Ecosystems are linked by spatial subsidies, the bi-directional flows of nutrients, materials and energy that cross ecosystem boundaries. Considered one of the planet’s most productive and diverse meta-ecosystems, the broad interface between land and sea is crossed by innumerable abiotic and biotic spatial subsidies, including migratory animals. Routinely crossing ecological boundaries, migrants play significant roles in subsidizing receiving ecosystems, including influencing ecosystem productivity, diversity, community structure and trophic cascades. On the Pacific coast of North America, spatial subsidies driven by migratory Pacific salmon have been intensively studied. Like many of the world’s migrants, however, salmon populations have declined considerably and most of our scientific knowledge has been gained from a diminished subsidy. Other subsidies, including those driven by migratory species in decline, remain relatively unknown. Each year, Pacific herring (Clupea pallasii) migrate to shallow waters to spawn on nearshore and intertidal substrates. Despite suggestions in the literature that herring, an abundant, nearshore/intertidal spawning forage fish, subsidizes coastal ecosystems, there had been no investigation of cross-ecosystem interactions. Just as stable isotopes and fatty acids have been used to explore wrack (drift macrophytes) subsidies to intertidal ecosystems, we combined both approaches to trace the input of Pacific herring and wrack to semi-terrestrial amphipods (Traskorchestia spp.), which are highly abundant detritivores in beach ecosystems. Brown algae and seagrass were major contributors to amphipods but when available, herring was also a significant resource. Because amphipods are prey for terrestrial consumers, including bears (Ursus spp.), we also identified indirect trophic linkages between herring and terrestrial ecosystems. Bears are major consumers and vectors of salmon into terrestrial ecosystems, but little is known regarding their involvement in other spatial subsidies. Using a model-based inference approach paired with remote cameras to monitor intertidal black bear (U. americanus) activity, we determined that the best predictors of black bear intertidal activity were major intertidal prey items (herring and amphipod biomass) and Julian day. Bears positively responded to herring and amphipod biomass on beaches but it was the analysis of scats that determined the contribution of herring eggs to the diets of bears. In 2010, the herring spawn was relatively poor and consumption of eggs was negligible, with amphipods constituting a major portion of bear diets. In following years, herring egg loading was relatively high and eggs were the dominant dietary item in bear scats. Tracing the contribution of herring into terrestrial areas proved challenging and instead, we furthered knowledge of the within-watershed spatiotemporal influences of salmon on conifer tree ring growth and δ15N signatures. Both tree ring growth and δ15N signatures tracked the known spatial distribution of salmon carcasses. Using a model-based inference approach, salmon abundance and interaction terms of salmon*temperature and salmon*distance into the forest best predicted tree growth. In contrast, salmon abundance was not a leading predictor of δ15N. By broadening our understanding of the fine-scale influence of salmon on a stand of ancient trees, this research is expected to contribute to future exploration of the terrestrial influences of Pacific herring. / Graduate / 0329 / cfox@uvic.ca

Four prograding reef terraces (6, 15, 30, and 50 m) have been repetitively exposed to marine and freshwater alteration during the Pliocene and Pleistocene periods. Prolonged freshwater alterations have resulted in many diagenetic overprints that obscure early diagenetic products. This study investigates the sequence of the diagenetic processes and products in the terrace deposits using five long cores and 14 short cores taken from these different reef terraces. The lithologic changes in the cores were documented for reconstruction of the original depositional frameworks prior to embarking on a diagenetic study. Both textural and geochemical changes were examined within all four different terraces in order to characterized the diagenetic history. The textural changes observed in the cores and thin sections, provided preliminary evidence of the diagenetic environment. Through the use of X-ray diffractometry, stable isotopes (C and O), and trace element data, the interpretation of the diagenetic environment can be constrained. The reef terraces were deposited as as shallowing upward units following a down-stepping carbonate sequence. The lithology of the cores is dominated by reefal facies, which consist of the back reef, reef crest, front, and fore reef facies. The exposure surfaces, observed at various depths, constrained the interpretation of early diagenetic environments (met. vadose and phreatic). Three major diagenetic environments can be characterized from the cores, these are meteoric vadose, meteoric phreatic, and dolomitizaton. These diagenetis environments produced different geochemical signatures, which can be quantified through analysis of the stable isotopes and trace elements incorporated into the cements. The different reef terraces represent different duration of exposure, with the higher terraces having been exposed longer than the lower ones. This study enables the documentation and comparison of the processes and products of the meteoric diagenesis that occurred within these different terraces. In addition, this study also constrain the early dolomitization observed in sigmoidal reef deposits. In order to further quantify the process of early dolomitization, mineralogy, isotopes C and O, trace elements, and the Sr-isotopes were examined as well.

In the Oueme River, a lowland river in Benin, Africa, artificial ponds constructed in the floodplain (whedos) are colonized during the high-water period by a presumably random sample of fishes from the river channel. As water slowly recedes from the floodplain, fishes are isolated in whedos until they are harvested near the end of the dry season. I surveyed fishes in whedos and adjacent main-channel and floodplain habitats during two low-water (2008 and 2009) and one falling-water (2010-2011) periods, and measured a suite of physicochemical variables including dissolved oxygen, temperature, specific conductivity, and percent cover of aquatic vegetation in the falling-water period to investigate if fish assemblage structure of whedos resulted from stochastic or deterministic processes. I also investigated food web structure of whedos by analyzing carbon (delta13C) and nitrogen (delta15N) stable isotope ratios of fish and primary producer tissue samples, and samples of net primary production, soluble reactive phosphorus (SRP), NH4+, NO2-, and NO3- collected during the falling-water period. Whedos were covered with dense growth of aquatic vegetation, and dissolved oxygen concentrations were lower in whedos compared to a natural floodplain depression and the main channel. Multivariate analyses revealed that habitat types were distinct with regard to fish assemblage structure and abiotic conditions. Assemblages in whedos and natural floodplain depressions were differentiated from those of the river channel, with the floodplain habitats being dominated by piscivorous fishes that tolerate aquatic hypoxia. These results indicate that fish assemblage structure of whedos was influenced by deterministic processes during the falling- and low-water periods when these water bodies were isolated. Floodplain habitats were more nutrient-rich than the river channel, and whedos were net heterotrophic. Microphytobenthos and C3 macrophytes accounted for a large fraction of fish biomass in whedos, compared with the river channel, which was mainly supported by seston. Whedo food webs had fewer trophic transfers compared to the food web of the river channel.

Thesis (PhD)--Montana State University--Bozeman, 2009. / Typescript. Chairperson, Graduate Committee: Todd Feeley. Includes bibliographical references.

Thesis (M.S.)--Southern Methodist University, 2007. / Includes bibliographical references.

Thesis (Ph. D.)--Miami University, Dept. of Zoology, 2007. / Title from second page of PDF document. Includes bibliographical references.

Although food quality is thought to play an important role in the survival of marine copepods, the extent of natural variability in food quality remains poorly characterized. Here I characterize the different scales at which food quality varies in copepods of the Strait of Georgia, British Columbia, Canada. Significant interannual variability occurs in the diet of Neocalanus plumchrus in the Strait of Georgia. Between 2001-06 the fatty acid profiles of N. plumchrus switched from omnivorous, oceanic signatures to herbivorous, diatom-dominated signatures. An index of food quality (DHA/EPA) is strongly correlated to the abundance of diapausing N. plumchrus, suggesting that the relative proportion of essential fatty acids provided by dinoflagellates and diatoms are related to the survival of this species. Combined fatty acid and stable isotope analysis indicated that the spring calanoid copepods of the Strait of Georgia occupy three trophic positions: Eucalanus bungii is herbivorous, Calanus marshallae and N. plumchrus are omnivorous, while Euchaeta elongata is carnivorous. Oceanic conspecifics of Strait of Georgia copepods experience a more omnivorous diet, as indicated by the presence of higher proportions of flagellate and carnivory markers, and lower proportions of diatom-based markers in their fatty acids. Despite spatial differences in the quality of their diets, the relative trophic positions of these copepods are constant as indicated by their stable isotope signatures. There is a correlation between the trophic information provided by stable isotopes and fatty acids. However, stable isotopes are not sensitive enough to capture the range of dietary variability observed in fatty acids, and fatty acids do not always provide reliable markers of carnivory and trophic position. Over the span of a season, copepods can utilize a wide range of dietary items including diatoms, flagellates, bacteria, detritus and microzooplankton. Copepods can switch from herbivory to carnivory in response to declining chlorophyll concentrations after the spring bloom, and are occasionally able to utilize detrital and bacterial sources. I conclude that the quality of copepod diets in the SoG varies on interannual, interspecific and seasonal scales. The implications of these findings are discussed in relation to ecosystem models of the area, and to copepod physiology.

The Western Tropical North Atlantic (WTNA) was once thought to be a net source of carbon dioxide (CO₂) to the atmosphere, but recent studies have shown that this Amazon River influenced region may actually act as a net sink for CO₂. During a 2010 research cruise to the WTNA, we characterized the impact of the Amazon River on offshore diazotrophy (N₂-fixation) and the resulting stimulation of biological carbon export from surface waters. Through the delivery of phosphate- and silicate-replete waters to the nitrogen (N) limited surface waters of the WTNA, the aging Amazon River plume promotes the growth of diatom-diazotoph associations (DDAs). Regions supporting large DDA blooms were associated with increased pCO₂ and DIC drawdown in the surface waters, reflecting the net export of carbon from the mixed layer. The existence of this biologically mediated linkage between the C and N cycles in productive surface waters is well known, but we have only recently discovered a stimulatory relationship in deep waters between oil/gas release and N₂-fixation. This association was first observed after the Deepwater Horizon oil spill in 2010 and we again saw evidence for it in the days following the Hercules 265 natural gas blowout. This blowout event was characterized by the release of an unknown quantity of natural gas into the shelf waters of the Northern Gulf of Mexico, but we detected a response from the marine microbial community within days. We observed a significant drawdown of dissolved oxygen and found biogeochemical evidence for the incorporation of methane-carbon into the food web, along with a modest stimulation of N₂-fixation. The episodic nature of anthropogenic blowouts makes them difficult to study, so we use cold seeps in the Gulf of Mexico as natural analogues. Interestingly, we have measured both methane oxidation and N₂-fixation at depth above some of the more active seeps. Using NanoSIMS analyses, we have taken the first steps towards physically characterizing the organisms utilizing these metabolisms. It appears that different organisms are carrying out these processes, with CH₄-assimilation occurring primarily in individual particles or small aggregates, whereas N₂-fixtion was associated with larger, sulfur-containing aggregates. Continued NanoSIMS work in combination with the use of microbial ID techniques will help to further characterize these unique deepwater diazotrophs.

Made available in DSpace on 2014-06-11T19:32:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-11-07Bitstream added on 2014-06-13T18:44:38Z : No. of bitstreams: 1 lotierzo_v_dr_botfmvz.pdf: 191277 bytes, checksum: 1ba95ee8099d388117f2bceb3f7d2f00 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Universidade Estadual Paulista (UNESP) / Este trabalho objetivou determinar o turnover do carbono no sangue, pâncreas e tíbia de suínos em diferentes períodos de crescimento, utilizando a técnica de isótopos estáveis. Foram utilizados 132 machos castrados e fêmeos, distribuídos ao acaso em quatros tratamentos que consistiam da substituição da dieta a base de milho (planta de ciclo fotossintético C4) por dieta a base de arroz (plantas do ciclo fotossintético C3) em dias distintos: 21; 42; 63; 110 dias de idade, respectivamente para os tratamentos 1, 2, 3 e 4. Para mensurar o turnover do carbono (diluição isotópica) nos tecidos em determinado intervalo de tempo, foram utilizados o modelo de equações de função exponencial do tempo ou modelo sigmoidal de regressão de Boltzmann. Os valores de meias-vidas foram: 15,9; 19,0 e 16,8 dias para o sangue; 14,1; 9,68 e 10,4 dias para o pâncreas; 14,3; 8,0 e 15,1 dias para tíbia com medula nos tratamentos com substituição aos 21, 42 e 63 de idade respectivamente. O pâncreas de acordo com valores de meia vida apresentou um rápido turnover, o sangue e a tíbia com medula apresentaram maiores valores de meia vida / This study aimed to determine the turnover of carbon in the blood, tibia and pancreas of pigs at different growth periods, using the technique of stable isotopes. We used 132 barrows and females were randomly assigned into four groups consisting of replacing the corn-based diet (plant C4 photosynthetic cycle) by diet of rice (C3 photosynthetic cycle plants) on different days: 21; 42, 63; 110 days of age, respectively for treatments 1, 2, 3 and 4. To measure the turnover of carbon (isotope dilution) in tissues given time interval, we used the model equations exponential function of time or template Boltzmann sigmoidal regression. Values of half-lives were 15.9, 19.0 and 16.8 days for the blood; 14.1, 9.68 and 10.4 days for the pancreas, 14.3, 8.0 and 15, one day to the tibia with bone replacement treatments at 21, 42 and 63 of age respectively. The pancreas according to half-life values showed a rapid turnover, blood and tibia with bone showed higher half-life

Made available in DSpace on 2014-06-11T19:32:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-08-02Bitstream added on 2014-06-13T20:24:28Z : No. of bitstreams: 1 araujo_pc_dr_botfmvz.pdf: 1063171 bytes, checksum: e36f35a00f1101a4f0b0cdd76d879705 (MD5) / Este trabalho teve como objetivo avaliar o turnover do carbono-13 no músculo peitoral e quilha de três linhagens de frango tipo colonial Máster Griss, Vermelhão Pesado e Label Rouge, em diferentes fases de crescimento. Foram alojados 768 pintos de um dia de idade, divididos em 6 grupos (G). Para avaliar o turnover nos tecidos, o grupo G0-21 recebeu dieta composta predominantemente por plantas do ciclo C3, os demais grupos tiveram a dieta C4 substituída pela dieta C3 aos 7 (G7-35), 14(G14-49); 21(G21-63), 28 (G28-84) e 35(G35-119) dias de idade. Foram coletadas amostras de músculo peitoral e quilha de 4 aves/grupo nos dias de coleta das aves tiveram suas dietas previamente substituídas para a determinação das razões isotópicas de carbono em espectrômetro de massa. Para mensurar a velocidade de substituição do carbono depois de determinado intervalo de tempo (turnover), foi empregada função exponencial de tempo obtida através do método de equações exponenciais de primeira ordem do softwareOriginPro®8 Professional. A Linhagem Label Rouge, apresenta maior turnover do carbono nos tecidos analisados comparado com as demais linhagens. A idade e os tecidos analisados influenciaram o turnover de carbono-13, variando seus valores em função da atividade metabólica do tecido. A quilha e o músculo peitoral apresentaram rápida taxa de metabolismo na primeira semana de vida das aves, com valores de meias-vidas muito próximas, enquanto que nas aves mais velhas apresentaram taxas metabólicas consideravelmente diminuídas. / This study aimed to assess the carbon-13 turnover in pectoral muscle and keel of three colonial broiler chicken strains, Máster Griss (MG), Vermelhão Pesado (VP), and Label Rouge (LR) at different stages of growth.Were housed 768 one-d-old chicks, and distributed into 6 groups (G). To assess the tissue turnover, the group G0-21 received a diet consisting primarily of C3 plants cycle, the other groups had the diet replaced by C4 to C3 diet at 7 (G7-35), 14 (G14-49), 21 (G21 -63), 28 (G28-84), and 35 (G35-119) days of age. Pectoral muscle and keel samples were collected from 4 birds/group in several consecutive days the birds have their diets previously substituted for the determination of carbon isotope ratios in the mass spectrometer. To measure the speed of carbon substitution after a certain time interval (turnover) was employed exponential function of time obtained through the method of the first order exponential equations of softwareOriginPro®8 Professional. The Label Rouge strain has a higher carbon turnover in the tissues analyzed compared with the other strains. The age and tissues analyzed affected the carbon-13 turnover, varying their values depending of the metabolic function of the tissue. The keel and pectoral muscle showed fast metabolism rate in the first week of bird life, with values of half-lives very close, whereas in older birds showed significantly decreased metabolic rates.