Effects of seascape context on condition, abundance, and secondary production of a coral reef fish, Haemulon plumierii

摘要

ABSTRACT: Variation in seascape composition has the potential to impact habitat quality for fishes, and characteristics of the surrounding seascape have been correlated with abundance of organisms in many systems. Less studied is how seascape context may affect other aspects of habitat quality including growth, condition, or production of focal species. Juvenile white grunts Haemulon plumierii are known to rest on patch reefs during the day and move into seagrass habitat at night to feed, linking multiple habitats through these daily foraging migrations. We created artificial reefs across a gradient of seagrass cover and determined how juvenile white grunt condition, growth, abundance, and secondary production were related to seagrass cover within the seascape. White grunt abundance was positively correlated with the cover of seagrass within the seascape, while condition (relative condition factor, K_n) and growth rate (measured using the ratio of RNA to DNA) did not vary among reefs within different seascapes. Secondary production of white grunts was found to be highest on reefs in seascapes with more seagrass. Our results are consistent with the hypothesis that increased food resources associated with higher seagrass cover contribute to increased grunt production. Differences in habitat quality among reefs in different seascapes were manifest at the population (abundance) and ecosystem function (secondary production) levels and not at the individual level (individual growth rate or condition factor). These results highlight the importance of considering multiple levels of individual and population responses in assessments of habitat quality, and add evidence that seascape composition should be considered in spatially explicit management strategies.