Adaptive mechanisms of invasion of Chthamalus challengeri (Hoek, 1883) in the trans-oceanic zone of coastal China

Abstract

Chthamalus challengeri Hoek, 1883 (Crustacea, Cirripedia) is typically found in the Bohai Sea and Yellow Sea along the coast of China. However, until 2009, it was never seen in the East China Sea. In 2010, C. challengeri was discovered at Yangshan Port in Zhoushan, East China Sea, and it has since been found to invade several islands in the Zhoushan Islands area successfully. Although the population that invaded Yangshan Port has disappeared in recent years, the population that successfully invaded the other islands in Zhoushan has been increasing in density. To study the ecological adaptability of C. challengeri larvae from the Zhoushan Sea Area, we conducted an experiment observing the larvae’s response to different temperatures and salinity gradients. The results indicate that the C. challengeri larvae are highly adaptable to different temperatures and salinities, and under temperatures ranging from 10–25 °C and salinities of 25–35, nauplius can complete all six stages of development and reach a settlement. We found that the survival and settlement rates during larval development were highest at 20 °C and salinity 30, which could be considered the optimum conditions for C. challengeri larvae. At these conditions, it took approximately 11.5 days for the larvae to undergo development from nauplius I to complete settlement. However, lower temperatures slowed down the development rate and settlement of C. challengeri larvae to some extent, while high temperatures can directly lead to the death of C. challengeri. According to the results of this study, the settlement period of C. challengeri in a new habitat can last as long as 7 months (April to November) compared to its original environment. This extended settlement period could provide favorable conditions for the long-distance dispersal of C. challengeri and enhance its invasive ability in new habitats.