Thesis (M.M.P.)--University of Delaware, 2007. / Principal faculty advisor: George R. Parsons, College of Marine and Earth Studies. Includes bibliographical references.

Around 70% of the world is covered with water but only 2.5% of it is freshwater and even less is available for the ecosystem and humanity. The limited available fresh water is facing increasing challenges from water pollutions and eutrophication is one of the major concerns worldwide. The reason of eutrophication is the presence of excessive amounts of phosphorus and nitrogen in water bodies, which may cause algal blooms and a variety of harms to aquatic ecosystem in association with algal blooms. Among these two components, phosphorus plays a major role in eutrophication control and recovery since atmospheric N2 can be fixed by biological nitrogen fixation (BNF) processes and is therefore of little meaning to control. In this study, we investigated for the first time the potential of using controlled growth of algae and, in particular, filamentous cyanobacterium Spirulina platensis, for eutrophic water restoration. This study investigated the algal cell growth, algal by-product production, and removal of phosphate by S. platensis at different phosphate levels in artificial wastewaters and eutrophic waters. Results indicate that S. platensis could remove 90.17% of phosphorus from artificial wastewaters containing 10 mg/L phosphate in a 16-day cultivation period. When tested for eutrophic water restoration, S. platensis was able to convert hypo-eutrophic, eutrophic, and meso-eutrophic waters to oligotrophic water. It was shown that by using 100- micron nylon mesh cloth we could keep biomass concentration to be lower than 0.30±0.02 g/L. In the meantime, light/dark tests indicate that the dissolved oxygen level would not go below the hypoxic level, i.e., 4 mg/L after a 12-hour dark period at biomass concentration up to 1 g/L. These results indicate that it is possible to use S. platensis for both control of point source discharge and eutrophic water restoration.

Boshers dam vertical slot fishway, James River, Virginia, U.S.A., opened in 1999 and restored connectivity to 543.3 km of spawning habitat for anadromous fish. The fishway also allowed local movement of resident species. Video observation from 2001-2005 was used to evaluate environmental predictors of American shad (Alosa sapidissima) and sea lamprey (Petromyzon marinus) passage. The ecological effects of restoring connectivity to upstream habitat for gizzard shad (Dorosoma cepedianum) and blue catfish (Ictalurus furcatus) are also discussed. Regression analysis determined that the best predictor of increased daytime American shad passage is higher water temperatures and discharge and for increased daytime sea lamprey passage, a higher water temperature and increasing water temperature trend. Day length, and indirectly, barometric pressure also played a role in passage. Sea lamprey and American shad peak passage rates were dissimilar when comparing preferred water temperature ranges. Sea lamprey peaked (5.30/hr) at 16-17.99°C, while American shad peaked (1.05/hr) at 20-21.99°C. The diel pattern of passage for American shad indicated a strong diurnal tendency. All passage occurred during daytime hours, peaking from 1100 to 1900 hours. Diel patterns of sea lamprey indicated a strong nocturnal tendency (66% of passage occurring at night), with peak passage between 0300 and 0700 hours. More complete nightly passage data and passage data from periods when the water is too turbid for video observation would improve the accuracy of determining environmental predictors of passage.

This Diploma Thesis deals with small water reservoirs as significant landscape elements, that have the essential influence on preservation or increase of generic diversity of the whole territory. In a specific example of the proposal of restoration of a small water reservoirs the pond Panský in the cadastral area of Lhota by Kamenice nad Lipou is presented the suitable way of approach to original, natural functions of this minor dam considering the interest of the owner, who uses the pond for semiintense fish farming.