Browsing by Author "Pipinis Troupakis, Michail"

Climate change and overexploitation are an increasing threat in marine ecosystems as human activities have risen over the past decades. One of the main tools for protecting biodiversity and ecosystem functions is the designation and implementation of Marine Protected Areas (MPAs). Despite their potential for conservation, recent assessments question the effectiveness of MPAs to conserve ecologically resilient ecosystems. In this thesis, I aim to assess the effectiveness of MPAs in Finland using long-term phytoplankton data, which have been collected for almost 60 years (1960-2020) in the Finnish territorial waters from over 700 sites and contain 991 different phytoplankton taxa. Phytoplankton is the basis of marine food networks and thus shifts in phytoplankton communities can affect higher trophic levels. I compared the total biomass, species richness and species diversity of the phytoplankton communities between protected and unprotected sites. To control for the confounding effects of environmental variables that affect phytoplankton biomass and distribution, and to isolate the effect of protection, I employed nonparametric distance matching; essentially, this process selects comparable pairs of samples from protected and unprotected sites. I found that even though there was a general increase in species diversity with time, protection had no effect on phytoplankton biomass, species richness or species diversity. The size and age of the MPAs did not affect the protection outcomes. However, strictly protected MPAs harbored lower biomass compared to unprotected sites, which could indicate that MPAs can help reduce the effects of eutrophication. These results suggest that MPAs in Finland still have room to be improved and there is a need to accurately assess their effectiveness in order to successfully safeguard biodiversity. Considering the phytoplankton component during the designation and planning of the MPA network in Finland could be valuable for marine conservation.