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The character and magnitude of predation by Calliopius laeviusculus on the intertidal eggs of capelin (Mallotus villosus) were examined. Average endobenthic densities at Bryant's Cove (NFLD) in 1988 for both amphipods and capelin eggs during capelin egg development (June 17-August 8) were 0.78 amphipods cm$ sp{-2}$ and 62 eggs cm$ sp{-3}$ (750 cm$ sp{-2}$) respectively. At this average capelin egg density, laboratory results suggest that, on a daily basis, only gut capacity and clearance time limit amphipod predation on eggs. In situ, C. laeviusculus biomass closely tracked capelin egg biomass indicating that reproductive cues operating for both capelin and amphipods may be linked. In 1988, ca. 50% of the annual production of C. laeviusculus resulted from predation on capelin eggs. Given the bioenergetic demands of C. laeviusculus and the annual variation in capelin spawning effort, the temporal overlap between capelin eggs and high amphipod biomass could result in predation mortalities ranging from ca. 15-30% of the total capelin egg deposition.

The physical and physiological condition of larval fishes throughout their development is believed to influence their survival, and ultimately to contribute to recruitment to the adult population. The study of larval condition is therefore central to larval fish ecology. / In this thesis I sought to (1) carry out an appraisal of the characteristics and the reliability of condition measures now being used, (2) assess the importance of maternal contribution to the nutritional status of larval fish, (3) evaluate the possibility that diel variability in metabolism could lead to serious biasing of the interpretation of condition measures obtained over time, and (4) assess the time course of the condition of larval fishes subjected to periods of intermittent feeding. / The experiments described in chapter 2 were designed (1) to assess the impact of female nutritional status on the quality of the eggs and larvae they produced, (2) to determine which of a series of nucleic acid and protein measurements were most responsive to post-hatching starvation, and (3) to determine whether the starvation dynamics of those measures was affected by female source. No significant correlation could be found between any of the maternal traits studied and eggs and larval measures. The results did show, however, that egg size was more variable between-clutches than within-clutch, was independent of embryonic developmental rate, but was positively related to larval size. / The existence and ontogeny of circadian (24 hrs.) and ultradian (<24 hrs.) oscillations in the nucleic acids and protein content of larval capelin was investigated in the laboratory experiments outlined in chapter 3. The most obvious long-terms trends occurred during the embryonic period when DNA and RNA content increased constantly, and during the post-yolk-sac period when RNA and protein decreased following sub-optimal feeding. / The objectives of the study described in chapter 4 were threefold, (1) to determine which of a series of nucleic acid and protein measurements were affected by intermittent (delayed-fed and delayed-starved) feeding conditions in capelin larvae, (2) to determine the dynamics and shape of the time response, and (3) to determine whether the empirical data gathered were consistent with models developed as a consequence of the review of the literature (chapter 1). Only the dry weight, and the quantity of DNA, RNA, and protein per dry weight differed significantly between starvation and ad libitum feeding controls. Starvation dynamics were less consistent with predictions. Of the indices investigated, the dynamics of the quantity of DNA and RNA per dry weight were the most consistent dynamics with model predictions. (Abstract shortened by UMI.)

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