Sampling native and non-native mobile epifauna with baited traps and habitat collectors - Port of Gdynia case study (southern Baltic Sea, Poland)

The effectiveness of two artificial habitat collectors, crab condo (HC1) and habitat crate (HC2), providing a refuge for small mobile fauna, was tested along with two commercial baited traps, Chinese box trap (BT1) and Gee's Minnow trap (BT2) recommended for only single deployments under a harmonized survey of the Baltic and the North-East Atlantic. Our objective was also to determine whether a multi-deployment of baited traps in the growing season increases the diversity and abundance of collected mobile epifauna. Nineteen species of benthic mobile epifauna, including six non-indigenous species (NIS), were collected between May and October 2014 using all tested types of traps in the Port of Gdynia (southern Baltic Sea). Crustaceans, represented by 16 taxa, constituted the group with the highest diversity and abundance. Our study showed that HC1 and HC2 are more effective gear than BT1 and BT2, as both species richness (including NIS) and abundance were higher. Furthermore, the double deployment of BT1 and BT2 increased the diversity and abundance of the captured fauna. The use of artificial habitat collectors as an additional method to the already recommended baited traps for mobile epifauna monitoring in ports should be considered and the number of baited trap deployments should be increased during the growing season.