Les zones polaires sont les premières à subir les effets du réchauffement climatique.L'estimation de l‟impact physiologique d‟une augmentation de température sur les espèces de ces régions est capitale afin de prédire l'évolution des écosystèmes polaires. Les conséquences physiologiques de l‟augmentation des températures peuvent affecter les capacités de résistance et de survie des organismes. Le krill constitue un maillon clé des écosystèmes polaires, il est aussi à la base de la chaine trophique de ces régions. Dans ce contexte, une étude comparative de la thermotolérance de trois espèces de krill polaires a été effectuée. Deux espèces d‟Antarctique Euphausia superba et Euphausia crystallorophias, et une espèce d‟Arctique, Thysanoessa inermis. La détermination de la température limite de tolérance (CT50) a été estimée sur ces 3 espèces. E. superba et T. inermis présentent des tolérances thermiques similaires, alors que E. crystallorophias a une CT50 légèrement inférieure. Cinq isoformes d‟Hsp70 ont été caractérisées, pour chaque espèce. Leur expression génique a été suivie au cours d‟augmentations de la température du milieu. Le suivi de ces biomarqueurs a permis d‟estimer la température limite à laquelle les premiers dommagescellulaires apparaissent. Les cinétiques d‟expressions de chaque espèce se sont révéléesdifférentes : une forte réponse Hsp70 a été observée chez T. inermis, alors que chez E.crystallorophias celle–ci est beaucoup plus faible. Aux mêmes températures E .superba ne développe pas de réponse Hsp70, malgré sa forte thermotolérance. La multiplication des expériences de choc thermique sur cette espèce (intensité et durée) n'a pas révélé de réponseHsp70, mais confirmé sa grande thermotolérance pour un organisme antarctique. / Polar regions are the first to be impacted by global warming. The physiological impact appraisal of a temperature increase over local species is critical to foresee future evolutions of polar ecosystems. Physiological consequences of temperature rises can affect organisms both in their hardness and survival. Krill stands as a key component for polar ecosystems and therefore constitutes the core diet of local predators. In such context, a thermal tolerance comparative analysis of three distinct polar krill species has been carried out: two Antarctic species Euphausia superba and Euphausia crystallorophias, and one Arctic species,Thysanoessa inermis. The determination of thermal tolerance (CT50) was conducted on these three species. E. superba and T. inermis analysis showed similar thermal tolerances, while E.crystallorophias CT50 was slightly lower. Five isoforms of Hsp70 have been characterized foreach species. Their gene expression has been monitored through temperature increases of their environment. This biomarkers monitoring allowed an estimation of the critical temperature at which cellular damages appear. Kinetic expressions vary for each species: a strong response was observed in Hsp70 T. inermis, whereas response is much lower in E.crystallorophias. For similar temperatures, E .superba does not provide any Hsp70 response,despite its high thermal tolerance. The accumulation of heat shock experiments on this species, in intensity and duration, still did not provide any Hsp70 response, although it confirmed its highly noticeable heat tolerance for an Antarctic organism.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 34-36). Also available on the World Wide Web.

The fishery for Antarctic krill (Euphausia superba) has received considerable attention in recent years, owing largely to the possibility of its significant expansion and the ecological implications of increased extraction of a keystone species. This thesis employed Ecological Footprint (EF) analysis and life cycle assessment (LCA) to measure the resource use, energy use, and emissions associated with three krill-derived products: meal and oil for aquaculture feeds, and omega-3 krill oil capsules for the nutraceutical market. The product supply chains of one krill fishing and processing company, Aker BioMarine, were used as a case study to examine Antarctic krill-derived products. Antarctic krill products were compared to products from similar fisheries targeting other species for reduction into meal and oil, including Peruvian anchovy (Engraulis ringens), Atlantic herring (Clupea harengus), blue whiting (Micromesistius poutassou) and Gulf menhaden (Brevoortia patronus), on the basis of marine footprint, carbon footprint, and fuel use intensity.

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains vii, 44 p. : ill. Includes abstract. Includes bibliographical references (p. 30-33).

The global climate is strongly regulated by the oceans, which store carbon away from the atmosphere for long periods. In an effort to understand the role of the oceans in the carbon cycle, it is necessary to understand the nuances of specific regional and functional marine ecosystems. The continental shelf of the West Antarctic Peninsula (WAP) is one particularly important regional ecosystem that plays a vital role in the Southern Ocean carbon export. Within the seasonally productive marginal ice zone of the WAP, I sought to identify the long-term drivers of particulate organic carbon (POC) flux. The vast majority of exported POC on the WAP was previously found to be made up of krill fecal pellets. I provide evidence that supports the hypothesis that the inherent life cycle of krill drives the observed 5-year oscillation in POC export. At the end of their life cycle, when krill are at their largest body size, the WAP experiences anomalously high POC export events through the production and sinking of large, carbon-rich krill fecal pellets. Conversely, when krill are young and small, POC export is anomalously low. This pattern shows that ecology exerts a first-order control on the the biogeochemical cycles of the WAP. Upon identifying the source and driver of POC export on the WAP, I set out to determine the role heterotrophic bacteria play in POC flux attenuation. I collected krill fecal pellets on the WAP over three years and measured bacterial metabolic activity in terms of bacterial production and respiration, thereby identifying the amount of organic carbon within the sinking fecal pellets that is lost due to bacteria. Overall, fecal pellet POC turnover rate by bacteria is very low. The relationship between bacteria and POC is complex with each having an affect on the other. Despite varied reactions of the free-living bacterial populations to the presence of krill fecal pellets, a consistent pattern emerged in the concentration of nucleic acid within each bacterial cell. Access to fecal pellets increased the metabolic activity of the free-living bacterial population. This finding shows that the egestion of krill fecal pellets metabolically stimulates the surrounding bacterial community, even though bacteria play a minor role in fecal pellet POC flux attenuation. Though bacteria were found to play a minimal role in organic carbon uptake on krill fecal pellets, they are still vital members of the WAP ecosystem and biological pump. I next sought to identify which bacteria in particular were responsible for colonizing and consuming the fecal pellet POC. Krill fecal pellets were genetically sequenced after timed exposure to the free-living water column bacterial community. I found that there is an endemic population of bacteria that are associated with each population of krill and their fecal pellets. This community of fecal pellet-associated bacteria does not change over time, indicating little colonization by free-living bacteria. Krill fecal pellets, aside from being good agents of POC export, seem to be selective environments for certain specialized copiotrophic bacteria. Further, I find that only a small subset of these endemic copiotrophs actively partake in carbon consumption on krill fecal pellets. Overall, these results show that a small endemic, specialized bacterial community play an outsized role in krill fecal pellet POC degradation and flux attenuation, but that krill fecal pellets remain efficient agents of carbon export to the deep ocean.

Bifenilos policlorados (PCBs) e pesticidas organoclorados são compostos que não ocorrem naturalmente no ambiente e não são facilmente degradados química ou microbiologicamente. Seu estudo no ambiente é importante devido à sua persistência, toxicidade, lipossolubilidade e conseqüente biomagnificação. Por isso, representam a maioria dos poluentes orgânicos persistentes (POPs) considerados prioritários pela UNEP (United Nations Environmental Programme) e banidos ou restritos pela Convenção de Estocolmo, de maio de 2001. Tais poluentes podem ser facilmente emitidos para a atmosfera, atingindo áreas remotas como a Antártida, integrando um processo cíclico de contaminação conhecido como destilação global. No presente trabalho otimizou-se uma metodologia analítica capaz de detectá-los em ovos gorados de pingüins e indivíduos de krill coletados na Baía do Almirantado, Ilha Rei Jorge, Antártida. Tal metodologia foi avaliada e enquadrou-se em critérios internacionais de controle de qualidade. Os compostos mais presentes foram, de um modo geral, os PCBs, DDTs e o HCB e a ocorrência pareceu ser espécie-específica dentro do gênero Pygoscelis. Em todos os casos, o teor dos compostos não foi superior ao de aves árticas em nível trófico semelhante. A análise do krill permitiu estimar a biomagnificação dos compostos encontrados nos ovos, cuja única fonte de contaminação é a transferência fêmea-filhote. / Polychlorinated biphenyls (PCBs) and organochlorine pesticides are compounds that do not occur naturally in the environment and are not easily degraded by chemical or microbiological action. Their study in the environment is important due to persistence, toxicity, liposolubility and consequent biomagnification. For these reasons, they represent the majority of the persistent organic pollutants (POPs), considered to have priority by the UNEP (United Nations Environmental Programme) and banished and/or restricted by the Stockholm Convention of May, 2001. Such pollutants can be easily ejected into the atmosphere and reach areas as remote as Antarctica, integrating a cyclical contamination process known as ?global distillation?. In the present work an analytical methodology capable of detecting such compounds in unhatched penguin eggs and whole krill was optimized. The samples were collected in Admiralty Bay, King George Island, Antarctica. This methodology was evaluated and fitted international quality control criteria. The compounds found in higher levels were, in most of the samples, the PCBs, DDTs and HCB and the occurrence seemed to be species-specific for the Pygoscelis genus. In all of the cases, the levels found were not higher than the ones in arctic birds in a similar trophic level.The krill samples analysis made it possible to estimate the biomagnification of the compounds found in eggs, whose only source of contamination is the female-offspring transfer.

Fatores exógenos, como fotoperíodo, temperatura da superfície do mar e abundância de presas, e endógenos, como os ciclos circadianos e circanuais e alterações metabólicas são conhecidos como iniciadores dos movimentos migratórios. Este trabalho tem como objetivo estabelecer os principais parâmetros iniciadores da migração das baleias-jubarte. Foram analisados o fotoperíodo, índice de oscilação do oceano austral (SOI), temperatura da superfície do mar, concentração de clorofila-a e densidade de krill em relação ao número máximo de indivíduos avistados e o dia do pico de avistagem. O fotoperíodo mostrou ser o principal fator que influencia a migração da Antártica em direção a Abrolhos, enquanto que o caminho contrário, além de fotoperíodo, parece ser influenciado também pelo os fatores tais como temperatura da superfície do mar e a quantidade de presas disponíveis no verão anterior. Quanto maior a densidade de krill, maior o número máximo de indivíduos avistados e a temporada reprodutiva mais longa. O SOI mostrou ter influência no ciclo reprodutivo do krill. Valores negativos registraram maior densidade de krill e valores positivos, menor densidade de krill, através do modelo GLM. Altos valores de TSM apresentaram correlação negativa com a densidade de krill, e com o número de baleias avistadas e o tempo de permanência na área reprodutiva, indicando que o aquecimento da região antártica impõe condições não favoráveis para a temporada reprodutiva das baleias. / Exogenous factors, such as photoperiod, sea surface temperature and abundance of prey, and endogenous, such circadian and circannual cycles and metabolic changes are known as initiators of migratory movements. This work aims to establish the main parameters initiators of the migration of the humpback whales. The photoperiod, the Southern Ocean Index (SOI), the sea surface temperature, the chlorophyll-a concentration and the density of krill were analyzed in relation to the maximum number of individuals sighted and the duration of the reproductive season. The photoperiod showed to be the main factor that influences the migration from Antarctica to Abrolhos, while the opposite way, besides photoperiod, seemed to be influenced also by other factors such as sea surface temperature and the amount of prey available in the previous summer. The higher the density of krill, the greater the maximum number of individuals sighted and the longer the reproductive season. The SOI showed to have influence on the reproductive cycle of krill. Negative values correspond to higher density of krill, and positive values, lower density of krill, through the GLM model. High values of TSM presented negative correlation with the density of krill, and with the number of whales sighted and the reproductive season duration in the reproductive area, indicating that the Antartic warming impose unfavorable conditions for the reproductive season of whales.

Fatores exógenos, como fotoperíodo, temperatura da superfície do mar e abundância de presas, e endógenos, como os ciclos circadianos e circanuais e alterações metabólicas são conhecidos como iniciadores dos movimentos migratórios. Este trabalho tem como objetivo estabelecer os principais parâmetros iniciadores da migração das baleias-jubarte. Foram analisados o fotoperíodo, índice de oscilação do oceano austral (SOI), temperatura da superfície do mar, concentração de clorofila-a e densidade de krill em relação ao número máximo de indivíduos avistados e o dia do pico de avistagem. O fotoperíodo mostrou ser o principal fator que influencia a migração da Antártica em direção a Abrolhos, enquanto que o caminho contrário, além de fotoperíodo, parece ser influenciado também pelo os fatores tais como temperatura da superfície do mar e a quantidade de presas disponíveis no verão anterior. Quanto maior a densidade de krill, maior o número máximo de indivíduos avistados e a temporada reprodutiva mais longa. O SOI mostrou ter influência no ciclo reprodutivo do krill. Valores negativos registraram maior densidade de krill e valores positivos, menor densidade de krill, através do modelo GLM. Altos valores de TSM apresentaram correlação negativa com a densidade de krill, e com o número de baleias avistadas e o tempo de permanência na área reprodutiva, indicando que o aquecimento da região antártica impõe condições não favoráveis para a temporada reprodutiva das baleias. / Exogenous factors, such as photoperiod, sea surface temperature and abundance of prey, and endogenous, such circadian and circannual cycles and metabolic changes are known as initiators of migratory movements. This work aims to establish the main parameters initiators of the migration of the humpback whales. The photoperiod, the Southern Ocean Index (SOI), the sea surface temperature, the chlorophyll-a concentration and the density of krill were analyzed in relation to the maximum number of individuals sighted and the duration of the reproductive season. The photoperiod showed to be the main factor that influences the migration from Antarctica to Abrolhos, while the opposite way, besides photoperiod, seemed to be influenced also by other factors such as sea surface temperature and the amount of prey available in the previous summer. The higher the density of krill, the greater the maximum number of individuals sighted and the longer the reproductive season. The SOI showed to have influence on the reproductive cycle of krill. Negative values correspond to higher density of krill, and positive values, lower density of krill, through the GLM model. High values of TSM presented negative correlation with the density of krill, and with the number of whales sighted and the reproductive season duration in the reproductive area, indicating that the Antartic warming impose unfavorable conditions for the reproductive season of whales.

1. Antarctic krill (Euphausia superba) form aggregations known as swarms that vary greatly in size and density. Six acoustic surveys were conducted as part of multidisciplinary studies at two study sites, the western and eastern core boxes (WCB and ECB), during the 1997, 1998 and 1999 austral summers, at South Georgia. A quantitative, automated, image processing algorithm was used to identify swarms, and calculate swarm descriptors, or metrics. In contrast to acoustic surveys of aggregations of other pelagic species, a strong correlation (r = 0.88, p = 0.02, 95% C.I.= 0.24 to 0.99) between the number of krill swarms and the mean areal krill density [rho.hat] was found. Multivariate analysis was used to partition swarms into three types, based on contrasting morphological and internal krill density parameters. Swarm types were distributed differently between inter-surveys and between on and off-shelf regions. This swarm type variation has implications for krill predators, by causing spatial heterogeneity in swarm detectability, suggesting that for optimal foraging to occur, predators must engage in some sort of adaptive foraging strategy. 2. Krill predator-prey interactions were found to occur at multiple spatial and temporal scales, in a nested, or hierarchical structure. At the largest inter-survey scale, an index of variability, I, was developed to compare variation in survey-scale predator sightings, sea temperature and [rho.hat]. Using I and a two-way ANOVA, core box, rather than year, was found to be a more important factor in determining species distribution. The absence of Blue-petrels (Halobaena caerulea) and the elevated number of Antarctic fur seals (Arctocephalus gazella) suggest that 1998 was a characterised by colder than average water surrounding South Georgia, and a high [rho.hat] in the ECB. At the smaller, intra-survey scales (<80 km, <5 day), the characteristic scale (distances in which predator group size, or krill density were similar, L_s) were determined. For krill and predators L_s varied by survey and the L_s of krill also varied by depth within a survey. Overlap in L_s were stronger between predator species than between a predator species and krill, indicating predators were taking foraging cues from the activity of predators, rather than from the underlying krill distribution. No relationship was found between swarm characteristics and predator activity, suggesting either there is no relationship between krill swarms and predators, or that the predator and acoustic observation techniques may not be appropriate to detect such a relationship. 3. To overcome the 2-D sampling limitations of conventional echosounders, a multibeam echosounder (MBE) observed entire swarms in three-dimensions. Swarms found in the nearshore environment of Livingston Island situated in the South Shetland Islands, exhibited only a narrow range of surface area to volume ratios or roughnesses (R = 3.3, CV = 0.23), suggesting that krill adopt a consistent group behaviour to maintain swarm shape. Generalized additive models (GAM) suggested that the presence of air-breathing predators influenced the shape of a krill swarm (R decreased in the presence of predators: the swarm became more spherical). A 2D distance sampling framework was used to estimate the abundance, N, and associated variance of krill swarms. This technique took into account angular and range detectability (half-normal, [sigma_r.hat] = 365.00 m, CV = 0.16) and determined the vertical distribution of krill swarms to be best approximated by a beta-distribution ([alpha.hat] = 2.62, [CV.hat] = 0.19; [beta.hat] = 2.41, [CV.hat] = 0.15), giving the abundance of swarms in survey region as [N.hat] = 5,062 ([CV.hat] = 0.35). This research represents a substantial contribution to developing estimation of pelagic biomass using MBEs. 4. When using a single- or split-beam missing pings occur when the transmit or receive cycles are interrupted, often by aeration of the water column, under the echosounder transducer during rough weather. A thin-plate regression spline based approach was used to model the missing krill data, with knots chosen using a branch and bound algorithm. This method performs well for acoustic observations of krill swarms where data are tightly clustered and change rapidly. For these data the technique outperformed the standard MGCV GAM, and the technique is applicable for estimating acoustically derived biomass from line transect surveys.

The zooplankton community of Marguerite Bay, western Antarctic Peninsula, was investigated in relation to variability in chlorophyll concentrations and sea ice dynamics, using a combination of satellite remote sensing techniques and plankton net data. SeaWiFS chlorophyll data were validated with concurrent in situ data measured by HPLC and fluoromentric methods, and results indicate that SeaWiFS chlorophyll is an accurate measure of in situ values when HPLC data are used as ground truth. Climatology data of SeaWiFS chlorophyll west of the Antarctic Peninsula showed that the Bellingshausen Sea and Marguerite Bay usually had higher and more persistent chlorophyll concentrations compared with northern regions. These predictable phytoplankton blooms could provide the Antarctic krill, Euphausia superba, with the food required for successful reproduction and larval survival. Unusually high krill reproduction in 2000/2001 was coincident with above-average chlorophyll concentrations throughout the study area and was followed by the largest juvenile recruitment since 1981. High larval densities at the shelf break along the Antarctic Peninsula may have resulted, in part, from krill spawning in the Bellingshausen Sea. Interannual differences in sea ice also probably contributed to the variability in larval krill abundances. Interannual differences were observed in the species composition of the zooplankton of Marguerite Bay during fall, and these were linked to variability in the environmental conditions. Thysanoessa macrura was the most abundant euphausiid in 2001, while Euphausia crystallorophias dominated in 2002, and E. superba had intermediate densities during both years. Copepods were more abundant in 2001 by a factor of 2.6. Copepods and T. macrura showed a rapid population response to unusually high chlorophyll concentrations in the Bellingshausen Sea and Marguerite Bay during spring-summer 2000/2001, whereas E. superba and E. crystallorophias had a longer term response and showed increased recruitment in fall 2002. There were no clear associations between the distribution of zooplankton and environmental conditions in fall; however there was a significant relationship between chlorophyll concentrations in the Bellingshausen Sea during the preceding spring and zooplankton patterns during fall.