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
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28955 |
| Date | 24 July 1969 |
| Creators | Haertel, Lois Steben |
| Contributors | Osterberg, Charles |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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