A study of the biogeography of Peromyscus maniculatus was undertaken in order to ascertain a few of the environmental parameters important in defining the distribution of this species and how the species in turn has adapted to these parameters. The Columbia Gorge was chosen as it presents a climatic gradient from maritime to continental with very little elevation gain. Changes along this gradient in topography, soils and vegetation community structure are discussed.

Benthic communities in the estuarine portion of the James River are controlled mainly by salinity. Pollution effects are localized and difficult to assess because of the rigorous physical environment. Mesohaline and oligohaline communities were very similar to those in other east coast estuaries. except for the dominance of Rangia cuneata in the oligohaline zone. Communities of the tidal freshwater zone are most affected by pollution. In the areas of Richmond and Hopewell, where the major portion of the pollution load enters the river, communities are most severely depressed. Separate multivariate analyses of species distributional patterns, and pollution and physical parameters produced similar results dividing the river into mesohaline, oligohaline, and upper and lower tidal freshwater zones. Further analysis of only the tidal freshwater portion, to eliminate the effect of salinity, indicated that the distribution of benthic communities reflected the location and concentration of pollution sources along the river. The communities were dominated·by the introduced Asiatic clam, Corbicula manilensis, tubificids of the genus Limnodrilus and the chironomid larva Coelotanypus scapularis. The fauna of the freshwater zones was very eurytopic and adapted to the silty habitats that characterize the tidal freshwater James River and had great resemblance to the fauna of eutrophic lakes. The classical concept that a sharp increase in the number species occurs from the oligohaline to freshwater zones was found to be misleading. The increase does not occur until nontidal freshwater areas of greater habitat diversity are reached. Various aspects of the ecology of the poorly known tidal freshwater habitat are also discussed. This dissertation is from the Joint Program Degree from the College of William & Mary and University of Virginia and awarded by the University of Virginia.

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No description available.

No description available.

Aquatic macrophytes are important components in structuring aquatic communities because they provide physical and biological functions that contribute to the stability of the ecosystem. Macrophytes provide the basis for the aquatic food-web and also provide habitat and refugia for aquatic fauna. In systems that lack macrophytes, anthropogenic re-establishment may be a feasible management approach to improve aquatic ecosystems. Understanding environmental factors that regulate colonization, dispersal, and persistence of aquatic macrophytes is pertinent to re-establishment efforts. The purpose of this study is to test hypotheses regarding success of macrophyte re-establishment efforts in Little Bear Creek Reservoir, Alabama using different macrophyte species, water depths, plant patch size and protection against herbivores at planting sites. In addition, a deductive GIS model is used to predict suitable areas to focus re-establishment efforts. Knowledge generated from hypothesis testing and application of GIS modeling provides novel information and tools for managing aquatic ecosystems.

Studies conducted to determine life history and starch allocation of common reed (Phragmites australis), and evaluate haplotype susceptibility to aquatic labeled herbicides. Twelve 0.1 m2 samples were taken from four sites in the Mobile River delta from January 2006 to December 2007. Samples separated into above and belowground biomass dried and weighed. Starch determination used the amylase/amyloglucosidase method. Biomass decreased with decreasing temperature. Aboveground biomass was 2200 and 1302 g m2 in October 2006 and December 2007. Belowground biomass was 1602 and 1610 g m-2 in November 2006 and December 2007. Aboveground starch was highest in December of 2006 and November of 2007. Belowground starch peaked in August of 2006 and September of 2007. RFLP methodologies were used to identify populations of I and M used for herbicide sensitivity screening. No difference detected in the susceptibility of haplotypes. Glyphosate, imazapyr, and triclopyr are effective herbicides for common reed control.

A point intercept survey was conducted from 2005 to 2010 on the Ross Barnett Reservoir near Jackson, MS to calculate the frequency of occurrence of all aquatic plant species in the Reservoir. style='mso-spacerun:yes'> Water lotus ( style='mso-bidiont-style:normal'>Nelumbo lutea Willd.) was the native species that occurred most often, while alligatorweed (Alternanthera style='mso-bidiont-style:normal'> philoxeroides [Mart.] Griseb.) occurred most often with regard to non-natives. A logistic regression model indicated that as species richness increases, the probability of observing a non-native species also increases. Herbicide evaluations implied that the chemical imazapyr provided the largest biomass reduction in alligatorweed over a twelve week period; however, 2,4-D would be the most economical option for long-term control. A pathogen study on alligatorweed revealed the presence of the fungus (Ceratorhiza style='mso-bidiont-style:normal'> hydrophilum [ class=SpellE>Xu, Harrington, Gleason, Et class=SpellE>Batzer, Comb., Nov. ( style='mso-bidiont-style:normal'>Sclerotium hydrophilum [Sacc.]). style='mso-spacerun:yes'> Future studies should verify the potential or lack thereof of this fungus being a biological control agent on class=SpellE>alligatorweed.

No description available.

No description available.