Evidence for Mutualistic Interactions in Freshwater Oligochaete Communities

Mutualistic interactions between closely related invertebrate species are not much known from the literature and evidence for their existence are rare. Here I present evidence for mutualistic interactions - «reciprocal facilitation» - between oligochaete species forming characteristic species associations in freshwater. These associations are the likely results of species-specific feeding on bacteria colonizing the fecal pellets of the component species. In laboratory tests with the species association Potamothrix moldaviensis and Tubifex tubifex each species grows significantly better when fed upon the fecal pellets of the other species, suggesting mutual advantages