2019年南海北部近海水母暴发原因种的分子鉴定

Molecular identification on the causative species jellyfish blooms in the northern South China Sea in 2019

我国水母暴发主要发生在黄渤海和东海海域,在南海海域较为少见。文章对2019年5月海南海口、文昌和广东茂名等南海北部多处海域的水母暴发原因种进行了形态学观察和分子鉴定。形态学观察结果显示,海口与文昌附近海域的暴发水母为同一种水母,其伞部为半球形,生殖下穴呈梨形突起,口腕布满丝状物并在末端有1条鞭状附属物,与鞭腕水母(Acromitus flagellatus)形态相似;而茂名附近海域暴发水母区别于海口和文昌,该水母伞部呈较平的半球形,生殖下穴乳状突起,口腕无丝状物,与端棍水母(Catostylus townsendi)形态相似。基于线粒体核糖体大亚基基因(16S r RNA)序列比对,海口和文昌附近海域暴发水母与东太平洋鞭腕水母相似性为97.5%和97.7%,茂名附近海域暴发水母与马六甲海峡端棍水母相似性为93.5%。基于线粒体COI基因和16S r RNA基因构建的系统发育树结果表明,海口和文昌附近海域水母为同一种水母,与鞭腕水母聚在一支,而茂名附近海域水母与端棍水母亲缘关系近。结合形态学观察和分子系统数据认为,海口和文昌附近海域暴发水母为鞭腕水母(Acromitus flagellatus),茂名附近海域暴发水母为端棍水母(Catostylus sp.)。

Jellyfish blooms mostly occur in the Bohai Sea and Yellow Sea as well as in the East China Sea,but rarely in the South China Sea.We conducted morphological observations and molecular identification of blooming jellyfish in many waters of the northern South China Sea,including Haikou,Wenchang and Maoming in May 2019.Morphological results showed that the jellyfish in Haikou and Wenchang were the same species with hemispherical umbrella,pear-shaped protrusion in the lower reproductive point,and the oral arms are covered with filaments and a whip appendage at the end,which are highly similar to the Acromitus flagellatus.The jellyfish in Maoming were different:the umbrella was relatively flat hemispherical,the subgenital pits were milky protrusions and the oral arms had no filaments,which were similar to Catostylus townsendi.Based on the comparison of mitochondrial ribosomal large subunit(16S rRNA)gene sequences,the blooming jellyfish of Haikou and Wenchang were 97.5%and 97.7%similar to A.flagellatus of the eastern Pacific Ocean,and jellyfish of Maoming was 93.5%similar to C.townsendi from the Strait of Malacca.The phylogenetic tree constructed based on mitochondrial COI gene and 16S rRNA gene suggested that the jellyfish of Haikou and Wenchang were the same and belong to the same branch with A.flagellates;the jellyfish of Maoming were close to C.townsendi.Therefore,combined with morphological observations and molecular analyses,we considered Acromitus flagellatus to be the jellyfish in Haikou and Wenchang,and Catostylus sp.in Maoming.