Interactive effects of nutritional condition and refuge availability on survival of a temperate reef goby

Abstract

Variation in individual performance and condition of marine organisms can influence larval supply and the outcome of post-settlement processes. The broad applicability of these patterns among systems and under different environmental conditions, however, remains relatively unknown. We determined whether nutritional condition would affect the survival of recently settled recruits of a temperate reef fish, the blackeye goby, and whether refuge availability would modify the importance of condition. Recruits were fed high or low food rations in the laboratory for 15 d, after which pairs of high- and low-ration fish were marked and placed on standardized plots of rock rubble in the field. Plots were monitored daily to determine mortality over 12 d. To examine the combined effects of condition and refuge availability, pairs of fish were placed on plots of high, medium, or low amounts of refuge. Laboratory experiments examined the effect of condition on burst swimming speed to elucidate the mechanisms underlying the observed patterns of survival. On standardized plots, fish fed low rations experienced higher mortality than fish fed high rations. When refuge was manipulated, low-ration fish experienced higher mortality than high-ration fish at higher levels of refuge. Surprisingly, higher mortality was observed for high-ration fish on low-refuge plots, possibly due to differences in risk-prone behavior. A reduction in the overall probability of mortality resulted in an unanticipated dampening of the importance of condition for survival. Our results indicate that the ecology of individuals, mediated by environmental conditions, is an important constituent in the population demography of reef fishes. © Inter-Research 2010.