全球每年约800万吨塑料经河流、海岸带等途径进入海洋，约占全球海洋垃圾数量的80%。经潮汐和海流输送，塑料在海洋表层和海床聚集，对可能误食塑料或被塑料缠绕的海洋生物造成威胁。然而对于部分物种，塑料正成为繁育和捕食的新基底。
在厦门大学近海海洋环境科学国家重点实验室，宋希坤博士正在研究附生于海床塑料表面的深海海洋生物。通过“深海勇士号”载人潜水器，宋希坤与中国科学院深海科学与工程研究所彭晓彤等科学家在西沙海槽多个海沟的塑料堆中采集到塑料袋、塑料瓶等塑料制品，有些样品的采集深度超过3000米（注：包括“嘉庚”号科考船在南海采集的塑料样品，“北斗号”科考船、韩国“全洋号”科考船分别在黄海和南极海域采集的参考样品）。这项研究分析了附着在塑料上的1200多个底栖生物个体，鉴定出49种底栖生物，包括珊瑚、甲壳动物、寄生扁形动物和贝类卵囊，这意味着深海海床上积累的塑料堆正成为深海生物多样性新热点（X. Song et al. Environ. Sci. Technol. Lett. 8, 148–154; 2021），这个发现出乎人们的意料。
阅读链接：研究人员发现深海塑料生物群落并被《自然》遴选为研究亮点
宋希坤在山东济南长大，2017年获中国科学院大学博士学位，博士期间研究海洋水螅的进化，这是一类体型较小的深海捕食动物（注：水螅虫纲包括水螅体和水母体两个生活史阶段，几乎在全球、全水深分布）。宋希坤研究了中国、美国、德国在南北极海域和中国海采集的100多种水螅种类、2000多号标本，包括现生标本和化石。他结合了形态学、分子生物学和地层古生物学等多学科交叉方法开展研究，并于2017年获厦门大学近海海洋环境科学国家重点实验室杰出博士后基金。
阅读链接：博士后宋希坤专著《中国与两极海域桧叶螅科刺胞动物多样性》出版
阅读链接：研究人员发现寒武纪海洋高等水螅化石拓展水母亚门进化史
宋希坤认为，深海与极地是海洋科学最新的研究前沿。据了解，今年3月，中国将深海列为“十四五”规划的优先研究领域，将加快建立新的海洋科学研究机构、强化国际研究合作、加大海洋装备如潜水器的研制。2020年，中国研制的“奋斗者号”载人潜器下潜至10,909米，接近美国10,927米的最深下潜记录。载人潜器已被各国用于勘探深海沉积物组成，甚至在获得国际海底协会（ISA）批准后开采海底矿藏。但研究人员担心开采深海矿藏可能扰动海底沉积环境、改变沉积结构，进而影响特定深海物种的生存，影响深海生态系统，因此呼吁同时加强深海生物多样性和保护研究（Nature 571, 465–468; 2019）。
XIKUN SONG: Deeply curious
An estimated 8 million tonnes of plastic enter the ocean each year from coastlines, rivers and other sources, accounting for 80% of global marine debris. Carried by the tides and accumulating in surface waters and on the sea floor, plastic poses a major threat to marine organisms that might ingest or become entangled in it. But for some species, it’s become an unlikely hub of breeding and feeding.
At the State Key Laboratory of Marine and Environmental Science at Xiamen University in China’s Fujian province, Xikun Song is investigating the deep-sea lifeforms that gather on discarded plastic. Using the crewed submersible Shenhai Yongshi (‘Deep sea warrior’), Song and his colleagues collected items including plastic bags, bottles and wrappers from large debris dumps in the Xisha Trough of the South China Sea, some from trenches more than 3,000 metres deep.
Roughly 1,200 organisms from 49 species, including corals and crustaceans, were identified on these items, as well parasitic flatworm and sea snail eggs. The study, published in January, suggests that some deep-sea pollution dumps are functioning as new biodiversity hotspots (X. Song et al. Environ. Sci. Technol. Lett. 8, 148–154; 2021). “It was completely unexpected,” says Song.
Song grew up in the city of Jinan, capital of eastern China’s Shandong province. In 2016, he completed his PhD at the University of Chinese Academy of Sciences in Beijing on the evolution of small, deep-sea predators called hydroids. Song’s research, which investigated hundreds of living and fossil specimens collected by Chinese, American and German expeditions in Arctic and Antarctic locations, was awarded an outstanding postdoctoral fellowship by the State Key Laboratory of Marine Environmental Science at Xiamen University for its multidisciplinary approach combining morphological, molecular and palaeontological data.
Song describes the world’s deep sea and polar regions as the “final frontiers in marine and ocean science”. In March, China named deep-sea exploration as a priority research area in its latest five-year plan, which sets the nation’s social and economic development guidelines. Among the plan’s goals are speeding up the establishment of marine-science institutions, strengthening international research collaborations and increasing spending on technologies such as submersibles — a major asset in China’s deep-sea missions.
In 2020, China’s crewed vessel Fendouzhe (‘Striver’) plunged 10,909 metres to transmit the first live video feed of the deepest point of the Mariana Trench, narrowly missing the 10,927-metre world record set by American explorer Victor Vescovo in 2019.
The submersible has also been used to investigate deep-sea deposits containing nickel, copper, cobalt and manganese, as China readies itself to become the first nation to mine the sea floor once regulations are approved by the UN-backed International Seabed Authority (ISA). The mining code, a ruleset that aims to regulate prospecting, exploration and exploitation of marine minerals in international waters, was set to be finalized by the ISA last year, but the process has been delayed by the pandemic.
As Nature reported in 2019, researchers have expressed fears that deep-sea mining could devastate certain species and ecosystems across vast areas due to sediment displacement and other disturbances (see Nature 571, 465–468; 2019).
