The shallow, wave-swept sea floor off the central Oregon coast
is used by 0-age flatfishes as a nursery ground. This dissertation
is based on a series of projects designed to: 1) identify the dominant
meiobenthic nematodes present in a coastal nursery area; 2)
describe the important temporal and spatial scales of nematode variability
at this site; 3) discuss the role of sediment disturbance in
structuring nematode assemblages; and 4) relate seasonal and spatial
differences in the distributions of meiobenthos to observed changes
in the diet of flatfishes.
The 19 numerically dominant nematode species found at the study
site showed significant fluctuations in density over a 15 month
period, yet their rank order based on abundance did not change. Four
mechanisms capable of producing seasonal changes in nematode abundance
without altering species proportions are discussed: winnowing from sediments, non-selective predation, seasonally variable food resources,
and compensatory links between birth and death rates among species.
Significant differences in the abundance of nematodes were found
over horizontal distances of kilometers and centimeters. Sediment
disturbance contributes to the generation of these spatial patterns.
Over broad scales there were two distinct faunal groups associated
with different water depths. The division between these assemblages
was closely correlated with the threshold depth at which sediments
are influenced by passing waves. On small scales (<0.25 m²), the
distributions of the numerically dominant species varied seasonally.
In the winter, frequent storm activity mixes the bottom sediments and
randomly distributes the fauna over the sea floor. In the late
spring and summer, physical disruption of sediments is minimal and
biological factors, e.g., attraction between males and females, lead
to aggregation.
Food habits of juvenile English sole were a function of location
of capture within the study area, season, and fish length. Diets of
fish less than 35 mm SL varied greatly both between seasons in the
same year and between years. Diets of English sole captured in
trawls obtained at the same depth and different depths were similar
in January 1979 but were highly variable in May 1979. These temporal
and spatial differences in feeding are thought to be related to
seasonal changes in the abundance and spatial distributions of benthic
prey. / Graduation date: 1982
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28438 |
| Date | 13 October 1981 |
| Creators | Hogue, Everett Wayne |
| Contributors | Carey, Andrew G. Jr |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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