Surface waters are becoming browner throughout the Northern
hemisphere and beyond. While the reasons behind this process are still not
completely understood, it was proved that changes in soil chemistry due to past
acid rain, increased precipitation due to climate change and land use practices
are factors promoting water browning by increasing the release of dissolved
organic matter and other components (e.g. Fe) in run off. We are providing
evidence that the brownification process is altering the biodiversity,
structure and functioning of aquatic ecosystems. Our study location is the Evo
Natura 2000 area, Southern Finland (61°120N, 25°070E). It has a long history of
research projects in forestry and environmental sciences. Long term surveys of
water quality, flora and fauna have been conducted at several lakes providing a
rigorous field knowledge. We tested the link between lake water colors and
invertebrate and duck population parameters. We established that invertebrate
abundance has dramatically decreased as a consequence to brownification. This
result leads to concerns for species which are foraging on aquatic
invertebrates. Fenno-Scandinavian lakes are the most important waterfowl
breeding areas in Europe. Changes affecting waterfowl breeding output might
turn out to have dramatic effects on their whole population.