The importance of bacterial film composition for germination of zoospores of the green alga Ulva

Conference poster, 2014

The green macroalga Ulva is a worldwide known and distributed fouling organism on ship hulls. The initial rate of germination is a critical process in macroalgae as it contributes to the success of colonization. The germination process is essential for the survival of settled zoospores and has consequences in relation to competition for space on surfaces with other fouling organisms. In this study the role of bacteria for germination and initial growth of zoospores from the green alga Ulva was investigated. The presence of a bacterial biofilms was seen to enhance germination. Further the influence of different bacteria biofilm composition was investigated using natural bacterial assemblages. The natural assemblages contained different proportions of Alphaproteobacteria, Gammaproteobacteria and Bacteriodetes and were analyzed/ characterized with the Fluorescent in Situ Hybridisation (FISH). More zoospore germination occurred on biofilms with a high proportion of Gammaproteobacteria. The possible consequences of different bacterial densities and community composition for Ulva spore germination are discussed.