Seaquest DSV: a compact Deep-water Sonar and Visual sampler for exploring the marine twilight zone

Seaquest DSV：用于探索海洋暮光区的紧凑型深水声纳和视觉采样器

• 批准号: NE/T008830/1
• 负责人: Andrew Brierley
• 金额: $ 19.11万
• 依托单位: University of St Andrews
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FT008830%2F1
• 关键词: Seaquest; DSV; compact; Deep; water

Animals in the deep sea, including a diverse array of fish, squid and zooplankton, are hard to sample, but play important roles in ocean ecosystem function (e.g. they are food for species such as tuna and some cetaceans), biogeochemical cycling (e.g. helping transport atmospheric carbon to the deep sea, buffering climate change), and may be targeted directly by fishers. We need fundamentally to gain a good understanding of which species are where, and in what abundance. We propose an acoustic and optical sampling device that will help with this, opening a new window on the mesopelagic zone (200 to 1,000 meter depth range) by overcoming some present day sampling difficulties.Traditional net surveys suggest that there are about 1,000 million metric tonnes (MT) of fish in the mesopelagic zone. In 2014, an international team suggested, controversially, that these old estimates were an order of magnitude too low, and that there may in fact be more than 10,000 MT of mesopelagic fish [1]. Their estimate was made using single-frequency (38 kHz) scientific echosounder data collected on a single circumnavigation of the globe. They assumed that all of the echo energy from the mesopelagic came from fish but did not have any net samples to confirm this. Different sized fish return different intensities of echo energy, and some zooplankton thought to be abundant in the mesopelagic (siphonophores) have gas-bearing pneumatophores that can return stronger echoes than some fish. In the absence of species or size information, therefore, there is scope for considerable uncertainty in any 'fish' biomass estimate arising from a blanket scaling of echo intensity to fish biomass. Due to this headline figure, there is now growing commercial interest in mesopelagic biomass as a potential major source of protein. We need as a scientific community to better understand mesopelagic community composition so we can better inform society of the ecosystem services of the organisms that live there and their potential for harvest.Basic acoustic theory (e.g. [2]), our own work [3] and that of colleagues [4] focusing on the mesopelagic, has shown that fish and siphonophores cannot be differentiated by single frequency sampling. Multiple frequency data can however give information on size and, in some circumstances, can enable separation of species [5]. Typical ranges of frequencies used for fish/zooplankton identification/sizing range from tens to several hundred kHz. The physics of sound propagation limits the effective range of the high end of this spectrum to a few tens of m in seawater, so in order to acoustically sample the mesopelagic we need to lower the echosounder into deep water. The instrument we propose will enable this. Furthermore, we will use stereo video to capture images of some of the organisms we detect acoustically. This will enable us to determine the acoustic target strength (TS, a ratio measure of the proportion of sound energy backscattered from a target) of species of known size (size influences TS) across a spectrum of frequencies and so enable quantitative evaluation of acoustic survey data and progress towards better understanding of global biomass distribution. Combining acoustic and stereo optics provides an innovative and world-leading new way to sample the mesopelagic.1. Irigoien, X. et al. 2014. Large mesopelagic fishes biomass and trophic efficiency in the open ocean. Nat Comm, 5: 3271. 2. Simmonds, E., and MacLennan, D. 2005. Fisheries acoustics. Blackwell Science Ltd. 3. Proud, R., et al. 2018. From siphonophores to deep scattering layers: uncertainty ranges for the estimation of global mesopelagic fish biomass. ICES JMS.4. Kloser, R. J. et al. 2016. Deep-scattering layer, gas-bladder density, and size estimates using a two-frequency acoustic and optical probe. ICES JMS. 73: 2037-2048. 5. Brierley, A. S. et al. 1998. Acoustic discrimination of Southern Ocean zooplankton. DSR Part II:TSIO. 45: 1155-1173.

深海中的动物，包括种类繁多的鱼类、鱿鱼和浮游动物，很难取样，但在海洋生态系统功能（例如，它们是金枪鱼和一些鲸目动物的食物）、海洋地球化学循环（例如，帮助将大气中的碳输送到深海，缓冲气候变化）方面发挥着重要作用，并可能成为渔民的直接目标。我们需要从根本上很好地了解哪些物种在哪里，以及丰度如何。我们提出了一个声学和光学采样装置，这将有助于这一点，打开一个新的窗口，中层区（200至1 000米深度范围）通过克服一些目前的采样困难，传统的网调查表明，有大约10亿公吨（MT）的鱼在中层区。2014年，一个国际团队提出，这些旧的估计值太低了，实际上可能有超过10，000公吨的中层鱼类[1]。他们的估计是使用单频（38千赫）科学回声测深仪数据进行的，这些数据是在地球仪单次环球航行中收集的。他们假设所有来自中层的回声能量都来自鱼类，但没有任何渔网样本来证实这一点。不同大小的鱼返回不同强度的回声能量，一些浮游动物被认为是丰富的中层（管水母）有含气的气托，可以返回比一些鱼更强的回声。在没有物种或大小的信息，因此，有相当大的不确定性，在任何“鱼”的生物量估计所产生的回声强度的毛毯缩放鱼类生物量的范围。由于这一标题数字，现在对中层生物量作为蛋白质的潜在主要来源的商业兴趣越来越大。作为一个科学界，我们需要更好地了解中层群落的组成，以便我们能够更好地告知社会生活在那里的生物的生态系统服务及其收获潜力。基本声学理论（例如[2]），我们自己的工作[3]和同事的工作[4]专注于中层，已经表明鱼类和管水母不能通过单一频率采样来区分。然而，多频率数据可以提供关于大小的信息，并且在某些情况下，可以实现物种分离[5]。用于鱼类/浮游动物识别/尺寸确定的典型频率范围从几十kHz到几百kHz。声音传播的物理学限制了这一频谱高端的有效范围，在海水中只有几十米，因此，为了对中层进行声学采样，我们需要将回声测深仪降低到深水中。我们提出的文书将能够做到这一点。此外，我们将使用立体视频来捕捉我们声学检测到的一些生物体的图像。这将使我们能够确定声学目标强度（TS，从目标反向散射的声能的比例的比率测量）的已知大小的物种（大小影响TS）在整个频谱的频率，从而使声学调查数据的定量评估和进展，更好地了解全球生物量分布。结合声学和立体光学提供了一种创新的和世界领先的新方法来采样介电层。伊里戈因角等，2014年。公海中大型中层鱼类生物量和营养效率。Nat Comm，5：3271。2. Simmonds，E.，和MacLennan，D. 2005.渔业声学3.中国科学院普劳德河，等，2018年。从管水母到深层散射层：全球中层鱼类生物量估算的不确定性范围。ICES JMS.4.克洛瑟河J. et al. 2016.使用双频声学和光学探测器的深散射层、气囊密度和尺寸估算。ICES JMS. 73：2037-2048。5. Brierley，A. S.等，1998年。南大洋浮游动物的声音辨别。DSR第二部分：TSIO。45：1155-1173。