中文导读

海藻林常被称为“海底森林”，能为鱼类和其他海洋动物提供食物与栖身之处。日本伊豆半岛沿岸的海藻林却在短短几年里几乎消失。文章先交代这一现象和海藻林的重要性，再介绍研究人员如何把长期记录、卫星数据、鱼类调查和实验室测试结合起来，接着说明黑潮路径变化带来的急剧升温，以及高温与鱼类进食季节延长如何“双重夹击”海藻。最后，文章提醒这项研究揭示的是密切关联而非对每个原因的证明，且只涉及一段海岸。阅读时可留意 however、but、still 等词如何标出转折，以及 suggest、might 等词如何表达研究结论的确定程度。

正文

For decades, the rocky coast of Japan’s Izu Peninsula, southwest of Tokyo, was home to thick underwater forests of brown seaweed called kelp. Now many of those forests are gone. A study by a team including researchers at the University of Tsukuba, published in the journal Global Change Biology and shared again by the science news site Phys.org on 27 October, tries to explain why the kelp disappeared and why it has not come back.

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几十年来，位于东京西南方向的日本伊豆半岛，其岩石海岸一直生长着茂密的水下褐藻森林，这类海藻被称为海带类大型褐藻（kelp）。如今，其中许多海藻林已经消失。一项由包括筑波大学研究人员在内的团队完成、发表于《全球变化生物学》期刊、并于 10 月 27 日由科学新闻网站 Phys.org 再次转载的研究，试图解释这些海藻为何消失、又为何没有恢复。

Kelp forests matter far beyond their own plants. They give food and shelter to many fish and small sea animals, and they help coastal waters stay productive and store carbon. Across Japan, however, more reefs are turning into what Japanese people call “isoyake”, a state in which large seaweeds are largely missing from the rocks.

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海藻林的意义远远超出植物本身。它们为许多鱼类和小型海洋动物提供食物和庇护，还帮助沿海水域保持生产力并储存碳。然而在日本各地，越来越多的礁石正变成日本人所说的“矶烧”（isoyake）状态，即岩石上基本见不到大型海藻。

The team combined several kinds of evidence. They used more than 40 years of records on one kelp species, Ecklonia cava, along about 200 kilometres of coast. They added satellite data on sea temperature and heat waves, monthly counts of plant-eating fish in 2021 and 2022, and laboratory tests on young kelp.

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研究团队结合了多种证据。他们使用了沿约 200 公里海岸、40 多年来对一种海藻——鹅掌菜（Ecklonia cava）的记录，又加入了关于海水温度和热浪的卫星数据、2021 年和 2022 年每月对植食性鱼类的计数，以及对幼小海藻的实验室测试。

The results point to a powerful ocean current. The warm Kuroshio Current usually flows some distance offshore. But from August 2017 to April 2025, its path made a long bend toward the coast, the longest such period since records began in 1965. It pushed warm water toward Izu. Before 2017, the local sea warmed by about 0.15C every ten years. During the bend, the rate was close to 3C per decade.

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结果指向一股强大的洋流。温暖的黑潮通常在离岸有一段距离的地方流动。但从 2017 年 8 月到 2025 年 4 月，它的路径向海岸方向长时间弯曲，这是自 1965 年有记录以来持续最久的一次。它把温暖的海水推向伊豆。2017 年以前，当地海水大约每十年升温 0.15 摄氏度；而在这次弯曲期间，升温速度接近每十年 3 摄氏度。

The kelp suffered quickly. In 2009, it covered about 75% of the reefs that were checked. By around 2023, it had dropped to almost zero. In the laboratory, the plants began to struggle above about 29.5C and died at 32 to 33C, temperatures the sea passed in the summers of 2023 and 2024.

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海藻很快受到影响。2009 年，它覆盖了被调查礁石约 75% 的面积；到 2023 年前后，这一比例已降到几乎为零。在实验室中，这种海藻在约 29.5 摄氏度以上开始难以维持正常状态，在 32 至 33 摄氏度时死亡，而 2023 年和 2024 年夏天的海水温度超过了这些数值。

Heat was only part of the story. Warmer water also gave fish that eat seaweed a longer season to feed, up to 86 extra days a year. The researchers suggest that the two pressures worked together: heat weakened the kelp, and hungry fish ate the young plants that might have helped the forests recover.

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高温只是原因的一部分。更暖的海水还让以海藻为食的鱼类有了更长的进食季节，每年最多多出 86 天。研究人员认为，这两种压力共同起了作用：高温削弱了海藻，而饥饿的鱼又吃掉了原本可能帮助海藻林恢复的幼小植株。

The study shows a strong link rather than proof of every cause, and it covers only one stretch of coast. Still, a research note in the journal Nature Ecology & Evolution has pointed to it as a clear example of how warming seas can turn a rich kelp forest into a bare reef within a few years.

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这项研究显示的是一种密切关联，而不是对每一个原因的证明，而且它只涉及一段海岸。尽管如此，《自然·生态与进化》期刊上的一篇研究简评仍把它视为一个清楚的例子，说明变暖的海洋如何能在短短几年内把繁茂的海藻林变成光秃秃的礁石。

新闻来源

• Phys.org · Ocean warming and herbivorous fish grazing drive kelp forest collapse along Japan’s Izu Peninsula (27 Oct 2026)
• University of Tsukuba · Research News on the Izu Peninsula kelp forest study
• Global Change Biology · Unprecedented Warming and Increased Herbivory Drive Collapse of Japan’s Kelp Forests (Harvey et al., 2026)
• Nature Ecology & Evolution · Grazing cements kelp collapse

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