Collaborative Research: Midwater animal models: Optical measurement of metabolic transitions in pelagic biota

“该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。“尽管涵盖了地球上99%以上的宜居空间，但中层水环境及其居民是地球上研究最少的，主要是由于其偏远和技术限制，无法直接研究。使用光学技术，包括光谱学和视频图像分析，对生理功能进行直接、非侵入性成像，将中层水动物（浮游动物和微浮游生物）转化为理想的生理模型。在这种情况下，透明度，一种在远洋环境中无处不在的伪装策略，从字面上讲，允许洞察动物生理学（即它有助于生理成像）。因此，现在可以对中层水动物进行生理学实验，这些实验与对更健壮的鱼类和哺乳动物进行的常规实验具有相同的复杂性，但时间分辨率更高。本项目是侵入性较小的采样和光学生理方法的新型组合，将阐明中层水生物在以大部分中层水环境为特征的极端缺氧中生存所采用的代谢策略。研究人员将进一步利用这些氧气最低区不断变化的二氧化碳浓度作为天然实验室，以测试对海洋酸化的生理反应。他们将量化与氧浓度有关的代谢转变，这些代谢转变在生态上很重要，但研究不足，中层水生物。他们将测试与透明度（即捕食者的可见度）和代谢率有关的假设，作为躲避捕食者能力的指标。具体而言，研究者将测量血氧结合率、心率、每搏输出量、通气率和通气量、组织氧化态（NAD+：NADH）和全动物耗氧率。并非所有上述参数都与待研究的所有物种相关。他们将研究来自广泛的浮游动物和微浮游动物群体的透明代表，包括鱼类、幼虫、毛颚类、多毛类、水母、海鞘、端足类，和腹足类，但将重点放在头足类，因为1）他们的封闭循环系统和血氧结合蛋白允许充分开发和利用光学生理技术和2）因为它们生理学的独特方面对耐缺氧特别重要，使它们容易受到海洋酸化的影响。该方法有可能揭示海洋生物对全球变暖和海洋酸化的耐受性。此外，最低含氧区正在扩大，可能对海洋生物群造成严重后果。该项目包括在URI和杜克大学为三名研究生提供与光学生理学相关的一套独特技术的培训。调查人员还将为几名研究生和本科生提供出海的机会。该项目将促进与德国科学家及其学生的合作。将尽可能与来自不同机构的科学家和学生分享所要求的船舶和潜水时间。此外，深海和海洋生物学对公众的吸引力很大。调查人员将通过布卢姆协会（www.bloomassociation.org）向公众提供所获得的图像和视频（其中一些是有史以来最近距离和最详细的）。Bloom是一个非营利组织，其使命是通过教育公众了解环境问题来保护海洋，特别是深海。Bloom的创造者Claire Nouvian过去曾参加过游轮旅行，并同意参加拟议的探险活动。

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)." Despite encompassing more than 99% of the livable space on the planet, the midwater environment and its inhabitants are among the least studied on the planet, primarily due to their remoteness and the technological limitations that have precluded direct study. The use of optical techniques, including spectroscopy and video image analysis, for direct, non-invasive imaging of physiological function transforms midwater animals (zooplankton and micronekton) into ideal physiological models. In this case, transparency, a ubiquitous camouflage strategy in the pelagic environment, allows, literally speaking, insights into animal physiology (i.e. it facilitates physiological imaging). Thus, it is now possible to conduct physiological experiments on midwater animals that are of equal complexity, but greater temporal resolution, to those routinely performed on more robust fishes and mammals. The present project is a novel combination of less invasive sampling and optical physiological methods that will elucidate the metabolic strategies employed by midwater organisms for survival in the extreme hypoxia characterizing much of the midwater environment. The investigators will further use the changing CO2 concentrations through these oxygen minimum zones as a natural laboratory to test physiological responses to ocean acidification. They will quantify metabolic transitions relating to oxygen concentration for ecologically important, but understudied, midwater organisms. They will test hypotheses relating transparency (i.e. visibility by predators) and metabolic rates as an indication of the capacity for predator avoidance. Specifically, the investigators will measure blood oxygen binding, heart rate, stroke volume, ventilation rate and volume, oxidation state of the tissues (NAD+:NADH) and whole-animal oxygen consumption rates. Not all of the above parameters are relevant to all species to be studied. They will study transparent representatives from a broad spectrum of zooplankton and micronektonic groups, including fishes, larvaceans, chaetognaths, polychaetes, jellies, salps, amphipods, and gastropods but will focus on cephalopods because of 1) their closed circulatory systems and blood oxygen binding proteins allow the full development and utilization of optical physiological techniques and 2) because unique aspects of their physiology are of special interest for hypoxia tolerance and render them vulnerable to ocean acidification.This project provides a model for an integrated approach to studying the ecological physiology of pelagic organisms. The approach has potential to reveal the tolerance of oceanic organisms to global warming and ocean acidification. Furthermore, oxygen minimum zones are expanding with potentially severe consequences for oceanic biota. The project includes training at both URI and Duke University for three graduate students in a unique suite of techniques relevant to optical physiology. The investigators will also provide opportunities to go to sea for several graduate and undergraduate students. The project will foster collaboration with German scientists and their students. The ship and submersible time requested will be shared to the extent possible with scientists and students from diverse institutions. Further, the public appeal of deep-sea and oceanic biology is great. The investigators will make the images and video obtained (some of the most close-up and detailed ever taken) available to the public via the Bloom Association (www.bloomassociation.org). Bloom is a non-profit association whose mission is to protect the oceans and, more particularly, the deep sea, through education of the greater public about environmental problems. The creator of Bloom, Claire Nouvian, has participated in cruises in the past and has agreed to take part in the proposed expeditions.