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Factors Restricting Recruitment Of Ascophyllum Nodosum L (Le Jolis), Paula K B Philbrick

Doctoral Dissertations

Ascophyllum nodosum dominates a wide zone on the shore. Juveniles occur high in the zone where canopy is continuous and grazing animals few. Settlement could account for the restricted range if it were enhanced under canopy or on the upper shore. Settlement was monitored under canopy and in the open at four shore levels during spring 1983. Propagules settled everywhere. Settlement does not restrict plant establishment. Germlings caged and not caged were placed under canopy and in the open through the zone to evaluate the effects of animals and the physical environment (shore level x frond cover) on survival and …

Analysis Of Signal Output By The Ethylene Receptor Etr1 From Arabidopsis, Xiang Qu

Doctoral Dissertations

Ethylene is one of the most important plant hormones and regulates many processes during plant growth and development. In Arabidopsis, the ethylene receptor family consists of five members: ETR1 and ERS1 have a functional histidine kinase domain and form subfamily 1; members of subfamily 2, including ETR2, ERS2, and EIN4, possess a highly diverged histidine kinase domain predicted not to be functional. To analyze signal output by the ethylene receptor ETR1 from Arabidopsis, mutant-based approaches were taken. Initially, the role of the proposed signal output region of ETR1 in ethylene signaling was examined. For this purpose, the ability of mutant …

Fire Dynamics In Amazonia, Manoel Cardoso

Doctoral Dissertations

Fires are major disturbances for ecosystems in Amazonia. Because of their short time scale and strong links to biogeochemical cycles, fires significantly affect fluxes and stocks of carbon and nutrients, change air composition, and modify ecosystems structure and functioning. Fires are strongly related to land-use, land-cover and climate conditions. Because the increasing development of the region, these factors have been changing and leading to different patterns of fire activity. Thus it is very important to understand the dynamics of fires in the region and to develop models that can project their potential changes. To contribute in all these subjects, we …

Assessing Hemlock Woolly Adelgid Induced Decline And Susceptibility Using Hyperspectral Technologies, Jennifer Pontius

Doctoral Dissertations

The ultimate goal of this study was to provide the scientific framework for using narrow band hyperspectral instruments to assess early hemlock decline and susceptibility to the introduced hemlock woolly adelgid (HWA). To this end, spectral data from an ASD FieldSpec Pro was used to develop a 6-term linear regression equation, which predicted a detailed decline rating (0--10) with an R2 of 0.71 and RMSE of 0.591. To scale up this method to a remote sensing platform, NASA's Airborne Visible Infrared Imaging Spectrometer (AVIRIS) was used to create a hemlock abundance map, correctly identifying hemlock dominated pixels (>40% basal …

Impact Of Macular Pigment Optical Density On Photophobia Threshold, Adam James Wenzel

Doctoral Dissertations

Two carotenoids, lutein and zeaxanthin, accumulate in the central retina where they are collectively referred to as macular pigment (MP). By absorbing short-wavelength light, MP may attenuate photophobia (PP)---visual discomfort induced by normal light exposure---for targets composed of short-wavelength light. The aim of this study was twofold: first, to investigate a possible relationship between integrated macular pigment optical density (MPOD) and PP thresholds for short-wavelength targets relative to mid- to long-wavelength targets; and second, to measure changes in PP thresholds after increasing MP with lutein supplements.

MPOD was measured psychophysically at 20', 30', 60' and 120' eccentricity with a Macular …

A Study Of Basidiomycetes Isolated From Coarse Woody Debris And Contiguous Soil Horizons In A Mixed Deciduous-Conifer Forest In New Hampshire, United States Of America, Therese Ann Thompson

Doctoral Dissertations

The wood decay fungus Hypholoma sublateritium (Fr.) Quel., links the mineral (BC & E) and organic (Oe) soil layers to decomposing coarse woody debris (CWD) in a northern hardwood forest. This link supports the possibility that energy stored in woody debris can facilitate the vertical transfer of elements and compounds within the soil profile. This potential transfer implies new pathways for biogeochemical cycling within forests. H. sublateritium was isolated from basidiocarp fruiting bodies (October 1997 & 1998), Acer rubrum L. bole wood (June 1999), and three soil horizons (October 1999 and October 2000) from one of six research sites in …

The Effects Of Temperature On The Physiology And Locomotory Behavior Of The American Lobster, Homarus Americanus, Suzanne M. Cooke

Doctoral Dissertations

Temperature has a pervasive influence on the physiology and behavior of all lobsters, and especially those found in habitats where temperature fluctuates the most. One population of lobsters undergoes a seasonal migration in the Great Bay estuary system in NH, entering the estuary in late spring and returning to the coast in the late summer and fall. This migration may be triggered by physiological or behavioral responses to seasonal temperature shifts.

The first set of experiments examined the effect of temperature on heart rate in order to further understand the influence of temperature on lobster metabolism. Heart rate was measured …

Genetic Diversity And Structure Of Calanoid Copepods: Molecular Evolutionary Patterns In Coastal Estuaries (Acartia Tonsa) And The Open Ocean (Calanus Spp), Robert Sean Hill

Doctoral Dissertations

Calanoid copepods are an important part of marine and estuarine ecosystems. However, it has been difficult to study their life histories, population structure, and evolution because they share a conserved morphology that complicates species identification. A primary focus of this study was the genetic and physiological variation of the calanoid copepod Acartia tonsa from four estuaries along the East Coast of the USA (Great Bay, NH, Buzzards Bay, MA, Narragansett Bay, RI, and Beaufort Inlet, NC). Based on DNA sequence variation for the mitochondrial cytochrome oxidase I (mtCOI) gene, significant population structure was observed between all pairs of estuarine populations …

Approach To The Identification Of Sex-Determining Genes In The Tilapia Genome By Genetic Mapping And Comparative Positional Cloning, Bo-Young Lee

Doctoral Dissertations

Tilapia (Oreochromis species) are one of the most dominant species in the aquaculture market. Genomic approaches may contribute to tilapia culture in the near future by identifying genes controlling traits valuable at the market. One of the most important traits for farming of tilapia is sex because monosex culture shows the best efficiency of culture. In tilapia, however, the mechanisms of sex-determination have been poorly understood because of the variation in the genetic basis of sex-determination and the lack of morphological differences between sex chromosomes.

To facilitate QTL analysis of these traits, a genetic linkage map was constructed from hybrids …

Development Of Muscle Structure And Function In Loliginid Squids, Gabriela Maria Martinez

Doctoral Dissertations

Squid embryos are able to contract their mantle early during the embryonic period.

This dissertation examines the onset of contractile capabilities and subsequent maturation of the main locornotor structures in embryos of two species of loligind squids with a focus on the mantle musculature. The functional implications of the differentiation and organization of the musculature is investigated.

The results of these series of studies indicate that the development and emergence of functional competence of the mantle musculature in loliginid squids is a dynamic process. Differentiation and organization of the musculature of the main locomotor structures does not occur simultaneously and …

Inter-Annual And Decadal Variation In The Pelagic Marine Ecosystem Of The Yellow And East China Seas, Seung-Hyun Son

Doctoral Dissertations

The water-leaving radiance measurements and chlorophyll concentrations of the Coastal Zone Color Scanner (CZCS) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) were compared to investigate decadal trends in the Yellow and East China Seas (YECS). A unified bio-optical algorithm was derived to convert CZCS pigments to SeaWiFS chlorophyll concentrations. The conversion is applied to level-2 CZCS data.

We established monthly variations in the stratified and well-mixed areas using a coupled ocean wave-circulation model and the ocean color satellite data for estimating primary productivity in the Yellow Sea using satellite observations. The model results were compared with remotely sensed sea surface …

An Investigation Of Genetic Variation Within Northwest Atlantic Porphyra (Bangiales, Rhodophyta) With Specific Phylogeographic Analysis Of The Common, Rocky Intertidal Species, Porphyra Umbilicalis, Brian William Teasdale

Doctoral Dissertations

To investigate the phylogeography of the rocky intertidal red alga, Porphyra umbilicalis Kutzing, a restriction fragment polymorphism assay (RFLP) of the ribulose bisphosphate carboxylase large subunit ( rbcL) was developed to accurately distinguish P. umbilicalis from the other morphologically similar species in the North Atlantic. Initial screening of ∼800 Porphyra specimens resulted in the additional discovery of a cryptic Porphyra taxon.

The presence and variability of group-I introns of the ribosomal small subunit (SSU) were screened in North Atlantic species of Porphyra in order to assess whether they could be biogeographically informative. In an initial screening for the helix 50 …