The role of coastal accumulations of the Spirogyra spp. filamentous algae as a methane source in the littoral zone of Lake Baikal

Abstract

Excessive input of nutrients is one of the main causes of large-scale blooms of benthic algae in the coastal zone of water bodies, which has significant deleterious effects on biodiversity, abundance, and biomass of benthic littoral community. The decay of massive coastal accumulations of benthic algae can lead to secondary pollution in the littoral zone as well as be a source of methane, the second most important greenhouse gas. We experimentally studied methane production during decomposition by native microbial community of algal biomass of the Spirogyra spp. coastal accumulation from Lake Baikal. Methanogenesis was recorded both in the absence of additionally introduced biogenic elements and under elevated concentrations of phosphates. Under mesophilic temperature conditions (24 ° C and 37 ° C), the methane yield was 0.005-0.006 m 3 CH 4 kg − 1 of the algal dry weight. Among the methanogens, we detected the members of the genera Methanobacterium and Methanosphaerula