Bathymetry,substrate and fishing areas of Southeast Atlantic high-seas seamounts

Most of the Southeast Atlantic Ocean is abyssal, and global bathymetries suggest that only ～3.2% of the areas beyond national jurisdiction (ABNJ; also known as the high seas, as defined in the United Nations Convention on the Law of the Sea [UNCLOS]) are shallower than 2 500 m. This study mapped bathymetry and characterised substrates in selected seamount summit areas, including several that have been or may become fishing areas. The southernmost location, the Schmitt-Ott Seamount, has exposed volcanic bedrock with surrounding flats covered by thin biogenic sediments and/or coral rubble that appears ancient. At Wüst, Vema, Valdivia and Ewing seamounts the basaltic base appears to be overlain by coral caps and other coral substrates (sheets, rubble). Adjacent summit plains have biogenic sediments of varying thickness. Vema has a flat, roughly circular summit, <100 m deep, with the shallowest point being a 22-m-deep summit knoll; the upper slopes have ancient coral framework, but the summit has a mixture of coralline and volcanic rock and coarse sediments, including extensive areas with coralline algae and kelp forests. Valdivia Bank is a 230-m-deep, flat, rocky area (～11 × 5 km), protruding steeply from the extensive multi-summit Valdivia subarea of the Walvis Ridge. The distribution of past fisheries in the Convention Area of the South East Atlantic Fisheries Organisation (SEAFO) was considered in relation to the new information on bathymetry and substrate.     

Patterns in megabenthic assemblages on a seamount summit (Ormonde Peak,Gorringe Bank,Northeast Atlantic)

Gettysburg and Ormonde are two shallow peaks located on the Gorringe seamount about 200 and 240 km WSW off Cape St. Vincent (Portugal, NE Atlantic), within the Portuguese Economic Exclusive Zone. Despite the ecological importance of the biological assemblages on these peaks and the need to preserve seamounts as valuable habitats, no management plans have been yet implemented at this site, which only recently has been included in the list of Sites of Community Importance of Portugal. Video imagery collected using a ROV during the 2011 Oceana campaigns was used here to analyse qualitative and quantitative patterns of benthic assemblage composition at the summit of the seamount (between 30 and 230 m depth). The results suggest that Ormonde is a biologically important area made up of vulnerable marine ecosystem elements that change significantly with depth. These include: kelp beds, in the euphotic zone; encrusting coralline algal communities and solitary colonies or mixed associations of suspension‐feeders (scleractinians, gorgonians, antipatharians, encrusting demosponges and ascidians), at the lower limit of the euphotic zone; mixed coral gardens and erect sponges, in the disphotic zone; and dense sponge aggregations, on the upper slope. These results were further used to propose amendments to the European Nature Information System habitat classification as a tool to work towards resolving the seamounts management issue. The results also provide information on taxa and habitats with high ecological value and classified as threatened or vulnerable, which is essential for the implementation of the cornerstones of Europe's biodiversity conservation policy, namely the OSPAR Convention and the EU Habitats Directive.     

Method‐dependent influence of environmental variables on reef fish assemblages when comparing trap and video surveys

Despite substantial survey effort and a large body of literature on abiotic and biotic factors in temperate reef ecosystems, knowledge of the complex and interactive effects of environmental variables on those communities is limited. Various survey methods have been developed to study environmental predictors of biodiversity, but there remains a gap in our understanding of how survey results are influenced by environmental factors. Here, we surveyed the fish assemblage associated with southeastern U.S. temperate marine reefs with simultaneous, paired trap, and camera gears throughout a ~50,000 km² area during 2011–2013 and assessed the influence of environmental variables on the trap‐ and video‐surveyed assemblages. Predictor variables in the multivariate general linear models included depth, temperature, month, year, location, substrate relief, percent sessile biota, biota type, and turbidity. Depth and latitude had the greatest influence on the fish assemblage for both gears. The influence of habitat variables differed between methods and percent biota explained more variation in the fish assemblage when assessed by traps, while substrate relief and biota type explained more variation in the fish assemblage when assessed by video. In general, habitat complexity was positively related to the abundance of fishes in the video survey, but there was a negative relationship in the trap survey. Differences between gears were species‐specific and the influences of environmental variables were similar for some species such as Haemulon plumierii and Hyporthodus niveatus. The methods presented here can be used to assess method‐dependent differences in fish assemblages, which is a necessary precursor to assess the effect of environmental variables on the accuracy of surveys.     

声学地层剖面深水探测研究与开发

深水浅部地层精细探测是深海地质勘探与资源开发的重要调查内容。与浅水海域声学地层剖面探测相比,深水地层剖面探测会遇到严重的能量衰减、大数据量长时间反射序列采样、纵向地层分辨率降低以及横向空间覆盖率偏稀等问题,为解决这些问题,国外仪器商采用了不同的方法。采取重采样减少数据量会严重影响纵向分辨率;采取MultiPing技术可以很好解决横向空间覆盖率问题,但多Ping接收采用海底追踪变深度范围采集会造成反射同相轴跳跃突变,或采用短时间间隔采集会造成回波数据无法准确计算海底深度。为了解决这些技术问题,作者研究开发了相关的技术处理方法,解决MultiPing技术反射同相轴拼接改正处理和海底深度记录延迟处理,这些问题的解决为深水浅部地层精细探测提供了技术保障。     

Actions taken by fishing Nations towards identification and protection of vulnerable marine ecosystems in the high seas: The Spanish case (Atlantic Ocean)

In reply to the United Nations General Assembly Resolutions on sustainable fisheries, Spain, either by itself or in collaboration with other Nations, has been carrying out studies on vulnerable marine ecosystems (VMEs) in the high seas of the Atlantic Ocean (areas beyond national jurisdictions) since 2005. Such studies provide advice to the Spanish Government, the Regional Fisheries Management Organizations and the European Union. This paper presents the multidisciplinary methodology used and summarises the following management results: (i) contribution to identification of cold-water corals and provision of evidence to close part (∼16,000 km²) of the Hatton Bank (NE Atlantic) to bottom fishing; (ii) compilation of an international data base to identify VMEs on the slopes of the Grand Banks of Newfoundland, Flemish Pass, and Flemish Cap (NW Atlantic) and to redefine areas currently closed to fishing; (iii) improvement of knowledge about deepwater ecosystems on Walvis Ridge and adjacent seamounts (SE Atlantic) as a pilot project for implementation in this region; and (iv) identification of VMEs and closure of an area (∼41,300 km²) on the high seas of the SW Atlantic. Also discussed are progress and challenges related to identifying and protecting VMEs.     

海岛礁磁偏角测量原理与方法

如何在海岛礁上进行地磁测量是当前海洋测量领域面临的技术难题。基于较为成熟的陆上流动地磁测量模式,结合海岛礁磁偏角测量的特殊性,提出了较完整的海岛礁磁偏角测量技术流程,包括工作原理、测量仪器、数据采集和处理过程、指标要求等关键环节,初步构建了海岛礁地磁测量技术基础框架。     

Ecophysiological differences between vesicomyid species and metabolic capabilities of their symbionts influence distribution patterns of the deep‐sea clams

This study provides an analysis of vesicomyid bivalve–symbiont community distribution across cold seep and hydrothermal vent areas in the Guaymas Basin (Gulf of California, Mexico). Using a combination of morphological and molecular approaches including fluorescent in situ hybridization (FISH), and electronic microscopy observations, vesicomyid clam species and their associated symbionts were characterized and results were analyzed in light of geochemical conditions and other on‐site observations. A greater diversity of vesicomyids was found at cold seep areas, where three different species were present (Phreagena soyoae [syn. kilmeri], Archivesica gigas, and Calyptogena pacifica). In contrast, A. gigas was the only species sampled across the hydrothermal vent area. The same haplotype of A. gigas was found in both hydrothermal vent and cold seep areas, highlighting possible contemporary exchanges among neighboring vents and seeps. In either ecosystem, molecular characterization of the symbionts confirmed the specificity between symbionts and hosts and supported the hypothesis of a predominantly vertical transmission. In addition, patterns of clams could reflect potential niche preferences for each species. The occurrence of numerous traces of vesicomyid movements on sediments in the sites colonized by A. gigas seemed to indicate that this species might have a better ability to move. Furthermore, variation in gill sulfur content could reveal a higher plasticity and sulfur storage capacity in A. gigas. Thus, the distribution of vesicomyid species across the chemosynthetic areas of the Guaymas Basin could be explained by differences in biological traits of the vesicomyid species that would allow A. gigas to more easily exploit transient and punctual sources of available sulfide than P. soyoae.     

关于海上定点验潮站潮位数据推算的可行性及可操作性检验

结合海上定点验潮站的实际情况,提出采用最小二乘潮位拟合法来推算海上定点验潮站未来时刻的潮位值,并根据某次海上定点验潮作业的实测数据对该方法进行了检验,推算误差等统计参数表明该方法具有可行性及可操作性,建议海上定点验潮作业可以根据本方法进行,从而节省人力与物力,为海道测量事业服务。     

Ocean bottom tiltmeter with acoustic data retrieval system implanted by a submersible

Sensitive Ocean Bottom Implanted Tiltmeters (OBITs) with a sophisticated data retrieval system have been developed in order to observe directly the subduction of oceanic lithosphere. The OBIT is the first long-term geophysical instrument which was designed to be deployed by a manned deep-sea submersible. When the OBIT is put on oceanic lithosphere which is bending and is about to subduct under a deep sea trench, the OBIT records the subduction by observing the tilt of the surface of the lithosphere. The OBIT system has a sensitivity of 10^-8 radian, which is enough to detect the ongoing subduction in months or years. The OBIT may give an answer to the question whether there are fluctuations in the subduction rate.Two OBITs were successfully deployed on a seaward slope of the Kuril Trench by the newly built French deep submersible, Nautile. The OBITs were installed on the northwest shoulder of Erimo seamount, at a depth of 3930 m, in the Kuril Trench. In order to attain stable long-term observations of crustal deformations, the sensing unit was cemented onto bare rock by mortar. We have not yet had an opportunity to recover the data.The life of the instruments is expected to be more than five years. An acoustic data transmission system has been developed for the OBIT data recovery. The stored data can be retrieved at any moment during the observation period, with no need to retrieve the instruments nor to interrupt the observation, by use of the acoustic system. The acoustic system has a high data transmission rate as well as extremely low power consumption. This will be the first long-term crustal deformation measurement on the sea floor.     

北冰洋公海渔业权益争端的博弈分析——基于环北极国家视角

北冰洋公海尚处于冰封状态,但气候变暖、海冰加速融化使未来公海出现新渔场成为可能,其战略价值因而得到国际关注。当前,环北极国家已率先展开渔业权益争夺。为分析北冰洋公海渔业事务的国际走势,文章基于博弈论思想,构建非对称懦夫博弈模型及古诺模型来模拟和探究环北极国家在渔业利益争夺中的合作或冲突行为,研究得出:现阶段北冰洋公海渔业权益争端主要表现为渔业管理权的争夺,在该博弈中,非北冰洋沿岸国采取退让策略,沿岸国采取进攻策略,可以达到进化稳定均衡;一旦公海具备捕鱼条件,争端将演化为开发模式选择的博弈,此时,北冰洋沿岸国采取合作开发策略可以有效保护公海渔业资源,并实现国家的长期利益。     

Unexpected records of ‘deep‐sea’ carnivorous sponges Asbestopluma hypogea in the shallow NE Atlantic shed light on new conservation issues

Marine cave communities have been a continued source of ecological surprises, among other things because of their close ecological and evolutionary ties with the deep sea. The discovery of cladorhizid sponges, the deepest occurring poriferan family, in shallow Mediterranean caves in the 1990s was one such surprise, leading to the generally accepted hypothesis that the whole family was carnivorous, an unprecedented feeding mode for sponges. The recent observation of the cave species Asbestopluma hypogea in the Mediterranean bathyal, confirmed the view that some shallow caves can occasionally shelter otherwise deep‐dwelling species. Here we present new distribution data of A. hypogea, from deep Mediterranean locations, and for the first time from Atlantic locations. Among the new Atlantic records, the most surprising ones are located in three different geographic areas (Ria de Arousa, Groix Island and Cherbourg) of the NW European coasts, from the Iberian Peninsula to the English Channel, where A. hypogea reaches SCUBA depths (5–50 m), while not sheltered in marine caves. The carnivorous sponge however reaches its shallowest occurrence (5 m), in a small cave at Groix Island. The ecological significance of these discoveries, particularly the very patchy distribution and peculiar dynamics, are noteworthy, and the shallow occurrence of A. hypogea, together with other deep‐water or uncommon species, constitute unique assemblages that must be considered in conservation plans.     

典型浅海环境参数对声传播损失影响及试验验证

针对典型浅海环境参数对声传播损失影响问题,提出了一种基于海底边界反射系数修正的改进耦合简正波–抛物方程模型,设计并开展了典型南海海域声传播损失测试试验,模型相对误差小于 4%、均方根误差小于 3 dB,验证了模型的准确性。接着,分别对声速剖面、海面海况、海底底质、海底地形 4 种海洋环境参数,设计了 5 种工况,进行仿真计算分析。得出声速剖面主要影响声会聚区的分布,负梯度下声会聚区能量多集中于海底和声源深度附近,而正梯度下声会聚区能量多集中于海面附近;浅海环境下声传播损失分布受海面海况、海底底质因素影响较大;海底地形是影响水下声传播损失的主要因素,海底斜坡既可以汇集声波能量,也可以使其发散。     

Patterns and drivers of asteroid abundances and assemblages on the continental margin of Atlantic Canada

Although continental shelf and slope environments typically exhibit high epifaunal biomass and have been subjected to increasing fishing pressure, ecological information on assemblages of non‐commercial invertebrate species from subtidal and bathyal areas remains limited. Sea stars (Echinodermata: Asteroidea), which are known to influence communities through their feeding habits, have received less attention than structural taxa such as corals and sponges. To better understand the ecological roles of asteroids on continental shelves, we investigated ~30 species and assessed their distributions and co‐occurrence with other benthic invertebrates on the shelf and slope of Eastern Canada. Using fisheries data and in situ video footage, we compiled a large dataset covering ~600,000 km² that included over 350,000 individual asteroid records (37–2243 m depth). Multivariate analyses revealed geographically distinct asteroid assemblages, with a maximal overall density at 400–500 m and the highest diversity at 500–700 m. The most abundant and densely occurring species was Ctenodiscus crispatus. We found that asteroids associate with corals, sponges, bivalves, and other echinoderms, and that depth and substrate influence these assemblages. We identified species likely to affect coexisting organisms by their burrowing behavior that can disrupt epi‐ and infauna (C. crispatus) and through predation on ecologically important corals (Hippasteria phrygiana). In addition to providing baseline distribution and ecological information for many bathyal asteroid species in the Northwest Atlantic, this work highlights the abundance and diversified roles of asteroids within continental shelf and slope ecosystems.     

海面与海底地磁日变化差异及其对海洋磁力测量的影响

给出了海面与海底地磁日变化的计算公式,仿真分析了海面与海底地磁日变化差异,探讨了其对海洋磁力测量地磁日变改正的影响。结果表明:对于不同的地磁日变,海面与海底的地磁日变存在着较大的差异,且其随着地磁倾角的变化而变化,对磁测有一定的影响。为此,远海区海洋磁力测量中,建议联合采用地面日变站和海底日变站来减小或消除海面与海底地磁日变差异对磁测的影响,提高地磁日变改正的精度。     

基于深度学习和时空特征融合的海洋渔船密度预测方法

为了从海量渔船轨迹数据中挖掘隐含的信息和知识,进而为渔业行政主管部门的决策提供科学依据,本研究以AIS渔船轨迹数据为研究对象,提出了一种基于深度学习和面向时空特征融合的海洋渔船密度预测方法：首先,利用渔船轨迹数据集对渔船行驶区域进行网格划分;其次,筛选出渔船高密度区域进行研究,避免数据稀疏性问题;再次,根据渔船轨迹数据的时空分析,构建三维时空融合矩阵;最后,通过卷积循环神经网络模型捕获渔船分布的时间和空间特征,并利用卷积神经网络的堆叠加强对空间特征的学习。实验通过东海海域渔船真实轨迹数据进行具体测试,结果表明渔船密度预测值与真实值非常接近,平均绝对误差为4×10-4,模型较好地拟合了渔船密度分布特征,有效地提高了渔船捕捞热点预测的准确性和鲁棒性。     

Biological structures as a source of habitat heterogeneity and biodiversity on the deep ocean margins

Biological structures exert a major influence on species diversity at both local and regional scales on deep continental margins. Some organisms use other species as substrates for attachment, shelter, feeding or parasitism, but there may also be mutual benefits from the association. Here, we highlight the structural attributes and biotic effects of the habitats that corals, sea pens, sponges and xenophyophores offer other organisms. The environmental setting of the biological structures influences their species composition. The importance of benthic species as substrates seems to increase with depth as the complexity of the surrounding geological substrate and food supply decline. There are marked differences in the degree of mutualistic relationships between habitat-forming taxa. This is especially evident for scleractinian corals, which have high numbers of facultative associates (commensals) and few obligate associates (mutualists), and gorgonians, with their few commensals and many obligate associates. Size, flexibility and architectural complexity of the habitat-forming organism are positively related to species diversity for both sessile and mobile species. This is mainly evident for commensal species sharing a facultative relationship with their host. Habitat complexity is enhanced by the architecture of biological structures, as well as by biological interactions. Colony morphology has a great influence on feeding efficiency for suspension feeders. Suspension feeding, habitat-forming organisms modify the environment to optimize their food uptake. This environmental advantage is also passed on to associated filter-feeding species. These effects are poorly understood but represent key points for understanding ecosystems and biodiversity on continental margins. In this paper we explore the contributions of organisms and the biotic structures they create (rather than physical modifications) to habitat heterogeneity and diversity on the deep continental margins.     

深海ARV在海洋资源调查中的应用及展望

深海自主/遥控式水下机器人（ARV）作为新兴的复合型水下机器人,融合了自主式水下机器人的灵活性和遥控式水下机器人的人机交互性等优势,开启了自主与遥控混合作业的新模式。深海ARV可切换为AUV自主航行模式,独立采集周边区域近海底地形地貌、地质结构以及环境参数等数据,也能下潜至目标区域后切换为ROV遥控模式进行局部观察和采样操作,其探测作业一体化技术代表了具备复杂使命执行力的第三代深海水下机器人的发展方向。通过分析国内外深海混合型水下机器人的发展现状,结合ARV在中国深海矿产资源调查中的主要应用案例和取得的成果,以6000米级 “问海一号”ARV系统的研发为例,给出其关键技术集成以及面对的技术挑战,并对未来深海ARV的应用场景、功能集成和发展方向提出了一些设想和建议。