Rapid assessment of the invasive Xenostrobus securis on cultured oysters in Hong Kong

Abstract

The recently introduced bivalve Xenostrobus securis, which has established itself in the estuarine environments in Hong Kong, represents a potential threat to the local oyster aquaculture industry and native communities. Through a rapid assessment survey, the fouling bivalves on the cultured oyster Crassostrea hongkongensis were sampled along Deep Bay in February 2017. Six common fouling bivalves were identified in this survey, including the invasive X. securis, native Hiatella sp., Neotrapezium liratum, Arcuatula senhousia, Brachidontes variabilis and cryptogenic Perna viridis. Significant difference in bivalve assemblage was found between sampling sites along Deep Bay (). Across Deep Bay, X. securis was the most abundant fouling bivalve on C. hongkongensis (up to 3574 ind m−2), suggesting ecological advantages over native species. The sampled X. securis appeared to be comprised of juvenile individuals with an average shell length of 10.05 mm ( 1.96 SD). This study documents the first record of X. securis as a major fouling species on cultured oysters in Hong Kong. Although X. securis was the most abundant bivalve on cultured oysters in Deep Bay, its overall density was relatively low compared to other invaded regions. Therefore, we encourage the development of early response frameworks to monitor the population of X. securis and prevent potential economic and ecological losses in the area.