Wilhelm Granéli,
Professor emeritus

My research focus is on “brownification” (browning) of streams, lakes and coastal waters. Many fresh waters, but also brackish coastal waters, are more or less strongly brown colored by terrestrial humic matter, both in temperate and tropical climate zones. During the last few decades there has been a marked increase in this coloring of surface waters in northern Europe and North America. Since brownification causes a deterioration of the light climate and adds organic matter that is the substrate for bacteria, it is a process that has profound effects on aquatic ecosystems, including ecosystem services as recreation, fishing and drinking-water supply. In a multidisciplinary project we are trying to find the cause of brownification and its effect on aquatic ecosystems. We use paleolimnology to reconstruct past water color as well as catchment vegetation, for lakes in S Sweden. In field experiments the effects of acid deposition (SO4) on soil water color has been studied.

Through comparison of lakes in a color gradient and experimental studies we have investigated effects from brownification on lake thermal stratification, light climate and phytoplankton species composition and the balance between production and respiration.

I have also been studying freshwater crayfish ecology, especially population development and production of the introduced North American signal crayfish (Pacifastacus leniusculus). Populations show more or less dramatic fluctuations, but the underlying mechanism is still unknown. Temperature during critical phases in the life cycle may be an explanation. We have used modeling and long-term catch data to test this hypothesis.

Additional interest is the Baltic Sea: how should eutrophication be combated? Which nutrient should be reduced and can lake-type restoration approaches, e. g. mixing/aeration, chemical sediment treatment and fish manipulation be used?

Earlier in my limnological life I studied sediment respiration, e. g. effects of bioturbation and temperature, and the exchange of nutrients between sediment and water. I have also worked with reed, Phragmites australis, its ecology and possibilities to use reed as a biofuel.

I am examiner for the PhD-program in Limnology and Marine Ecology and serve as teacher on undergraduate courses in aquatic ecology.

Selected publications

von Einem, J. and Granéli, W. 2010. Effects of fetch and dissolved organic carbon on epilimnion depth and light climate in small forest lakes in southern Sweden. Limnol. Oceanogr. 55:920-930

Olsson, K., Graneli, W., Ripa, J. And Nyström, P. 2010. Fluctuations in harvest of native and introduced crayfish are driven by temperature and population density in previous years. Can. J. Fish. Aquat. Sci. 67:157.164

Stenroth, P., Holmqvist, N., Nyström, P., Berglund, O., Larsson, P. and Granéli, W. 2008. The influence of productivity and width of littoral zone on the trophic position of a large-bodied omnivore. Oecologia. 156:681-690

Säwström, C., Graneli, W., Laybourn-Parry, J. and Anesio, A. M. 2007. High viral infection rates in Antarctic and Arctic bacterioplankton. Environmental Microbiology. 9:250-255

Daniel, C., Granéli, W., Kritzberg, E. S., and Anesio, A. M. 2006. Stimulation of metazooplankton by photochemically modified dissolved organic matter. Limnol. Oceanogr. 51:101-108

Anesio, A. M., Granéli, W., Aiken, G. R., Kieber, D. J. and Mopper, K. 2005. Effect of humic substance photo degradation on microbial growth and respiration in lake water. Applied and Environmental Microbiology. 71:6267-6275

Daniel, C., Gutseit, K., Anesio, A. M. and Granéli, W. 2005. Microbial food webs in the dark: independence of lake plankton from recent algal production. Aquat. Microb. Ecol. 38:113-123

Kritzberg, E. S., Cole, J. J., Pace, M. L., Graneli, W. and Bade, D. L. 2004. Autochthonous versus allochthonous carbon sources to bacteria: Results from whole-lake 13C addition experiments. Limnol. Oceanogr. 49:588-596

Granéli, W., Lindell, M. and Tranvik, L. 1996. Photooxidative production of dissolved inorganic carbon in lakes of different humic content. Limnol. Oceanogr. 41:698-706

Granéli, E., Wallström, K., Larsson, U., Granéli, W. and Elmgren, R. 1990. Nutrient limitation of primary production in the Baltic Sea Area. Ambio 19:142-151

Book chapters

Graneli, E. and Graneli, W. 2008. Nitrogen in inland seas. In: Capone, D., Bronk, D. A., Mulholland, M. R. and Carpenter, E. J. Nitrogen in the marine environment, 2nd edition. Academic Press, pp. 683-704.

Popular-scientific articles

Granéli, W. 2006. Ekologisk ingenjörskonst för Östersjön – inget att rekommendera. – In Östersjön – hot och hopp pp 91-100, FORMAS Fokuserar, FORMAS, Stockholm 2006, ISBN 91-540-5970-4 (in Swedish).

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