Relative Importance of Nutritional Condition and Refuge Availability for Survival of the Blackeye Goby (Rhinogobiops nicholsii)

The objectives of my research have been to determine (1) whether nutritional condition affects the survival of recently settled recruits of the blackeye goby (Rhinogobiops nicholsii) and (2) whether refuge availability may influence the importance of nutritional condition. For the experiments I conducted at WIES in 2002-05, recruits were fed high or low food rations in the laboratory for 15 d, after which pairs of high- and low-ration fish of the same size were placed on standardized 0.25-m2 rock plots constructed in Big Fisherman Cove, Santa Catalina Island. Laboratory data include condition indices (Fulton's Condition Factor) and growth rates for high- and low-ration fish. In the field, plots were monitored daily to determine mortality over 12 d. Behavioral data were also taken; we recorded whether fish were out, exposed on the plot or hiding, on top of the rocks or between the rocks, and if they were at the exterior of the plot or the interior. Additionally, we recorded the number of recruits that settled to each plot during the daily surveys. Gobies that survived to the end of the field experiment were collected so that field growth rates could be calculated. For experiments examining the interactive effects of refuge availability, pairs of fish were placed on plots in three levels of refuge availability: high, medium, and low. The same types of data were collected during experiments looking at the importance of both condition and refuge availability. In the summer of 2006, laboratory experiments will be conducted looking at the effects of predator presence on stress, feeding behavior, and growth of the blackeye goby. We will cross two levels of refuge availability (low/high) with two predator-exposure treatments (present/absent). Data collected will include cortisol (stress hormone) levels, growth rates, and feeding behavior (how many fish actively feeding, how many fish swim up in water column to food).