Sediment samples were collected from eight sampling sites
along the Yaquina Estuary, Oregon from Yaquina Bay to Elk City near
the head of the estuary. Samples were collected in November 1973,
February 1974, May 1974 and August 1974 from two or three intertidal
levels depending on the magnitude of the intertidal area exposed
at low tide. Concurrent sediment and water samples were obtained
for the determination of water temperature, salinity, sediment size,
and percentage of organic carbon and cabonate in each sample.
Incident light and exposure period data were obtained for the sampling
year.
A total of 36,564 diatoms identified and counted in 71 samples
was separated into 390 taxa (species or varieties). Of the 390 taxa,
31%, representing 30% of the total cell count, could not be identified
from available literature. The relative abundance values of the taxa
were utilized for the comparisons of several community composition
parameters (the Information measure, Simpson's diversity index,
redundancy, niche breadth, and a measure of similarity) which were
used for comparisons of spatial and temporal distributions of
sediment-associated diatom assemblages within the estuary. Multivariate
analyses (clustering, disciminant analysis, principal
components, canonical correlation) of species and environmental data
were employed to analyze the distribution of sediment-associated
diatom assemblages relative to the sampling strategy and to environmental
gradients.
The distribution of sediment-associated diatoms in Yaquina
Estuary was regulated primarily by mean salinity and characteristics
of the sediment. Above Yaquina Bay the prominent taxa exhibited
overlapping distributions along the salinity gradient to a location in
brackish water where the mean salinity was approximately 5°/oo.
Here, a relatively sharp discontinuity in the diatom flora existed which
appeared to be the product of the biochemical and biophysical mechanisms
involved in osmotic regulation of mesohalobian and oligohalobian
assemblages. Relatively large disparities in the structure of
sediment-associated diatom assemblages were found within relatively
small local areas of Yaquina Bay. These differences were attributed
to the properties of the sediment, Responses of the
diatom assemblages to light intensity, temperature and exposure to
intertidal emergence were not obvious. Approximately one-half of the
numerical variation in the diatom flora apparently was related to
factors other than the physical and chemical variables considered in
this study.
Comparisons of previous distributional surveys in Yaquina
Estuary indicated that the diatom flora associated with the sediments
was dissimilar in species composition to proximal epilithic, epiphytic
and planktonic diatom assemblages. Species diversity was generally
high throughout the intertidal sediments, irrespective of tidal height
and season, while redundancy was generally low. High diversity
values may represent contamination of samples, behavioral-physiological
adaptations of the sediment flora, or the spatial
heterogeneity of intertidal sediments. / Graduation date: 1977
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/29207 |
| Date | 17 March 1977 |
| Creators | Amspoker, Michael C. |
| Contributors | McIntire, C. David |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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