RUI: Elevated environmental CO2 impairs acclimation to hypoxia in crustaceans

生活在沿海水域的生物每天都暴露在低氧条件下（缺氧）。一些动物通过增加向组织输送氧气的呼吸色素水平来适应缺氧。例如，在氧气有限的高海拔地区，人类比在海平面上产生更多的红细胞。其他生物，如深海潜水和冬眠动物，可以降低新陈代谢，减少对氧气的需求。河口生物依靠这些和其他策略来耐受缺氧。不太为人所知的是，高水平的二氧化碳，即高碳酸血症，会在沿海水域缺氧的情况下自然发生，从而导致严重的酸化。然而，缺氧和高碳酸血症对河口物种的综合影响几乎一无所知。在目前的研究中，太平洋白对虾（Litopenaeus vannamei）和大西洋蓝蟹（Callinectes sapidus）将暴露在低氧和高二氧化碳的组合中。通过测量心脏和呼吸频率，以及呼吸色素的分子组成及其结合氧气的能力，可以量化向组织输送氧气的变化。接下来，我们将寻找代谢的变化和能量昂贵的蛋白质合成过程。最后，我们将测试虾和蟹在进行能量要求高的活动时对低氧和高二氧化碳的反应。通过这些研究，我们希望证明高碳酸血症干扰了河口甲壳类动物对缺氧的正常适应。在测试这个想法的同时，我们将继续与来自两个主要本科院校的学生一起教学、培训和出版。拟议的工作还提请注意虾和蟹种群的未来活力，它们在世界范围内构成了数十亿美元海鲜市场的基础。这些结果也将有助于理解这些经济和生态上重要的物种将如何受到未来全球变化的影响。

Organisms living in coastal waters are exposed daily to low oxygen conditions (hypoxia). Some animals adapt to hypoxia by increasing levels of the respiratory pigment that delivers O2 to tissues. For example, humans make more red blood cells at high altitude where O2 is limited than at sea level. Other organisms, such as deep-diving and hibernating animals, can lower their metabolism, reducing their need for O2. Estuarine organisms rely on these and other strategies to tolerate hypoxia. Less well-recognized is that high levels of CO2, hypercapnia, occur naturally with hypoxia in coastal waters, causing significant acidification. Yet, virtually nothing is known about the combined effects of hypoxia and hypercapnia on estuarine species. In the current studies Pacific whiteleg shrimp, Litopenaeus vannamei, and Atlantic blue crabs, Callinectes sapidus, will be exposed to combinations of low O2 and high CO2. Changes in O2 delivery to tissues will be quantified by measuring heart and breathing rates, as well as the molecular composition of their respiratory pigment and its ability to bind O2. Next, we will look for changes in metabolism and the energetically expensive process of protein synthesis. Finally we will test how shrimp and crabs respond to low O2 and high CO2 when performing energetically demanding activities. With these studies we expect to show that hypercapnia interferes with normal adaptations to hypoxia in estuarine crustaceans. While testing this idea, we will continue to teach, train and publish with students from two primarily undergraduate institutions. The proposed work also draws attention to the future vitality of shrimp and crab populations which, world-wide, form the basis of a multi-billion dollar seafood market. These results should also prove useful in understanding how these economically and ecologically important species will be impacted in response to future global changes.