Temporal variation in the levels of Cu and Cd in zooplankton, phytoplankton and water taken from five pelagic stations in Hamilton Harbour during three separate sampling periods (June, August and October/November 1990) was examined. Significant seasonal variation occurred in the Cu and Cd levels measured in water and phytoplankton (Cu Water: df=2, F=32.28, P≤.0001, Cu Phytoplankton: df=2, F=48.94, P≤.0001 and Cd Water: df=2, F=18.98, P≤.0001, Cd Phytoplankton: df=2, F=58.81, P≤.0001). However, the Cu levels observed in zooplankton did not vary significantly with season (df=2, F=1.79, P≤.1919). The maximal levels of Cd in zooplankton in November may be due to increased ingestion of material that is resuspended during turnover. Similarly, the peak levels of Cu and Cd recorded in November in phytoplankton may be due to a combination of processes: a) change in the size structure of the phytoplankton community to smaller individuals with higher metal sorption capacities and/or b) contamination of phytoplanktonic tissue samples by resuspended material. Phytoplankton metal levels (Cu and Cd) are negatively correlated with chl a concentrations (n=45, r=.8171, ≤.0001 and n-41, r=-.5961, P≤. 0001, respectively). These relationships are likely the result of a dilution effect. Zooplankton Cd levels were positively correlated with water and phytoplankton Cd concentrations (n=41, r=.3211, P≤.0407 and r=.7667, P≤.0001) while Cu levels were not correlated with any of the variables tested. The difference between the correlatedness of Cd levels in zooplankton to water and phytoplankton Cd levels compared to the lack of this type of relationship with regard to Cu may be attributable to the biological function of each metal in zooplankton. Cu is required in small amounts for physiological processes and may be regulated whereas Cd has no known biological function. / Thesis / Master of Science (MS)

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Monthly samples of nutrients, phytoplankton and zooplankton were taken in the Columbia River estuary over a period of 16 months in order to determine distribution with season and salinity, and interrelationships between plankton and nutrients. Nitrate and phosphate levels in the river water entering the estuary are high in the winter and show depletion during the summer. Silicate levels are high in the river water at all seasons. Nitrate and phosphate levels are high in the entering ocean water during summer offshore upwelling. The nutrient levels in the estuary generally show a linear relationship with salinity, resulting from the levels of nutrients in the entering river and ocean water. Superimposed upon this linear relationship is a tendency for the nutrients to be enriched in the bottom waters of the central part of the estuary. The estuary phytoplankton are primarily composed of freshwater forms, and probably represent a downstream extension of the river flora. Regression analysis of phytoplankton levels vs. light, nutrients, and river flow indicates that light probably limits phytoplankton abundance on most dates. The zooplankton of the estuary are composed of three groups, preferring fresh, oligohaline, and polyhaline waters respectively. Regression analysis indicates a strong correlation between abundance of the freshwater group and river temperature. The factors controlling the abundance of the oligohaline and polyhaline groups are less obvious. The oligohaline group, principally Eurytemora affinis, reaches the greatest population density (100,000/m³ or more). Regression analysis indicates a close correlation between Eurytemora abundance and phosphate levels. This indicates a strong potential for zooplankton regeneration of phosphate necessary for phytoplankton growth. / Graduation date: 1970

Thesis (M. Phil.)--University of Hong Kong, 1996. / Includes bibliographical references (leaf 84-93).

Thesis (M.S.)--San Diego State University, 1989. / Includes bibliographical references (leaves 90-103).

Thesis (doctoral)--Ludwig-Maximilians-Universität München, 2006. / Title from PDF t.p. (viewed on May 14, 2006). Includes reprints of papers co-authored with others. Vita. Includes bibliographical references.

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