Legrand Erwann, Svensen Øyvind, Husa Vivian, Lelièvre Yann, Svensen Rudolf
Institute of Marine Research, Nordnesgaten 50, 5005 Bergen, Norway.
Svensen Biologi, Helgesens gate 22, 0553 Oslo, Norway.
Mar Pollut Bull. 2025 Feb;211:117440. doi: 10.1016/j.marpolbul.2024.117440. Epub 2024 Dec 9.
The spread of the invasive ascidian Didemnum vexillum represents a major ecological and economic threat in many parts of the world. Recorded for the first time in Norway in 2020, this species is now established in several localities, often characterized by busy port activities. The new detection and expansion of D. vexillum raise significant concerns in Norway, especially due to the potential extension of its distribution range into higher latitudes. This study presents the results of an in situ monitoring of the growth of eleven D. vexillum colonies in Stavanger between December 2020 and September 2022. Colony growth was calculated from underwater photographs taken approximately once a month. Overall, our findings indicate significant growth of most colonies after 624 days, increasing in size from 78 cm to 1008 cm. Seasonal variations in seawater temperature are a major factor affecting the size and growth of the colonies. Most of the growth occurred during the summer months, when seawater temperature was between 13 °C and 18 °C. A rapid decline in colony growth rates was observed in November, as temperatures dropped below 13 °C, followed by colony regression below ~8 °C. These results therefore confirm the general understanding of D. vexillum as rapidly spreading species, characterized by a high colony growth rate. Its ongoing spread toward northern Norway is likely to have negative impacts on key coastal ecosystems (e.g., kelp forests, rhodolith beds, seagrass meadows), as well as on several industries critical to Norway's economy (e.g., oil industry, aquaculture, fisheries). Based on the information provided here, it is essential to continue implementing measures to prevent further spread to the north and to develop localized mitigation strategies.
入侵性海鞘皱瘤海鞘的扩散在世界许多地区构成了重大的生态和经济威胁。该物种于2020年在挪威首次被记录，目前已在多个地区定殖，这些地区通常港口活动繁忙。皱瘤海鞘的新发现和扩散在挪威引起了重大关注，特别是因为其分布范围有可能扩展到更高纬度地区。本研究展示了2020年12月至2022年9月期间在斯塔万格对11个皱瘤海鞘群体生长情况进行原位监测的结果。群体生长情况是根据大约每月拍摄一次的水下照片计算得出的。总体而言，我们的研究结果表明，大多数群体在624天后显著生长，大小从78平方厘米增加到1008平方厘米。海水温度的季节性变化是影响群体大小和生长的主要因素。大部分生长发生在夏季，此时海水温度在13°C至18°C之间。11月，随着温度降至13°C以下，观察到群体生长速率迅速下降，随后在温度低于约8°C时群体出现衰退。因此，这些结果证实了人们对皱瘤海鞘作为快速扩散物种的普遍认识，其特点是群体生长速率高。它继续向北挪威扩散可能会对关键的沿海生态系统（如海带森林、红藻床、海草草甸）以及对挪威经济至关重要的几个行业（如石油工业、水产养殖、渔业）产生负面影响。基于此处提供的信息，必须继续采取措施防止其进一步向北扩散，并制定局部缓解策略。
