Ecology of the Starfish Asterias amurensis (Lütken, 1871) in Russia’s East

Abstract

The Northern Pacific Starfish, Asterias amurensis (Lutken, 1871), is an active consumer of valuable bivalve mollusks, well adapted to a wide range of temperatures observed in the sea. Thanks to its ecological flexibility, this species significantly expanded its geographical range with ballast water and, due to colonization of artificial substrata by larvae, raised panic among marine aquaculture farmers. Within 2-3 months after settling on a substrate, its juveniles begin actively feeding on valuable bivalve mollusks: Patinopecten yessoensis, Mytilus trossulus, and Chlamys nipponensis. As it cannot eat adult P. yessoensis, the predator has adapted to its prey by coincidence of dynamics in their abundance. These dynamics have a quasi-two-year pattern, with the odd-numbered years within the interval 1977-1986 being fruitful in these two species. In 1986, a new 22-year solar cycle began, and since then the even-numbered years during the 23-year period were fruitful in these two species. However, after another 22-year solar cycle started since 2008, the odd-numbered years became fruitful again. A. amurensis uses alternative sources of food, and, due to the non-fastidious dietary habits, its nutritional demands vary depending on abundance of bivalves. As a result, the dynamics of bivalves population becomes smoothed. Abundance of A. amurensis larvae is adversely affected by industrial cultivation of M. trossulus; the red king crab Paralithodes camtschaticus, as in the case of introduction into the waters of Australia, Tasmania and New Zealand, can also reduce the abundance of A. amurensis spawners.