Boreal aquatic ecosystems with forested and peatland catchments naturally receive high loads of terrestrial organic matter. Moreover, catchment management of carbon rich soils, particularly forestry operations and peat mining, may greatly add to the load of organic humic matter. To some extent, bacteria and microbial food webs in lakes can take nutritional advantage of terrestrial organic carbon. Bacteria, however, are poor-quality food for upper trophic levels.
Organic matter deposition also impacts on lake phytoplankton, which produce polyunsaturated fatty acids that are beneficial for the whole food web as well as for human health and that are not produced by bacteria. Organic matter and sediment that is washed into waterways may also contain mercury, which in anoxic conditions is easily methylated into poisonous methyl mercury.
TERLA is a multidisciplinary research consortium aimed at establishing the effects of terrestrial organic carbon on lake food webs – phytoplantkon, bacteria, zooplankton, fish – as well as on the health of fish-consuming humans. Questions associated with organic carbon deposition are addressed using the methods and expertise of limnology and ecotoxicology, forestry, public health and environmental law.
A further aim is to produce scientific evidence that will provide a more accurate assessment of the effectiveness of environmental regulation. The research methods include modelling of terrestrial organic carbon loading, analysis of databases compiled by different research institutes, food web experiments, measurements and analysis of selected variables at different levels of the food web and in fish-consuming humans, as well as a legal dogmatic approach.
The consortium involves three projects:
1. Lake ecosystem responses (principal investigators Docent Paula Kankaala, Dept of Biology, University of Eastern Finland; Sirpa Piirainen, Doctor of Agriculture and Forestry, Finnish Forest Research Institute; and Docent Marko Järvinen, Finnish Environment Institute)
2. Human health impacts (principal investigator Professor Tomi-Pekka Tuomainen, Institute of Public Health and Clinical Nutrition, University of Eastern Finland)
3. Environmental regulation (principal investigator Ismo Pölönen, PhD, Dept of Law, University of Eastern Finland)