Investigation of Tychonema sp. tropism to the sponge body in the experiment of co-cultivation of cyanobacteria with primmorphs

Abstract

Mass death of endemic sponges accompanied by the growth of cyanobacterial biofilms on their bodies has been registered in recent years in Lake Baikal. These biofilms are formed by the cyanobacterium Tychonema sp., which grows on various types of substrates in the littoral zone and is often found on sponges. The aim of the study was to conduct an experiment on co-cultivation of Tychonema sp. with Baikalospongia sp. primomorphs to test the hypothesis about the tropism of Baikal cyanobacterium to the body of sponges. In the experiment, gradual fouling of the primmorphs with cyanobacterium filaments, destruction of their structure and death of sponge cells were registered. In the control without addition of cyanobacteria, the primmorphs remained alive during the whole time of the experiment.