CLAS: Colby Liberal Arts Symposium

The Risk Perception Associated with Model Apex Predators by Mesopredatory Fishes in Coral Reef Ecosystems

Diamond 145

Trait-mediated interactions are a form of indirect interactions in which predators influence prey by stimulating costly defensive traits. At present, little research has been conducted on these interactions in coral reef environments because of the difficultly of manipulating the presence of top-order predators such as sharks. The aim of this study was to determine if models of apex predators (a reef shark, Carcharhinus sp, and a coral trout, Plectopomus sp) constructed of fiberglass were successful in instigating trait-mediated interactions with smaller piscivorous reef fish that function as mesopredators in reef environments. Bait bags were deployed with underwater cameras under three treatment conditions and one control. These treatments were with a model of a blacktip reef shark, a model of a large or small coral trout and a PVC pipe (control). The cameras recorded the number of species of mesopredatory fishes observed in each of three different size categories and the greatest number of fish observed in a single video frame around each of the treatments. In the presence of the large models (the shark and the large trout) there were less small species observed around the bait bag, and fewer individual fish observed in a single video frame than with either the small coral trout or the control. In some instances (10), reef sharks appeared around the bait bag. When this occurred the numbers and diversity of fishes in the control and small trout treatment declined to match those of the shark and large trout treatments. These findings suggest that the apex predator models were effective in instigating trait-mediated interactions with piscivorous fish and could potentially aid in future research as apex predator models could be utilized in understanding the impacts of apex predator declines.

https://digitalcommons.colby.edu/clas/2015/program/294