ii Abstract Tapeng Bay has distinct dry (October to May) and wet (June to September) seasons. The salinity was 33‰ in the dry season, but may as low as 21‰ during the wet season. The yearly average temperature, salinity and chlorophyll a of Tapeng Bay are 26.9 ¢J, 29.7 ‰ and 2.24 £gg/L respectively. Thirty-six species of copepods belonging 18 families and three orders plus 16 unidenitified species were found in the materials of this study. The average abundance of copepods was 5.8 ¡Ó8.4 x10 5 ind./100m 3 . The nine most dominant species were Acartia tsuensis , Paracalanidae (copepodites), Acartiidae (copepodites), Parvocalanus crassi rostris , Oithonidae (copepodites), Oithona dissimilis , n auplius, Acrocalanus indicus and Zausodes spp., contibuting to 81% of the total copepods. Majority of the dominant species exhibited clear seasonal changes in abundance, varying positively with temperature. Acartia tsuensis and Acartiidae were dominant species in station N in the wet season, but other dominant species had higher abundance in the dry season. Aurelia aurita (Cnidaria, Scyphozoa) which was dominant in the dry season, may play the role of a keystone species at stations S and C. Species composition was different among stations. Fish-pond species was dominant at station S, copepodite and nauplii, and neritic species at station N. The abundance of copepods may be influenced by tidal action. When inlet species abundance is higher than neritic species, total copepod abundance at high tide is lower than at low tide, but the trend is reverse for neritic species. The grazing impact of copepods on phytoplankton was 0.04 to 40.36 % per day.

A abundância dos taliáceos e sua relação aos demais grupos do zooplâncton, além da avaliação do impacto alimentar das salpas, foram observados a partir de amostras da região da plataforma continental sudeste brasileira durante o verão de 2002. As salpas estiveram presentes em maior concentração na região de plataforma interna, enquanto os dolíolos apresentaram maior abundância na plataforma externa. Ambos os grupos foram encontrados principalmente nas camadas mais superficiais. Os maiores valores de biomassa foram registrados nas estações onde os gelatinosos estiveram presentes, sendo o máximo de 131 mg C m-² obtido para as salpas e 636 mg C m-² para os dolíolos. A ocorrência de salpas esteve relacionada à maior concentração de clorofila e menores valores de temperatura. Já para os dolíolos não foi possível observar o mesmo padrão. Os resultados apontaram que as salpas estiveram associadas à mistura das massas AT e ACAS e os dolíolos às águas tropicais (AT). A abundância dos organismos zooplanctônicos não apresentou reduções significativas quando comparadas as concentrações de salpas e dolíolos, sendo correlacionadas positivamente. Em ambientes eutróficos, como o caso das áreas de ressurgência, o alimento não é um fator limitante, sendo possível a ocorrência simultânea de diversos grupos de organismos que em outro cenário competiriam por alimento. As maiores taxas de ingestão e impacto alimentar causado pelas salpas foram registradas na região de plataforma interna, sendo associadas aos maiores valores de biomassa observados para o grupo e a elevada concentração de clorofila. / The abundance of thaliaceans and its relation to other zooplankton groups, as well as salp grazing impact, were studied on the southeastern shelf of Brazil based on samples collected during summer 2002. Salps occurred at higher numbers on the inner shelf, while doliolids were more abundant on the outer shelf. Both taxa were found mainly in the upper layers of the water column. Highest biomass values were recorded in stations where gelatinous plankton were present, with maxima of 131 mg C m-² for salps and 636 mg C m-² for doliolids. Salp occurrence was positively corelated to higher chlorophyll concentrations and lower temperatures. Doliolids did not follow such pattern. Salps were associated to areas where Tropical Water and South Atlantic Central Water mixed, and doliolids dominated in Tropical Water. The abundance of other zooplankton taxa did not show significant decrease when salps and doliolids were abundant, as the correlation among salps, doliolids and other groups were usually positive. During upwelling events food is usually not limiting; thus the same planktonic taxa that will compete for food in other areas may coexist in such eutrophic to mesotrophic environments. The highest ingestion rates and feeding impact associated to salps were recorded on the inner shelf, where the highest salp abundance and chlorophyll-a concentration occurred.

A abundância dos taliáceos e sua relação aos demais grupos do zooplâncton, além da avaliação do impacto alimentar das salpas, foram observados a partir de amostras da região da plataforma continental sudeste brasileira durante o verão de 2002. As salpas estiveram presentes em maior concentração na região de plataforma interna, enquanto os dolíolos apresentaram maior abundância na plataforma externa. Ambos os grupos foram encontrados principalmente nas camadas mais superficiais. Os maiores valores de biomassa foram registrados nas estações onde os gelatinosos estiveram presentes, sendo o máximo de 131 mg C m-² obtido para as salpas e 636 mg C m-² para os dolíolos. A ocorrência de salpas esteve relacionada à maior concentração de clorofila e menores valores de temperatura. Já para os dolíolos não foi possível observar o mesmo padrão. Os resultados apontaram que as salpas estiveram associadas à mistura das massas AT e ACAS e os dolíolos às águas tropicais (AT). A abundância dos organismos zooplanctônicos não apresentou reduções significativas quando comparadas as concentrações de salpas e dolíolos, sendo correlacionadas positivamente. Em ambientes eutróficos, como o caso das áreas de ressurgência, o alimento não é um fator limitante, sendo possível a ocorrência simultânea de diversos grupos de organismos que em outro cenário competiriam por alimento. As maiores taxas de ingestão e impacto alimentar causado pelas salpas foram registradas na região de plataforma interna, sendo associadas aos maiores valores de biomassa observados para o grupo e a elevada concentração de clorofila. / The abundance of thaliaceans and its relation to other zooplankton groups, as well as salp grazing impact, were studied on the southeastern shelf of Brazil based on samples collected during summer 2002. Salps occurred at higher numbers on the inner shelf, while doliolids were more abundant on the outer shelf. Both taxa were found mainly in the upper layers of the water column. Highest biomass values were recorded in stations where gelatinous plankton were present, with maxima of 131 mg C m-² for salps and 636 mg C m-² for doliolids. Salp occurrence was positively corelated to higher chlorophyll concentrations and lower temperatures. Doliolids did not follow such pattern. Salps were associated to areas where Tropical Water and South Atlantic Central Water mixed, and doliolids dominated in Tropical Water. The abundance of other zooplankton taxa did not show significant decrease when salps and doliolids were abundant, as the correlation among salps, doliolids and other groups were usually positive. During upwelling events food is usually not limiting; thus the same planktonic taxa that will compete for food in other areas may coexist in such eutrophic to mesotrophic environments. The highest ingestion rates and feeding impact associated to salps were recorded on the inner shelf, where the highest salp abundance and chlorophyll-a concentration occurred.

The aims of this thesis were to: 1) develop a new method for the determination of interstitial pH at rest and during exercise in vivo, 2) systematically explore the effects of different ingestion regimes of 300 mg.kg-1 sodium citrate on blood and urine pH at rest, and 3) to combine the new interstitial pH technique with the findings of the second investigation in an attempt to provide a greater understanding of H+ movement between the extracellular compartments. The purpose of the first study was to develop a method for the continuous measurement of interstitial pH in vastus lateralis was successfully developed using microdialysis and 2,7-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF). To avoid the presence of an artificial alkalosis during exercise, it was necessary to add 25 mM HCO3- to the perfusate. The outlet of the probe was cut less than 10 mm from the skin and connected to a stainless steel tube completing the circuit to a microflow-through cuvette (8 fÝl) within a fluorescence spectrophotometer. This prevented the loss of carbon dioxide from the dialysate and any subsequent pH artefact. Interstitial pH was collected from six subjects before, during and after five minutes of knee-extensor exercise at three intensities 30, 50, and 70 W. Mean,,bSEM interstitial pH at rest was 7.38,,b0.02. Exercise reduced interstitial pH in an almost linear fashion. The nadir value for interstitial pH at 30, 50 and 70 W exercise was 7.27, 7.16 and 7.04, respectively. The lowest pH was obtained 1 min after exercise, irrespective of workload, after which the interstitial pH recovered in a nearly exponential manner. The mean half time of interstitial recovery was 5.2 min. The changes in interstitial pH exceeded the changes in venous blood pH. This study demonstrated that interstitial pH can be measured using microdialysis and that it is continuously decreased during muscle activity. The purpose of the second study was to establish an optimal ingestion regime for the ingestion of 300 mg.kg-1 of sodium citrate and maximise the alkalotic effect while minimising any side effects. Increasing the effectiveness of alkali ingestion may lead to further increases in muscle performance. Ingesting 300 mg.kg-1 sodium citrate at a rate of 300 mg.min-1 was identified as the optimal ingestion regime to maximise alkalosis at rest, which occurred 3.5 h post-ingestion. This was determined by monitoring eight human subjects ingesting 300 mg.kg-1 sodium citrate at five different rates, control (no ingestant), bolus, 300, 600 and 900 mg.kg.min-1 on five days separated by at least 48 hours. Sodium citrate was ingested in capsule form with water ad libitum, with the exception of bolus, which was combined with 400 ml less than 25 percent orange juice and consumed in less than 1 min. Arterialised blood (mean 71.3,,b3.5 mmHg) acid-base and electrolyte status was assessed via the withdrawal of ~5 ml of blood every 30 min across an eight hour duration, placed on ice and analysed within five minutes. No alkalotic difference was found between ingestion rates (mean 7.445,,b0.004, 7.438,,b0.004 and 7.442,,b0.004 for 300, 600 and 900 mg.min-1, respectively). All experimental ingestion regimes were associated with elevations in [HCO3-] (29.6, 29.7, 29.8, 29.9 and 26.3 mmol.l-1 for bolus, 300, 600, 900 and control, respectively). The 300 ingestion regime had the greatest impact on [H+], a 0.66 meq.l-1,,e10-8 change. Bolus ingestion (3.93,,b0.08 mmol.l-1) of sodium citrate had no effect on control (4.06,,b0.08 mmol.l-1) blood [K+], however, 300 mg.min-1 decreased blood [K+] (p less than 0.05). There was no effect of sodium citrate on blood [Cl-], but after 2.5 h blood [Cl-] was lower than pre-ingestion values (p less than0.05). All ingestion rates of sodium citrate increased (p less than 0.05) urine pH above control. This is the first study to investigate the effect of varying ingestion rates on acid-base status at rest in humans. The results suggest that ingesting sodium citrate in small doses in quick succession induce a greater blood alkalosis than the commonly practised bolus protocol. Using the interstitial pH technique described above and the optimal ingestion regime (300 mg.min-1) identified above, the final experiment was designed to assess the influence of sodium citrate ingestion on interstitial pH at both rest and during exercise. Five subjects ingested 300 mg.kg-1 sodium citrate at 300 mg.min-1 again in capsule form with water ad libitum. Prior to ingestion, each subject had a cannula placed into their cephalic vein and one microdialysis probe (CMA-60) inserted into their left thigh, orientated along the fibres of vastus lateralus. This probe was used for the measurement of pH as described above. At the end of this period, an exercise protocol required five subjects to perform light exercise (10 W) for 10 min, before starting an intense exercise period (~90-95% leg VO2peak) to exhaustion followed by a 15 min recovery period. Dialysate and blood samples were collected across all periods. Mean,,bSEM interstitial pH for placebo and alkalosis were 7.38,,b0.12 and 7.24,,b0.16, respectively. Sodium citrate ingestion was not associated with an interstitial alkalosis. An exercise induced acidosis was observed in the interstitium during placebo but not during alkalosis (p less than 0.05). Mean,,bSEM venous pH were 7.362,,b0.003 and 7.398,,b0.003 for placebo and alkalosis, respectively. Sodium citrate ingestion was not associated with a venous alkalosis. Sodium citrate ingestion was associated with an increase in mean,,bSEM venous [HCO3-] (placebo 25.5,,b0.2, alkalosis 28.1,,b0.2). This increase in the blood bicarbonate buffer system was not associated with an increase in time to exhaustion (placebo 352,,b71, alkalosis 415,,b171). This was the first study to investigate the effects of sodium citrate ingestion on interstitial pH. The results of this study demonstrated that an interstitial alkalosis does not ensue after alkali ingestion, however, it was associated with the lack of an exercise induced acidosis suggesting an improved pH regulation during exercise.

Submitted by Maria de Lourdes Mariano (lmariano@ufscar.br) on 2017-01-12T13:03:39Z No. of bitstreams: 1 MAGALHÃES_Raphaella_2014.pdf: 2191160 bytes, checksum: fcf55d3e818013ffdb2045bcec90cf2b (MD5) / Approved for entry into archive by Maria de Lourdes Mariano (lmariano@ufscar.br) on 2017-01-12T13:03:50Z (GMT) No. of bitstreams: 1 MAGALHÃES_Raphaella_2014.pdf: 2191160 bytes, checksum: fcf55d3e818013ffdb2045bcec90cf2b (MD5) / Approved for entry into archive by Maria de Lourdes Mariano (lmariano@ufscar.br) on 2017-01-12T13:03:58Z (GMT) No. of bitstreams: 1 MAGALHÃES_Raphaella_2014.pdf: 2191160 bytes, checksum: fcf55d3e818013ffdb2045bcec90cf2b (MD5) / Made available in DSpace on 2017-01-12T13:04:07Z (GMT). No. of bitstreams: 1 MAGALHÃES_Raphaella_2014.pdf: 2191160 bytes, checksum: fcf55d3e818013ffdb2045bcec90cf2b (MD5) Previous issue date: 2014-05-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Preliminary studies on reservoir Itupararanga indicate that the seasonal dynamics of plankton community is not being strongly controlled by bottom-up forces. Cianobactéria Cylindrospermopsis raciborskii and clorofícea Monoraphidium contortum are the dominant phytoplankton species in this reservoir. Bosmina freyi, recently described, is the dominant zooplankton in Itupararanga and there is no records of studies feeding habits of this specie. Therefore, the present study aims to assess the importance of the cladoceran Bosmina freyi as consumers of phytoplankton species: Monoraphidium contortum and Cylindrospermopsis raciborkii to better understand the ecological role of this organism in the planktonic food web in reservoir Itupararanga. M. contortum and three types of strain C.raciborskii, toxic strain (Cy.tox), strain with large filaments (Cy.grd) and strain with small filaments (Cy.peq) where ofered for Bosmina freyi. For each treatment, were calculated the density, cell volume, biovolume before and after incubation with B. freyi.Also calculated the ingestion and filtration rates. Qualitative models have also been made to describe and make predictions on the plankton community Itupararanga when there are changes in the population of Chaoborus sp. It was noted that B. freyi is able to efficiently ingest C.raciborskii including toxic strain, but presented difficulties in filter and ingest filaments of Cy.grd.Besides, B.freyi seems to be able to cut up filaments of C.raciborskii for ingestion. No food preference was observed by M.contortum. Qualitative models made in this study corroborate the hypothesis that seasonal variations in plankton reservoir Itupararanga may be being controlled by top-down forces due the presence of Chaoborus sp. / Estudos preliminares no Reservatório de Itupararanga indicam que a dinâmica sazonal da comunidade planctônica não está sendo fortemente controlada por forças botton-up. A cianobactéria Cylindrospermospisi raciborskii e a clorofícea Monoraphidium contortum são as espécies fitoplanctônicas dominantes neste reservatório. Bosmina freyi, espécie descrita recentemente, é a dominante do zooplâncton em Itupararanga e não há registros de estudos sobre os hábitos alimentares desta espécie. Devido a isso o presente trabalho pretende avaliar a importância do cladócero Bosmina freyi como consumidor das espécies fitoplanctônicas: Monoraphidium contortum e Cylindrospermopsis raciborkii para melhor entender o papel ecológico deste organismo na teia alimentar planctônica no reservatório de Itupararanga. Foram oferecidos M. contortum e três tipos de cepa C.raciborskii, cepa tóxica (Cy.tox), cepa com filamentos grandes (Cy.grd) e cepa com filamentos pequenos (Cy.peq) para Bosmina freyi. Para cada tratamento, calcularam-se as densidades, volumes celulares, biovolumes antes e depois do período de incubação com B. freyi, além disso, foram calculadas as taxas de filtração e ingestão. Foram feitos também modelos qualitativos para descrever e fazer previsões na comunidade planctônica do reservatório de Itupararanga quando há alterações na população de Chaoborus sp.Observou-se que B. freyi é capaz de ingerir eficientemente C.raciborskii inclusive a cepa tóxica, porém apresentou dificuldades em filtrar e ingerir filamentos de Cy.grd. Além disso, B.freyi parece ser capaz de cortar filamentos de C.raciborskii para ingestão. Não foi observado preferência alimentar por M.contortum. Os modelos qualitativos feitos neste estudo corroboram com a hipótese de que as variações sazonais do plâncton no reservatório de Itupararanga podem estar sendo controladas por forças top-down pela presença de Chaoborus sp.

Made available in DSpace on 2014-12-17T14:33:07Z (GMT). No. of bitstreams: 1 FabricioRC_DISSERT.pdf: 838962 bytes, checksum: 3096b614c5fa73cd030f8193624b3469 (MD5) Previous issue date: 2012-08-31 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Protozoa may be an important alternative food source for Calanoida copepods in these environments. Aiming to quantify the feeding preferences of N. cearensis by ciliates in the presence of cyanobacteria, in vitro experiments were conducted, using mixed cultures in different concentrations of total food for copepod. Two ciliates species (Paramecium sp. and Cyclidium sp.) and a cyanobacteria toxic strain (Microcystis aeruginosa) were offered as food. Previous experiments were done to identify the copepod s maximum ingestion rate through the use of a type II functional response model when each prey is offered separately. High maximum ingestion rate were found when those protists were offered as prey. N. cearensis showed significant preference for protozoal prey over the cyanobacterium tested both in low (corresponding 95.15% of the diet) and in high food concentration treatments (about 91.56% of the diet), preferring the bigger ciliate in lower concentrations (67.52% of the diet). The meaningful involvement of heterotrophic organisms in the zooplankton diet emphasis the microbial loop participation in the energy transition from copepods to higher trophic levels. This data contributes to understand the stability of existing trophic interactions in reservoirs subjected to eutrophication and assists trophic cascade studies in these environments / Protozo?rios podem ser uma importante fonte alternativa de alimento para cop?podos Calanoida em ambientes dominados por cianobact?rias. Com o objetivo de quantificar a prefer?ncia alimentar de Notodiaptomus cearensis por ciliados em presen?a de cianobact?rias, experimentos in vitro foram conduzidos, utilizando-se culturas mistas em diferentes concentra??es totais de alimento para o cop?podo. Duas esp?cies de ciliados (Paramecium sp. e Cyclidium sp.) e uma cepa t?xica de cianobact?ria (Microcystis aeroginosa) foram ofertados como alimentos. Experimentos pr?vios visando identificar as taxas de ingest?o m?xima do cop?podo atrav?s do uso de um modelo de resposta funcional do tipo II quando cada uma das presas ? ofertada separadamente tamb?m foram realizados. O cop?podo apresentou maior taxa de ingest?o m?xima quando ciliados s?o ofertados como presa. N. cearensis mostrou prefer?ncia significativa por protozo?rios em detrimento da cianobact?ria testada tanto em tratamentos com menor (correspondendo a cerca de 95,15% da dieta) quanto com maior concentra??o de alimento (cerca de 91,56% da dieta), preferindo o ciliado de maior tamanho nas menores concentra??es (67,52% da dieta). A participa??o significativa de organismos heterotr?ficos na dieta do zoopl?ncton d? maior ?nfase ? participa??o da al?a microbiana na passagem de energia para n?veis tr?ficos superiores. Tal dado colabora para o entendimento da estabilidade das intera??es tr?ficas existentes em reservat?rios sujeitos a eutrofiza??o e auxilia estudos de cascata tr?fica nesses ambientes

Most climate change predictions focus on the response of individual species to changing local conditions and ignore species interactions, largely due to the lack of a sound theoretical foundation for how interactions are expected to change with climate and how to incorporate them into climate change models. Much of the variability in species interaction strengths may be governed by fundamental constraints on physiological rates, possibly providing a framework for including species interactions into climate change models. Metabolic rates, ingestion rates and many other physiological rates are relatively predictable from body size and body temperature due to constraints imposed by the physical and chemical laws that govern fluid dynamics and the kinetics of biochemical reaction times. My dissertation assesses the usefulness of this framework by exploring the community-level consequences of physiological constraints. In Chapter 2, I incorporated temperature and body size scaling into the biological rate parameters of a series of realistically structured trophic network models. The relative magnitude of the temperature scaling parameters affecting consumer energetic costs (metabolic rates) and energetic gains (ingestion rates) determined how consumer energetic efficiency changed with temperature. I systematically changed consumer energetic efficiency and examined the sensitivity of network stability and species persistence to various temperatures. I found that a species' probability of extinction depended primarily on the effects of organismal physiology (body size and energetic efficiency with respect to temperature) and secondarily on the effects of local food web structure (trophic level and consumer generality). This suggests that physiology is highly influential on the structure and dynamics of ecological communities. If consumer energetic efficiency declined as temperature increased, that is, species did best at lower temperatures, then the simulated networks had greater stability at lower temperatures. The opposite scenario resulted in greater stability at higher temperatures. Thus, much of the community-level response depends on what species energetic efficiencies at the organismal-level really are, which formed the research question for Chapter 3: How does consumer energetic efficiency change with temperature? Existing evidence is scarce but suggestive of decreasing consumer energetic efficiency with increasing temperature. I tested this hypothesis on seven rocky intertidal invertebrate species by measuring the relative temperature scaling of their metabolic and ingestion rates as well as consumer interaction strength under lab conditions. Energetic efficiencies of these rocky intertidal invertebrates declined and species interaction strengths tended to increase with temperature. Thus, in the rocky intertidal, the mechanistic effect of temperature would be to lower community stability at higher temperatures. Chapter 4 tests if the mechanistic effects of temperature on ingestion rates and species interaction strengths seen in the lab are apparent under field conditions. Bruce Menge and I related bio-mimetic estimates of body temperatures to estimates of per capita mussel ingestion rates and species interaction strengths by the ochre sea star Pisaster ochraceus, a keystone predator of the rocky intertidal. We found a strong, positive effect of body temperature on both per capita ingestion rates and interaction strengths. However, the effects of season and the unique way in which P. ochraceus regulates body temperatures were also apparent, leaving room for adaptation and acclimation to partially compensate for the mechanistic constraint of body temperature. Community structure of the rocky intertidal is associated with environmental forcing due to upwelling, which delivers cold, nutrient rich water to the nearshore environment. As upwelling is driven by large-scale atmospheric pressure gradients, climate change has the potential to affect a wide range of significant ecological processes through changes in water temperature. In Chapter 5, my coauthors and I identified long-term trends in the phenology of upwelling events that are consistent with climate change predictions: upwelling events are becoming stronger and longer. As expected, longer upwelling events were related to lower average water temperatures in the rocky intertidal. Furthermore, recruitment rates of barnacles and mussels were associated with the phenology of upwelling events. Thus climate change is altering the mode and the tempo of environmental forcing in nearshore ecosystems, with ramifications for community structure and function. Ongoing, long-term changes in environmental forcing in rocky intertidal ecosystems provide an opportunity to understand how temperature shapes community structure and the ramifications of climate change. My dissertation research demonstrates that the effect of temperature on organismal performance is an important force structuring ecological communities and has potential as a tractable framework for predicting the community level effects of climate change. / Graduation date: 2013 / Access restricted to the OSU Community, at author's request, from Nov. 20, 2012 - Nov. 20, 2014