Balancing the demands of physiological processes: Decapod crustacean feeding and digestion in hypoxia

在过去的几十年里，沿海地区的溶解氧水平变化比其他任何环境变量都要大，导致了普遍的低氧。甲壳类是对缺氧最敏感的生物之一，因此可以作为健康环境的重要指示物种。在预测低氧对底栖动物群落的长期影响时，了解它们的行为和生理反应将是非常宝贵的。甲壳动物一般通过增加通气率来应对氧气压力的下降，以维持稳定的氧气摄取，在一定水平上它们无法维持氧气摄取，此后氧摄取与环境一致下降。所有生物都必须进食才能生存，随后对食物的消化会导致新陈代谢的普遍增加，称为特殊动力作用(SDA)。因此，在生物体需要吸收更多氧气用于消化过程时，目前的缺氧趋势将减少可用溶解氧。 这项研究将研究几种具有不同耐缺氧能力的十足类甲壳类动物(岩蟹、青蟹、龙虾、邓吉尼斯蟹)在缺氧条件下摄食和消化时，如何平衡心肺变量(呼吸、心功能、血液化学)。如果动物在缺氧期间不能保持对氧气的摄取，我们将确定它们是否能够减缓或停止消化过程(机械、昂贵的“生理机制”。将使用LOGO SHOTLEBOX®确定进纸状态是否会改变氧气偏好。该设备允许动物在两种供氧状态之间进行选择，同时计算机可以跟踪运动。通过监测运动速度、氧气选择和摄食活动，我们将能够确定是否喂食和饥饿的动物有不同的氧气偏好，或者是否发生了权衡，即随着饥饿时间的增加，动物更有可能将能量消耗到低氧气中以获得食物奖励。 在过去的十年里，生态生理学有了复兴，这种综合的方法研究整个动物生理和行为之间的联系，在研究动物与环境之间的相互作用时很重要。在历史上，科学家们是在受控条件下进行实验的，在这种条件下，喂养是精心控制的，这项研究的结果将表明，在更自然的条件下，多种应激源可能会如何相互作用。鉴于气候变化和缺氧的指数性增加，这项研究的结果不仅将引起科学界的兴趣，而且对于环境资源管理者了解社区对环境变化的潜在反应也将是重要的。

Dissolved oxygen levels in coastal areas have changed more than any other environmental variable during the past few decades, leading to widespread hypoxia. Crustaceans are among the most sensitive organisms to hypoxia and could therefore act as important indicator species of a healthy environment. Knowledge of their behavioural and physiological responses will be invaluable when predicting long-term effects of hypoxia on benthic communities. In general crustaceans respond to a decline in oxygen tension by increasing ventilation rate in an attempt to maintain a stable oxygen (O2) uptake, at a certain level they are unable to maintain O2 uptake and thereafter it drops in line with that of the environment. All organisms must feed in order to survive and the subsequent digestion of a meal leads to a general increase in metabolism termed the specific dynamic action (SDA). Thus current trends in hypoxia will reduce the available dissolved O2 at a time when organisms need to uptake more O2 for digestive processes. This research will investigate how several species of decapod crustaceans (rock crab, green crab, lobster, Dungeness crab) with differing ability to deal with hypoxia balance cardiorespiratory variables (respiration, cardiac function, blood chemistry) when they feed and digest in hypoxia. If animals are unable to maintain O2 uptake during hypoxia we will determine if they can slow or halt digestive processes (mechanical costly” physiological mechanisms. A Loligo shuttlebox® will be used to determine if feeding status alters O2 preference. The apparatus allows animals to choose between two O2 regimes while a computer tracks movement. By monitoring speed of movement, O2 choice and feeding activity we will be able to determine if fed and starved animals have different O2 preferences, or if trade-off occurs whereby with increasing starvation time an animal will be more likely expend energy entering into low O2 in order to obtain a food reward. Ecophysiology has had a renaissance in the last decade and this integrative approach studying the connections between whole animal physiology and behaviour is important when investigating interactions between the animal and its environment. Historically scientists carried out experiments under controlled conditions where feeding was carefully regimented, the results of this research will show how multiple stressors may interact in more natural conditions. In light of climate change and the exponential increase in hypoxia the results of this research will not only be of interest to the scientific community, but will also be important for environmental resource managers in understanding potential responses of communties to environmental change.