Use of ferrybox measurements for the Baltic Sea environment assessment

The spatially heterogeneous character of aquatic life and rapid changes in pelagic communities make it difficult to assess the status of the marine environment using traditional monitoring methods. In order to distinguish between human induced and natural changes in the ecosystem the environmental parameters and the factors affecting them need to be monitored at a wide range of temporal and spatial scales. The capacity of any single monitoring method or strategy should not be overestimated. Instead, different methods complement each other. In the Baltic Sea high frequency recordings of phytoplankton biomass and related environmental parameters (temperature, salinity, nutrients, chlorophyll a) in the near surface layer (4-5m) have been conducted with unattended water sampling onboard several commercial ferries over the last 14 years. The collected data have been used for delivery of almost on-line information for environmental authorities and public, for developing HELCOM indicator fact-sheets and indexes/maps characterising inter-annual and short-term changes of productivity and phytoplankton biomass in different sea areas, and for forecasts of algae blooms. The combination of high frequency automated sampling onboard merchant ships with satellite imagery, traditional sampling and meteorological information has increased the understanding of ecological processes in the Baltic Sea.