• Energy Research

The injection of anthropogenically-produced CO2 into the atmosphere will lead to an increase in temperature and a decrease in pH at the surface of the oceans by 2100. Marine intertidal organisms possess the ability to cope in the short term with environmental fluctuations exceeding predicted values. However, how they will cope with chronic exposure to elevated temperature and pCO2 is virtually unknown. In addition, individuals from the same species/population often show remarkable levels of variation in their responses to complex climatic changes: in particular, variation in metabolic rates often is linked to differences in individuals' performances and fitness. Despite its ecological and evolutionary importance, inter-individual variation has rarely been investigated within the context of climatic changes, and most investigations have typically employed orthogonal experimental designs paired to analyses of independent samples. Although this is undoubtedly a powerful and useful approach, it may not be the most appropriate for understanding all alterations of biological functions in response to environmental changes. An individual approach arguably should be favored when trying to describe organisms' responses to climatic change. Consequently, to test which approach had the greater power to discriminate the intensity and direction of an organism's response to complex climatic changes, we investigated the extracellular osmo/iono-regulatory abilities, upper thermal tolerances (UTTs), and metabolic rates of individual adults of an intertidal amphipod, Echinogammarus marinus, exposed for 15 days to combined elevated temperature and pCO2. The individual approach led to stronger and different predictions on how ectotherms will likely respond to ongoing complex climatic change, compared with the independent approaches. Consequently, this may call into question the relevance, or even the validity, of some of the predictions made to date. Finally, we argue that treating individual differences as biologically meaningful can lead to a better understanding of the physiological responses themselves and the selective processes that will occur with complex climatic changes; selection will likely play a crucial role in defining species' responses to future environmental changes. Individuals with higher metabolic rates were also characterized by greater extracellular osmo/iono-regulative abilities and higher UTTs, and thus there appeared to be no evolutionary trade-offs between these functions. However, as individuals with greater metabolic rates also have greater costs for maintenance and repair, and likely a lower fraction of energy available for growth and reproduction, trade-offs between life-history and physiological performance may still arise.

AbstractThere is growing evidence that climate change will increase the prevalence of toxic algae and harmful bacteria, which can accumulate in marine bivalves. However, we know little about any possible interactions between exposure to these microorganisms and the effects of climate change on bivalve health, or about how this may affect the bivalve toxin-pathogen load. In mesocosm experiments, mussels, Perna viridis, were subjected to simulated climate change (warming and/or hyposalinity) and exposed to harmful bacteria and/or toxin-producing dinoflagellates. We found significant interactions between climate change and these microbes on metabolic and/or immunobiological function and toxin-pathogen load in mussels. Surprisingly, however, these effects were virtually eliminated when mussels were exposed to both harmful microorganisms simultaneously. This study is the first to examine the effects of climate change on determining mussel toxin-pathogen load in an ecologically relevant, multi-trophic context. The results may have considerable implications for seafood safety.

Research on the effects of climate change in the marine environment continues to accelerate, yet we know little about the effects of multiple climate drivers in more complex, ecologically relevant settings - especially in sub-tropical and tropical systems. In marine ecosystems, climate change (warming and freshening from land run-off) will increase water column stratification which is favorable for toxin producing dinoflagellates. This can increase the prevalence of toxic microalgal species, leading to bioaccumulation of toxins by filter feeders, such as bivalves, with resultant negative impacts on physiological performance. In this study we manipulated multiple climate drivers (warming, freshening, and acidification), and the availability of toxic microalgae, to determine their impact on the physiological health, and toxin load of the tropical filter-feeding clam, Meretrix meretrix. Using a structural equation modeling (SEM) approach, we found that exposure to projected marine climates resulted in direct negative effects on metabolic and immunological function and, that these effects were often more pronounced in clams exposed to multiple, rather than single climate drivers. Furthermore, our study showed that these physiological responses were modified by indirect effects mediated through the food chain. Specifically, we found that when bivalves were fed with a toxin-producing dinoflagellate (Alexandrium minutum) the physiological responses, and toxin load changed differently and in a non-predictable way compared to clams exposed to projected marine climates only. Specifically, oxygen consumption data revealed that these clams did not respond physiologically to climate warming or the combined effects of warming, freshening and acidification. Our results highlight the importance of quantifying both direct and, indirect food chain effects of climate drivers on a key tropical food species, and have important implications for shellfish production and food safety in tropical regions.

L'aquaculture joue un rôle important dans la sécurité alimentaire et fournit des moyens de subsistance et des emplois à des millions de personnes dans les communautés côtières du monde entier. Cependant, le secteur aquacole en pleine croissance a également suscité des débats sur sa durabilité écologique à long terme, sa viabilité économique, les inégalités sociales potentielles et les problèmes de gouvernance. Nous avons étudié les défis et les opportunités perçus pour parvenir à une aquaculture durable du crabe de boue dans les régions côtières tropicales en utilisant l'étude de cas des fermes côtières de crabe de boue dans l'Andhra Pradesh, en Inde. Sur la base des perceptions et des données financières indicatives d'un échantillon de parties prenantes, nous avons étudié les résultats économiques potentiels dans différents scénarios représentant des niveaux de rendement, des facteurs de risque et des périodes de projet variables. Les principaux risques identifiés par les parties prenantes étaient associés à l'approvisionnement limité en graines de crabe de boue et au manque d'accès aux programmes de soutien gouvernementaux et non gouvernementaux. Il n'y a pas de tampons financiers, donc des épidémies majeures ou des conditions météorologiques extrêmes causées par le changement climatique entraîneraient une perte de moyens de subsistance. Cet article met également en évidence le facteur le plus critique déterminant le niveau de succès de l'élevage du crabe de boue étant le taux de survie du crabe qui est influencé par une variété de facteurs, y compris l'augmentation de la température de la surface de la mer. Les résultats de cette étude montrent que l'élevage de crabes de boue à petite échelle comporte moins de risques et une plus grande flexibilité que l'élevage de crabes de boue à grande échelle. Il pourrait s'agir d'une entreprise économiquement durable et servir d'outil de réduction de la pauvreté dans les pays en développement si un soutien et une formation en matière de microfinance sont disponibles. La acuicultura desempeña un papel importante en la seguridad alimentaria y proporciona medios de subsistencia y empleo a millones de personas en las comunidades costeras de todo el mundo. Sin embargo, el creciente sector de la acuicultura también ha creado debates en torno a su sostenibilidad ecológica a largo plazo, viabilidad económica, posibles desigualdades sociales y problemas de gobernanza. Investigamos los desafíos y oportunidades percibidos para lograr una acuicultura sostenible de cangrejo de fango en las regiones costeras tropicales utilizando el estudio de caso de las granjas costeras de cangrejo de fango en Andhra Pradesh, India. Con base en las percepciones y los datos financieros indicativos de una muestra de partes interesadas, investigamos los posibles resultados económicos en diferentes escenarios que representan diferentes niveles de rendimiento, factores de riesgo y períodos de tiempo del proyecto. Los principales riesgos identificados por las partes interesadas se asociaron con el suministro limitado de semillas de cangrejo de fango y la falta de acceso a esquemas de apoyo gubernamentales y no gubernamentales. No hay amortiguadores financieros, por lo tanto, los grandes brotes de enfermedades o las condiciones climáticas extremas causadas por el cambio climático conducirían a la pérdida de los medios de vida. Este documento también destaca que el factor más crítico que determina el nivel de éxito del cultivo de cangrejo de fango es la tasa de supervivencia del cangrejo, que está influenciada por una variedad de factores, incluido el aumento de la temperatura de la superficie del mar. Los resultados de este estudio muestran que el cultivo de cangrejo de fango a pequeña escala tiene menos riesgos y una mayor flexibilidad que el cultivo de cangrejo de fango a gran escala. Podría ser una empresa económicamente sostenible y servir como una herramienta para el alivio de la pobreza en los países en desarrollo si se dispone de apoyo y capacitación en microfinanzas. Aquaculture plays a significant role in food security and provides livelihoods and employment for millions of people among coastal communities worldwide. However, the growing aquaculture sector has also created debates around its long-term ecological sustainability, economic viability, potential social inequalities and governance issues. We investigated the perceived challenges and opportunities to achieving sustainable mud crab aquaculture in tropical coastal regions by using the case study of coastal mud crab farms in Andhra Pradesh, India. Informed by perceptions and indicative financial data from a sample of stakeholders we investigated the potential economic outcomes under different scenarios representing varying yield levels, risk factors and project time periods. The main risks identified by the stakeholders were associated with the limited supply of mud crab seeds and the lack of access to governmental and non-governmental support schemes. There are no financial buffers, therefore major disease outbreaks or extreme weather conditions caused by climate change would lead to a loss of livelihoods. This paper also highlights the most critical factor determining the level of success of mud crab farming being the crab survival rate which is influenced by a variety of factors including increasing sea surface temperature. The results of this study show that small-scale mud crab farming has fewer risks and higher flexibility involved than large-scale mud crab farming. It could be an economically sustainable enterprise and serve as a tool for poverty alleviation in developing countries if microfinance support and training are available. تلعب تربية الأحياء المائية دورًا مهمًا في الأمن الغذائي وتوفر سبل العيش وفرص العمل لملايين الأشخاص بين المجتمعات الساحلية في جميع أنحاء العالم. ومع ذلك، فإن قطاع تربية الأحياء المائية المتنامي قد خلق أيضًا مناقشات حول استدامته البيئية طويلة الأجل، وقابليته الاقتصادية، وعدم المساواة الاجتماعية المحتملة، وقضايا الحوكمة. لقد حققنا في التحديات والفرص المتصورة لتحقيق تربية مستدامة لسرطان البحر الطيني في المناطق الساحلية الاستوائية باستخدام دراسة حالة لمزارع سرطان البحر الطيني الساحلية في ولاية أندرا براديش، الهند. استنادًا إلى التصورات والبيانات المالية الإرشادية من عينة من أصحاب المصلحة، قمنا بالتحقيق في النتائج الاقتصادية المحتملة في ظل سيناريوهات مختلفة تمثل مستويات عائد متفاوتة وعوامل خطر وفترات زمنية للمشروع. ارتبطت المخاطر الرئيسية التي حددها أصحاب المصلحة بمحدودية المعروض من بذور سرطان البحر الطيني وعدم الوصول إلى خطط الدعم الحكومية وغير الحكومية. لا توجد حواجز مالية، وبالتالي فإن تفشي الأمراض الرئيسية أو الظروف الجوية القاسية الناجمة عن تغير المناخ ستؤدي إلى فقدان سبل العيش. تسلط هذه الورقة الضوء أيضًا على العامل الأكثر أهمية الذي يحدد مستوى نجاح زراعة سرطان البحر الطيني وهو معدل بقاء سرطان البحر الذي يتأثر بمجموعة متنوعة من العوامل بما في ذلك زيادة درجة حرارة سطح البحر. تظهر نتائج هذه الدراسة أن زراعة سرطان البحر الطيني على نطاق صغير تنطوي على مخاطر أقل ومرونة أعلى من زراعة سرطان البحر الطيني على نطاق واسع. يمكن أن يكون مشروعًا مستدامًا اقتصاديًا وأن يكون بمثابة أداة للتخفيف من حدة الفقر في البلدان النامية إذا توفر الدعم والتدريب في مجال التمويل الأصغر.