Following fish feeding associations in marine and freshwater habitats

Abstract

Following fish feeding associations are composed of nuclear species that disturb the substratum when foraging, and followers that capitalise on food resources. In marine and freshwater ecosystems, bottom disturbance is the main predictor of follower composition; hence, other features, such as fish behaviour, may also converge between these habitats. Comparisons of the following associations in marine and freshwater habitats could provide a better comprehension of this interaction, which is known to increase the feeding of participating species. We compared following associations between a marine reef and a freshwater stream. Associations in the freshwater resembled the following three iconic reef interactions: (1) a carnivorous follower moving in front of a nuclear species; (2) a shoal of omnivores feeding on particles loosened by the nuclear fish; and (3) a shoal of omnivores feeding on particles expelled by the nuclear fish. The major differences between the marine and freshwater associations were (1) the greater morphological variety of nuclear species in the reef and (2) the main nuclear species often foraged in groups in the reef, whereas the freshwater counterparts foraged solitarily. These similarities between the systems outnumbered the differences, probably because of the shared water environment and the relatively simple requirements for fishes in these associations.