Environmental influences on fish cardiovascular function and control

鱼类在全球范围内分布，生活在温度从-1.8℃到42℃之间的水域，这些水域几乎不含氧气（即缺氧），并且含盐量可能变化很大（如河口）。此外，人类活动（包括加速的气候变化）给这些鱼类带来了更大的压力，在某些地区，这导致了物种的迁移或灭绝。如果鱼类要在这些环境变量的短期和长期变化中生存下来，促进向组织输送氧气的生理调整（例如，心脏泵出更多的血液、血红蛋白水平的增加、通气的调整、血流的再分配）是至关重要的。事实上，已经有人提出，温度升高时心脏功能的限制是鱼的热耐受性的主要决定因素。拟议的研究将为以下方面提供重要见解：1)哪些因素（机制）限制了高温下鱼类的心脏功能；2)鱼的免疫系统、应激生理和心血管功能之间的相互作用；3)为什么适应长期缺氧后心脏功能受损；4)有多少血流向卵巢（卵子），是否可以控制，以及它如何受到温度、水氧水平和盐度变化的影响。后一项研究很重要，因为在不同的环境条件下，维持卵子的氧气和营养输送可能对确保大量可存活的后代的产生至关重要，从而对鱼类种群的健康至关重要。

Fish have a truly global distribution and live in waters where temperatures range from -1.8 to 42oC, that can contain little to no oxygen (i.e., are hypoxic), and may vary dramatically in salt content (e.g., estuaries). Further, human activities (including accelerated climate change) are placing added pressures on these fish, and in some areas this has lead to the displacement or extinction of species. Physiological adjustments that promote an increase in oxygen delivery to the tissues (e.g. more blood pumped by the heart, an increase in blood haemoglobin levels, adjustments in ventilation, the redistribution of blood flow) are critical if fish are to survive short- and long-term variations in these environmental variables. Indeed, it has been suggested that limitations in cardiac function as temperatures increase are a primary determinant of a fish's thermal tolerance. The proposed research will provide important insights into: 1) what factors (mechanisms) limit heart function in fishes at high temperatures; 2) interactions between the fish's immune system, stress physiology and cardiovascular function; 3) why heart function is compromised following acclimation to prolonged hypoxia; and 4) how much blood flows to the ovaries (eggs), whether it can be controlled, and how it is impacted by changes in temperature, water oxygen levels and salinity. The latter studies are important because the maintenance of oxygen and nutrient delivery to the eggs under varied environmental conditions is likely vital to ensuring that a large number of viable offspring are produced, and thus, the health of fish populations. Overall, this work provides a comprehensive and integrative (from whole animal to genomic) view of numerous aspects of fish cardiorespiratory physiology, and of the capacity of fish to deal with environmental stressors of ecological importance. Such studies are key to understanding how changing environments will affect fish populations and fisheries, and will provide researchers, resource managers and policy makers with information vital to planning for them.