LITTORAL SPECIES DIVERSITY AND BIOMASS: CONCORDANCE AMONG ORGANISMAL GROUPS AND THE EFFECTS OF ENVIRONMENTAL VARIABLES
Kimmo T. Tolonen1, Ismo J. Holopainen2, Heikki Hamalainen1, Minna Rakhola-Sorsa1, Pasi Ylostalo4, Krista Mikkonen2 and Juha Karjalainen3 1Department of Ecology, Karelian Institute, University of Joensuu, P.O. Box 111, FIN-80101 Joensuu, Finland; 2 Department of Biology, University of Joensuu, P.O. Box 111, FIN-80101 Joensuu, Finland; 3 Department of Biological and Environmental Sciences, University of Jyvaskyla, P.O. Box 35, FIN-40351 Jyvaskyla, Finland;4 Finnish Environment Institute, P.O. Box 140, FIN-02251 Helsinki, Finland (e-mail: kimmo.tolonen@ymparisto.fi)


OBJECTIVES: The aim of this study is to find out hotspots or habitat patches of high diversity and biomass that are common to six groups of aquatic organisms within a single large lake system.

METHODS: Biomass and species diversity (richness and evenness) of littoral organisms were explored in 27 sites in three basins of the large Lake Symaa system in eastern Finland. The basins differed in degree of nutrient loading and trophic status. Six organismal groups, i.e., phytoplankton, periphyton, macrophytes, crustacean zooplankton, benthic macroinvertebrates and fish were studied. 

RESULTS: Factors affecting the biomass of these groups were explained by the same variables, mainly nutrients while diversity was associated with different environmental factors among the studied groups. The biomass of periphyton, phytoplankton, zooplankton and fish correlated significantly with each other. There was also an apparent association between the biomass of macrophytes and that of benthic invertebrates. However, no significant correlations were found among the diversity of the studied groups. In accordance with previous studies, our result did not support the existence of species-rich hotspots or possibility of using any surrogate taxon to reveal overall biodiversity.

CONCLUSIONS: For conservation planning, biological surveys should include extensive collection of taxonomic groups and organisms at all tropic levels.

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