The Reaction of the Starfish Asterias amurensisand Patiria pectinifera (Asteroidea) from Vostok Bay (Sea of Japan) to a Salinity Decrease

Abstract

The reactions of the starfish Asterias amurensis and Patiria pectinifera that live in Vostok Bay at the salinity of 32–33‰ to a salinity decrease were studied under laboratory conditions. The lower limits of the desalination tolerance range of A. amurensis and P. pectinifera were, respectively, 24 and 20‰. A. amurensis proved to be less resistant to desalination. Under experimental conditions, all specimens of this species survived the salinity of 22‰, while those of P. pectinifera tolerated 18‰. At the same time, A. amurensis responded more actively than P. pectinifera to unfavorable changes in the environment. Turned to their dorsal side and exposed to a salinity of 16 to 32‰, the former reverted to the normal position within a shorter time than the latter. Being a more euryhaline species, P. pectinifera endured a salinity decrease to 6 or 8‰ over, respectively, 21 or 28 h. However, only 30–40% of all specimens could recover locomotory activity 12 or 8.5 h after being placed into water of normal salinity.