Climate driven Antarctic invasion? Physiological impacts of temperature and hypoxia on life stages of reptant decapod crustaceans and implications for distribution shifts

响应气候变化的生态系统变化包括地理分布的向极移动。这些变化在很大程度上是由环境温度和其他威胁共同驱动的，例如世界海洋中氧气含量的减少。这也许可以解释最近在南极水域发现的帝王蟹。卵和浮游生物幼虫是塑造当代物种分布的工具，可能是最容易受到这种（地球物理，生物化学）变化的生命阶段。除了海洋变暖之外，最近沿海地区缺氧区（死亡区）的增加进一步加剧了这一问题，因为海洋中可溶氧的可用性减少，温度升高。更高的温度增加了海洋动物的氧气消耗，同时，在温暖的海水中溶解的氧气也更少。了解生命早期阶段如何在细胞和生态系统水平上对这些变化作出反应，对于预测温度和/或低溶解氧（DO）导致的新物种入侵南极以及物种分布的总体变化至关重要。鉴于研究这些方面的研究缺乏，因此本项目将研究不同生命阶段的生理反应，特别关注卵和早期幼虫，考虑到经常被忽视的重要问题，如亲代投资和由此产生的脂质和蛋白质含量的个体发生变异性及其对幼虫适应性的影响。为了测试不同生命阶段的温度和缺氧耐受性及其对南极入侵的影响，我以爬行动物十足类作为模型组提出了以下工作假设：1)从细胞到有机体水平测量的卵的热耐受窗口比幼虫，雄性和携带卵的雌性要小。因此，生命阶段的“卵”将决定物种的分布界限。2)海水低DO会降低卵和幼虫的热耐受性3)亲代投资依赖于温度，低DO水平对孵化幼虫的发育和适合度有不利影响。4)虫卵发育过程中的环境条件对田间幼虫的适合度和招募有影响。该提案旨在确定物种最敏感的生命阶段，并将允许首次可行的测量早期生命阶段（卵和孵化幼虫）对温度和低DO协同效应的相对脆弱性。预计气候变化引起的外部压力将影响卵的发育，导致幼虫死亡，迫使物种将其分布界限向两极转移并入侵南极水域。

Ecosystem changes in response to climate change include pole ward shifts in geographical distribution. These changes are largely driven by environmental temperature in combination with other threats, such as decreasing oxygen levels in the world oceans. It might explain the recent findings of king crabs in Antarctic waters. Eggs and planktonic larvae, which are instrumental in shaping contemporary species distribution, are likely the most vulnerable life stages to such (geophysical, biochemical) changes. In addition to ocean warming the recent increase of hypoxic areas (dead zones) around coastal regions further compounds the problem by reducing the availability of soluble oxygen and higher temperatures in the oceans. Higher temperatures increase the oxygen consumption of marine animals and at the same time there is less oxygen dissolved in warmer sea water. The understanding of how early life stages will respond to these changes at a cellular and ecosystem level are crucial for predicting temperature and/or low dissolved oxygen (DO) induced Antarctic invasion of new species and shifts in species distribution in general. Given the paucity of studies investigating these aspects, this project will therefore investigate physiological reactions of varying life stages with special focus on eggs and early larvae considering the often neglected important issue such as parental investment and resulting ontogenetic variability in lipid and protein contents and its implications for larval fitness. In order to test the temperature and hypoxia tolerance in varying life stages and its implications for Antarctic invasion, I propose the following working hypotheses using reptant decapod species as a model group:1) The thermal tolerance window of eggs, measured from the cellular to the organismic level, is smaller in comparison to larvae, males and egg carrying females. Therefore, the life stage “egg” will determine the distribution limits of the species.2) The thermal tolerance of eggs and larvae will be decreased by low DO in sea water3) The parental investment is dependent on temperature and low DO levels negatively affect the development and fitness of hatching larvae.4) The environmental conditions during egg development have an impact on larval fitness and recruitment in the field.The proposal aims to identify the most sensitive life stage of a species and will allow the first viable measurement of the relative vulnerability of early life stages (eggs and hatching larvae) to synergistic effects of temperature and low DO. It is expected that the external stress due to climate change will affect egg development and result in deceased larval fitness forcing species to shifttheir distribution limits pole wards and invade Antarctic waters.