Title
Environmental quality and fish community ecology in an agricultural mountain stream system of Taiwan
Degree Type
Dissertation
Date of Award
1989
Degree Name
Doctor of Philosophy
Department
Animal Ecology
First Advisor
Bruce W. Menzel
Second Advisor
Dennis L. Scarnecchia
Abstract
A 1.5 year environmental and faunal analysis was conducted in headwater streams of the upper Ta-chia River in mountainous central Taiwan. The area had distinct wet and dry seasons owing to monsoonal-typhoonal rainfall patterns. Compared to natural stream areas, agriculturally impacted reaches had greater discharge fluctuation, warmer temperatures, higher turbidity, increased nutrient loads, and reduced bedform diversity;Stream biotic communities varied according to local habitat characteristics. Coldwater algae existed mainly within natural stream reaches while eutrophication indicators occurred abundantly at agriculturally impacted sites. Large-bodies shredder-collector and predatory insects inhabited natural stream areas while smaller scraper-collectors were dominant in an agriculturally modified stream;Four fish species occur in the system: the endangered Taiwanese landlocked masu salmon (Oncorhynchus masou formosanus), kooye minnow (Varicorhinus barbatulus), Taiwanese tasseled-mouth loach (Crossostoma lacustre) and stream goby (Rhinogobius brunneus). Originally, this stream system was uniquely hospitable to the salmon owing to suitable cold water, a gentle gradient, moderate climate, and rich invertebrate food resources. In the last half-century, the salmon has become restricted because of overexploitation, population fragmentation by dams, and habitat deterioration caused by landslides and agricultural impacts;Multivariate analyses indicated that the minnow is a habitat generalist primarily associated with boulder cover while the loach is a specialist associated with boulder plus fast current. Both minnow and loach fed extensively upon attached algae and algal detritus, and small insect larvae; the latter ate significantly more insects than the former. Cyclical fluctuations of these food resources are chiefly determined by discharge events;There is no evidence that the salmon is detrimentally affected by any of its three ichthyofaunal associates because of their spatial and trophic segregation; however, its future could be imperiled by landslides, dams, and any expansion of row-crop agriculture. A comprehensive recovery plan for the salmon is proposed.
DOI
https://doi.org/10.31274/rtd-180813-9076
Publisher
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Copyright Owner
Ching-ming James Wang
Copyright Date
1989
Language
en
Proquest ID
AAI8920195
File Format
application/pdf
File Size
142 pages
Recommended Citation
Wang, Ching-ming James, "Environmental quality and fish community ecology in an agricultural mountain stream system of Taiwan " (1989). Retrospective Theses and Dissertations. 9250.
https://lib.dr.iastate.edu/rtd/9250
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