PARENT SESSION
Poster Session # 20: Predator - Prey / Mutualism - Parasitism Ecology.
Thursday, August 7 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
A field test of the antipredator responses of two native cyprinid prey fish exposed to predation by introduced brown trout.
Nannini, Michael*,1, Belk, Mark2, 1 Environmental Protection Agency, Research Triangle Park, NC, USA2 Brigham Young University, Provo, UT, USA
ABSTRACT- We examined how differences in antipredatory strategy affected mortality where introduced brown trout Salmo trutta prey on two native cyprinids, leatherside chub Gila copei and redside shiner Richardsonius balteatus. Previous work has determined that leatherside chub and redside shiner respond to both the presence of brown trout and simulated attacks by a model brown trout. However, the response of these two prey species differs markedly. Redside shiner increase their activity level in the presence of brown trout, respond earlier and quicker to attacks, and have a more maneuverable escape response. In contrast, leatherside chub decrease their activity level in the presence of brown trout, respond to attacks later and slower, and have a less maneuverable escape response. Antipredatory strategies used by other similar prey indicate that the strategy used by redside shiner ought to be more effective against brown trout predation than the strategy used by leatherside chub. To test this hypothesis we examined the mortality inflicted upon these two prey species by brown trout in a field setting. Enclosures were set up so that equal numbers of both prey species were either exposed to predation by brown trout or not. Brown trout significantly affected survival of both species. There was also a trout by species interaction in which the effect of brown trout on mortality of leatherside chub was stronger than the effect of brown trout on mortality of redside shiner. These results indicate that leatherside chub are more heavily impacted by brown trout than redside shiner.
Key words: introduced predator, antipredator response, predator-prey coevolution