TESTING THE APPLICABILITY OF TRAIT-BASED FUNCTIONAL DIVERSITY IN PHYTOPLANKTON COMMUNITIES AS A TOOL FOR WATER QUALITY MONITORING

Károly Pálffy, Lajos Vörös, Centre for Ecological Research, HAS, Balaton Limnological Institute, Hungary

Abstract

Studying the effect of changes in the environment on water quality has a long history, however, our knowledge on the complex relationships underlying these impacts is rather limited. Investigating phytoplankton communities, as the main sources of aquatic primary production from a functional point of view has the potential to provide additional information about water quality-related ecosystem processes and responses to changes in the environment. On the other hand, in order to recognize and interpret long-term environmental changes, there is a growing need for gathering data on ecosystems at a broad geographical and temporal scale.
Considering the above, our study aimed at revealing temporal patterns in the functional diversity of phytoplankton and finding links between the observed changes and environmental parameters in the framework of the EnvEurope Life+ project (“Environmental quality and pressures assessment across Europe”). The project proposes a design for environmental high quality monitoring sites and the exemplary establishment of common parameter sets to be collected across the LTER-Europe (Long-Term Ecosystem Research) network.
The functional classification of planktonic algae can be realized in the context of various ecologically relevant traits of the species present in a community, such as cell size, the surface to volume ratio, photosynthetic pigment composition, N2-fixation, phagotrophy, the degree of organisation (unicell, filamentous, colony-forming) or motility. After assigning trait values to each species, there is a wide range of methods for multivariate analysis to determine functional groups and diversity within the algal assemblages. Our preliminary results on the phytoplankton communities in Lake Balaton, Hungary have pointed out that the variability in functional diversity is more sensitive to ecological processes than a traditional taxonomic measure of diversity. Moreover, we found a significant negative relationship between functional diversity and trophic state. All these findings suggest that the applied index could be a promising tool for revealing and monitoring changes in community functioning and an effective contribution to indicating water quality changes. In the next step of our study the analysis will be extended to several freshwater and marine sites of the EnvEurope project with various geographical location, size, depth and physico-chemical characteristics, enabling us to test the functional approach of phytoplankton diversity on a European scale.