First record of the tropical holothurian stichopus naso semper, 1867 (Echinodermata: Holothuroidea: Synallactida) from the temperate coast of Kyushu Mainland, Japan, in relation to ocean warming

Abstract

In 2011, a tropical holothurian was found off the temperate coast of Kagoshima, Kyushu, Japan. This holothurian was identified as Stichopus naso Semper, 1867, which was first described in the Philippines, and is known to be distributed within the tropical Indo-West Pacific region. Herein, we examined its morphological characteristics and compared it with pre-described examples and discuss its origin from the perspective of climate change and artificial transfer. We considered that both perspectives are plausible because sea water temperature has recently risen around Japan, creating the possibility of eggs and larval transfer from southern re-gions and the consequent establishment of adult S. naso populations. Accidental introduction via ballast water from vessels and other pathways may not be implausible. In any case, ocean warming caused by global climate change is considered as a key factor in the survival and settlement of adult S. naso populations.