The demographic responses of reef fish to their environment can be complex and in many cases, quite strong. Growth, mortality, longevity, and even reproductive effort have been demonstrated to vary for the same species of reef fish over scales of 100s to 1,000s of kilometers due to physiological and ecological interactions. Though few studies have explicitly documented it, this sort of habitat-mediated demography can also exist at very local scales. Here we present the results of a 2-year study of the bicolor damselfish, Stegastes partitus, in the Florida Keys, USA. We measured density and distribution, calculated key demographic rates (growth, survival, and fecundity), and characterized the environment (resident fish assemblage, substrate type and complexity, and food availability) of populations living in two adjacent but different habitats, the continuous fore reef and patchy back reef. Fish on the fore reef had an elevated growth rate and asymptotic size, increased mortality, and higher fecundity than fish on the back reef. We identified four potential causative mechanisms for these differences: food availability; competition; intraspecific density-dependent effects; and predation risk. Our data did not support an effect of either food availability or intraspecific density-dependence, but rather suggested that demographic responses are affected by both competition and predation risk.
Bibliographical noteFunding Information:
on improving this manuscript. We thank B. Kennington and A. Anderson of SubTropic Dive Center for technical support in Key West. The research was funded by Environmental Defense, Oak Foundation, PADI Foundation, a Fulbright post-doctoral fellowship (G.R.) and graduate fellowships from Duke Marine Lab Fellowship and McCurdy Endowment Fund (S.L. and W.F.). The research was conducted under FKNMS permit numbers FKNMS-99-057 and FKNMS-2001-002.
- Coral reef fish
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Aquatic Science