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The seasonal variation of anammox is yet to be comprehensively studied, unlike denitrification, the more traditional sink for fixed nitrogen. A seasonal study of anammox, denitrification and benthic oxygen consumption using the revised isotope pairing technique is presented in Chapter 2. Experimental temperature and NO3- concentration were kept constant throughout so that the capacity of the sediment for anammox could be estimated. Similar seasonal variations in the rates of anammox, denitrification and oxygen consumption suggest that anammox is controlled by the availability of organic carbon. Furthermore the effect of tidal inundation by overlying water rich in NO3- was investigated by measuring rates of anammox, denitrification and oxygen consumption at three tidal elevations throughout the year. A significant relationship between anammox and denitrification was established at each tidal elevation, which increased in strength as length of inundation decreased. To complement this seasonal study, additional experiments were undertaken, which are described in Chapter 3, to determine how anammox, denitrification and sediment metabolism responds to variations in experimental NO3- concentration and temperature. There were significant increases in rates of anammox, denitrification and sediment metabolism with temperature until 20oC when rates of anammox began to reduce. Furthermore there was significant variation in the response of all three processes to temperature in samples collected at different dates, which suggested that reduced bioavailability of organic carbon in the winter months was limiting the response to temperature. In addition to exploring how inorganic N is cycled in estuarine sediments, the ability of estuarine sediments to oxidize urea via nitrite was examined using 15N and 13C labelled substrates. Results, which are presented in Chapter 4, indicate that urea added to anaerobic sediment slurries was rapidly hydrolysed to ammonium before being oxidized via the anammox pathway.

<div>Documenting trophic relationships in aquatic ecosystems can facilitate understanding of not only system processes, but also the potential responses of food webs to stressors. Often, trophic studies assume consistent behavior and trophic roles among individuals in a population, but intraspecific diet variation, such as individual specialization, can play a critical role in food web complexity and can promote ecosystem resilience. In Lake Michigan, the introduction of invasive species (e.g., zebra mussel, Dreissena polymorpha; quagga mussel, Dreissena bugensis; round goby, Neogobius melanostomus) and reduced nutrient loading has resulted in changes in nutrient dynamics, system productivity, and community composition over the past two decades. As a result, abundances of many forage fish have declined, including alewife (Alosa pseudoharengus) which have historically supported the five dominant salmonid species of Lake Michigan (brown trout, Salmo trutta; Chinook salmon, Oncorhynchus tshawytscha; Coho salmon, Oncorhynchus kisutch; lake trout, Salvelinus namaycush; rainbow trout, Oncorhynchus mykiss). With these ecosystem changes, there is uncertainty as to the extent of how different species of salmonids will transition to alternative prey items (e.g., round goby). Common methods for examining diet patterns and trophic linkages include stomach content analysis, stable isotope ratios (e.g., δ13C and δ15N), and fatty acid composition, but these methods vary in temporal resolution and have differential biases. Furthermore, elucidating agreement of these trophic indicators and whether or not agreement is consistent across species can improve their use in future food web studies. The first research chapter of this thesis investigated the diet complexity of Lake Michigan salmonids by evaluating stomach content composition, diversity, and potential specialized consumption of different alewife lengths. Stomach contents revealed that Chinook salmon almost exclusively consumed alewife and had a lower diet diversity compared to the other four species, which consumed round goby (brown trout and lake trout), aquatic invertebrates (Coho salmon), and terrestrial invertebrates (rainbow trout) in addition to alewife. Although there were clear spatio-temporal and size-related feeding patterns for each species, much of the variation in diet composition and diet diversity was present at the individual-level. Additionally, salmonid species appeared to consume the entire size range of alewife that were available to them and individually specialized on alewife lengths. Due to their reliance on alewife, it is likely that Chinook salmon may be more negatively impacted than other salmonid species if alewife abundance continue to decline in Lake Michigan. The second research chapter assessed the agreement of multiple trophic indicators. Although we found agreement among trophic indicators across the five salmonid species using linear and logistic models, particularly between stomach contents, δ13C, and fatty acid 16:1n-7, there was significant variation in relationships across species, potentially due to variation among salmonids in specific prey items consumed (e.g., alewife and round goby) and species-specific regulation of fatty acids. Additionally, δ15N estimated from stomach contents using linear mixing models were typically greater relative to observed δ15N, which may suggest small alewife were underrepresented in stomachs of 2016 angler-caught salmonids. Lastly, stomach contents underestimated benthic resource use by rainbow trout, which may be related to biases associated with fish collection methods and stomach content analysis. Overall, the results of trophic indicator comparisons indicate that caution should be taken when generalizing trophic relationships across species and to consider biases associated with trophic indicators, especially when relying on a single diet metric.</div>

Made available in DSpace on 2014-06-11T19:35:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-07-19Bitstream added on 2014-06-13T18:47:07Z : No. of bitstreams: 1 alves_rcp_dr_botib.pdf: 4373370 bytes, checksum: 868dbf433604bb75f86e445787dedfc8 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Os organismos planctônicos são a base das cadeias alimentares no ecossistema aquático e os herbívoros zooplanctônicos, em particular, são importantes para o fluxo de energia nos ecossistemas aquáticos, sendo um elo entre os produtores primários e níveis tróficos mais elevados. Este estudo se propôs a ampliar o conhecimento da herbivoria do zooplâncton sobre o fitoplâncton em uma lagoa marginal ao rio Paranapanema. Foi realizado um experimento in situ, com instalação de enclosures com paredes de polietileno fechados no fundo que permitiram a realização de quatro tratamentos: 0% da densidade natural de zooplâncton (apenas fitoplâncton), 50 % (metade da densidade natural), 100% (densidade natural) e 150% (densidade acima da natural). A variação da densidade do zooplâncton foi conseguida por meio de filtração da água por rede de abertura de malha de 50μm. Água da lagoa também foi coletada. Todos os tratamentos foram realizados em tréplica. O experimento durou 18 dias. As coletas foram realizadas a cada seis dias (quatro coletas). A temperatura foi obtida em campo e água foi coletada para análise de oxigênio dissolvido, saturação, pH, condutividade elétrica, concentrações de fósforo total, nitrogênio total, material em suspensão total, material em suspensão orgânico, material em suspensão inorgânico, clorofila-a e feofitina-a. Foram coletadas também amostras de zooplâncton e fitoplâncton que foram contadas e identificadas, normalmente, até ao nível de espécie. Rotifera teve sua abundância relativa alterada em todos os tratamentos, com o favorecimento de Keratella cochlearis e Polyarthra vulgaris provavelmente porque o enclosure as protegeu de predadores. Cladocera foi dominado em todos os tratamentos por Bosmina freyi e B. hagmanni, bioindicadores de eutrofização... / The planktonic organisms are the basis of food chains in the aquatic ecosystems, and the grazer zooplankton, specifically, are very important to energy flow in the aquatic ecosystems, being a link between primary producers and higher trophic levels. The aim of this study is enhance the knowledge of zooplankton grazing over phytoplankton in a lateral lake by Paranapanema River, Brazil. The experiment was conducted in situ, with installation of enclosures of polyetilene walls, closed at the bottom, which allowed the manipulation of four treatments: 0% of the natural density of zooplankton (phytoplankton only); 50% (half of natural density); 100% (natural density) and 150% (a higher density than the natural). The zooplankton density range was obtained by water filtration in zooplankton web with 50μm mesh. The water of the lake was collected either. All the treatments were made using three replications each one. The experiment was carried out for 18 days. The samplings were made each six days (four samplings). The water temperature was measured at field, and a water sample was collected for dissolved oxygen, saturation, pH, conductivity, and concentrations of total phosphorus, total nitrogen, total suspended matter, organic suspended matter, inorganic suspended matter, chlorophyll-a and pheophytin-a analyses. Samples of zooplankton and phytoplankton were also taken. They were counted and identified until specie level, mostly. Rotifera had its relative abundance changed in all treatments, showing the increasing of Keratella cochlearis and Polyarthra vulgaris, probably because the enclosures protected them from predators. Cladocera dominated all treatments by Bosmina freyi and B hagmanni, which are bioindicators of water euthophication. The absolute abundance of this group was the one that best responded... (Complete abstract click electronic access below)

Orientador: Raoul Henry / Banca: Claudia Fileto / Banca: Danielli Cristina Granado Romero / Banca: Maria Stela Maioli Castilho Noll / Banca: Silvia Maria Caglierani / Resumo: Os organismos planctônicos são a base das cadeias alimentares no ecossistema aquático e os herbívoros zooplanctônicos, em particular, são importantes para o fluxo de energia nos ecossistemas aquáticos, sendo um elo entre os produtores primários e níveis tróficos mais elevados. Este estudo se propôs a ampliar o conhecimento da herbivoria do zooplâncton sobre o fitoplâncton em uma lagoa marginal ao rio Paranapanema. Foi realizado um experimento in situ, com instalação de enclosures com paredes de polietileno fechados no fundo que permitiram a realização de quatro tratamentos: 0% da densidade natural de zooplâncton (apenas fitoplâncton), 50 % (metade da densidade natural), 100% (densidade natural) e 150% (densidade acima da natural). A variação da densidade do zooplâncton foi conseguida por meio de filtração da água por rede de abertura de malha de 50μm. Água da lagoa também foi coletada. Todos os tratamentos foram realizados em tréplica. O experimento durou 18 dias. As coletas foram realizadas a cada seis dias (quatro coletas). A temperatura foi obtida em campo e água foi coletada para análise de oxigênio dissolvido, saturação, pH, condutividade elétrica, concentrações de fósforo total, nitrogênio total, material em suspensão total, material em suspensão orgânico, material em suspensão inorgânico, clorofila-a e feofitina-a. Foram coletadas também amostras de zooplâncton e fitoplâncton que foram contadas e identificadas, normalmente, até ao nível de espécie. Rotifera teve sua abundância relativa alterada em todos os tratamentos, com o favorecimento de Keratella cochlearis e Polyarthra vulgaris provavelmente porque o enclosure as protegeu de predadores. Cladocera foi dominado em todos os tratamentos por Bosmina freyi e B. hagmanni, bioindicadores de eutrofização... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The planktonic organisms are the basis of food chains in the aquatic ecosystems, and the grazer zooplankton, specifically, are very important to energy flow in the aquatic ecosystems, being a link between primary producers and higher trophic levels. The aim of this study is enhance the knowledge of zooplankton grazing over phytoplankton in a lateral lake by Paranapanema River, Brazil. The experiment was conducted in situ, with installation of enclosures of polyetilene walls, closed at the bottom, which allowed the manipulation of four treatments: 0% of the natural density of zooplankton (phytoplankton only); 50% (half of natural density); 100% (natural density) and 150% (a higher density than the natural). The zooplankton density range was obtained by water filtration in zooplankton web with 50μm mesh. The water of the lake was collected either. All the treatments were made using three replications each one. The experiment was carried out for 18 days. The samplings were made each six days (four samplings). The water temperature was measured at field, and a water sample was collected for dissolved oxygen, saturation, pH, conductivity, and concentrations of total phosphorus, total nitrogen, total suspended matter, organic suspended matter, inorganic suspended matter, chlorophyll-a and pheophytin-a analyses. Samples of zooplankton and phytoplankton were also taken. They were counted and identified until specie level, mostly. Rotifera had its relative abundance changed in all treatments, showing the increasing of Keratella cochlearis and Polyarthra vulgaris, probably because the enclosures protected them from predators. Cladocera dominated all treatments by Bosmina freyi and B hagmanni, which are bioindicators of water euthophication. The absolute abundance of this group was the one that best responded... (Complete abstract click electronic access below) / Doutor

Pharmaceutical contamination is increasing in the environment and the consequences this will bring are of growing concern. The highest contamination of pharmaceuticals can be found in aquatic ecosystems and the organisms of these systems are therefore of utmost importance to research in order to understand the ecological consequences of pharmaceutical contamination. This report will reveal the effect contamination can have on an important apex predator often found in temperate aquatic systems, the Northern pike (Esox lucius) when exposed to the psychiatric pharmaceutical Oxazepam. The predatory performance of pike was studied before and after Oxazepam exposure by monitoring how fast each pike caught three prey of roach (Rutilus rutilus), as well as observing the amount of failed predation attempts when hunting the roach. The exposed pike displayed more failed predation attempts after exposure as opposed to the control group. Furthermore it took the exposed pike longer to catch all three roach after exposure while the mean for the control group decreased. Hence, Oxazepam exposure seem to have an effect on predation performance of pike but no definite conclusion could be drawn about to which extent this affects the foraging success and thereby the survival of the pike considering the complex nature of aquatic systems. More studies are therefore needed in order to determine the full effect pharmaceutical contamination can have on complex aquatic ecosystems and more specifically on an apex predator.

Laboratory studies conducted at 5, 15, 25, and 35 C measured changes in gilling rates and oxygen consumption of green sunfish in response to exposure to bentonite clay suspensions. The tests indicate that gilling rates are not affected by bentonite clay suspensions below 2125 FTU at 5 C, 1012 FTU at 15 C, and 898 FTU at 25 C. At turbidity levels exceeding 1012 FTU at 15 C and 898 at 25 C, gilling rates increased 50-70%. Tests were inconclusive at 35 C. Oxygen consumption rates were found to be unaffected by turbid suspensions below 3500 FTU at all four temperatures. Evidence suggests that increased gilling rates under highly turbid conditions are a means of compensating for reduced respiratory efficiency and a strategy for maintaining a constant oxygen uptake. Evidence indicates that the cost of increased gilling rates is probably met by a reduction in activity.

The environmental health of aquatic ecosystems depends amongst others, on the chemical pollution coming from activities in the catchment's area. In the Swan River Estuary, Western Australia, the chemical pollutants of concern released into the river are petroleum hydrocarbons and sodium pentachlorophenate (NaPCP). Decreased water quality causes a loss of biotic diversity especially amongst fish populations. The health of aquatic ecosystems can be monitored by fish health, especially fish located at higher levels in the food chain. Pink snapper (Pagrus auratus), an endemic Western Australian fish species, was tested for its potential as a bioindicator of aquatic environmental health. This thesis presents data on the responsiveness of pink snapper to the contaminants of concern, using biomarkers such as serum sorbitol dehydrogenase (SDH), mixed function oxygenase (MFO), metabolic enzymes such as citrate synthase (CS), cytochrome C oxidase (CCO) and lactate dehydrogenase (LDH) and the histological alteration such as hepatic cell lesions (hyperplasia and hypertrophy), and glycogen and lipid droplets. The metabolic enzymes CCO and LDH as well as the hepatic MFO induction and histopathology were proven to be the most suitable biomarkers for use for routine monitoring of the Swan River Estuary using pink snapper as a bioindicator. However, CS activity and hepatic cell lesions (hyperplasia and hypertrophy) did not respond to exposure to contamination and are therefore not suited as biomarkers of effects in pink snapper. The first phase of the study aimed at investigating the responsiveness of juvenile pink snapper to an MFO inducer. Polychlorinated biphenyl isomer # 126 was selected as a model MFO inducer for this study. In the initial experiment, MFO activity was measured as a biomarker of exposure, and serum SDH activity was assessed as a biomarker of liver damage. / MFO and SDH activities were of special interest as these biochemical tools have not previously been validated for any Western Australia fish species. Juvenile pink snapper were injected intraperitoneally (i.p.) with 0, 10, 100, 500, 1000 microgram PCB-126 per kilogram. Fish were sacrificed 10 days postinjection, and liver and blood were collected for MFO and SDH analysis, respectively. Doses of 10 and 100 microgram PCB-126 per kilogram caused the highest MFO induction, while doses of 0 and 1000 microgram PCB-126 per kilogram did not result in higher MFO activity relative to carrier-injected (peanut oil) control fish. SDH activities were not significantly different among treatments indicating that hepatocellular damage was not responsible for the reduced MFO activity at the highest dose. Metabolic enzymes in pink snapper exposed by NaPCP were studied in the second phase of the experiment. The aim of this second experiment was to test the responsiveness of pink snapper to contaminants known to cause metabolic perturbations in vertebrates. Juvenile pink snapper were intraperitoneally (i.p.) injected with 0, 5, 10, 20 mg per kilogram. Oxidative enzymes were assessed by measuring CS and CCO activities and glycolytic enzyme was assessed by measuring LDI-1 activity in liver and white muscle tissues. CS activity remained unchanged in both the white muscle and in the liver. CCO activity was significantly enhanced in liver in all treated fish relative to control fish, but not in the white muscle. LDH activity was also higher in liver in all treated fish as compared to control fish, while in white muscle, LDH activity significantly increased at the highest dose injected. / The use of a suite of biochemical markers is useful in determining the effects of xenobiotic exposure of aquatic organisms, because it provides a holistic approach with biomarkers at different levels of biological organization. For the third and final phase of the study the suite of biomarkers selected were MFO, metabolic enzyme (CS, CCO and LDH) activities, and histological alternations in combination with physiological indices. The aim of this last experiment was to investigate if a modified liver metabolic activity would alter the MFO induction potential. To test if altered liver metabolism would influence liver detoxication capacities, juvenile pink snapper were i.p. injected with peanut oil (control), or pentachlorobiphenyl # 126 (PCB 126), with sodium pentachlorophenate (NaPCP), or combination of PCB 126+NaPCP. Relative to controls, ethoxyresorufin-O-deethylase (EROD) activity was induced in the PCB 126 and PCB 126+NaPCP fish, but not in the NaPCP group. In the liver, CCO activity was enhanced by the treatments while CS activity remained unchanged and LDH activity was increased in the NaPCP treatment only. In the white muscle, only the PCB 126+ NaPCP treatment enhanced CCO activity, with all other enzymatic activities remaining unchanged. Low serum sorbitol dehydrogenase (sSDH) activity and histopathology of the liver indicated no significant alteration of cellular structure, albeit the lipid droplet size was increased in the PCB 126 and in the PCB 126+NaPCP treatments. / It is concluded that the hepatic metabolic changes correspond to histopathological observations, but an altered metabolic capacity does not influence the metabolism of xenobiotics by liver enzymes, as measured by EROD activity. These experiments answered the need to identify a suitable fish species for routine monitoring of the aquatic environment in Western Australia. It also identified the most suitable biochemical markers of exposure and effects, and the suitability of the pink snapper as a bioindicator. Finally, the experiments investigated interactions between biomarkers and provided new knowledge useful to scientists using MFO and/or metabolic enzymes in field or laboratory toxicology.

A series of physical and chemical analyses were conducted over a fifteen month period to establish the ecological risk, if any, of discharging minewater into aquatic ecosystems. Organic and inorganic analyses were used to determine the extent of contamination of minewater with soluble hydraulic fluids and other contaminant species. Throughout the sampling period the pithead discharge water exhibited a neutral pH and low levels of iron, manganese, zinc and potassium were found. Parallel toxicological and chemical studies identified elevated zinc levels above published toxicity levels for the test species Ceriodaphnia Dubia, but were not confirmed by subsequent study. The presence of organic species in the pit head discharge water was also identified, but the levels were found to be quite variable. Treatment processes involving the detention of the surface minewater and subsequent passage through wetlands exhibited a beneficial effect in reducing pollutant levels prior to disposal. Comparisons of the chemical composition of the minewater discharge with those of local waters were carried out and found to be similar in nature. / Master of Science (Hons)

Made available in DSpace on 2014-10-09T12:40:57Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:22Z (GMT). No. of bitstreams: 1 04019.pdf: 3977762 bytes, checksum: 21b56916c7935f0514332dff16138d5b (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP