Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Distribution and quantitative characteristics of four invasive alien species off the Black Sea coast of Georgia.

Abstract

The invasion of alien species in the Black Sea began about 200 years ago and is ongoing. Although the invasive alien species have caused significant changes in the Black Sea ecosystem, the knowledge about their distribution, population status and impact along the Black Sea coast of Georgia is still scarce. The aim of the present study was to assess the distribution and quantitative composition of four of the most common alien marine species in Georgia: the ctenophores Mnemiopsis leidyi and Beroe ovata, the crustacean Amphibalanus improvisus and the bivalve Anadara kagoshimensis. In May 2018, the two ctenophore species were recorded at the same depths, being most abundant and with the highest biomass at 40-50 m. Mnemiopsis leidyi occurred more frequently than B. ovata. Amphibalanus improvisus was present at all stations sampled in 2018, with the highest abundance registered in autumn and the lowest in spring. Anadara kagoshimensis was also recorded at all studied stations. Its quantitative parameters had the highest values at stations with higher salinity. Our results confirm that the four invasive alien species studied have established stable populations off the Black Sea coast of Georgia and may play a key role as factors which influence the native biodiversity.