Phytoplankton dynamics in Auke Bay, Alaska, were studied during
summer, 1969. Nitrate, chlorophyll a, particulate organic carbon,
phytoplankton and zooplankton species composition and hydrographic
and meteorological data were collected and analyzed.
Nitrate input into Auke Bay through freshwater runoff was negligible.
A bloom of Thalassiosira aestivalis formed the spring bloom
in Auke Bay in 1969. No phytoplankton bloom occurred during a June
period when winds were light and variable. Two major blooms of
Skeletonema costatum occurred after periods when Auke Bay surface
layers were mixed by wind-induced turbulence. The water column
became nearly isothermal after periods of high wind mixing although
a pronounced density and halal structure persisted, a consequence of
input of freshwater to the bay from Auke Creek.
Examination of fecal pellets collected from the bay and results
of laboratory grazing experiments suggested that Skeletonema costatum
was not grazed by zooplankton living in Auke Bay.
Nonlinear ordinary differential equations were written to describe
phytoplankton and nitrate dynamics in Auke Bay. The phytoplankton dynamics equation included formulations for time-varying
insolation and for time-varying wind mixing coefficients. Formulations
for effects of nitrate concentration on the photosynthetic assimilation
number and for effects of phytoplankton standing crop on the
extinction coefficient of light in the water column were included.
The nitrate dynamics equation included a formulation for effects
of wind-mixing of nitrate-rich water into the euphotic zone from
deeper layers of the water column, as well as a formulation for utilization
of nitrate in phytoplankton growth.
Computer simulation response of the equations reproduced the
bloom pattern observed in the field data with some discrepancies
caused by assumptions used in model development. The phytoplankton
and nitrate model response was strongly coupled to the pattern of the
wind-mixing coefficient, as required by the field data. Variations in
model parameters had little effect on phase relations between model
response and field data but strongly affected model response magnitude. / Graduation date: 1972
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28442 |
| Date | 22 December 1971 |
| Creators | Iverson, Richard L. |
| Contributors | Curl, Herbert C. Jr |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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