Distribution and growth of non-native bryozoan Pectinatella magnifica (Leidy, 1851) in four large rivers in South Korea

Pectinatella magnifica Leidy, 1851 is a non-native freshwater bryozoan species that has successfully established in temperate climate regions in the northern hemisphere. There is an ongoing rapid spread of this species in East Asia, but distribution studies to date have failed to examine the growth characteristics of P. magnifica. We surveyed the distribution of P. magnifica and its temporal growth at 52 sites in the four major rivers of South Korea. We used artificial substrates in the four rivers to observe their growth. The frequency of occurrence of colonies across all sites was 28.2%. Pectinatella magnifica was broadly distributed from meso-to eutrophic conditions. The dominant substrates for colony attachment were submerged dead trees and stones; however, P. magnifica showed no specific preference. Colonies were identified from May to June, but these became detached owing to heavy flooding during the monsoon season. Our study identified habitat conditions of P. magnifica and provides a guidance for the effective management of introduced freshwater bryozoan species.