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

Thesis (M.S.)--Oregon State University, 1989. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Etheostoma spectabile, E. punctulatum, and Cottus carolinae were sampled Mar., 1983, - Feb., 1984, in Flint Creek, Oklahoma. Immature E. spectabile ate primarily microcrustaceans, while mature fishes relied more on mayflies and amphipods. Juvenile E. punctulatum fed upon mayflies, amphipods, and Asellus. Mature E. punctulatum ate primarily mayflies, and other relatively larger prey. Cottus carolinae consumed chironomids almost exclusively in Jan. - Feb., 1984, while mayflies were predominant the remainder of the year. No significant habitat partitioning between the two darters, and seasonal habitat segregation between C. carolinae and the two darters was found. Dietary overlap between the darters was significantly correlated (p<0.0005) to differences in x prey sizes.

Abstract not available

Water temperature is a critical factor affecting the abundance and richness of freshwater stream aquatic macroinvertebrate communities. Variable seasonal river temperature patterns are a critical factor in maintaining temporal segregation in aquatic invertebrate communities, allowing for resource partitioning and preventing competitive exclusions, while spatial differences in water temperatures permit zonation of species. This research investigated whether the degree of predictability in a stream’s water temperature profile may provide some indication of the degree of structure and functional predictability of macroinvertebrate communities. Quarterly aquatic macroinvertebrate sampling over a single year along the longitudinal axes of two river systems, Keurbooms River in the southern Cape, and the Kowie River in the Eastern Cape, were undertaken as the core component of this research. The two river systems shared similar ecoregions and profile zones, however were expected to differ in their thermal variability, based on the hydrological index and flow regimes for their respective quaternary catchments. Hourly water temperature data were collected at each sampling site from data loggers installed at five paired sites on each stream system. The aquatic biotopes sampled were in close proximity to the loggers. Multivariate analysis techniques were performed on the macroinvertebrate and water temperature data. Macroinvertebrate taxon richness was greater on the perennial Keurbooms than the non-perennial Kowie River where, on a seasonal basis, taxon richness increased from winter to autumn on both systems. Macroinvertebrate species turnover throughout the seasons was higher for sites having lower water temperature predictability values than sites with higher predictability values. This trend was more apparent on the Keurbooms with a less variable flow regime. Temporal species turnover differed between sites and streams, where reduced seasonal flows transformed the more dominant aquatic biotopes from stones-in-current into standing pools. Findings included aquatic macroinvertebrates responding typically in a predictable manner to changing conditions in their environment, where water temperature and flow varied. The findings of this research demonstrate that macroinvertebrate taxa do respond in a predictable manner to changes in their environment. This was particularly evident in relation to variability in water temperature and flow. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

Stability of the macrobenthic community in a regulated section of the Brazos River, Texas, was evaluated. Physicochemical data and information on spatial distribution of macrobenthos were collected. Populations of two invertebrate species, Isonychia sicca and Neoperla clymene, had been greatly reduced since 1970-71 and I. sicca had been practically eliminated from this section of the Brazos. Three other insect populations, Choroterpes mexicanus, Cheumatopsche campyla and Cheumatopsyche lasia, had more than doubled their numbers since the 1970-71 study. A physicochemical gradient existed in this regulated section of the Brazos but it appeared to have changed little in comparison of earlier chemical data. A gradation of the macrobenthic community was evident as distance from the dam increased,

Large woody debris (LWD) was added to North Fork Stony Creek and North Prong Barbours Creek as an experimental stream enhancement technique. The purpose of this study was to determine the stream channel responses to LWD additions at the scale of the stream reach and around individual logs, to determine benthic macroinvertebrate relations to physical habitat, and to determine the potential effects of LWD created stream channel alterations on benthic macroinvertebrates. Pool frequency and total surface area increased substantially at the expense of riffles in the random and controlled placement sections one year after LWD additions in Stony Creek. Although logs oriented as ramps produced more channel scouring, only log dams created pools. Results in Barbours Creek were similar but less pronounced. Substratum detritus was greater in pools than riffles for both streams, but there was no difference between years, sections, or as a result of LWD additions. Most functional feeding groups and invertebrate orders were significantly more abundant in riffles than pools. The exception were collector gatherers which accounted for a large proportion of the benthic macroinvertebrate assemblage. Increased poor area at the expense of riffle area may decrease the overall relative abundances of functional feeding groups and result in a reduction of the stream's substratum detritus processing capabilities. Decreased riffle area should result in an overall decrease in the abundance of potential food items for brook trout in Barbours Creek, but not in Stony Creek. However, average biomass was not significantly different between pools and riffles for either stream. Biomass may therefore compensate for a loss of prey items for brook trout because, although numbers may decrease, average individual weight increases with an increase in pool habitats. / Master of Science

I investigated streambed stability in spawning microhabitats of warmwater fishes in the upper Roanoke River, Virginia. Spawning microhabitats used by four reproductive guilds (egg-clusterers, mound-builders, egg-buriers, and pit-builders) were identified and ranges of 15 microhabitat variables used by each guild were compared to available microhabitat conditions to investigate habitat selection. Habitat usage by egg-clusterers was most characterized by selection for spawning rocks in the cobble size range, substrate roughness elements in the cobble to boulder size range, high roughness Reynolds number and moderate water column velocity. The mound-building bluehead chub (Nocomis leptocephalus) was distinct in its selection of substrate in the small gravel range, low water velocity and non-turbulent flow. Egg-buriers were the least distinct of the four guilds, exhibiting much variation in habitat use among the component species. However, all species used areas with small substrate (sand to gravel range), high velocity, and high turbulence. The pit-building central stoneroller (Campostoma anomalum) was distinct in its usage of areas with high velocity and turbulence, gravel sized substrate, and low embeddedness. Stability of each guild's spawning microhabitats was empirically evaluated through analysis of tracer particle movement and repeated surveying of bed elevation along stream transects. Logistic regression equations developed from tracer particle data predicted that microhabitats selected by egg-clusterers are among the most stable of all available habitats during high flows. Microhabitats utilized by mound-builders, egg-buriers, and pit-builders are predicted to be less stable. Repeat transect surveying corroborates model predictions in that egg-burier habitats experienced changes in bed elevation in high flows, while egg-clusterer habitats did not. / Master of Science

published_or_final_version / Education / Doctoral / Doctor of Philosophy

published_or_final_version / Biological Sciences / Master / Master of Philosophy