Pumping rates of the giant barrel sponge Xestospongia muta on Caribbean reefs: size scaling, envionmental controls, and bleaching effects.

就多样性、数量丰度和生物量而言，海绵是珊瑚礁上的优势生物之一。它们从水柱中过滤颗粒（例如病毒、细菌、浮游植物）的能力有助于水的清澈，这是支持珊瑚和其他珊瑚礁生物的必要条件，也是从水柱向底栖生物运输碳的必要条件，也称为底栖-远洋耦合。尽管它们的重要性得到公认，但只有少数机制研究量化了海绵过滤速率。这项提议通过测量加勒比海珊瑚礁上最显眼的海绵——巨大的桶状海绵（Xestospongia muta）的抽水速度，解决了我们知识上的部分差距。X. muta的标本可占加勒比海珊瑚礁海绵生物量的60%，其大小范围（直径）跨越三个数量级。这些海绵和珊瑚一样，会受到海水温度升高的影响，导致白化。海绵和它们的共生体的损失。高达25%的变异x虫种群可能受到热漂白的影响，对个体和种群水平的过滤率都有未知的后果。准确测量抽水速率以及水柱过滤速率对于评估非常重要，因为海绵对珊瑚礁的能量流动有如此深远的影响。本建议的主要目标是：(1)测量海绵中水的外流速度，以计算体积流量；(2)量化抽吸与组织体积之间的比例关系，以解释群体内大小差异导致的海绵抽吸变化；(3)描述抽水的时间格局及其与环境变量的关系；(4)确定相对于健康海绵，海绵漂白对抽吸速率的影响。为了满足我们对海绵生物学和珊瑚礁生态学的理解中的这些关键需求，首席研究员将使用声学多普勒测速仪（ADV）对海绵的泵送速率进行现场测量。ADV利用声波频率的变化来测量水流速度，可以在短时间（10分钟）内准确测量海绵直径范围内的水流速度，也可以在24小时或更长时间的长期泵送测量中准确测量水流速度。这些测量将与水质测量同时进行，以评估海绵抽水的时间趋势和环境控制。该项目将大大有助于我们了解海绵在珊瑚礁上的作用，并加强北卡罗来纳大学威尔明顿分校（UNCW）的研究和教育基础设施的发展。当adv未用于本项目时，首席研究员将提供adv用于教育或研究。首席研究员是UNCW的新教员，目前正在更新海洋生物学（本科）和生物海洋学（研究生）的课程，并参与本科生和研究生的培训和教育。这些学生还将有机会参加高度合作的国际研究游轮。参加这些游轮活动为这些学生提供了发展国际合作和拓宽研究兴趣的绝佳机会。

Sponges are among the dominant organisms on coral reefs in terms of diversity, numerical abundance, and biomass. Their ability to filter particles (e.g. viruses, bacteria, phytoplankton) from the water column contributes to both water clarity, which is necessary to support corals and other coral reef organisms, and for the transport of carbon from the water column to the benthos, also known as benthic-pelagic coupling. Despite their acknowledged importance, there are only a few mechanistic studies that have quantified sponge filtration rates. This proposal addresses part of that gap in our knowledge by measuring the pumping rates of the most conspicuous sponge on Caribbean reefs, the giant barrel sponge, Xestospongia muta. Specimens of X. muta can comprise up to 60% of sponge biomass on Caribbean reefs, and exhibit a size range (diameter) that spans three orders of magnitude. These sponges, like corals, can be affected by increases in seawater temperature that result in the ?bleaching? of the sponges and the loss of their symbionts. Up to 25% of the X. muta population can be affected by thermal bleaching with unknown consequences for both individual and population level filtration rates. Accurate measurements of pumping rate, and therefore water column filtration rates, are important to assess because sponges have such a profound influence on energy flow on coral reefs. The principal objectives of this proposal are to; (1) measure the excurrent velocities of water from sponges in order to calculate volumetric flow rates; (2) to quantify the scaling relationships between pumping and tissue volume to account for the changes in sponge pumping due to size differences within a population; (3) to describe the temporal patterns of pumping and its relationship to environmental variables; and (4) to determine the effects of sponge bleaching on pumping rates relative to healthy sponges. To address these critical needs in our understanding of sponge biology and reef ecology the principal investigator will take field measurements of pumping rates from sponges using an Acoustic Doppler Velocimeter (ADV). An ADV uses shifts in the frequency of sound waves to measure water flow velocities and can accurately measure these velocities across the diameter of sponges over both short time scales of pumping (10 minutes), and also during longer term pumping measurements of 24 hr or more. These measurements will be made concurrently with water quality measurements to assess temporal trends and environmental controls of sponge pumping. This project will contribute significantly to our understanding of the role(s) of sponges on coral reefs and enhance the development of research and education infrastructure at the University of North Carolina at Wilmington (UNCW). When not in use for this project, the the principal investigator will make available the ADVs for use in education or research. The principal investigator is a new faculty member at UNCW and is currently updating courses in Marine Biology (undergraduate) and Biological Oceanography (graduate), and is involved in the training and education of undergraduates and graduate students. These students will also have the opportunity to participate in highly collaborative, international research cruises. Participation in these cruises represents an unparalleled opportunity for these students to develop international collaborations and broaden their research interests.