Molecular identification of filamentous cyanobacteria overgrowing the endemic sponge Lubomirskia baicalensis

In recent years, the surfaces of endemic Baikalian sponges have exhibited signs of damage and disease such as tissue bleaching, atypical microbial films, and necrotic areas. One of the most common sources of damage on branching sponges Lubomirskia baicalensis is a reddish-brown mucous film fully or partially covering the body of the sponge. Sequencing of the 16S rDNA gene revealed that the film on the surfaces of the sponge consists of Oscillatoriales cyanobacteria belonging to the following genera: Tychonema, Phormidium, and Leptolyngbya, with 44 of the 86 identified sequences belonging to Tychonema. Cyanobacterial fouling of the Baikalian sponge may be caused by changes in environmental conditions of the sponge habitat, in particular, temperature increases and eutrophication of the lakes.