Graduation date: 1984

Thesis (Ph. D.)--University of Oregon, 2008. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 171-198). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.

Thesis (Ph. D.)--University of Illinois, 1920. / "Contributions from the Entomological laboratories of the University of Illinois, no. 69." Bibliography: p. 135-140.

Thesis (doctoral)--Ludwig-Maximilians-Universitat zu Munchen, 1906.

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Patterns of variability in growth, development and mortality in early life histories were examined at two levels--general and specific. At the general level, I examined the functional significance of larvae in metazoan life cycles. This was achieved by surveying the metazoa at the class level and categorizing mode of development by habitat. Three long-standing hypotheses for the paucity of larval development in fresh water were rejected. I argue that viewing metazoan larvae as a means for feeding and growth provides a unifying framework for evaluating the features of habitats which correlate with the range of variation expressed in development modes. I offer a modelling framework to investigate variation in developmental modes within and between habitats. The suggested model requires input on larval growth rates, larval period duration (development time), and size-specific mortality rates. These variables, and the interactions between them, are also central to the specific analysis which addresses the ecological processes and mechanisms which affect survival and hence recruitment during the early life histories periods of marine fishes. Winter flounder (Pleuronectes americanus) was used as a model species to investigate phenotypic variability in patterns of growth and development and their survival consequences. Using laboratory-reared fish, I demonstrate that size-at-age does not diverge continuously during the larval and juvenile periods. The results show that fish which grow slowly as larvae, compensate for their slow growth by growing rapidly as juveniles. This compensation in growth rate causes juvenile size-at-age to converge, or at least, prevents divergence in juvenile size-at-age. In addition, I provide some of the first estimates of individual variability in larval growth trajectories for a marine fish. I conducted the first experiment which separates the effects of both size and age on the vulnerability to predation in recently metamorphosed fishes. Th

Environmental control of interactions between larval fish and their prey, and the potential influence of this relationship on fish feeding and recruitment, were assessed using empirical models developed using data drawn from the literature and developed in field studies. Ingestion rates of larval fish in laboratory and natural environments were found to differ in relation to food density. In laboratory studies, larvae show a strong functional response to prey density. Larvae situated in situ consume food at much higher races than would be predicted from laboratory studies and these rates are independent of prey density at known in situ densities. This discrepancy between laboratory and field feeding rate-food density relationships can be partly explained by the in situ contribution of small-scale turbulence to predator-prey encounter rates. Field studies of the influence of wind on nearshore hydrography showed that wind-induced upwelling generated favorable combinations of nutrients, light, and small-scale turbulence for production by phyto- and zooplankton. The distribution of microplankton $(<$80 $ mu$m) that resulted from these upwelling episodes was quantitatively described by the cumulative longshore wind velocity during the summer months. Microplankton abundance was greatest within 4 km of a major spawning site for capelin, Mallotus villosus, an economically and ecologically important forage species in the north Atlantic Ocean. Interannual variability in the intensity and frequency of upwelling-favorable winds was positively and significantly correlated with recruitment levels in the NAFO 2J3K capelin population. A new recruitment forecasting model, using an upwelling-related wind index as an input, explained more of the variance in capelin recruitment than did a previously published model. These results suggest that larval capelin are more likely to be food-limited in years when wind conditions are unfavorable for upwelling, and that recruitment in this fi

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