Colonial ascidian Didemnum vexillum Kott, 2002 is an alien species in Peter the Great Bay (Sea of Japan)

Abstract

In November 2013 in Vostok Bay (Peter the Great Bay, Sea of Japan), in the fouling of the experimental installation of the Mytilus trossulus mussel culture, mass settlements of colonial ascidian not previously observed in Peter the Great Bay were registered. The taxonomic identification of colonial ascidians is rather complicated, and frequently the morphological and genetic methods of the species determination do not give a clear result. The usage of molecular-phylogenetic methods allowed us to indicate the sequences of nucleotides obtained from three colonies of ascidians from Vostok Bay as inherent to the invasive species Didemnum vexillum Kott, 2002. This species is known as an invasive in aquaculture settlements of mussels and oysters in various regions of the World Ocean in different years.