Inaug - Diss. - Münster. / Lebenslauf. "Literatur": p. 49.

Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 100-105).

Hydraulic retention time (HRT) might contribute to the substantial variation in phosphorus-chlorphyll and chlorophyll-zooplankton models because rapid flushing might depress plankton development. However, for a world-wide data set. HRT was not correlated with chlorophyll. Total phosphorus had no effect on chlorphyll when hypereutrophic sites were considered separately, but chlorophyll was negatively related to HRT. Short term HRT, averaged over periods up to one month, was not correlated with chlorophyll, or zooplankton biomass, in seven impoundments on the St. Lawrence and Ottawa Rivers. The size distribution of algae was not affected by HRT. The proportion of rotifer to total zooplankton biomass was positively related to HRT, but this trend disappeared when nauplius biomass was removed from the total. These results indicate that rapid flushing does not necessarily reduce planktonic biomass and that short term HRT is not useful for the prediction and management of planktonic biomass in these systems.

Thesis (M.S.)--Baylor University, 2006. / Includes bibliographical references (p. 62-67).

No description available.

No description available.

The availability of phosphorus from the anoxic hypolimnia of lakes to epilimnetic plankton was investigated by experimental studies on eight lakes in Ontario and Quebec. Availability was determined with a short-term bioassay based on the standardized retardation of planktonic uptake of phosphorus tracer in the presence of orthophosphate; availability was also estimated by SRP (soluble reactive phosphorus) analysis, since approximately 90% of SRP was available in anoxic waters. / Iron concentrations were high in some hypolimnia, but should become diluted after mixing with surface water. When iron concentrations after mixing exceeded 0.20 mg/L, aeration lowered availability and SRP. Therefore, samples from anoxic hypolimnia were kept anoxic. The fate of hypolimnetic phosphorus at turnover was studied by construction of a budget for SRP, total phosphorus, particulate iron containing phosphorus and particulate biological phosphorus at fall turnover in Lake Magog. Despite high concentrations of hypolimnetic iron, only 30% of the upwelling hypolimnetic phosphorus combined with iron after complete mixing, 30% was incorporated into biomass and 38% stayed potentially available as SRP. / In two lakes, hypolimnetic iron was undetectable hydrogen sulfide concentrations were high. H(,2)S interfered with the SRP analysis and poisoned plankton. After degassing, routine SRP analysis was possible, and availability was close to 100%. Iron and H(,2)S interference in the SRP analysis were circumvented by degassing or by maintaining anoxia. A simpler method, the analysis of TRP (total reactive phosphorus) after aeration, was developed which analyses SRP quantitatively in anoxic waters.

The overall aim of this thesis was to determine the relative importance of heterotrophy and autotrophy in lake plankton. Empirical analyses using extensive surveys of literature data revealed three specific patterns in metabolism and biomass structure in freshwater plankton. First, the ratio of phytoplankton production to plankton respiration (P/R ratio) tends to be low in unproductive lakes ($<$1), and increases along gradients of enrichment. Second, the contribution of planktonic heterotrophs (bacteria and zooplankton) to community respiration is highest in oligotrophic lakes. Third, planktonic heterotrophs dominate community biomass in oligotrophic lakes, whereas phytoplankton increasingly dominate plankton biomass along gradients of enrichment. These three distinct patterns were then tested simultaneously in a set of lakes that span a wide trophic gradient. Results indicated that the plankton of oligotrophic and mesotrophic lakes were characterized by P/R ratios well below unity, and a high contribution of heterotrophs to both community respiration and biomass. These trends are completely the opposite in the most productive lakes. The plankton communities of oligotrophic temperate lakes are predominantly heterotrophic and extensively utilize external inputs of carbon, and therefore only the plankton of eutrophic lakes conformed to the classical phytoplankton-based food web. In most lakes, excess heterotrophic activity could be supported by inputs of organic matter from the drainage basin. Excess plankton respiration, fueled by allochthonous organic carbon, could represent an important source of CO$ sb2$ to lakes.

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xxii, 277 p.; also includes graphics. Includes bibliographical references (p. 252-277). Available online via OhioLINK's ETD Center.

No description available.