The purpose of this investigation was an attempt to clarify the relatives taxonomic position of and to formulate some of the basic cyclic morphological and physiological processes occurring in an aquatic actinomycete possessing streptomycetal characteristics.

No description available.

No description available.

No description available.

Elevated mercury levels have been observed in a wide variety of aquatic systems. A mass balance non-steady state model was developed to examine mercury cycling in lakes and reservoirs. Hg(ll), methylmercury, Hg° , dimethylmercury and solid phase HgS cycles were interconnected. Compartments included air, water, sediment, suspended solids, plankton, benthos, and two generic fish categories based on diet. Bioenergetics equations for individual fish were extended to consider mercury dynamics for entire fish populations. Biota represented large methylmercury fluxes in the water column and were found to be important methylmercury repositories. In a simulation of a generic well-mixed shield lake in Ontario, the fish population contained about 4 times as much methylmercury as water. Uptake of methylmercury by individual walleye and yellow perch was predicted to be dominated by the food pathway (eg. 99% of total uptake). Based on simulations for the generic shield lake, the watershed has the potential to be an important source of methylmercury in some shield lakes (exceeding in-situ methylation in the generic simulation). Methylation in the water column and sediments were both simulated to be significant. Simulated net production of methylmercury in the generic shield lake was on the order of 0.05 to 0.15 ug methylmercury m⁻² year⁻¹ in the water column, with similar rates in sediments. Simulated rates of net methylation in polluted sytems were higher. Fractions of total dissolved Hg(II) or methylmercury available for methylation and demethylation in aerobic waters were thermodynamically predicted to be small (e.g. <1%). Dissolved organic carbon and sulphides (if present) were thermodynamically predicted to dominate Hg(II) and methylmercury complexation in freshwaters. Hg(II) burial and outflows represented about 85-90% of total mercury losses for the generic shield lake (2 year hydraulic retention time). Volatilization of Hg° , produced by demethylation and Hg(II) reduction, represented the remaining 10-15% of losses. Considerable system to system variability is expected for sources and sinks of total mercury and methylmercury in shield lakes. In simulations of two mercury contaminated environments, Lake St. Clair and Clay Lake, Ontario, sediment return of Hg(II) caused the lakes to be net sources of mercury to downstream areas. Sediment return of mercury could partially explain observed two-phase recoveries of fish methylmercury levels in some polluted systems. The time required for Hg(II) and methylmercury concentrations in various compartments to respond to changes in loads was simulated. There was a tendency towards relatively rapid internal cycling of Hg(II) and methylmercury, but slower overall system response times (eg. years to decades to respond to recover from flooding or pollution episodes). / Thesis / Master of Engineering (ME)

Ecologists try to understand how changing habitats alter the populations of organisms living within them, and how, in turn, these changing populations alter the environment. By linking individual or cellular (physiological) processes to system level responses, mechanistic models can help describe the feedback loops between organisms and the environment. Aquatic systems have long used mechanistic models, but increasing model complexity over the last 50 years has led to difficulty in parameterization. In fact, it is often unclear how researchers are choosing parameters at all, even though small changes in parameters can change qualitative predictions. I explore the challenges in parameter estimation present in even an ideal situation. Specifically, I conduct individual experiments for all of the needed parameters to describe a simple lab-based, aquatic system; estimate those parameters using the results from these experiments supplemented with literature data; and run a large experiment designed to test how well the lab-estimated parameters predict actual zooplankton populations and nutrient changes over time. I document best practices for finding and reporting parameter choices and show whole ecosystem level consequences of a variety of decisions. To get the best predictions I find that a mix of parameter estimation methods are necessary. Trait-based approaches are another method to understand species-environment interactions. Trait-based methods aggregate species into functional traits, perhaps making qualitative predictions easier. Theory suggests that more functionally diverse systems will be more resilient. I test this prediction in a simple aquatic system but am unable to find consistent support for this hypothesis, and instead finding that results are highly dependent on what measures of ecosystem recovery are used. Overall, more species-specific information is critical to building better models for both mechanistic and trait-based approaches. I expand species-specific data by providing new information, and collating information from literature on a small, tropical Cladocera. / Thesis / Doctor of Philosophy (PhD) / Predicting what will happen to a habitat after a disturbance is critical for conservation and management. Species specific information is useful for building a mechanistic understanding of ecology. Predictions that include underlying processes (mechanisms) may be more robust to a changing environment than predictions based on correlations. Eutrophication, the addition of excess nutrients, is a common problem in freshwater habitats. Being able to predict the effects of nutrient addition is critical for ensuring the health of freshwater ecosystems. By using species-specific life history and morphological information and a simple lab system, I test different methods of predicting and understanding the consequences of eutrophication. I find that the ramifications of eutrophication are not easily predicted by species' categorizations or with a more detailed mechanistic model.

Community structure in backswimmers (Hemiptera: Notonectide), was investigated via extensive sampling throughout southern Arizona, USA, and Sonora, Mexico, from 1980 through 1985. Co-occurrence and relative abundance data were collected in more than 65 ponds, and in 177 rock basin pools (tinajas) in 21 canyons in the Southwest. Eleven species were collected in Arizona and Sonora, and were divided into two groups, species found in ponds and species found in tinajas. Only two species occurred significantly in both habitats. Tinaja species are largely Southwst endemics, and pond species are widespread or tropical in distribution. Data from artificial habitats suggest that the tinaja species use relatively high topographic relief, and pond species use relatively large surface area as cues to find their respective habitats. Two body size patterns are consistent with a competition explanation of local community structure. The body sizes of co-occurring species are relatively evenly distributed among species occurring in pond and tinaja habitats, and species of similar body size tend not to co-occur (body size ratio <1.3). For example, Notonecta kirbyi and N. lobata only co-occur in tinajas at intermediate elevations; lobata is absent at high elevations and kirbyi is absent at lower elevations. N. indica occurs in ponds at lower elevations and N. unifasciata occurs at higher elevations. Buenoa hungerfordi and B. arizonis both occur in tinajas, but not at the same time of year. Predation was shown experimentally not to be important in producing the body size pattern. Notonecta spp. preyed heavily on the smaller of two Buenoa species presented, an effect that would act to reduce the community-wide body size ratio. Because notonectid communities have larger body size ratios than expected by chance, predation would seem not to be involved in producing this pattern. However, predation does appear to reinforce microhabitat partitioning between the two genera in that Buenoa occupy deeper portions of the water column in the presence of Notonecta than in their absence. This further displaces coexisting individuals of the two genera in space, and reduces overlap in foraging for aquatic insect prey and promotes coexistence.

Orientador: Antonio Fernando Monteiro Camargo / Banca: Massanori Takaki / Banca: Raoul Henry / Banca: Denise de Campos Bicudo / Banca: Marcelo L.M. Pompêo / Resumo: O objetivo deste trabalho foi estudar a distribuição das macrófitas aquáticas em rios da planície costeira da bacia do rio Itanhaém. A abordagem adotada foi uma combinação de estudos observacionais e experimentais. No primeiro capítulo, estudou-se a distribuição das macrófitas aquáticas em relação a variáveis ambientais da água e do sedimento em 97 km de rios em duas estações do ano (verão e inverno). A salinidade foi a principal variável ambiental responsável pela separação das macróf5tas aquáticas em duas comunidades distintas, a do estuário e a dos rios. As principais espécies que ocorreram no estuário foram Spartina alterniflora. Crinum procerum e Scirpus califhrnicus, sendo que a primeira ocorreu em trechos de maior salinidade, a segunda em trechos com salinidade intermediária e a última em trechos de menor salinidade. As espécies de água doce mais freqüentes foram Egeria densa, Eichhornia azurea, Eichhornia crassipes. Pistia stratiotes, e Salvínia molesta. Egeria densa tendeu a ocorrer em trechos com maior transparência. menor nitrogênio total e maior fração areia no sedimento. Eichhornia azurea tendeu a ocorrer em locais com alta transparência e baixas concentrações de nitrogénio total. Finja siratiotes tendeu a ocorrer em trechos de rios com maiores concentrações de nitrogênio total na água. A freqüência de ocorrência das principais espécies não diferiu entre o verão e o inverno, provavelmente devido a ausência de uma estação seca. No segundo capítulo, se estudou a ocorrência das macrófitas aquáticas em função da vegetação ciliar e da morfologia de canal em três trcchos distintos de rios. No estuário do rio ltanhaém. a ocorrência de macrófitas aquáticas emergentes foi correlacionada com o sombreamento das árvores de mangue e a declividadc da área litorânea... (Resumo completo, clicar acesso eletrônico abaixo). / Abstract: The aim of this research was to study the distribution of aquatic macrophytes in coastal piam rivers of ltanhaém basin. lhe research approach was based on observational and experimental studies. In the first chapter, the distribution of aquatic macrophyte was correlated to water and sediment environmental variables in 97 km of rivers and in two periods (summer and winter). Salinity was the most important environmental variable to separate the aquatie rnacrophytes in two distinct communities: estuarine and freshwater communities. The main species found in the estuary were Spartina alterniflora, Crinum procerum and Scirpus califohiicus. lhe first species was found in water with higher salinity, the second in water with intermediate salinity and the Iatter in less saline water. lhe most frequent &eshwater species were Egeria densa, Eichhornia azurea, Eichhornia crassipes, Pistia strarioles and Sal Wnia molesta. Egeria densa tended to be present in river sections with high water transparence. low total nitrogen, and high sand fraction in sediment. Eichhornia azurea tended to occur in sections with high water transparence and low total nitrogen. Pistia stratiotes tendecl to occur in river sections with high total nitrogen. lhe &equency of occurrence aquatic macrophyrtes did not significantly differed hetween sunimer and winter. due probably to the absence of a dry season. In the second chapter, we investigated the influence of riparian vegetation and stream channel morphology on aquatie rnacrophyte distribution in three streams with dstinguished landscape. In the estuary of ltanhaëm River, the occurrence of emergent rnacrophytes was correlated with mangrove shading and slope of littoral region. In Preto River... (Complete abstract, click electronic address below). / Doutor

Made available in DSpace on 2014-06-11T19:30:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-11-18Bitstream added on 2014-06-13T19:40:36Z : No. of bitstreams: 1 leung_r_dr_rcla.pdf: 1545935 bytes, checksum: 392e9cf661ed29a1efe4f5cf02fdf7f3 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O objetivo deste trabalho foi estudar a distribuição das macrófitas aquáticas em rios da planície costeira da bacia do rio Itanhaém. A abordagem adotada foi uma combinação de estudos observacionais e experimentais. No primeiro capítulo, estudou-se a distribuição das macrófitas aquáticas em relação a variáveis ambientais da água e do sedimento em 97 km de rios em duas estações do ano (verão e inverno). A salinidade foi a principal variável ambiental responsável pela separação das macróf5tas aquáticas em duas comunidades distintas, a do estuário e a dos rios. As principais espécies que ocorreram no estuário foram Spartina alterniflora. Crinum procerum e Scirpus califhrnicus, sendo que a primeira ocorreu em trechos de maior salinidade, a segunda em trechos com salinidade intermediária e a última em trechos de menor salinidade. As espécies de água doce mais freqüentes foram Egeria densa, Eichhornia azurea, Eichhornia crassipes. Pistia stratiotes, e Salvínia molesta. Egeria densa tendeu a ocorrer em trechos com maior transparência. menor nitrogênio total e maior fração areia no sedimento. Eichhornia azurea tendeu a ocorrer em locais com alta transparência e baixas concentrações de nitrogénio total. Finja siratiotes tendeu a ocorrer em trechos de rios com maiores concentrações de nitrogênio total na água. A freqüência de ocorrência das principais espécies não diferiu entre o verão e o inverno, provavelmente devido a ausência de uma estação seca. No segundo capítulo, se estudou a ocorrência das macrófitas aquáticas em função da vegetação ciliar e da morfologia de canal em três trcchos distintos de rios. No estuário do rio ltanhaém. a ocorrência de macrófitas aquáticas emergentes foi correlacionada com o sombreamento das árvores de mangue e a declividadc da área litorânea... . / The aim of this research was to study the distribution of aquatic macrophytes in coastal piam rivers of ltanhaém basin. lhe research approach was based on observational and experimental studies. In the first chapter, the distribution of aquatic macrophyte was correlated to water and sediment environmental variables in 97 km of rivers and in two periods (summer and winter). Salinity was the most important environmental variable to separate the aquatie rnacrophytes in two distinct communities: estuarine and freshwater communities. The main species found in the estuary were Spartina alterniflora, Crinum procerum and Scirpus califohiicus. lhe first species was found in water with higher salinity, the second in water with intermediate salinity and the Iatter in less saline water. lhe most frequent &eshwater species were Egeria densa, Eichhornia azurea, Eichhornia crassipes, Pistia strarioles and Sal Wnia molesta. Egeria densa tended to be present in river sections with high water transparence. low total nitrogen, and high sand fraction in sediment. Eichhornia azurea tended to occur in sections with high water transparence and low total nitrogen. Pistia stratiotes tendecl to occur in river sections with high total nitrogen. lhe &equency of occurrence aquatic macrophyrtes did not significantly differed hetween sunimer and winter. due probably to the absence of a dry season. In the second chapter, we investigated the influence of riparian vegetation and stream channel morphology on aquatie rnacrophyte distribution in three streams with dstinguished landscape. In the estuary of ltanhaëm River, the occurrence of emergent rnacrophytes was correlated with mangrove shading and slope of littoral region. In Preto River... (Complete abstract, click electronic address below).

Low back pain (LBP) is a widespread problem affecting a number of people. Traditionally treated by nonoperative approaches the recent development of water currents and treadmills imbedded into pools has spurred physical therapists and athletic trainers to incorporate the use of aquatic therapy into their rehabilitation programs. OBJECTIVE: Determine if select trunk muscle activity levels are different in water-based exercises compared to land-based exercises. METHODS: 11 healthy male participants age 25.9 ± 5.53 years, whom did not have a history of and were not currently experiencing LBP or injury. Muscle activity was monitored via electromyography (EMG) at the rectus abdominis (RA), external oblique (EO), lower abdominals (LA), erector spinae (ES), and lumbar multifidis (MT). Each subject performed (1) maximum voluntary contractions (MVC’s), (2) land-based exercises, and (3) water-based exercises. A paired samples t test was used to compare abdominal bracing (ABbrace), abdominal hallowing (ABhol), Anterior/Posterior pelvic tilts (APTilts), and lateral pelvic tilts (LatTilts) between comparable land and water conditions; general linear model-repeated measures was run to compare the 11 different water exercises; ABbrace, ABhol, APTilts, LatTilts, physioball push down (PBPushDown), PB lateral flexion, PB transverse rotations, stationary marching, leg abduction, and wall sits with sagittal and transverse plane arm movements. Follow-up multiple comparisons (LSD) were performed between water exercises using a Holm’s corrected alpha level set at 0.05. RESULTS: Land-based exercises elicited greater EMG activity compared to water-based activities for all muscles (%MVC land vs. %MVC water): RA %MVC (8.3-19.3 vs. 2.1-9.7, P = .003-.029); LA %MVC (27-105 vs. 5.2-25, P = .001-.016); EO %MVC (13-59 vs. 4.8-24.5, P = .001-.303); ES %MVC (19.1-37.6 vs. 7.75-22.1, P = .001-.039) and MT %MVC (16-25.4 vs. 5.9-8.8, P = .00-.005). For water comparison ABbrace and PB exercises produced the most muscle activity while WallSitSag/Trans consistently produced the least muscle activity. CONCLUSION: Even with reduced muscle activity in the water, the calculated % mean MVCs were high enough (at or below 25% MVC) to provide muscle endurance and stability gains. With the information provided from the analysis of water exercise comparison, practitioners can effectively progress patients through a rehabilitation program.