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A Comparative Study Of The Ecology Of Smooth Flounder, Pleuronectes Putnami, And Winter Flounder, Pleuronectes Americanus, From Great Bay Estuary, New Hampshire, Michael Patrick Armstrong

Doctoral Dissertations

Smooth flounder, Pleuronectes putnami, and winter flounder, Pleuronectes americanus, co-occur in estuaries along the east coast of North America from Labrador to Massachusetts. Results of a three year sampling program indicated that the two species were partially segregated along salinity and depth gradients in upper Great Bay Estuary, New Hampshire. Along the salinity gradient, smooth flounder were most abundant at the oligo-mesohaline riverine habitat while winter flounder were most abundant at the meso-polyhaline open bay habitat. Both species exhibited a generalized up-river movement with seasonally increasing salinity. Smooth flounder showed ontogenetic changes in distribution along the depth gradient, with the …

Radiatively Active Trace Gas Emissions From Waste Management Systems, Peter Matthew Czepiel

Doctoral Dissertations

Current waste management practices present significant potential for emissions of radiatively active trace gases to the atmosphere. This dissertation describes the quantitative assessment of nitrous oxide (N$\sb2$O) emissions from liquid waste and residuals treatment, emissions of methane (CH$\sb4$) from landfills, and the effects of microbial oxidation on landfill CH$\sb4$ emissions.

N$\sb2$O emissions were measured from liquid treatment process at a wastewater treatment plant where the highest emissions occurred during secondary aeration. Emission factors derived from the measurements included 3.2 g N$\sb2$O person$\sp{-1}$ year$\sp{-1}$ and $1.6\times10\sp{-6}$ g N$\sb2$O (liter wastewater$\sp{-1}$). The potential for N$\sb2$O emissions from the composting of the residual …

A Proposed Acrosomal System For Identifying Stages Of The Cycle Of The Seminiferous Epithelium And A Model For The Kinetics Of Spermatogenesis In The Rabbit, Antonio Carlos S Castro

Doctoral Dissertations

Most quantitative investigations of spermatogenesis requites identification of stages of the cycle of the seminiferous epithelium. The current "tubular morphology" system of staging for the rabbit permits identification of only eight stages and is not applicable to all experimental conditions. A more advantageous staging system, based on changes in the acrosome and morphology of the developing spermatids, had not been developed for the rabbit. Knowledge of spermatogonial kinetics, including the identity of spermatogonial subtypes and the number and timing of spermatogonial divisions, is also important, but had not been fully elucidated in this species. This investigation was undertaken to develop …