First record of copepod Pseudodiaptomus inopinus Burckhardt, 1913 in Peter the Great Bay, Sea of Japan

Abstract

The population density and distribution of copepod Pseudodiaptomus inopinus Burckhardt, 1913 were studied in Peter the Great Bay (the mouth of the Razdolnaya River of Amur Bay and Posyet Bay). This species is new in the fauna of this part of the Sea of Japan. The first record of the species with density of 225 ind./m³ was reported in the mouth of the Razdolnaya River in August 2005. The highest density of this species (up to 354 ind./m³) was reported in the mouth of the Razdolnaya River in August 2015. This species was likely brought with the ballast water of commercial vessels. The increase in the share of P. inopinus in the total zooplankton abundance from 3 to 7% in the period of 2005–2015 indicated its gradual naturalization in the ecosystem.