Field studies evaluating developmental and reproductive effects of chemical exposure in the coral reef fish, Abudefduf sordidus (Pomacentridae)

Assessing chemical impacts in coral reef environments has been difficult due to a lack of baseline monitoring criteria as well as appropriate benchmarks for risk assessment. Knowledge of concentrations in the field at which adverse effects are observed is limited since many coral reef monitoring programs are designed to quantify ecological responses but not specific stressors.; This dissertation utilized field studies to assess effects of polychlorinated biphenyl (PCB) contamination on reproduction and development in natural populations of the coral reef fish, Abudefduf sordidus. Differences in the occurrence of developmental abnormalities, larval morphology, and temporal spawning patterns were assessed in PCB contaminated and uncontaminated areas within Johnston Atoll, Central Pacific Ocean. A genetic parentage study using microsatellite loci assessed male and female site fidelity, number of maternal contributors to individual clutches, and female spawning frequency and patterns.; A significant positive residue-effect relationship was found between PCB concentrations in adult tissues and embryo abnormalities. Site and treatment differences were found in the relationship between larval length and yolk sac area at hatching. While larger larvae from all sites had similar yolk sacs at hatching, smaller larvae from PCB sites had smaller yolk sacs compared to those from reference sites. Variable spawning patterns were observed between Abudefduf sordidus colonies at PCB contaminated and uncontaminated sites, but variation was related to colony size not contamination. Semilunar spawning cycles were observed in colonies with more than 12 nest sites while colonies with fewer nesting males showed acyclic spawning patterns.; Genetic evidence suggested that male A. sordidus used the same sites repeatedly, clutches were spawned by one female, and each clutch within a nest was spawned by a different female. Many females identified spawned only once during the study. Multiple spawning females mated with multiple males. Thus from the genetic evidence it appears that multiple embryo and larval samples within a nest are independent.; The combined results from these studies provide new monitoring criteria for coral reef environments contaminated with PCBs as well as valuable life history information needed in order to use this and other pomacentrids for future biological monitoring efforts.