Rapid assessment of marine non-indigenous species on mooring lines of leisure craft: new records in Croatia (eastern Adriatic Sea)

Leisure-craft mooring lines were surveyed in six berthing areas along the Croatian coast during June 2014. The aim of this study was to investigate the presence of non-indigenous species (NIS) on mooring lines known as ‘lazy’ lines. Four NIS were observed during the survey: the tunicate Styela plicata , the serpulid Hydroides elegans and two bryozoans, Celleporaria brunnea , and Amathia verticillata . Three cryptogenic species were also found during the survey: the amphipod Elasmopus rapax , the barnacle Amphibalanus amphitrite , and the bryozoan Watersipora subtorquata . Styela plicata, C. brunnea , and W. subtorquata represent the first records for Croatia. Furthermore, C. brunnea and W. subtorquata are new to the whole Adriatic Sea. All NIS and cryptogenic species were recorded in Biograd na Moru. In addition, S. plicata was also recorded in Zadar. The use of ‘lazy’ lines proved to be a rapid and effective method for recording sessile species and monitoring NIS presence. This method could be undertaken for regular NIS surveys of leisure-craft berthing areas.