Biologists from St Petersburg University are the first in the world to study snails from the northernmost chemosynthetic communities of the Pacific Ocean

Gastropods found in different restorative communities of the Bering Sea
Gastropods found in different restorative communities of the Bering Sea

Chemosynthetic, or recovery, communities are marine ecosystems in which living organisms obtain energy from inorganic or simple organic compounds, such as methane. Such communities are unevenly distributed on the ocean floor – as a rule, in places of geothermal vents or accumulations of submerged wood, the density of settlement of such marine organisms is high, despite the great depth.

The results of the study, supported by a grant from the Russian Science Foundation, were published in the scientific journal Deep Sea Research Part II: Topical Studies in Oceanography.

During expeditions on the research vessel Akademik M.A. Lavrentiev in 2016 and 2018, biologists from the National Scientific Center for Marine Biology of the Far East Branch of the Russian Academy of Sciences took samples of benthic fauna for the first time in two chemosynthetic regions of the Bering Sea: on the underwater Piipa volcano and methane seeps of the Koryak slope Chukotka Peninsula. Then gastropods from these flights were transferred to St. Petersburg University for study by biologists.

Piip Volcano is an underwater volcano at a depth of 368–495 meters, a zone of geothermal activity, where, along with the release of a mixture of volcanic gases, an increase in water temperature is also observed. Methane seeps located at a depth of 400 to 700 meters, on the contrary, are not associated with volcanic activity; methane seeps may indicate accumulations of this element in bottom sediments. These are the northernmost regions in the Pacific Ocean, based on chemosynthesis – a method of nutrition in which the oxidation reactions of inorganic compounds serve as an energy source for organisms.

According to Ivan Nekhaev, senior researcher at the Department of Applied Ecology at St Petersburg University, during the expedition of the research vessel Akademik M.A. Lavrentyev, scientists managed to find 27 species of shell gastropods in these areas – at least six of them belong to species new to science. , and five species are new to the fauna of the Bering Sea and adjacent areas of the Pacific Ocean.

Experts from St. Petersburg State University, the Zoological Institute of the Russian Academy of Sciences, the A.N. Severtsov Institute for Ecology and Evolution Problems of the Russian Academy of Sciences, and the P.P. Shirshov Institute of Oceanology of the Russian Academy of Sciences took part in the scientific work. The study of samples was carried out on the basis of the Science Park of St. Petersburg State University: at the interdisciplinary scientific center “Nanotechnologies”resource center “Development of molecular and cellular technologies”as well as in the center for collective use of equipment “Chromas”. The work was supported by a grant from the Russian Science Foundation No. 21-74-00034.

“Notably, nine new species have been found at Piipa Volcano, including two taxa found only in chemosynthesis-based communities. One of them – Parvaplustrum wareni – is already described us, a description of another, belonging to the genus of sea snails Provanna, is currently being prepared,” explained Ivan Nekhaev, senior researcher at the Department of Applied Ecology at St. Petersburg State University.

Mollusk Buccinum kashimanum, Piip volcano, depth 376 m. Photo taken by NSCMB FEB RAS staff using the Comanche 18 submersible
Mollusk Buccinum kashimanum, Piip volcano, depth 376 m. Photo taken by NSCMB FEB RAS staff using the Comanche 18 submersible

The reasons for the abundance of mollusks in one zone and their small number in another, according to Ivan Nekhaev, can indicate both the different ages of ecosystems and the features of their formation. Most of the discovered species do not have a full-fledged dispersal stage in their life cycle, that is, it is difficult for them to disperse far to the north. Therefore, the methane seeps of the Koryak slope remain populated completely or predominantly by “background” species, which cannot form such large aggregations as on the Piipa volcano.

According to the St Petersburg University expert, now scientists have to determine the distinctive features of the found species, because some of their properties may be useful for understanding the evolution of marine ecosystems. The study of the material selected during the expeditions was carried out in the laboratory of macroecology and biogeography of St. Petersburg State University, as well as on special equipment in resource centers Science Park of St. Petersburg State University.

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