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

应对气候变化的生态系统变化包括地理分布的极移。这些变化在很大程度上是由环境温度和其他威胁共同推动的，例如世界海洋中氧气水平的下降。这可能解释了最近在南极水域发现的帝王蟹。卵和浮游幼虫有助于形成当代物种的分布，很可能是最容易受到这种(地球物理、生物化学)变化影响的生命阶段。除了海洋变暖之外，最近沿海地区周围缺氧区(死区)的增加进一步加剧了这一问题，因为它减少了可溶氧的供应和海洋温度的升高。较高的温度增加了海洋动物的耗氧量，同时较温暖的海水中溶解的氧气较少。了解早期生命阶段将如何在细胞和生态系统水平上响应这些变化，对于预测温度和/或低溶解氧(DO)导致的南极新物种入侵和物种分布总体上的变化至关重要。鉴于这些方面的研究很少，因此，本项目将调查不同生命阶段的生理反应，特别是卵和早期幼虫，考虑到经常被忽视的重要问题，如亲本投资和由此导致的脂肪和蛋白质含量的个体发育变异及其对幼虫适合性的影响。为了测试不同生命阶段的耐温耐低氧能力及其对南极入侵的影响，我以爬行动物十足类物种为模型组，提出了以下工作假设：1)卵的耐热窗口(从细胞水平到组织水平)比幼虫、雄性和带卵雌性要小。因此，卵的生活阶段将决定物种的分布范围。2)卵和幼虫的耐热性将因海水中的低DO而降低。3)亲本的投资依赖于温度，低DO水平对孵化幼虫的发育和适合度有负面影响。4)卵发育过程中的环境条件对幼虫在田间的适合度和招募有影响。该建议旨在确定物种最敏感的生活期，并首次可行地测量早期生命阶段(卵和孵化幼虫)对温度和低DO协同作用的相对脆弱性。预计气候变化造成的外部压力将影响卵的发育，并导致幼虫死亡，迫使物种转移其分布极限，向极地方向移动，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.