Experiments on the colonization of artificial substrates by stream benthos were
conducted in upper Chingmei Stream, Taiwan. The artificial substrates were colonized by
stream benthos for periods of 3, 6 12, 21, 30 and 42 days.The two experiments were
designed for different purposes. Experiment I from December 15, 1990 to January 29,
1991 investigated the colonization patterns of stream benthos at two sites: a polluted site
caused by coal mining activities (Site 1) and a recovery site further downstream of the
polluted site (Site 2). Experiment II from March 14, 1991 to April 28, 1991 tested the
effect of two different sizes of substrate (cobble and gravel) on the colonization patterns
of stream benthos at Site 2.
In Experiment I, the total number of individuals and taxa were significantly affected
by exposure period of experimental substrates and sites which indicate the occurrence of
succession and the detrimental effect of coal mining activities on the benthic community.
At Site 1, only Caenis sp., Euphaea sp. and Chironomidae occurred on all sampling dates
and were abundant. The other taxa may just continue to drift away from the site. The
chironomid larvae were most abundant. They accounted for over 90% of the colonizing
individuals from day 12 to day 42. At Site 2, Baetis spA and Chironomidae were most
abundant. They accounted for over 80% during the experiment, except on day 21. The
relative abundance shifted from Baetis sp.A to Chironomidae with an increase in
colonization time. Association analysis was performed on the abundance of taxa pairs
within the same functional feeding group at Site 2. The results suggest that filter-feeders
and predators have concordant colonization patterns. The relationship between taxa and
abundance at the two sites also was tested by lognormal distribution to determine the
degree of equilibrium of the community.
In Experiment II, the substratum types influenced only the total number of individuals
colonizing baskets. The gravel substrate provides more surface area for stream benthos
and supports more individuals. Baetis sp.A and chironomid larvae were abundant; they
accounted for over 84% of the individuals from day 6 to 42 on both gravel and cobble.
The chironomid larvae comprised 36% of the fauna on the gravel substrate and 35 - 79%
of the fauna on the cobble substrate. The results of association analysis on the abundance
of taxa pairs within the same functional feeding group showed that there were more taxa
pairs with significant associations on cobble than on gravel. The negatively significant
associations also occurred more on the cobble substrate. This indicates that biological
interactions may be important in determining the development of community on the
cobble substrate. Disturbance caused by floods influenced the colonization patterns,
especially on the gravel substrate. It reset the artificial substrates back to earlier
conditions. This study only suggests that competition may occur in the subtropical
Taiwanese stream and further experimentation is needed to demonstrate whether
competition occurs. / Graduation date: 1992
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/36998 |
| Date | 13 December 1991 |
| Creators | Shieh, Sen-her |
| Contributors | Anderson, N. H. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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