Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

First record of the invasive biofouling mussel Mytella strigata (hanley, 1843) (Bivalvia: Mytilidae) from clam ponds in Taiwan.

Abstract

In 2019, a survey of hard clam-cultured ponds along the southwestern coast of Taiwan revealed an unknown, almost ubiquitous, brackish water mussel. The mussels were attached to the concrete walls and drainage systems of the clam ponds, hulls of boats, bottom sediment, and riverbanks of the estuary. The largest individual had a shell length of over 6 cm. The general external color of the shells was uniformly dark brown or black, but shells with a dark greenish color were also found. The mitochondrial DNA cytochrome c oxidase gene sequences obtained from specimens were consistent with Mytella strigata from Singapore, India, and the Philippines. Based on interviews with farmers, the occurrence of this species has become common since 2014 and is increasing in abundance and density, suggesting that its first invasion may have occurred before 2014. The introduction vector of M. strigata may be ballast water discharged from ships or bio-fouled ship hulls from its native range or somewhere else in Asia. This report represents the first time this invasive tropical mussel (M. strigata) has been recorded in Taiwan and the fifth time it has been reported from the Indo-Pacific region. The rapid growth, high fecundity, and broad salinity tolerance of this species makes it a competitive threat to clams in the ponds as well as other native species.