PARENT SESSION
Contributed Oral Session 161: Predator - Prey Ecology: Aquatic Habitat and Food Webs
Friday, August 12, 8:00 AM - 11:30 AM, Meeting Room 519 B, Level 5, Palais des congrès de Montréal
Differential habitat use of an assemblage of coral reef-fish recruits and their potential predators.
Valles, Henri*,1, L. Kramer, Donald1, Hunte, Wayne2, 1 McGill University, Montreal, Quebec, Canada2 University of the West Indies, Cave Hill, Barbados
ABSTRACT- Spatial heterogeneity may be a crucial factor in shaping the distribution and abundance of organisms via predation. In coral reef fish communities, it probably plays a major role soon after settlement, when reef fish are most vulnerable to predation, but little is known of such role. In this study we specifically examine the role of microhabitat in explaining the small-scale distribution of early recruits (standard length <15 mm) of abundant coral reef fishes (8 taxa) and their potential predators (12 species). The distribution of both predators and recruits was recorded at different spatial scales across 3 sites (2 to 5 km apart) on the west coast of Barbados. In each site, 3 permanent quadrats (36m2; 30 to 60 m apart) divided into 144 cells (0.25 m2), were surveyed bi-weekly over a recruitment season. Indirect and direct ordination techniques plus contour maps were used to summarize distributional patterns and relate them to microhabitat features inside the quadrats. Patterns of recruit distribution within quadrats were similar at the two smallest scales examined (0.25 m2 and 1m2), allowing taxa to be classified into turf-algae associates, turf-algae avoiders, sand/rubble associates, live coral associates, and undefined. The four most abundant potential predators also exhibited consistent differences in space use within quadrats related to habitat features. Two species were associated with areas of low physical complexity, rich in sand or/and rubble, another was associated with areas of high physical complexity, rich in live or/and dead coral, and a fourth suggested a more diverse space use. At the larger scale, across all quadrats, availability of favored microhabitat of recruits and predators was significantly correlated with abundance of some recruit species but not of predator species respectively. However, the abundance of different species of predators usually was correlated, suggesting more complex dynamics governing predator abundance and distribution. Our results show differential habitat use at small scales by both reef fish recruits and their potential predators: this is a fundamental step towards identifying the mechanisms and specific sources of predation on coral reef fish communities, and ultimately, towards understanding the dynamics of multi-species communities in patchy environments.
Key words: space heterogeneity, scale, marine