Oxidative status and stress during highly energetic life-history stages of Chinstrap Penguins: breeding versus molting

Life-history stages such as reproduction and molt are energetically costly. Reproductive costs include those associated not only with offspring production, but also protecting and provisioning young. Costs typically associated with molting include decreased thermoregulatory and locomotive performance, and increased metabolic and nutritional costs. Energetic demands may disrupt homeostasis, particularly in terms of its maintenance (e.g., oxidative stress and immunity). Few investigators have explored the relationship between effort (increased metabolic rate) and oxidative status and stress by comparing life-history stages with different energetic demands. However, comparative studies are crucial for understanding the processes of energy allocation and their consequences for different physiological functions. Our objective was to determine how two highly demanding life-history stages, breeding and molting, affected oxidative balance in Chinstrap Penguins (Pygoscelis antarcticus), a species where these two activities do not overlap. We found that the heterophil/lymphocyte (H/L) ratio was significantly higher during breeding than molting; oxidative damage was also higher during breeding. In contrast, we found no significant differences between these stages in total antioxidant capacity. We also found sex differences, with males having greater oxidative damage than females. Our results suggest that breeding is more stressful and more demanding for Chinstrap Penguins than molting, and provide further support for the relationship between effort, in terms of increased metabolic rate, and oxidative balance.his study was funded by the Spanish Ministry of Economy and Competitiveness (CTM2011‐24427 and CTM2015‐64720). RCC held a Spanish Ministry of Economy and Competitiveness FPI grant (BES2012‐059299)

Shifting Perspectives in Polar Research: Global Lessons on the Barriers and Drivers for Securing Academic Careers in Natural Sciences

BF received funding from the post-doctoral fellowships programme Beatriu de Pinós funded by the Secretary of Universities and Research (Government of Catalonia) and by the Horizon 2020 Programme of Research and Innovation of the European Union under the Marie Skłodowska-Curie grant agreement No. 801370 (Incorporation grant 2019 BP 00183) and the Juan de la Cierva Programme funded by the Ministry of Science and Innovation (Incorporation grant IJCI-2017-31478). PC and HJG were supported by NERC core funding to the BAS “Biodiversity, Evolution and Adaptation” Team.The polar regions provide valuable insights into the functioning of the Earth’s regulating systems. Conducting field research in such harsh and remote environments requires strong international cooperation, extended planning horizons, sizable budgets and longterm investment. Consequently, polar research is particularly vulnerable to societal and economic pressures during periods of austerity. The global financial crisis of 2008, and the ensuing decade of economic slowdown, have already adversely affected polar research, and the current COVID-19 pandemic has added further pressure. In this article we present the outcomes of a community survey that aimed to assess the main barriers and success factors identified by academic researchers at all career stages in response to these global crises. The survey results indicate that the primary barriers faced by polar early and mid-career researchers (EMCRs) act at institutional level, while mitigating factors are developed at individual and group levels. Later career scientists report pressure toward taking early retirement as a means of institutions saving money, reducing both academic leadership and the often unrecognized but vital mentor roles that many play. Gender and social inequalities are also perceived as important barriers. Reorganization of institutional operations and more effective strategies for long-term capacity building and retaining of talent, along with reduction in non-research duties shouldered by EMCRs, would make important contributions toward ensuring continued vitality and innovation in the polar research community.Secretary of Universities and Research (Government of Catalonia)Horizon 2020 Programme of Research and Innovation of the European Union under the Marie Skłodowska-Curie grant agreement No. 801370Juan de la Cierva Programme funded by the Ministry of Science and Innovation (Incorporation grant IJCI-2017-31478)NERC core funding to the BAS “Biodiversity, Evolution and Adaptation” Tea

Incubation increases oxidative imbalance compared to chick rearing in a seabird, the Magellanic penguin (Spheniscus magellanicus)

It is expected that activities which require a high use of energy could generate higher oxidative stress. In the present study, we have compared two breeding periods (incubation and chick rearing) with different energetic demands in the Magellanic penguin, predicting a higher oxidative unbalance during chick rearing since involves higher demanding activities such as chick feeding and greater nest protection than during incubation. Specifically, we predicted higher oxidative damage and lower antioxidant defences during chick rearing than during incubation. Fieldwork was conducted in a Magellanic penguin colony located in Estancia San Lorenzo (42°05′S, 63°49′W), Peninsula Valdes, Argentina, during the breeding season of 2014–2015. Surprisingly, our results did not support our initial prediction. Incubating adults had their oxidative status unbalanced showing significantly lower antioxidant levels than those rearing chicks. Moreover, oxidative damage did not show any significant variation between both breeding periods. Further, we did not find differences in oxidative status between sexes. Our results suggest that incubation is a highly demanding activity compared to chick rearing in terms of oxidative balance since the lower presence of antioxidants can be explained as they have probably depleted to limit oxidative damage by ROS. Differential foraging effort could explain such results as Magellanic penguins adjust their foraging location to prey availability performing longer foraging trips during incubation than during chick rearing which increases the energy costs and therefore imbalance penguins oxidative status. Our results show the importance of examining physiological markers such as oxidative stress to assess differences during the breeding cycle and how the behaviour at sea could explain such differences in seabirds.This study was funded by the Spanish Ministry of Economy and Competitiveness (CTM2011-24427). RCC received financial aid from an FPI and a mobility grant from the Spanish Ministry of Economy and Competitiveness (BES2012-059299 and EEBB-I-14-078877),Peer Reviewe