Natural populations of phytoplankton from Yaquina Bay, Oregon,
were incubated in large polyethelene bags in- situ, with and without
the natural assemblage of zooplankton. Samples were taken daily for
two weeks in April, 1974. The biomass of phytoplankton in the bag
without grazers reached values two to three times the biomass of
phytoplankton in the bag with grazers. Sixty-eight to 93% of the cells
in the bag without zooplankton were Thalassiosira fluviatilis, while
the major species in the bag with zooplankton were T. fluviatilis, T.
decipiens and Chaetoceros debilis, no one of which ever accounted for
more than 40% of the cells. Nitrate-nitrite became depleted two days
earlier in the bag without grazers and urea and ammonia values were
higher in the bag with the grazers. Primary productivity, per unit
cell volume, was higher in the grazed bag following nutrient depletion,
suggesting some productivity enhancement by grazers. Physiological
parameters indicate that the cells in the bag with zooplankton were
richer in carbon, nitrogen and chlorophyll a, a higher percentage of
the chlorophyll was degraded to phaeophytin and carbon to nitrogen
ratios were lower. Data obtained from the bag with zooplankton were
similar in range to data from the bay. The results support the contention
that zooplankton can have a large effect on phytoplankton in
terms of biomass, species composition, productivity and physiological
state. / Graduation date: 1975
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28553 |
| Date | 15 January 1975 |
| Creators | Deason, Ellen Elizabeth |
| Contributors | Curl, Herbert C. Jr |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
Page generated in 0.0024 seconds