Seasonal variation in growth rates of stalked barnacles (Lepas spp.): A proxy for floating time in temperate marine ecosystems

Abstract

Abstract Gooseneck barnacles of the genus Lepas are sessile crustaceans settling and growing on free-floating substrata. They can be used as indicators for floating time of objects such as plastic, algae, airplane wrecks or human corpses. Precise estimates of floating time are only possible when accurate growth rates of Lepas are known. However, many factors modulate the growth of these crustaceans, making floating time estimates difficult. In this study, we measured growth rates of L. australis and L. anatifera in the Central Humboldt Current System over two consecutive summer and winter seasons. Growth patterns were best described by a logistic growth curve. Using the asymptotic value (maximum size) for each species and each season, we selected the linear phase of growth to fit simple predictive linear models to estimate floating time. Growth rates of L. anatifera were almost twice as high in the warmer summer months compared to the winter season suggesting that growth rates are strongly associated with temperature. Consequently, seasonal or regional growth rates are required to precisely estimate floating time of objects at sea.