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Allelopathy is defined as direct or indirect biochemical interactions among primary producers (including macrophytes, microalgae...) and potentially also micro-organisms, mediated through release of allelochemicals by primary producers. Allelopathy explains dominance of species over others or changes in the structure of communities that cannot be understood by the mechanisms of competition or trophic interactions alone. In lakes, allelochemical interactions occur in all primary aquatic producer groups in pelagic, benthic and nearshore areas. Few microalgae and macrophytes species have been studied so far and the phenomenon of allelopathy remains underestimated. Such approaches are necessarily integrative and multidisciplinary, with studies that are carried out in microcosms, mesocosms and in natura. Our current research aims at focusing on:

1. Allelochemical phytoplankton interactions. The communities in the lakes are diverse and are characterized both by their seasonal successions and by hyperdominance patterns or blooms. As example, cyanobacterial blooms are often associated with a loss of phytoplankton biodiversity in relation to cyanotoxin. In Lake Bourget (France), the filamentous and toxic Planktothrix rubescens produces microcystins during its proliferation and asks the question of its allelopathic potential.
2.  Allelochemical macrophytes-macrophytes and macrophyte-microorganisms interactions. In littoral zone, such interactions are important to take into account in restauration or renaturation programs (e.g. Thypha) but also to explain alien or native plant dominance (e.g. Myriophyllum).

Finally, we are also involved in studying how environmental changes (pollutants, climate warming…) may also able to disturb such interactions and in fine some lake ecosystem functions.