Temporal development of coastal ecosystems in the Baltic Sea over the past two decades

Coastal areas are among the most biologically productive aquatic systems worldwide, but face strong and variable anthropogenic pressures. Few
studies have, however, addressed the temporal development of coastal ecosystems in an integrated context. This study represents an assessment of
the development over time in 13 coastal ecosystems in the Baltic Sea region during the past two decades. The study covers between two to six
trophic levels per system and time-series dating back to the early 1990s. We applied multivariate analyses to assess the temporal development
of biological ecosystem components and relate these to potential driving variables associated with changes in climate, hydrology, nutrient
status, and fishing pressure. Our results show that structural change often occurred with similar timing in the assessed coastal systems.
Moreover, in 10 of the 13 systems, a directional development of the ecosystem componentswas observed. The variables representing key ecosystem
components generally differed across systems, due to natural differences and limitation to available data. As a result of this, the correlation between
the temporal development of the biological components in each area and the driving variables assessed was to some extent area-specific. However,
change in nutrient status was a common denominator of the variables most often associated with changes in the assessed systems. Our results,
additionally, indicate existing strengths as well as future challenges in the capacity of currently available monitoring data to support integrated
assessments and the implementation of an integrated ecosystem-based approach to the management of the Baltic Sea coastal ecosystems