Guidelines for the monitoring of mobile and sessile epifauna.

Abstract

The Joint Harmonized Procedure by HELCOM and OSPAR (HELCOM & OSPAR, 2013) has been used to monitor mobile and sessile epifauna among other taxa, but only in port areas, and further observations on the presence of these species have been barely a side-product of other national monitoring programs and research projects. There have not been general guidelines for the monitoring of mobile and sessile epifauna in natural coastal habitats for the Baltic Sea thus far. Habitat collectors and fouling plates have been utilized in many coastal NIS sampling projects (Roche et al. 2009, Fowler et al. 2013; Brzana et al., 2019; Outinen et al., 2019). They provide a standardized and easily repeatable sampling method for crabs, fishes, mollusks and macroinvertebrates with manageable workload. Habitat collectors contain artificial habitat structures that provide refuges for these organisms instead of capturing them. Additionally, sampling of sessile species can be enhanced with PVC fouling plates that provide attachment surfaces for these organisms. These guidelines aim to cover the monitoring of mobile and sessile epifauna in natural coastal habitats. The obtained data provides input for the assessment of the HELCOM core indicator ‘Trends in arrival of non-indigenous species’, which compares the diversity of NIS at pre-selected temporal intervals to a baseline and evaluates the present status relative to previous temporal periods.