Vertical ambush corridors: Intriguing multi-mechanism ecological structures embedded in the kinetic fluid architectures of ocean living resource production systems

The concept of a ‘vertical ambush corridor’ is herein introduced to marine ecosystem science. In the open ocean, adequate physical cover from which to launch an unanticipated ambush attack is generally lacking. An available alternative is for a predator to channel its attack vertically upward from below, rendering an unlighted approaching predator extremely difficult for a downward viewing potential prey to visually identify against the profound blackness of the deep ocean background. Moreover, within sub-mesoscale structures wherein the ambient water is sinking, slightly warmer water temperatures within the core of the downward motion results in outward refraction of both sound and light waves, producing sound and light shadow patterns that may reduce the capacity of prey organisms to recognize the approach of an upwardly attacking predator. This suggests that presence of such submarine ‘vambush’ structures may enhance trophic transfer efficiency within marine ecosystems, as well as provide perhaps the best available explanation for such predator behaviours as the evident strong attraction to drifting flotsam and floating fish aggregation devices (FADs), as well as the repeated large amplitude ‘bounce dives’ undertaken by a large number of dominant oceanic predatory fish species. The oxygen constraints faced by water-breathing organisms are posed as controlling factors in the potential ecological operation of these vambush structures, that in turn may have potential vulnerability to the growing global problem of ocean deoxygenation. Increased identifiable habitat granularity represented by such sub-mesoscale features may have important utility in supporting empirical studies and applications of the comparative scientific method.     

远洋渔船电子监控技术应用研究进展及展望#br#

目前,中国正加强远洋渔业的监督和规范管理,长期以来,观察员在远洋渔业管理中发挥重要作用,但其低覆盖率一直是亟待解决的问题,新出现的电子监控(electronic monitoring,EM)成为其有效替代和辅助手段。通过分析国内外远洋渔船EM技术发展,闸明了远洋渔船运用EM的必要性。介绍了EM的组成、具体方法、目标种类及其在远洋渔船常用3种渔具的应用;论述了现今EM系统在远洋渔船的适用性及功能和EM的优缺点:EM技术在远洋渔船已有应用且具有一些观察员无法具备的优势,但缺乏针对各类远洋渔船和目标鱼种监控的高质量应用示范,且对渔业数据相关处理技术的研究精度与深度还不够。最后对EM研究现状进行了总结并对EM技术未来的研究方向和重点提出了具体建议,可为远洋渔船应用电子监控相关研究提供参考。     

轻量化神经网络在远洋鱿钓检测技术中的应用

中国远洋鱿鱼捕捞技术比较单一,智能化的鱿鱼捕捞技术对远洋渔业资源统计至关重要。在智能化鱿鱼捕捞作业过程中,以YOLOV3算法检测时,其特征提取网络Darknet53模型参数量较大,模型输出权重存储量较高,降低了检测速度。为此,建立轻量化MobileNetV3网络作为特征提取网络,进行初步有效特征提取,再设计CSP瓶颈层作为逆瓶颈结构,提高特征提取能力;最后通过CIoU模型建立网络模型的损失函数。在实验室环境下,使用Squid数据集验证轻量化网络模型的有效性,并对其主干网络与损失函数的性能进行分析。通过训练目标数据集,将轻量型网络模型与YOLOV3网络模型结构做消融试验,验证轻量化网络应用在远洋捕捞技术上的准确性以及实用性。结果显示,轻量化网络结构的性能明显优于YOLOV3网络模型结构,可以大幅度降低参数量,提高检测速度,缩短检测时间,提高检测率,提高了鱿鱼实时检测的工作效率。本研究成果为远洋渔业资源调查提供重要依据。     

规模化透水性人工鱼礁阻流效应的数值模拟

为在大尺度海洋模型中合理体现透水性人工鱼礁组合，基于海洋数值模式FVCOM（finite volume community ocean model）模拟了大陈岛拟建人工鱼礁区的水动力情况，比较了阻滞力法、实心礁法和附加底摩擦法在投礁前后的垂向流速、礁顶平面流速、水体向上输运通量和背涡流体积的差异，并根据投礁前后的流速差异，应用经验公式预测了投礁一年后底床泥沙冲淤情况。数值模拟结果表明，礁体组合迎流面产生上升流，礁体背流面流速减小，涨急时刻所形成缓流区长度在礁体组合长度20倍以上，年底床淤积厚度约0.05 m。阻滞力法以减少来流的动态功率密度来模拟礁体对水流的阻滞作用，可有效合理地实现对透水性人工鱼礁流场效应的模拟，避免了实心礁法在透水性鱼礁模拟中过高估计流场效应的问题，也没有附加底摩擦法只适用于低矮礁体的缺陷。阻滞力法可根据透水性礁体的造型、迎流面积、组合个数、布放方式和所处水层而设置各向和各水层的阻流参数，不仅适用于置底型透水性鱼礁，也适用于浮鱼礁。阻滞力法的建立、完善和应用对于今后的人工鱼礁水动力学和生态动力学研究具有重要意义。     

轻量化神经网络在远洋鱿钓检测技术中的应用

中国远洋鱿鱼捕捞技术比较单一,智能化的鱿鱼捕捞技术对远洋渔业资源统计至关重要。在智能化鱿鱼捕捞作业过程中,以YOLOV3算法检测时,其特征提取网络Darknet53模型参数量较大,模型输出权重存储量较高,降低了检测速度。为此,建立轻量化MobileNetV3网络作为特征提取网络,进行初步有效特征提取,再设计CSP瓶颈层作为逆瓶颈结构,提高特征提取能力;最后通过CIoU模型建立网络模型的损失函数。在实验室环境下,使用Squid数据集验证轻量化网络模型的有效性,并对其主干网络与损失函数的性能进行分析。通过训练目标数据集,将轻量型网络模型与YOLOV3网络模型结构做消融试验,验证轻量化网络应用在远洋捕捞技术上的准确性以及实用性。结果显示,轻量化网络结构的性能明显优于YOLOV3网络模型结构,可以大幅度降低参数量,提高检测速度,缩短检测时间,提高检测率,提高了鱿鱼实时检测的工作效率。本研究成果为远洋渔业资源调查提供重要依据。     

The Big Seaweed Search: Evaluating a citizen science project for a difficult to identify group of organisms

1. The Big Seaweed Search invites people to survey UK seashores for 14 conspicuous seaweeds. The science investigates: (i) impact of sea temperature rise; (ii) spread of non-native species; and (iii) impact of ocean acidification. Survey data submitted between June 2016 and May 2020 were analysed to evaluate and explore project directions in relation to citizen science project development.
2. Of the 378 surveys submitted, 1,414 people participated, contributing 1,531 person hours. Surveys were undertaken around the UK, with the highest proportion (46.7%) in the south west and the lowest (3.7%) in the north east.
3. After data verification, 1,007 (54%) records were accepted. Fucus serratus had the highest number of entries correctly identified (66%) and Undaria pinnatifida the lowest (5%), inferring that at least some seaweeds can be difficult to identify, although the overall misidentification rate was relatively low (c. 15%).
4. Apart from Alaria esculenta, U. pinnatifida and Saccharina latissima, the large brown seaweeds were abundant on at least some shores. Non-natives Sargassum muticum and Asparagopsis armata, were band-forming but in low numbers. Coralline algae, whilst band-forming on some shores, were most commonly patchy or sparse in abundance. Revisits, i.e. repeat surveys, at the same site with an interval of at least 1 year, are relatively low, with 18 sites revisited once and three sites revisited twice. Currently, data are insufficient to determine whether any changes in abundance could be detected.
5. This study highlights areas where project developments can enhance data quality and quantity, e.g. better identification resources, training programmes for dedicated volunteers, and an annual focus week of activities. The project framed around climate change impacts, aims to raise awareness of the ecological importance of, and threats faced by, this understudied habitat and introduce conservation concepts including the need to protect common species showing signs of decline.