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Caulerpa taxifolia is a marine alga notorious for its introduction and subsequent colonization of the Mediterranean Sea. It is recognized as one of the 100 worst invasive species, and it is suggested that much of its expansion may have been at the expense of native seagrass beds. To date, the bulk of research on C. taxifolia has centred on quantifying expansion and methods of eradication. There are few quantitative data on the relationship between C. taxifolia growth and environmental characteristics (e.g. light, temperature, nutrients). Furthermore, once C. taxifolia has been introduced to a system it is exceptionally difficult and expensive to eradicate. Accordingly the implications, both positive and negative, of this new habitat type must be considered in the context of the new habitat mosaic into which it fits. Australia is unique in that it has both native and invasive populations of C. taxifolia. These populations offer not only an opportunity to examine the dynamics of C. taxifolia beds and their associated communities at different latitudes and temperature and light regimes, but especially in the context of a high diversity marine coastal environment. The objectives of this thesis were to use native (Moreton Bay, Queensland) and invasive (Pittwater, New South Wales and Port River, South Australia) populations of C. taxifolia to: 1) quantify the relationship between environmental drivers (light, temperature, nutrients) and C. taxifolia growth, and 2) examine differences in habitat use and function between seagrass, C. taxifolia, unvegetated substrate. Most of the locations in Australia where large C. taxifolia beds occur are adjacent to urban areas that have a degraded water quality. Manipulative experiments in Moreton Bay demonstrated that nutrients stimulate C. taxifolia growth, however, light availability and seasonality appear to influence the response of C. taxifolia growth to nutrients. Short-term manipulative experiments were conducted across a range of seasons and locations, to capture the effects of temperature on growth. Temperature was the dominant factor affecting rate of stolon extension in both native and invasive locations. Colonization potential of C. taxifolia appears to be driven by ambient water quality (light and nutrients) and bed expansion is driven by temperature in systems where nutrients are saturating. Epifaunal communities sampled by beam trawl were dominated by the families Palaeomonidae, Terapontidae, Scorpaenidae, Monacanthidae, Syngnathidae, Gobiidae, and were largely similar between seagrasses and C. taxifolia; however, syngnathids were absent from C. taxifolia beds. I examined habitat use patterns between seagrass (Zostera muelleri), C. taxifolia, and unvegetated substrate. Fish preferred seagrass to C. taxifolia; however, in the absence of a seagrass fish used C. taxifolia. While C. taxifolia may have similar structural benefits to some seagrasses, there are fewer food resources available within C. taxifolia beds. Furthermore, grazing may be limited to a few specialist grazers. Within the habitat mosaic, C. taxifolia will provide some benefit over an unvegetated substrate; however, that benefit might mask losses in system quality or resilience by decreasing the threshold level for change within the community. Therefore, should a perturbation occur (e.g. sudden drop in water temperature, filamentous algal bloom) a system comprised solely of seagrass could withstand such stress; however, a habitat mosaic of seagrass and C. taxifolia could have a rapid and dramatic loss in its ability to sustain a diverse faunal community. Ultimately, it is most important to protect the system from anthropogenic degradation so it is more resilient to environmental changes.

Submitted by Marilene Donadel (marilene.donadel@unioeste.br) on 2017-09-27T22:59:59Z No. of bitstreams: 1 Guilherme_M_Castro_2017.pdf: 1489623 bytes, checksum: 1aecc4aefdf7b995bfb34f6e8cda4776 (MD5) / Made available in DSpace on 2017-09-27T22:59:59Z (GMT). No. of bitstreams: 1 Guilherme_M_Castro_2017.pdf: 1489623 bytes, checksum: 1aecc4aefdf7b995bfb34f6e8cda4776 (MD5) Previous issue date: 2017-03-03 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This work aimed to address the ecological and biotechnological aspects of microalgae for the preservation and conservation of the Toledo River. The study was carried out in five points in the Toledo River, with monthly collections of 300 mL of samples, filtered in phytoplankton networks of 20 μm in diameter, from July / 2015 to June / 2016. The phytoplankton community and the concentration of chlorophyll a were identified at the genus level. The abiotic parameters pH, conductivity, turbidity, ammonia, nitrite, nitrate, orthophosphate, total phosphorus and, BOD as the Carlson Trophic State Indexes modified by Lamparelli and Nygaard were determined. In the evaluation of the growth of the microalgae collected from the Toledo River, four strains were used, two mixed (with two or more genera) and two isolates of Chlorella sp, divided into four treatments, all in the synthetic medium BM, during 18 days with monitoring of Kinetics of growth and pH every 2 days. The water quality of the Toledo river was directly affected by the urban activities in its surroundings, mainly in the points P4 and P5. 41 genera of algae were identified, divided into 5 classes, 10 orders and 20 families, with predominance of Chlorophyceae (44%). Spatially, point P4 was the most representative in number of genera with 28 taxa and, seasonally, the summer season presented 30 taxa, the largest of the four seasons of the year. In the IET of Lamparelli, the river was classified as oligotrophic and, in Nygaard from oligotrophic to mesotrophic. The growth of microalgae was influenced by the number of genera present in the strain and by the algal inoculum of the culture. The unialgal T4 strain had the highest maximum cell density - DCM of 4960 x 105 cells mL-1 and the lowest DCM was recorded by mixed T2 cultivation with 513 x 105 cells mL-1. The pH remained in alkaline condition in most of the experiment, favoring the availability of the HPO4- orthophosphate fraction. In the ecological aspects evaluated, the composition of the phytoplankton of the Toledo River was directly affected by the anthropic activities of its surroundings, mainly in the urban stretch and it was not possible to affirm the real trophic state of the Toledo River, by the two models using completely different methodologies, A third index should be tested to confirm the trophic degree of the river. In biotechnology, the growth of the non-mixed cultures was higher than the mixed ones and the alkaline pH is the most adequate cultivation condition for the growth of the analyzed microalgae. / Este trabalho objetivou abordar aspectos ecológicos e biotecnológicos das microalgas para fins de preservação e conservação do Rio Toledo. O estudo foi realizado em cinco pontos no Rio Toledo, com coletas mensais de 300 mL de amostras, filtradas em redes de fitoplâncton de 20 μm de diâmetro, no período de julho/2015 a junho/2016. Foram identificados em nível de gênero a comunidade fitoplanctonica e a concentração de clorofila a. Os parâmetros abióticos pH, condutividade, turbidez, amônia, nitrito, nitrato, ortofosfato, fósforo total e, DBO assim que os Índices de Estado Trófico de Carlson modificado por Lamparelli e de Nygaard foram determinados. Na avaliação do crescimento das microalgas coletadas do Rio Toledo, foram utilizadas quatro cepas, sendo duas mistas (com dois ou mais gêneros) e duas isoladas de Chlorella sp, divididas em quatro tratamentos, todos no meio sintético BM, durante 18 dias com acompanhamento da cinética de crescimento e do pH a cada 2 dias. A qualidade da água do rio Toledo foi diretamente afetada pelas atividades urbanas no seu entorno, principalmente nos pontos P4 e P5. Foram identificados 41 gêneros de algas, divididos em 5 classes, 10 ordens e 20 famílias, com predominância das Chlorophyceae (44%). Espacialmente, o ponto P4 foi o mais representativo em número de gêneros com 28 táxons e, temporalmente, a estação verão apresentou 30 táxons, a maior dentre as quatro estações do ano. No IET de Lamparelli, o rio foi classificado como oligotrófico e, no de Nygaard de oligotrófico a mesotrófico. O crescimento das microalgas foi influenciado pelo número de gêneros presentes na cepa e pelo inóculo algal do cultivo. A cepa unialgal T4 apresentou a maior densidade celular máxima – DCM de 4960 x 105 cel mL-1 e a menor DCM foi registrada pelo cultivo misto T2 com 513 x 105 cel mL-1. O pH permaneceu em condição alcalina em grande parte do experimento, favorecendo a disponibilidade da fração de ortofosfato HPO4-. Nos aspectos ecológicos avaliados, a composição do fitoplâncton do Rio Toledo foi diretamente afetada pelas atividades antrópicas do seu entorno, principalmente no trecho urbano e não foi possível afirmar o real estado trófico do Rio Toledo, pelos dois modelos utilizarem metodologias completamente diferentes entre si, devendo ser testado um terceiro índice para confirmar o grau trófico do rio. Na biotecnologia, o crescimento dos cultivos não mistos foram maiores de que os mistos e o pH alcalino é a condição de cultivo mais adequada para o crescimento das microalgas analisados.

The Kennet and Avon Canal in southern England is experiencing severe water quality problems caused by inorganic sediment and algae. These water quality problems are affecting the angling sport of fishermen downstream of the confluence of the canal with the River Kennet. The Environment Agency has been called upon to remedy these issues, but before proceeding they desire a computer model capable of predicting the water quality impacts of various scenarios under consideration. No such model was available to them. This project identified the key solids generation and transport processes to be included in a water quality model for inland navigational canals. Where available, equations from the literature describing relevant processes were used or modified for inclusion in a canal modeling algorithm. Where literature was not available, water quality samples were taken to characterize needed relationships. The final algorithm was coded and tested using a simplified dataset that allowed clear evaluation of the simulated processes. After successful testing, the canal model was applied to the Kennet and Avon Canal. The time series predicted by the model were compared to observed hydrological, solids, and chlorophyll-a (representing algae) data at multiple points in the canal. The model adequately predicted all of these constituents at the monitored locations. The final task in the project required evaluation of six management scenarios proposed by the Environment Agency to address the water quality problem. The model suggests that filtration or other treatment of water in the canal near the confluence with the river is the best management option, as it will address both the elevated inorganic sediment and algae concentrations at the most critical point in the canal. Less desirable options include efforts that only target inorganic sediment, which could increase algal concentrations by increasing light availability; and diversion of surface flows from the canal, which could possibly damage the hydrologic balance of the canal while encouraging undesirable algal growth.

Passive sampling, as opposed to the conventional spot or bottle water sampling technique, has shown to be reliable and efficient in monitoring the toxicologically relevant, freely dissolved (e.g. bioavaialable) concentrations of a wide range of organic contaminants in water. At the same time, partitioning controlled delivery (passive dosing; PD) techniques promise to overcome many of the challenges associated with toxicity testing of hydrophobic substances that may bias the interpretation of toxicity data. The present study investigated the feasibility of coupling silicone rubber passive sampling devices (SR-PSDs) with bioassay techniques for both chemical and ecotoxicological assessment of complex mixtures of organic contaminants in the aquatic environment. SR-PSDs were deployed in water at various locations within the Ythan catchment (north east, Scotland, UK), Forth estuary and the Firth of Forth (east coast of central Scotland, UK) for 7 to 9 weeks. Following retrieval, extracts from the SR-PSDs were analysed for dissolved concentrations of a variety of organic contaminants including PAHs and PCBs using GC-MS and GC-ECD respectively and were screened for a wide range of pesticides using GC-MS/MS and LC-MS/MS. The extracts were further evaluated for acute cytotoxicity (i.e. neutral red uptake assay) and EROD induction potential using rainbow trout liver cell line (Oncorhynchus mykiss; RTL-W1) and for phytotoxicity and developmental toxicity potential using algal growth inhibition test (with a marine phytoplankton, Diacronema lutheri) and fish embryo toxicity test (with embryos from zebrafish Danio rerio) respectively. Overall, the individual and total dissolved concentrations of PAHs (ΣPAH40; parent and branched) and PCBs (ΣPCB32; ortho and mono-ortho) measured in water from the Ythan, Forth estuary and Firth of Forth were relatively low compared with other studies using PSDs. A number and level of pesticides, including insecticides, herbicides and fungicides of varying hydrophobicity (log KOWs ~2.25 to ~5.31) were detected in the silicone rubber (SR) extracts from the Ythan catchment, the Forth estuary and the Firth of Forth, suggesting input mainly from agricultural run-off and possibly from direct discharges. No statistically significant (p<0.05) acute cytotoxicity was observed following 48 h exposure of RTL-W1 cells to SR extracts from the Ythan catchment. But, on a sublethal level, for every site, statistically significant EROD activity was observed to some degree following 72 h exposure. In addition, developmental and algal toxicities on embryos of D. rerio and D. lutheri respectively, were measured in all the deployed samples compared with the procedural controls (undeployed samples). Interestingly, extracts of SR-PSDs from the Forth estuary and the Firth of Forth exhibited growth inhibitions on D. lutheri that were similar to those of extracts from the Ythan, even though, fewer numbers of pesticides were detected in the Forth estuary and Firth of Forth than the Ythan. This suggests that pesticides were not solely responsible for the observed effects in the Ythan catchment. To further improve data from toxicity testing of hydrophobic substances, the study identified the use of SR O-rings as a suitable passive dosing format in in vitro toxicity tests and was partially validated through their use in dosing RTL-W1 cells with two individual PAHs and subsequently determining cytotoxicity and EROD-activity.

From the Proceedings of the 1974 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 19-20, 1974, Flagstaff, Arizona / This study attempts to determine the water quality changes in stock tanks and what factors are instrumental in the changes, and to assess the effects of the changes. Algal growth was the most prominent change taking place in the tanks with time. Little change in the water chemistry was noted until just before the tanks dried up. As algae died, ions tied up by the algae were released to the water, causing an increase in concentration of many of the nutrients. In order to determine the impact of various factors on algal growth, the data from eight stock tanks were analyzed by stepwise linear regression. Although 20 variables were used in the complete analysis, six variables were associated with 56.3 percent of the variance: time (since first sampling), total n, potassium, pH, inflow (recharge to the tanks), and hco3 concentration. Time and total n explained 51.3 percent of the variance, and potassium increased the variance to 52.8 percent. The pH reversed the relative positions of time and total n, with total n becoming dominant. The last two factors, inflow and hco3 were negative (resulting in a decrease in algal population) and increased the coefficient of variance to 56.3 percent.