Montana Katherine O, Gosliner Terrence M, Crews Sarah C, Bonomo Lynn J, Carlton James T, Johnson Rebecca F
Department of Invertebrate Zoology, Institute for Biodiversity Science and Sustainability, California Academy of Sciences, San Francisco, California, United States of America.
Department of Biology, San Francisco State University, San Francisco, California, United States of America.
PLoS One. 2024 Dec 12;19(12):e0306586. doi: 10.1371/journal.pone.0306586. eCollection 2024.
In the aftermath of the 2011 east Japanese earthquake and tsunami, anthropogenic debris from the east coast of Japan floated across the Pacific Ocean to the west coast of North America. One such vessel from Iwate Prefecture arrived on the coast of Oregon, and the fouling community included specimens identified as the nudibranch Hermissenda crassicornis, which was previously thought to range from Japan to Baja California but has since been split into three species: H. crassicornis (northeastern Pacific), H. opalescens (southeastern Pacific), and H. emurai (western Pacific). Also aboard were nudibranchs of the genera Dendronotus and Eubranchus. Previous work suggested that all of the motile invertebrates found in the tsunami debris fouling community were either pelagic or Japanese in origin. Our study sought to determine whether the Hermissenda nudibranch specimens collected from the Iwate vessel were, according to the most updated classification system, only H. emurai as would be the case if the nudibranchs were Japanese in origin. In addition, we also sought to identify the Dendronotus and Eubranchus aboard. Results from DNA sequencing and limited morphological analysis indicate that specimens of H. crassicornis, as it is currently recognized, and H. opalescens were found on the vessel. Morphological or genetic data resolved the other nudibranchs as the Eastern Pacific Dendronotus venustus and Eubranchus rustyus. These findings indicate that these species settled after arrival to the west coast of North America. Data shared on GBIF and the iNaturalist platform were also used to map where eastern Pacific Hermissenda are currently understood to occur.
2011年东日本地震及海啸过后，日本东海岸的人为垃圾漂过太平洋抵达北美西海岸。一艘来自岩手县的船只抵达了俄勒冈海岸，附着生物群落中包括被鉴定为裸鳃亚目动物厚角海兔（Hermissenda crassicornis）的标本，该物种此前被认为分布于从日本到下加利福尼亚的区域，但后来被划分为三个物种：厚角海兔（东北太平洋）、乳光海兔（Hermissenda opalescens，东南太平洋）和枝手海兔（Hermissenda emurai，西太平洋）。船上还有枝背海牛属（Dendronotus）和真鳃海牛属（Eubranchus）的裸鳃亚目动物。此前的研究表明，在海啸残骸附着生物群落中发现的所有能活动的无脊椎动物要么是远洋生物，要么原产于日本。我们的研究旨在确定，根据最新的分类系统，从岩手县船只上采集的海兔裸鳃亚目动物标本是否仅为枝手海兔，就像如果这些裸鳃亚目动物原产于日本的话情况会那样。此外，我们还试图鉴定船上的枝背海牛属和真鳃海牛属动物。DNA测序和有限的形态学分析结果表明，在这艘船上发现了目前所认定的厚角海兔和乳光海兔的标本。形态学或遗传学数据将其他裸鳃亚目动物鉴定为东太平洋的细纹枝背海牛（Dendronotus venustus）和铁锈真鳃海牛（Eubranchus rustyus）。这些发现表明，这些物种是在抵达北美西海岸后定居下来的。全球生物多样性信息机构（GBIF）和iNaturalist平台上共享的数据也被用于绘制目前已知的东太平洋海兔的分布区域图。
