In this study, we tested the effect

In this study, we tested the effect of the extracts and exu- dates of Microcystis aeruginosa (toxic strain FACHB-905) on the seed germination and early seedling growth of the submerged macro- phyte species Potamogeton malaianus. M. aeruginosa is one of the most common (with a worldwide distribution) and harmful bloom- forming cyanobacterial species (e.g., Fogg, 1969; de Figueirdo et al.,
2004) that can completely dominate the summer phytoplankton in lakes (e.g., Liu et al., 2011). P. malaianus is or has often been the dom- inant macrophyte species in Chinese shallow lakes (Sun, 1992). In many lakes, e.g. Lake Dianchi, eutrophication was associated with a major decline in submerged vegetation (Gong et al., 2009; Lu et al.,
2012). P. malaianus is one of the few species that can persist in small stands in very nutrient-rich Chinese lakes (Lu et al., 2012). It germi- nates in May (Xiao et al., 2010) and thus potentially interacts with the cyanobacteria blooms which have been reported, for instance, at Lake Dianchi and Lake Taihu from April to October (with peak occurrences in June, July and/or August) since 1990 (Sheng et al.,
2012; Song et al., 2007). We hypothesize that M. aeruginosa can allelopathically inhibit the germination of submerged macrophyte seeds and the growth of early seedlings, and may thus contribute to the complex process of vegetation loss and failure of recovery in eutrophic lakes.