Exploring how climate change impacts the intersection of immunity and temperature in hypoxia-tolerant pacific fish and sharks

环境缺氧(即有限的氧气)是一种对动物可能致命的条件。许多鱼暴露在海洋或潮间带池塘中的水生缺氧环境中。令人担忧的是，气候变化正在增加低氧事件的频率和严重程度，以及水环境中低氧区域的大小。在过去几十年中，由于全球变暖而加剧的水温升高与海洋含氧量的下降有关，特别是在支持海洋水产养殖的沿海地区。因此，全球变暖导致的水生缺氧预计将随着气候危机的加剧而恶化，并对全球沿海海洋种群和水产养殖构成重大挑战。对所有动物来说，正常运作的免疫系统是生存的关键，也是鱼类抵御细菌和病毒感染以及受伤后愈合能力的关键。低氧和高温会削弱水生动物的免疫反应，因此，随着全球变暖的进程和水生低氧发生率的增加，水生动物的免疫功能可能会受到影响。尽管水生低氧对环境构成了挑战，但一些物种已经采取了策略，以确保在氧气有限的情况下生存。特别令人感兴趣的是生活在热带地区潮间带池塘中的鲨鱼，它们在那里暴露在严重缺氧和高水温的时期。这些耐缺氧的鱼类提供了一个很好的模型来研究支持耐缺氧和免疫的适应之间的相互作用。我们的目标是确定1)低氧是否激活耐低氧和不耐受鲨鱼的免疫反应，2)免疫系统激活是否影响耐低氧鲨鱼对低氧的适应性生理反应，以及3)低氧是否影响免疫能力。我们的合作者提供了对这些关键研究物种的访问，如果没有他们，这项研究将是不可能的。

Environmental hypoxia (i.e., limited oxygen) is a condition that can be lethal to animals. Many fish are exposed to aquatic hypoxia in the ocean or in intertidal pools. Alarmingly, climate change is increasing the frequency and severity of hypoxic events and the size of hypoxic regions in aquatic environments. In the past few decades, increases in aquatic temperatures exacerbated by global warming correlate with decreasing oxygen content in oceans, and particularly in coastal regions that support marine aquaculture. As a consequence, aquatic hypoxia due to global warming is expected to worsen with the acceleration of the climate crises and poses a significant challenge to coastal marine populations and aquaculture globally.For all animals, a properly functioning immune system is crucial for survival, and key to the ability of fish to resist infection by bacteria and viruses and to heal after injury. Immune responses are impaired by hypoxia and by high temperatures and thus aquatic animals may be immunocompromised by the progression of global warming and increasing incidence of aquatic hypoxia. Despite the environmental challenge posed by aquatic hypoxia, some species have adapted strategies to ensure their survival when oxygen is limited. Of particular interest are sharks that inhabit intertidal pools in tropical regions where they are exposed to periods of severe hypoxia in combination with high water temperatures. These hypoxia-tolerant fishes provide an excellent model to investigate interactions between adaptations that favour hypoxia-tolerance vs. immunity.Our OBJECTIVES are to determine 1) whether hypoxia activates an immune response in hypoxia-tolerant and -intolerant sharks, 2) whether immune system activation compromises adaptive physiological responses to hypoxia in hypoxia-tolerant sharks, and 3) whether hypoxia compromises immune competency. Our collaborators provide access to these key study species and this research would be impossible without them.