Structure of biocenoses formed on bitumen mounds in the abyssal zone of Lake Baikal

For the first time, a study has been performed on specific small biocenoses of bitumen mounds formed in the region of natural oil seeps in the abyssal zone of Lake Baikal. These biocenoses consist of diatom detritus populated by archaea, bacteria, aquatic fungi, nematodes, and ostracods. Fungi and bacteria decompose petroleum hydrocarbons, thereby contributing to biodegradation of crude oil. Microorganisms together with planktonic diatoms settling onto bitumen form a substrate for invertebrates. It is hypothesized that the cohabitation of three distinctive nematode species ( Eutobrilus mirandus , Monhystera naphthera , and Eumonhystera abyssalis ) in the same bitumen biocenosis is possible due to their different feeding strategies and the presence of bacterial symbionts.