species of reef fishes were monitored at Palau (western Pacific Ocean). At least 4 5 fishes ate fish feces in addition to other foods. Intraspecific coprophagy and autocoprophagy were very rare and most coprophagous interactions were between members of different trophic groups. Fecal material moved through a feeding network of fishes, from carnivores to herbivores with low carbonate diets (LCDs) of fleshy (principally red) microalgae to herbivores with LCDs of brown macroalgae to high carbonate diet (HCD) herbivores and detritivores. Intermediate links were often omitted. This network retained food material entering it, and, because herbivores ate piscivore feces, appeared to recycle some food. Fishes ate almost all the feces of zooplanktivores and other carnivores, and most of the feces produced by herbivores with LCDs of microalgae and by coralivores with LCDs of hard-coral tissue. Fishes ate few feces of LCD herbivores that led on brown macroalgae and virtually no feces of herbivores and detritivores with HCDs. A few fishes regularly associated with local concentrations of zooplanktivores and LCD microalgivores and consumed large amounts of the feces the latter produced. Although coprophagy is a common feeding tactic its importance to the 'average' members of the fish community is unknown.