Effects of 4-inch (10.16 cm) suction dredge mining on benthic macroinvertebrates in 3rd to 4th order streams were investigated in 1996 by evaluating four mining claim operations in Althouse Creek, Sucker Creek, and Taylor Creek in southwestern Oregon's Rogue River basin. The effects were site-specific. The study showed no significant (p>0.05) differences between treatment and control areas in density and species diversity of benthic macroinvertebrates. However, mean taxa richness significantly (p<0.05) increased thirty days following the end of the mining period. Collector-filterers were significantly (p<0.05) lower in dredged areas thirty days after the mining season. Because of constraints in sampling design, sample sizes and relatively small treatment areas, the results from this study are tenuous at best. There were apparent inherent differences in species dominance among sites possibly a result of differences in stream size and riparian conditions. This further confounds results of this study. / Graduation date: 2000

Macroalgae are an important part of the coral reef ecosystem that has largely been overlooked. However, in the past few decades their abundances have increased and this has been attributed to combinations of coral mortality opening up space in the reef, decreased grazing and increased nutrient load in reefs. This dissertation illustrates a novel means of investigating the effect of various growth and disturbance factors on the dynamics of macroalgae at three different levels (individual, population and 3-species community). Macroalgae are modular and clonal organisms that have differing morphologies depending on the environment to which they are exposed. These traits were exploited in order to understand the factors that were acting on the dominant and common macroalgae in the Florida Reef Tract: Halimeda tuna, Halimeda opuntia and Dictyota sp. The agent-based model SPREAD (SPatially-explicit REef Algae Dynamics) was developed to incorporate the key morphogenetic characteristics of clonality and morphological plasticity. It revolves around the iteration of macroalgal module production in response to light, temperature, nutrients, and space availability, while fragmentation is the source for mortality or new individuals. These processes build the individual algae then the population. The model was parameterized through laboratory experiments, existing literature and databases and results were compared to independently collected field data from four study sites in the Florida Keys. SPREAD was run using a large range of light, temperature, nutrient and disturbance (fragmentation without survival) levels and yielded six morphological types for Halimeda tuna, and two each for Halimeda opuntia and Dictyota sp. The model morphological types that matched those measured in two inshore patch reefs (Cheeca Patch and Coral Gardens) and two offshore spur and groove reefs (Little Grecian and French Reef), were formed in conditions that were similar to the environmental (light, nutrient and disturbance) conditions in the field sites. There were also differences between species in the important factors that influenced their morphologies, wherein H. opuntia and Dictyota were more affected by disturbance than growth factors, while H. tuna morphology was affected by both. Allowing for fragmentation with survival in the model resulted in significantly higher population abundances (percent cover and density). The highest abundances were achieved under high fragment survival probabilities and a high disturbance level (but not large fragment sizes). Incorporating fragmentation with survival and simulating the variations in light, nutrients and disturbance between the inshore patch reefs and offshore spur and groove reefs in SPREAD led to comparable abundances of Halimeda in the virtual reef sites. Adding competition for space and light and epiphytism by Dictyota on the two Halimeda species suggests that it can regulate the populations of the three macroalgae. However, comparing model abundances to the field, competition may not be a strong regulating force for H. tuna in all the sites and H. opuntia in the patch reefs. H. opuntia in the offshore reefs is possibly competitively regulated. Although SPREAD was not able to capture the patterns in the population abundance of Dictyota, this points to the potential importance of other morphometrics not captured by the model, a variation in growth curves between reef habitats, or the differential contribution of sexual reproduction.

Past monitoring has noted benthic macroinvertebrate community impairment downstream of both the Key Lake and Rabbit Lake uranium operations in northern Saskatchewan, Canada. The objective of this research was to try to identify the cause(s) of these impacts using a weight-of-evidence approach. Given that sediments generally accumulate contaminants that are related to metal mining activities (such as metals and radionuclides), the initial hypothesis for this research was that contaminated sediments were the primary cause of benthic community impairment at both operations.<p>In 2003 and 2004 a Sediment Quality Triad (SQT) approach confirmed the presence of an effect on benthic community structure, in addition to significant differences in surface-water, pore-water and whole-sediment chemistry at the immediate down-stream exposure sites at both uranium operations. However, no significant adverse effects were noted in 10-d whole-sediment bioassays with <i>Hyalella azteca</i>, although this lack of response could be partially due to sediment pore-water dilution resulting from the automated clean overlying water renewal process employed. Potential causes of benthic community impairment identified through the 2003 and 2004 SQTs for Key Lake include physical sediment composition, surface water pH and total ammonia, in addition to pore-water total ammonia and arsenic. Potential stressors identified at Rabbit Lake included high surface water manganese and uranium concentrations, and increases in pore-water total ammonia, manganese, iron, arsenic, and uranium levels.<p>In the summer of 2004, 4-d in-situ bioassays using <i>H. azteca</i> were conducted along with the SQTs to investigate the role both contaminated surface water and sediment played in benthic community impairment in-situ. Results from the Key Lake in-situ bioassay demonstrated that surface-water was the primary cause of acute toxicity to <i>H. azteca</i>. Results from the Rabbit Lake in-situ study also demonstrated that surface water as the primary cause of acute toxicity to <i>H. azteca</i>, although the relationship was not as strong. The cause of in-situ toxicity at Key Lake could not be correlated with any of the variables measured within the in-situ study, including trace metals, total ammonia, and pH. Of the measured constituents at Rabbit Lake, only concentrations of uranium in both surface water and pore-water were suspected of causing the observed in-situ mortality. Two data sets from two methods of surface water and pore-water collection supported these conclusions.<p>Due to time constraints and stronger cause-effect relationships, efforts were focused on the in-situ toxicity observed at Key Lake. Surface water collected in 2004 at the time of the related in-situ study was also found to be acutely toxic to <i>H. azteca</i> in separate laboratory surface water bioassays, thus verifying that contaminated surface water, not sediment, was the primary cause of the observed in-situ <i>H. azteca</i> mortality. Further information revealed that organic mill-process chemicals, which have been previously linked with sporadic effluent toxicity, were released at the Key Lake operation during the time of the in-situ experiment and associated surface water collection. Additional surface water samples collected in June and August, 2005, were not acutely toxic to <i>H. azteca</i>. Furthermore, a second bioassay with archived surface waters from the initial 2004 collection demonstrated that the water was no longer acutely toxic (i.e., acute toxicity disappeared after one-year storage). Chemistry comparisons of the toxic and non-toxic surface water samples, verified that trace metals, ammonia, pH, and major ions, including sulphate, were not the cause of toxicity, leaving only organic mill-process chemicals as a possible cause. Subsequent 4-d laboratory toxicity tests demonstrated that these process chemicals (kerosene, amine, and isodecanol) are toxic to H. azteca at the levels released in 2004, and are therefore believed to be the cause of the <i>H. azteca</i> mortality seen in the earlier in-situ experiment.<p>In short, this weight-of-evidence research provided new information on the possible causes of benthic macroinvertebrate community impairment downstream of both the Key Lake and Rabbit Lake uranium operations.

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.

Past monitoring has noted benthic macroinvertebrate community impairment downstream of both the Key Lake and Rabbit Lake uranium operations in northern Saskatchewan, Canada. The objective of this research was to try to identify the cause(s) of these impacts using a weight-of-evidence approach. Given that sediments generally accumulate contaminants that are related to metal mining activities (such as metals and radionuclides), the initial hypothesis for this research was that contaminated sediments were the primary cause of benthic community impairment at both operations.<p>In 2003 and 2004 a Sediment Quality Triad (SQT) approach confirmed the presence of an effect on benthic community structure, in addition to significant differences in surface-water, pore-water and whole-sediment chemistry at the immediate down-stream exposure sites at both uranium operations. However, no significant adverse effects were noted in 10-d whole-sediment bioassays with <i>Hyalella azteca</i>, although this lack of response could be partially due to sediment pore-water dilution resulting from the automated clean overlying water renewal process employed. Potential causes of benthic community impairment identified through the 2003 and 2004 SQTs for Key Lake include physical sediment composition, surface water pH and total ammonia, in addition to pore-water total ammonia and arsenic. Potential stressors identified at Rabbit Lake included high surface water manganese and uranium concentrations, and increases in pore-water total ammonia, manganese, iron, arsenic, and uranium levels.<p>In the summer of 2004, 4-d in-situ bioassays using <i>H. azteca</i> were conducted along with the SQTs to investigate the role both contaminated surface water and sediment played in benthic community impairment in-situ. Results from the Key Lake in-situ bioassay demonstrated that surface-water was the primary cause of acute toxicity to <i>H. azteca</i>. Results from the Rabbit Lake in-situ study also demonstrated that surface water as the primary cause of acute toxicity to <i>H. azteca</i>, although the relationship was not as strong. The cause of in-situ toxicity at Key Lake could not be correlated with any of the variables measured within the in-situ study, including trace metals, total ammonia, and pH. Of the measured constituents at Rabbit Lake, only concentrations of uranium in both surface water and pore-water were suspected of causing the observed in-situ mortality. Two data sets from two methods of surface water and pore-water collection supported these conclusions.<p>Due to time constraints and stronger cause-effect relationships, efforts were focused on the in-situ toxicity observed at Key Lake. Surface water collected in 2004 at the time of the related in-situ study was also found to be acutely toxic to <i>H. azteca</i> in separate laboratory surface water bioassays, thus verifying that contaminated surface water, not sediment, was the primary cause of the observed in-situ <i>H. azteca</i> mortality. Further information revealed that organic mill-process chemicals, which have been previously linked with sporadic effluent toxicity, were released at the Key Lake operation during the time of the in-situ experiment and associated surface water collection. Additional surface water samples collected in June and August, 2005, were not acutely toxic to <i>H. azteca</i>. Furthermore, a second bioassay with archived surface waters from the initial 2004 collection demonstrated that the water was no longer acutely toxic (i.e., acute toxicity disappeared after one-year storage). Chemistry comparisons of the toxic and non-toxic surface water samples, verified that trace metals, ammonia, pH, and major ions, including sulphate, were not the cause of toxicity, leaving only organic mill-process chemicals as a possible cause. Subsequent 4-d laboratory toxicity tests demonstrated that these process chemicals (kerosene, amine, and isodecanol) are toxic to H. azteca at the levels released in 2004, and are therefore believed to be the cause of the <i>H. azteca</i> mortality seen in the earlier in-situ experiment.<p>In short, this weight-of-evidence research provided new information on the possible causes of benthic macroinvertebrate community impairment downstream of both the Key Lake and Rabbit Lake uranium operations.

Persistent organic pollutants (POPs) have attracted the attention of scientists because they have the following characteristics: long-distance transmission, persistence, bioaccumulation and chronic toxicity. Due to their high hydrophobicity, POPs are easily absorbed by the suspended particles in the marine environment. The suspended particles then settle into the soil may pass through the food chain, resulting in bioaccumulation and biomagnifications and causing potentially hazardous effects on the environment and human health. This study focuses on the analysis of the persistent organic pollutants in different parts of 10 kinds of benthic fishes, including the muscle and visceral mass, adjacent to Hsiao-Liu-Chiu. The samples were analyzed using accelerated solvent extraction (ASE), and alumina column purification. Fifteen polycyclic aromatic hydrocarbons (PAHs) were determined by using gas chromatograph / mass spectrometer (GC/MS). After florisil column purification, polychlorinated biphenyls (PCBs) and 18 organochlorine pesticides (OCPs) were determined by using gas chromatograph / electron-capture detector (GC/ECD). The results showed that the concentration of PAHs range from 15 to 195 ng/g dw, with low ringed (3 rings) PAHs at a higher proportion. Total PCB concentrations range from 16 to 237 ng/g dw. The content of PCBs in muscles mainly consists of low chlorine numbers (1 to 4 chloride) -based, and in visceral and eggs the chlorine number (6 and 7 chlorine) are higher. The concentrations of OCPs range from 13 to 127 ng/g dw. Among the hexachlorocyclohexane (HCH) series, £^-HCH has the highest proportion, indicating the continued use of Lidane in recent years. In addition to the variance in POP levels among different species of fishes, different tissues also have high variations in PAH, PCB and OCP levels.

Two drilled cores were collected from the Jhuoshuei River delta for this study, which is focused on the analyses of sedimentological, statistical analysis, AMS C14 dating and paleoenvironment interpretation based on the benthic foraminiferal fossils. Foraminiferal shell do not exist between 30000 and 12000 yr B.P., indicating the environment of this sections might be terrestrial. Between 12000 and 8000 yr B.P., the southern core do not have traces of foraminifera, suggesting the deposition site was terrestrial. The northern core contains the benthic foraminiferal shell between 12000 and 9000 yr B.P. The foraminiferal assemblage indicates the sedimentation might be a inner shelf like enviroment. An estuarine like environment was suggested between 9000 and 8000 yr B.P.. Between 8000 and 6000 yr B.P., foraminiferal cluster analysis indicates a middle to inner shelf environment at the southern core site; a inner shelf at the northern core. From 6000 to 3000 yr B.P., foraminiferal cluster analysis indicates a inner shelf at the south core while northern core foraminifera became fewer and the environment gradually changing to terrestrial facies. From 3000 yr B.P. upwards, foraminiferal cluster analysis indicates a shallower inner shelf at the southern core. From 2000 yr B.P. to today, the southern core changed to terrestrial.

The surface sediments off Southwestern Taiwan were collected during three different cruises in May 2009, November 2009, and March 2010, respectively. The concentrations of chlorophyll-a and phaeopigment, as well as benthic foraminifera species, were analyzed. The results show that the concentration of chlorophyll-a decreases with the distance from the shore, and the concentration of chlorophyll-a also decreases with increasing water depth. The concentration of phaeopigment seems to have no significant relationship with the water depth. The relationships between the concentrations of benthic foraminifera, chlorophyll-a, and phaeopigment are also not significant. Because samples were collected from different water depths on the continental shelf, slope and in a canyon, the oceangraphic setting therefore may be one of the main factors which influences the distribution pattern of benthic foraminifera. According to the EOF analysis, the water depth in sampling sites plays a very important role in terms of the distribution of living benthic foraminifera in this study. The distribution do not show significant difference between collecting seasons. Finally, the concentrations of the chlorophyll-a and phaeopigment decrease drastically in a downcore record. Quinqueloculina spp., an epifaunal foraminifer, shows a significant peak concentration in the depth of 5-6 cm downcore. Bioturbation probably was responsible for this change.

The objective for this study was to provide the insight into the link between benthic foraminiferal assemblages and the surrounding environment. Stained sediment samples were collected from the continental shelf and slope off the southwest Taiwan, including the Kao-ping Submarine Canyon. In addition to faunal census, total organic carbon (TOC), carbonate, and coarse fraction of the sediments were also measured. Nevertheless, the downcore record of the excess 210Pb from selected sites offers the constraint for stratigraphy time frame for discussion. The benthic foraminiferal assemblages were analyzed by statistics. Clusters analysis shows that all species present in this study could be divided into two groupings. One is those distributed in outer shelf and the other is those found in the inner shelf of the southwest Taiwan. Different from previous studies, the spatial distribution of stained benthic foraminifera seems not to be related with TOC contents in the sediment and water depth. Both the diversity index and Eqitability show that sites inside of the canyon have lower values. The higher Living/Total ratios and lower dead tests at the head of Kao-ping Submarine Canyon than adjacent area might be the effect of migration. Furthermore, the species within the canyon are similar to the southern and northern continental shelf. These findings indicate that the spatial distribution of benthic forams within canyon might be the effect of transport, which could result from the complex interaction between tides and currents. Augmented with the profiles of excess 210Pb, the temporal variation of benthic foraminifera was revealed. Generally there is a progressive decrease in the abundance of Ammonia sp.. It is possible that the diminishing trend was caused by the increase of anthropogenic activity for the last 30 years.