Assessing environmental changes in Southern Ocean ecosystems is difficult due to its remoteness and data sparsity. Monitoring marine predators that respond rapidly to environmental variation may enable us to track anthropogenic effects on ecosystems. Yet, many long-term datasets of marine predators are incomplete because they are spatially constrained and/or track ecosystems already modified by industrial fishing and whaling in the latter half of the 20th century. Here, we assess the contemporary offshore distribution of a wide-ranging marine predator, the southern right whale (SRW, Eubalaena australis), that forages on copepods and krill from ~30°S to the Antarctic ice edge (>60°S). We analyzed carbon and nitrogen isotope values of 1,002 skin samples from six genetically distinct SRW populations using a customized assignment approach that accounts for temporal and spatial variation in the Southern Ocean phytoplankton isoscape. Over the past three decades, SRWs increased their use of mid-latitude foraging grounds in the south Atlantic and southwest (SW) Indian oceans in the late austral summer and autumn and slightly increased their use of high-latitude (>60°S) foraging grounds in the SW Pacific, coincident with observed changes in prey distribution and abundance on a circumpolar scale. Comparing foraging assignments with whaling records since the 18th century showed remarkable stability in use of mid-latitude foraging areas. We attribute this consistency across four centuries to the physical stability of ocean fronts and resulting productivity in mid-latitude ecosystems of the Southern Ocean compared with polar regions that may be more influenced by recent climate change.

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海蛇尾环境DNA 宏条形码技术的两套PCR引物构建

Development of Two New Sets of PCR Primers

for eDNA Metabarcoding of Brittle Stars

作者：Masanori Okanishi, Hisanori Kohtsuka, Qianqian Wu, Junpei Shinji, Naoki Shibata, Takashi Tamada, Tomoyuki Nakano, Toshifumi Minamoto

期刊：Metabarcoding and Metagenomics

海蛇尾（蛇尾纲）是一种海洋无脊椎动物，现存约2100个物种，被认为是棘皮动物门中最多样化的分类单元。作为一种用于监测生物多样性的非侵入性方法，本研究开发了两套全新的用于海蛇尾宏条形码技术环境DNA（eDNA）的聚合酶链式反应（PCR）引物。新的引物用于扩增线粒体16S rRNA基因的两个短区域，包括一个保守区（111-115个碱基对，平均112个碱基对；命名为“16SOph1”）和一个显示种间变异的高变区（180-195个碱基对，平均185个碱基对；命名为“16SOph2”）。引物的性能分别使用以下两个来源获得的eDNA进行测试：a）含有15种海蛇尾物种的2.5升或170升的水族箱饲养水，和b）从日本中部太平洋海岸三崎附近收集的天然海水，深度为从浅海（2米）至深海（大于200米）。为了建立一个参考数据库，本研究获取了从三崎周围及类似深度日本海域采集的海蛇尾标本的16S rRNA序列，和在国际协作核酸序列数据库中已登记的序列。将所获得的eDNA序列与参考数据库进行比较，通过16SOph1和16SOph2分析，分别检测到37个（包括隐存种）和26个具有一定特征的海蛇尾物种。在浅水区，用16SOph1检测到的非海蛇尾的物种数量和测序序列数量不到总数的10%。用16SOph2检测到的海蛇尾物种数量和测序序列数量不到总数的一半，检测到的非海蛇尾后生动物物种数量为20种到46种不等，涉及6到8个门类（只有水族箱样本的测序序列少于0.001%）。在取自海水深度为80米的天然海水样本中，两套引物测出来的的非海蛇尾物种数和测序序列均少于10%。这些研究结果表明，16SOph1对海蛇尾具有特异性，而16SOph2则适用于各种海洋后生动物。然而，为了避免eDNA提取物中可能会出现的PCR缺失，仍然有必要进一步优化引物序列。此外，还需要详细阐明研究区域的海蛇尾动物群，并在现有DNA数据库中准确识别海蛇尾物种。

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（实习生闻静编译）

Fig. 3 A–C. Map of Japan (A), showing the location of the 2 sea water sampling sites of Misaki Marina Biological Station (B) and 2 sea water sampling sites at shallow waters and aquarium tank (C) (Koajiro, Misaki, Miura, Kanagawa Prefecture).

Brittle stars (class Ophiuroidea) are marine invertebrates comprising approximately 2,100 extant species, and are considered to constitute the most diverse taxon of the phylum Echinodermata. As a non-invasive method for monitoring biodiversity, we developed two new sets of PCR primers for metabarcoding environmental DNA (eDNA) from brittle stars. The new primer sets were designed to amplify 2 short regions of the mitochondrial 16S rRNA gene, comprising a conserved region (111–115 bp, 112 bp on average; named “16SOph1”) and a hyper-variable region (180–195 bp, 185 bp on average; named “16SOph2”) displaying interspecific variation. The performance of the primers was tested using eDNA obtained from two sources: a) rearing water of an 2.5 or 170 L aquarium tanks containing 15 brittle star species and b) from natural seawater collected around Misaki, the Pacific coast of central Japan, at depths ranging from shallow (2 m) to deep (> 200 m) sea. To build a reference library, we obtained 16S rRNA sequences of brittle star specimens collected from around Misaki and from similar depths in Japan, and sequences registered in International Nucleotide Sequence Database Collaboration. As a result of comparison of the obtained eDNA sequences with the reference library 37 (including cryptic species) and 26 brittle star species were detected with certain identities by 16SOph1 and 16SOph2 analyses, respectively. In shallow water, the number of species and reads other than the brittle stars detected with 16SOph1 was less than 10% of the total number. On the other hand, the number of brittle star species and reads detected with 16SOph2 was less than half of the total number, and the number of detected non-brittle star metazoan species ranged from 20 to 46 species across 6 to 8 phyla (only the reads at the “Tank” were less than 0.001%). The number of non-brittle star species and reads at 80 m was less than 10% with both of the primer sets. These findings suggest that 16SOph1 is specific to the brittle star and 16SOph2 is suitable for a variety of marine metazoans. It appears, however, that further optimization of primer sequences would still be necessary to avoid possible PCR dropouts from eDNA extracts. Moreover, a detailed elucidation of the brittle star fauna in the examined area, and the accurate identification of brittle star species in the current DNA databank is required.

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 为何全球最干旱地区频遭洪涝灾害破坏？

Flash Floods: Why are More of Them

Devastating the World’s Driest Regions?

作者：Jie Yin, Yao Gao, Ruishan Chen, Dapeng Yu, Robert Wilby, Nigel Wright, Yong Ge, Jeremy Bricker, Huili Gong, Mingfu Guan

期刊：Nature

2022年，巴基斯坦发生严重洪涝灾害，造成全国三分之二区域被淹，超过1500人死亡、3300万人无家可归。非洲部分地区因洪灾导致超过2000人死亡，地处中东的阿联酋、沙特、伊朗、卡塔尔、阿曼、也门等国的部分区域（甚至沙漠地区）也不同程度地发生暴雨洪涝灾害。我国青海省大通县发生的“8.18”山洪灾害，暴雨在不到一小时内形成山洪泥石流，造成数十人死亡，超过1500栋房屋受损。根据EM-DAT数据分析显示：全球干旱半干旱地区暴雨洪涝灾害呈现快速上升的趋势，造成了极为严重的人员伤亡和经济损失。尤其是2000年以来，全球不到半数（约47%）的暴雨山洪致死事件发生在干旱半干旱地区，却造成了全球近四分之三（74%）的因灾死亡。绝大多数的暴雨山洪灾害事件（87%）及因灾死亡人数（97%）发生在中低收入国家和地区。气候变化和人类活动影响加剧，是导致全球干旱半干旱地区极端暴雨山洪灾害日益频发的主要因素。气候变化导致全球干旱半干旱地区暖湿化趋势显著，2010年代5日最大降水较1980年代上升了约8%。巴基斯坦5日最大降水则较1900年提高了75%。此外，全球干旱半干旱地区面积、人口数量和城市化水平也在不断上升，但仅有约1%的人口分布于发达国家。在此背景下，亟需决策者、研究者以及相关从业人员针对以下几个方面开展建模、评估以及减缓等措施以应对未来可能出现的极端灾害风险。

• 数据集成与风险制图
• 发展早期预警系统
• 实施洪水韧性措施
• 长期迁居移民规划
• 灾害风险金融机制
• 提高公众意识和响应

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译文来源：https://mp.weixin.qq.com/s/TwoiEjW21Ww307ajUndJKA

Fig. 4 Source: EM-DAT, CRED/UC Louvain (www.emdat.be); Analysis by J. Yin et al.

In 2022, around two-thirds of Pakistan was affected by widespread flash flooding, with more than 1,500 people killed and around 33 million made homeless. Almost 2,000 people died in flash floods across Africa, and parts of the United Arab Emirates, Iran, Saudi Arabia, Qatar, Oman and Yemen were inundated with water. On August 18^th, a flash flood in Datong town in Qinghai province, China, washed away more than 1,500 homes and killed dozens of people in less than one hour. Flash floods are a growing threat in the world’s arid or semi-arid regions, causing heavy casualties and economic losses. Our analysis using the Emergency Events Database (EM-DAT; www.emdat.be) shows that, since 2000, such regions experienced less than half (47%) of deadly flash floods globally, yet saw almost three-quarters (74%) of related deaths (see ‘Global flash-flood disasters’). The majority of these floods (87%) and associated deaths (97%) occurred in low- and middle-income countries. The increased impact of climate change and human activities is making such events more intense and frequent. Climate change has led to a significant “warming-wetting” trend in the arid and semi-arid regions worldwide, with the 5-day maximum level of rainfall about 8% higher in the 2010s than in the 1980s. In parts of Pakistan, the 5-day maximum level of rainfall is 75% greater today than it was before 1900 (see go.nature.com/41awzzj). By our calculation, more people are living in drylands, and cities in such areas are expanding rapidly. Yet only 1% of those people are living in developed countries. And the proportion of the world’s land area classed as arid or semi-arid is projected to increase as the world warms. Researchers, practitioners and policymakers need to model, assess and mitigate the risk of flash flooding in drylands in a changing environment. Here, we set out six research priorities for doing so.

• Gather data and map the risks
• Develop early-warning systems
• Boost resilience to sudden floods
• Plan for long-term resettlement
• Provide finance beyond disaster aid
• Improve public awareness and responses

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长寿哺乳动物觅食成功与终生健康之间的生理临界点

Physiological Tipping Points in the Relationship Between

Foraging Success and Lifetime Fitness of a Long‐Lived Mammal

作者：Roxanne S. Beltran, Keith M. Hernandez, Richard Condit, Patrick W. Robinson, Daniel E. Crocker, Chandra Goetsch, A. Marm Kilpatrick, Daniel P. Costa

期刊：Ecology Letters 

尽管人类活动的变化通常是渐进的，但如果在生理过程中能在获得能量、繁殖或生存之间产生临界点，则很有可能对动物种群产生巨大的影响。我们使用象海豹25年的行为、饮食和种群数据来描述这些与其终身健康的关系。在幼崽繁殖季节之前的长时间觅食旅行中，象海豹的存活率和繁殖率随着体重的增加而增加，并且有一个阈值，即体重增加4.8%（26公斤，从206公斤增加到232公斤）的个体，其终身繁殖成功率增加了三倍（从1.8只幼崽增加到4.9只幼崽）。这是由于幼崽出生概率增加了两倍（30%至76%），繁殖寿命增加了7%（6.0至6.4年）。体重增加和繁殖之间明确阈值的存在可能用于解释在许多物种中观察到的繁殖失败现象，并表明人类干扰导致的猎物数量小幅的逐渐减少可能对动物种群产生深远影响。

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（实习生齐千萌编译）

Fig. 5 Mass gain is positively correlated with mean foraging depth, and diet and distance from the coast are positively correlated. Probability density plots of behavioural strategies (diagonal panels), correlations and p values of behavioural strategies (upper panels) and relationships between behavioural strategies (bottom panels). Blue colour indicates statistically significant relationships, and the shaded band around the linear model is a pointwise 95% confidence interval on the fitted values.

Although anthropogenic change is often gradual, the impacts on animal populations may be precipitous if physiological processes create tipping points between energy gain, reproduction or survival. We use 25 years of behavioural, diet and demographic data from elephant seals to characterise their relationships with lifetime fitness. Survival and reproduction increased with mass gain during long foraging trips preceding the pupping seasons, and there was a threshold where individuals that gained an additional 4.8% of their body mass (26 kg, from 206 to 232 kg) increased lifetime reproductive success three-fold (from 1.8 to 4.9 pups). This was due to a two-fold increase in pupping probability (30% to 76%) and a 7% increase in reproductive lifespan (6.0 to 6.4 years). The sharp threshold between mass gain and reproduction may explain reproductive failure observed in many species and demonstrates how small, gradual reductions in prey from anthropogenic disturbance could have profound implications for animal populations.

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河口近岸水体酸化对硝化过程及副产物氧化亚氮排放的影响

Effects of Acidification on Nitrification and Associated

Nitrous Oxide Emission in Estuarine and Coastal Waters

作者：Jie Zhou, Yanling Zheng, Lijun Hou, Zhirui An, Feiyang Chen, Bolin Liu, Li Wu, Lin Qi, Hongpo Dong, Ping Han, Guoyu Yin, Xia Liang, Yi Yang, Xiaofei Li, Dengzhou Gao, Ye Li, Zhanfei Liu, Richard Bellerby, Min Liu

期刊：Nature Communications

随着大气二氧化碳（CO₂）浓度不断上升，陆源营养盐输入、海岸上升流和复杂生物地球化学过程大大加速了河口近岸水体酸化。因此，更深入地了解硝化微生物对加速酸化的反应机理，对于预测河口海岸生态系统的响应及其对全球气候变化的作用至关重要。该研究表明，酸化可以显著抑制硝化速率，但也会促进河口近岸水体中副产物氧化亚氮（N₂O）的生成。研究通过分别改变CO₂浓度和pH值，排除了酸化条件下CO₂升高对硝化微生物活性的有益影响（“CO₂施肥”效应）。宏转录组数据进一步表明，硝化微生物会显著促进与胞内pH平衡相关的基因表达以应对水体酸化的胁迫。该研究强调了水体酸化对硝化过程及相关温室气体氧化亚氮（N₂O）排放的分子基础，有助于预测气候变化和人类活动下河口海岸生态系统的反应与演变。

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（实习生申澳编译）

Fig. 6 Response of nitrification and associated N₂O production rates to simulated aquatic acidification in Yangtze Estuary and its adjacent coastal area.

a Nitrification rates. Data show the percentage changes of nitrification rates in the acidified treatments compared to the ambient control. For all the lines, P < 0.05. b N₂O production rates. Data show the percentage changes of N2O production rates in the acidified treatments compared to the ambient control. For all the lines, P < 0.05. Error bars represent SD (n = 3 biologically independent samples). ΔpH corresponds to the decrease between water pH before and after acidification. The fitting curve was obtained by polynomial fitting method. Equations and P values for the fitted curves are given in Supplementary Table 3. Source data are provided as a source data file.

In the context of an increasing atmospheric carbon dioxide (CO₂) level, acidification of estuarine and coastal waters is greatly exacerbated by land-derived nutrient inputs, coastal upwelling, and complex biogeochemical processes. A deeper understanding of how nitrifiers respond to intensifying acidification is thus crucial to predict the response of estuarine and coastal ecosystems and their contribution to global climate change. Here, we show that acidification can significantly decrease nitrification rate but stimulate generation of byproduct nitrous oxide (N₂O) in estuarine and coastal waters. By varying CO₂ concentration and pH independently, an expected beneficial effect of elevated CO₂ on activity of nitrifiers (“CO₂-fertilization” effect) is excluded under acidification. Metatranscriptome data further demonstrate that nitrifiers could significantly up-regulate gene expressions associated with intracellular pH homeostasis to cope with acidification stress. This study highlights the molecular underpinnings of acidification effects on nitrification and associated greenhouse gas N₂O emission, and helps predict the response and evolution of estuarine and coastal ecosystems under climate change and human activities.

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声明：本版块为尝试性栏目，旨在传播分享最新科研动态。中文翻译仅供参考，中英文若有不符之处，请以英文为准。如有不妥之处，请联系 [email protected] 进行订正或要求撤稿。

Disclaimer: This column is a new trial to share cutting-edge research with wider academic community. The Chinese is not an official translation, while the English is invoked from original publication. If there is anything inappropriate, please contact [email protected] to correct us or request for a retraction.

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2023年第21届中国水色遥感大会（COCC-21）将于 4月5至8日 在中国武汉举行

21st China Ocean Color Conference, Wuhan, China, 5-8 April

国际海洋考察理事会（ICES）研讨会：评估渔业对海洋碳循环的影响 将于 4月24至28日 在丹麦哥本哈根举行，请于 4月11日 前注册

Workshop: Assessing the impact of fishing on oceanic carbon, ICES, Copenhagen, Denmark, 24-28 April. Register by 11 April

2023年联合国世界海洋日“海洋星球，潮流之变”将于 6月8日 线上举行，点击注册

Virtual UN World Oceans Day 2023, ‘Planet Ocean: Tides are Changing’, 8 June. Register now

气候变化下大西洋经向翻转环流（AMOC）的观测需求研讨会 将于 7月18至20日 在德国汉堡 举行，请于 5月2日 前提交摘要

Workshop on Meeting AMOC Observation Needs in a Changing Climate, Hamburg, Germany, 18-20 July, submit an abstract by 2 May

生物多样性和生态系统服务政府间科学政策平台全体会议第十届会议（IPBES 10） 将于 8月28日至9月2日 在德国波恩举行

IPBES 10 Plenary, Bonn, Germany, 28 August - 2 September

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