Prey release

Indo-Pacific lionfish (Pterois spp.) have spread to and established sufficient numbers throughout the Caribbean. They are extreme generalists that feed on ecologically and economically important species, they can reduce recruitment of native fishes by up to 79%, and can occur in densities in orders of magnitude greater than in their home range. Because prey do not recognize lionfish as predators (prey naiveté), lionfish prey on fish and invertebrates using little energy. The purpose of this study was to test if lionfish in Bonaire were obese and if obesity was more pronounced in males over females. Because of limited research on invasive species obesity, the presence of interstitial fat and fat in the liver was used to determine if a lionfish was obese or not. A total of 161 lionfish for interstitial fat and 74 lionfish for liver fat were analyzed. All males in this study were obese (they all had both interstitial and liver fat) however, not all females had interstitial and liver fat. Females also possessed interstitial and liver fat in lesser quantities than males probably because of allocation of energy towards reproduction. This study highlights the importance of studying obesity on invasive species, an open topic in marine science that has not been addressed thoroughly.

This student research was retrieved from Physis: Journal of Marine Science XIV (Fall 2013)19: 89-95 from CIEE Bonaire.

Coral reef fish exhibit remarkably diverse hunting techniques such as solitary hunting, shadow stalking, nuclear hunting, and hunting in schools of fish. This study examines the differences in feeding rates of the Atlantic Trumpetfish, Aulostomus maculatus, while it utilizes four dissimilar foraging strategies. Observations were completed in Bonaire, Dutch Caribbean while SCUBA diving to record A. maculatus striking at its prey. Feeding rates were calculated from the number of bites at prey during an observation period, in order to rank the strategies. Although consumption of prey was not determined, it is expected that feeding rate will track the number of bites at prey items and is used as a proxy for feeding rate in this study. Solitary foraging was hypothesized to exhibit the highest feeding rate due to its high prevalence on the reef, followed by shadow stalking, nuclear hunting, and hunting in schools. Competition for prey during associations with other fish and rarity of dense aggregations of schooling fish was thought to support the hypothesis. In this study, the feeding rate during solitary foraging was found to be significantly lower than shadow stalking, nuclear hunting, and hunting in schools, which were not significantly different from each other. The results indicate that A. maculatus forage more successfully in groups and exhibit multiple foraging strategies to exploit prey most efficiently. The hunting behavior of A. maculatus affects prey and other associated species, thus understanding this behavior may lead to further knowledge of other predatory fish and interspecific interactions.

This student research was retrieved from Physis: Journal of Marine Science XVI (Fall 2014)19: 1-5 from CIEE Bonaire.

On Bonaire, we studied the effects of predator abundance and habitat availability on the abundance of the threespot damselfish Stegastes planifrons, a species that creates algal gardens at the expense of live coral cover. Across 21 sites, predator biomass ranged from 12 to 193 g m−2 (mean = 55.1; SD = 49.1) and benthic cover of S. planifrons’ preferred habitat (corals of the Orbicella species complex) ranged from 2.2 to 38.0% (mean = 14.3; SD = 9.6). Across these gradients, the local abundance of S. planifrons was significantly and negatively related to preda- tor biomass, but not to habitat availability. Increased local abundance of S. planifrons corre- sponded to an increasingly larger proportion of coral colonies affected by its ‘farming behavior’, resulting in an increased prevalence of coral disease. Thus, predators indirectly affected the com- position of reef communities around Bonaire by controlling damselfish abundance. Furthermore, the abundance of S. planifrons could not be correlated with its preferred habitat, despite such cor- relations having been observed elsewhere in the Caribbean.