Theses and Dissertations

Defense Date

12-8-2015

Document Type

Thesis

Degree Name

M.S. Marine Biology

First Advisor

Dave Kerstetter

Second Advisor

Stephanie Green

Third Advisor

Richard Spieler

Abstract

Predator satiation and prey-size preference were determined for locally caught lionfish, schoolmaster, and graysby, all co-occurring predatory fishes in the Florida coral reef ecosystem. Individuals were evaluated by exposing them to wild-caught killifish over a gradient of four size classes (20 mm to 60 mm, in 10 mm increments). Preference trials extended over a 2 hr time period and were filmed to determine the order in which each prey item was consumed. Satiation was evaluated by exposing the predators to an equal number of excess prey items for 24 hrs and evaluating consumed prey weight. Lionfish and schoolmaster showed a significant preference for the smallest size class (20-30 mm) while the graysby preferred the largest (50-60 mm) and smallest equally. Graysby were shown to consume the least amount of food per gram by biomass (0.034g/gram predator-1) while lionfish consumed the most (0.079g/gram predator-1). A significant difference was also found between consumption rates of lionfish and schoolmaster (0.053g/gram predator-1). If consumption is compared by length between species, lionfish ( = 0.051g/mm predator-1) and schoolmaster ( = 0.061g/mm predator-1) consumption was not significantly different. These results suggest that lionfish success may stem from its ability to target prey sizes not preferred by the graysby while able to outcompete schoolmaster for the same prey size class. However, if the lionfish is compared on an individual level to schoolmaster by individual or length, consumption is similar, suggesting lionfish consumption is not significantly greater on the reef than the native species on an individual basis.