The samples in this study were collected from the drilling cores W-2 and S-4 obtained from the slope-stability monitoring project inside the campus of NSYSU. The Sheng-Li (SL) core was drilled for groundwater monitoring project in the northern of Kaohsiung city. The mudstone sections in these three cores were sampled to reconstruct the sedimental history of the southwestern Taiwan. This study mainly contains 3 parts: firstly we dated the downcore records based on nannobiostratigraphy. Secondly, we analyzed the benthic foraminiferal assemblages in sedimentary sequences. Finally we chose specific benthic species and analyzed the shell trace metals, especially Mg/Ca and Sr/Ca ratio with an ICP-MS. Overall the mudstone sections analyzed in this study fall in the biostratigraphic range of small Gephyrocapsa Subchron, which spreads within 1242ka~1031ka according to the previous report. The age range in W-2 was further constrained within 1186ka~1065ka based on the oxygen isotope stratigraphy (Tseng, 2004). There are four dominant benthic species, including Bulimina spp., Uvigerina spp., Brizalina tainanesis and Siphogenerina raphanus in Cores W-2 and S-4. There are five dominant benthic species, including Brizalina spp., Pseudorotalia spp., Siphogenerina raphanus, Amphicoryna scalaris and Brizalina alata in Core SL. The benthic foraminiferal shell Mg/Ca ratios obtained from Core W-2 indicate the bottom water temperature are between 6 - 12¢J, which reflects the paleo water depth had varied between 300 - 700m. It also indicates that strata were uplifted and the deposition depth become shallow.

Thesis (M.S.)--University of North Carolina at Wilmington, 2003. / Vita. Includes bibliographical references (leaves : [37]-40).

Thesis (M.S.)--University of North Carolina at Wilmington, 2003. / Includes bibliographical references (leaves : [26]-29).

No description available.

No description available.

Littoral zone primary production is under-studied relative to the pelagic zone, despite recent work indicating its importance to the lake as a whole. Benthic extracellular material, shown to be important for food web dynamics and stabilization of the surrounding ecosystem in the marine intertidal, is even less frequently studied in lakes. I examined the environmental and community level drivers of benthic primary production, and found production to increase over the summer and to decrease with disturbance. I also found that maximum photosynthesis and efficiency under sub-saturating light both increased with depth, contrary to the existing, laboratory-derived paradigm of a trade-off between the two. I also examined how benthic primary production and environmental factors were correlated with the amount of extracellular material. I found that loosely bound colloidal extracellular material decreased with in situ photosynthesis and was affected by algal community composition, whereas tightly bound capsular extracellular material was affected only by date, indicating that capsular material is refractory in lakes just as it is in marine systems. Contrary to what is seen in marine systems, however, there were no direct effects of the environmental factors, possibly the result of physical differences between these systems. I also performed the first cross-ecosystem comparison of extracellular material. Despite relatively few studies from lakes and streams, and methods which have not been standardized, I found that lakes were similar to marine intertidal zones both in their median amounts of extracellular material and their relationships between extracellular material and chlorophyll a. This relationship appeared to be quite different in streams, with very low amounts of extracellular material found at sites with either high or low chlorophyll a concentrations. While the above studies will improve future estimates of lake carbon budgets and whole-lake production, my development of a permutation test for path analysis, and a novel application of the Bayesian principal components analysis, will assist all ecological studies that are often restricted in their sample sizes or compromised by missing data.

Littoral zone primary production is under-studied relative to the pelagic zone, despite recent work indicating its importance to the lake as a whole. Benthic extracellular material, shown to be important for food web dynamics and stabilization of the surrounding ecosystem in the marine intertidal, is even less frequently studied in lakes. I examined the environmental and community level drivers of benthic primary production, and found production to increase over the summer and to decrease with disturbance. I also found that maximum photosynthesis and efficiency under sub-saturating light both increased with depth, contrary to the existing, laboratory-derived paradigm of a trade-off between the two. I also examined how benthic primary production and environmental factors were correlated with the amount of extracellular material. I found that loosely bound colloidal extracellular material decreased with in situ photosynthesis and was affected by algal community composition, whereas tightly bound capsular extracellular material was affected only by date, indicating that capsular material is refractory in lakes just as it is in marine systems. Contrary to what is seen in marine systems, however, there were no direct effects of the environmental factors, possibly the result of physical differences between these systems. I also performed the first cross-ecosystem comparison of extracellular material. Despite relatively few studies from lakes and streams, and methods which have not been standardized, I found that lakes were similar to marine intertidal zones both in their median amounts of extracellular material and their relationships between extracellular material and chlorophyll a. This relationship appeared to be quite different in streams, with very low amounts of extracellular material found at sites with either high or low chlorophyll a concentrations. While the above studies will improve future estimates of lake carbon budgets and whole-lake production, my development of a permutation test for path analysis, and a novel application of the Bayesian principal components analysis, will assist all ecological studies that are often restricted in their sample sizes or compromised by missing data.

Fast paced population growth in urban areas of southern Ontario is putting increased pressure on the surrounding aquatic environment. The City of Guelph uses the Speed River to assimilate its municipal wastewater effluent. With a projected 57% population increase in the watershed by 2031, the assimilative capacity of the river may be challenged in the coming years. The Guelph Wastewater Treatment Plant uses tertiary treatment methods greatly reducing ammonia, suspended solids and phosphate concentrations in the effluent. However there are still impacts detectable related to excessive nutrients released into this relatively small river (6th order) which promotes algae and aquatic macrophyte growth. There is also concern about a variety of emerging contaminants that may enter the river and impact the health of the ecosystem. The research in this thesis examined the seasonal and spatial variability and extent of the impacts of the wastewater effluent on the riffle fish communities in the Speed River. Stable isotope signatures (δ13C and δ15N) were used to understand the changes in the dominant benthic fish species, Rainbow Darters (Etheostoma caeruleum) and Greenside Darters (E. blennioides), relative to changes in invertebrate signatures and their abundance. Rainbow Darters were extremely abundant relative to Greenside Darters at the site immediately downstream of the effluent outfall, particularly in August. The benthic invertebrate community was distinctly different downstream of the effluent outfall, especially in the summer, with a reduced abundance of Elmidae beetle larvae and increased abundance of isopods (Caecidotea intermedius) compared to upstream. δ13C and δ15N of the two darters species were similar at all sites in May and July, but in August and October Rainbow Darter signatures were more enriched in the two heavier isotopes at sites downstream of the effluent outfall. The vast majority of invertebrate taxa sampled were also enriched at the downstream sites. An analysis of Rainbow and Greenside Darter stomach contents revealed that Rainbow Darters incorporated more isopods and other invertebrates in their diet, especially at the immediate downstream sites suggesting that they are more adaptable to the altered downstream environment. The feeding habits of Greenside Darters appear to change between July and August in response to changes in habitat and food availability. They are potentially consuming food organisms with less enriched isotopic signatures, which results in their isotopic signatures not rising during these months like most of the invertebrates and other fish. Alternatively, the Greenside Darters may move across the stream to feed on invertebrates that remain unexposed to the wastewater effluent. These impacts, although subtle, may be a reflection of the Speed River ecosystem being compromised by nutrient inputs from the wastewater effluent. With the impending increase in demand on the treatment plant (e.g., population growth), ongoing treatment and infrastructure improvements may be needed in the future to maintain the current ecosystem structure.

A lake-wide benthic survey of Lake Erie during summer 2002 indicated that Dreissena bugensis is the dominant dreissenid in Lake Erie, especially in the east basin where this species was found at every station but no Dreissena polymorpha were collected. Mean (±SD) densities of dreissenid mussels were comparable between the west (601±2,110/m2,n=49) and central (635±1,293/m2; n=41) basins, but were much greater in the east basin (9,480±11,173/m2;n=17). The greater variability in mussel density among stations and replicate samples in the central and west basins than in the east basin is attributable to the preponderance of fine-grained substrata in the nearshore, higher episodic rates of sediment deposition and periodic hypoxia in bottom waters. Although there was little change in lake-wide mean dreissenid densities between 1992 and 2002 (declining from ca. 2,636 individuals/m2 to 2,025 individuals/m2), basin-averaged shell-free dry tissue mass increased by almost four-fold from ca. 6.8±15.6 g /m2 to 24.7±71.3 g/m2 in the same interval. Up to 90% of this biomass is in the eastern basin. Other changes in 2002 include the virtual absence of mussels in the 3 to 12 mm size range, probably because of predation by round gobies, and an increase in the average size of mature mussels. The substantial changes observed between 1992 and 2002 suggest that dreissenid populations in Lake Erie were still changing rapidly in abundance and biomass, as well as species composition. The results of this survey suggest that a direct link between Dreissena spp. and hypolimnetic hypoxia in the central basin is unlikely. The dominant organisms of Lake Erie in 2002 were D. rostriformis bugensis (38%), Oligochaeta (33%), Chironomidae (18%), Sphaeriidae (2.7%), Amphipoda (2.3%) and Hydrozoa (2.2%). Mean invertebrate density was greater in the east basin, especially on hard substrates, than either the west or central basin. In the central basin, sites ≥5m supported greater numbers of organisms, than shallow (≤2m) sites in the nearshore wave zone. The greatest number of taxa were observed in the central basin, likely a resutlt of greater sampling effort there. Gammarus fasciatus comprised 80% of all amphipods, being most abundant on Dreissena-dominated hard substrates in the east basin. The introduced species, Echinogammarus ischnus occured at only 11 of 69 sites, and was the only amphipod found at 4 east basin sites, but at relatively low densities. Diporeia were not found in our survey. Hexagenia was collected at only 4 stations, all in the west basin. Chironomids were dominated by Tanytarsus and Chironomus, with Procladius, Dicrotendipes and Polypedilum also being relatively common. Oligochaete Trophic Index for 2002 indicates a similarly mesotrophic condition throughout the lake and marginal nutrient enrichment of sediments between years 1979-2002. Multivariate ordination of community data indicates clear separation of sites by year and basin as expected given the extirpation of Diporeia and the introduction of Dreissena and E. ischnus, but also reveals subtle changes in benthic structure over the last 2 decades. The benthic community of Lake Erie in 2002 does not likely represent an equilibrium condition.

Meiofauna are an abundant, diverse and important component of the marine biota, however, much of their ecology has been neglected. Despite their high densities, meiofaunal abundance is often patchy. Meiofauna present in high numbers at one site will often be less abundant in seemingly similar adjacent sites. What factors govern this variability? How readily do these animals colonize new patches? How do various biological and environmental factors affect meiofaunal colonization rate and resulting assemblage structure? The response of meiofauna to changes in abiotic factors, including sediment grain size, depth, exposure and distance from the ocean floor, was quite variable. Often one factor would affect certain taxa and not others. Even slight increases in depth resulted in drastic declines of harpacticoid copepods while nematodes were unaffected. Meiofauna were also fewer in sediments with large interstitial spaces. Some meiofauna were most abundant in sediments placed closer to the ocean floor. Other taxa colonized distant substrata as rapidly as they did substrate located closer to the ocean floor. This suggested differences between taxa in their rates of active dispersal. The effects of macrofauna on meiofauna have been debated. In particular, how do clams affect the colonization and assemblage structure of meiofauna? Certain characteristics of clams were isolated and evaluated: feeding behaviour, bioturbation rate/depth and metabolic byproducts. Clams that caused the greatest meiofauna declines were shallow burrowing deposit-feeders. Constant disturbance to the upper sediment by these clams was likely responsible for meiofaunal impact. Conversely, suspensionfeeding clams that passed quickly to deeper sediment and remained stationary had little impact on meiofauna. Finally, a survey of local marine nematodes added nine genera new to Canada and 24 genera new to British Columbia. A review was also compiled that shows nematodes and other meiofauna have been neglected for much of Canada. Although these small and abundant animals are quick to colonize even distant habitats they are quite sensitive to cues from the surrounding biotic and abiotic environment. This sensitivity combined with their ease of collection make meiofauna a valuable asset to any number of ecological investigations. / Ecology