Exploring potential establishment of marine rafting species after transoceanic long-distance dispersal

Aim On March 11, 2011, the Great East Japan Earthquake triggered a massive tsunami that resulted in the largest known rafting event in recorded history. By spring 2012, marine debris began washing ashore along the Pacific Coast of the U.S. and Canada with a wide-range of Asian coastal species attached. We used this unique dataset, where the source region, date of dislodgment, and landing location are known, to assess the potential for species invasions by transoceanic rafting on marine debris. Location Northeast Pacific from 20 to 60°N Time period Current Major taxa studied Forty-eight invertebrate and algal species recorded on Japanese tsunami marine debris. Methods We developed Maximum Entropy (MaxEnt) species distribution models for 48 species recorded on Japanese tsunami marine debris to predict establishment potential along the Pacific Coast from 20-60°N. Models were compared within the context of historical marine introductions from Japan to this region to validate the emergence of marine debris as a novel vector for species transfer. Results Overall, 27% (13 species) landed with debris at locations with suitable environmental conditions for establishment and survival, indicating that these species may be able to establish new populations or introduce greater genetic diversity to already established non-native populations. A further 22 species have environmental match in areas where tsunami debris likely landed, but was not extensively sampled. Nearly 100 Japanese marine species previously invaded the northeastern Pacific, demonstrating this region's environmental suitability for rafting Japanese biota. Historical invasions from Asia are highest in California and largely known from bays and harbors. Main conclusions Marine debris is a novel and growing vector for non-native species introduction. By utilizing a unique dataset of Japanese tsunami marine debris species, our predictive models show capacity for new transoceanic invasions and can focus monitoring priorities to detect successful long-distance dispersal across the world’s oceans.

研究目标：2011年3月11日，东日本大地震引发特大海啸，造就了有记录以来已知规模最大的生物跨洋漂浮传播事件。至2012年春季，附着大量亚洲沿岸物种的海洋漂浮垃圾（marine debris）开始在美国与加拿大的太平洋沿岸被冲上岸。本研究依托该独有数据集——其包含物种的来源区域、脱离原生栖息地的日期及登陆位置等关键信息——评估了海洋漂浮垃圾介导的跨洋漂浮传播引发物种入侵的潜在可能性。
研究区域：北纬20°至60°的东北太平洋海域
研究时段：当前
研究类群：日本海啸海洋漂浮垃圾上记录到的48种无脊椎动物与藻类
研究方法：针对日本海啸海洋漂浮垃圾上记录的48个物种，本研究构建了最大熵（Maximum Entropy, MaxEnt）物种分布模型，以预测其在北纬20°至60°的太平洋沿岸的定殖潜力。同时结合日本向该区域历史上海洋物种引入的相关背景对模型进行比对验证，以确认海洋漂浮垃圾作为物种跨洋传播新型媒介的有效性。
研究结果：总体而言，27%的物种（共13种）随垃圾登陆的区域具备适宜其定殖与存活的环境条件，这表明这些物种可建立新的种群，或为已定植的外来种群引入更高的遗传多样性。另有22个物种在海啸垃圾大概率登陆的区域存在环境匹配性，但该区域未被广泛采样。此前已有近百种日本海洋物种入侵东北太平洋，证实该区域环境适宜日本生物随漂浮载体传播。历史上从亚洲引入的外来物种在加利福尼亚州数量最多，且多集中于海湾与港口区域。
主要结论：海洋漂浮垃圾是一类新兴且愈发重要的外来物种引入媒介。本研究依托日本海啸海洋漂浮垃圾物种的独有数据集，通过预测模型证实了跨洋漂浮传播引发新物种入侵的可能性，并可为全球范围内远洋长距离传播成功案例的监测工作提供优先方向。