SCIENTIFIC EDUCATIONAL CENTER science idea

As a result of the analysis of the material collected by 24 expeditions from 1949 to 2019 at depths of 0-3000 m near the Kuril Islands, 16 new and 11 rare species of bivalve mollusks were discovered for the fauna of this region, two of which belong to the genus Adonthorina (family Thyasiridae), described as new to science. A generalization of the results obtained and the literature data showed that 160 species of bivalves were recorded in the area of the Kuril Islands at the depths studied. The data obtained by scientists increased the species richness of the fauna of bivalves of the Kuril Islands by 10% and significantly expanded the geographical distribution and range of habitat depths of 27 species.

The Kuril Islands are one of the centers of speciation in the northwestern Pacific Ocean and the main route of migration of marine organisms from Asia to America and back. The latitudinal zonation of the islands stretching from Japan to Kamchatka, the interaction of cold and warm currents, active volcanic processes, the complex relief of the seabed and other environmental factors create extremely diverse living conditions for aquatic organisms and have a great influence on the composition and distribution of bottom animals, including bivalves. However, despite the great interest of researchers in this region, the fauna and distribution of bivalve mollusks off the Kuril Islands currently remain less studied than in other regions of the northwestern Pacific Ocean. First of all, this is due to the fact that studying the bottom fauna of this region is a difficult task. Collecting zoological material from the ship using dredges and dredges in the area of the Kuril Islands is very difficult due to strong currents and an abundance of stormy days, as well as the complex geomorphology of the seabed with steep rocky slopes and canyons, and rocky outcrops.

Thus, for the entire period of research of the bottom fauna of the Kuril Islands at depths of 1000-3000 m, only 17 samples with bivalves were collected. A scallop. Photo source: NSCMB FEB RAS Active research of marine biota in the Kuril Islands area was started by Russian scientists after the Second World War. In the period from 1949 to 1966. The P.P. Shirshov Institute of Oceanology of the Russian Academy of Sciences (Moscow) conducted 10 expeditions to the northwestern Pacific Ocean, as a result of which a large number of samples of bottom fauna from various depths near the Kuril Islands were collected. However, first of all, animals collected in deep-sea (more than 3,000 m) areas of the Pacific Ocean were studied. Therefore, the materials on bivalves collected at shallower depths were almost not processed. In the period from 1969 to 1971.

The Institute of Marine Biology of the Far Eastern Branch of the Russian Academy of Sciences (Vladivostok) organized 3 hydrobiological expeditions to study the macrobenthos of the shallow-water zone of all the Kuril Islands. During these expeditions, 1,070 samples were collected from depths up to 40 m. In the following years, 13 marine expeditions were organized to study the bottom fauna at depths up to 1000 m in various areas of the Kuril Islands. However, the bivalves from these expeditions remained largely unidentified. As a result of processing all this extensive material (including 1,120 samples with bivalves) collected at depths from 0 to 3,000 m off the Kuril Islands by 24 expeditions between 1949 and 2019, scientists at the A.V. Zhirmunsky National Scientific Center for Marine Biology of the Far Eastern Branch of the Russian Academy of Sciences discovered 16 species new to the marine fauna of this region (Two of which turned out to be new to science species of the genus Adontorhina (family Thyasiridae), as well as 11 rare species, some of which were described from single specimens. This has significantly expanded the geographical and vertical distribution of these 27 species, some of which are included in the diet of commercial fish and marine mammals (the results of this study were published in the journal Zootaxa). An analysis of all previously published and original data has shown that currently the fauna of bivalves of the Kuril Islands at depths of 0-3000 m is 160 species, of which scallops Mizuhopecten yessoensis and Chlamys albida are valuable commercial species. The new data obtained by scientists increased the species richness of the fauna of bivalves of the Kuril Islands by 10%. This study also showed that the fauna of bivalves in the area is well studied up to a depth of 1000 m. Of great scientific interest is the study of bottom fauna at depths over 1000 m, where new species of bivalves are expected to be found, some of which may be endemic to the Kuril Islands. Scallop eyes. Photo source: NSCMB FEB RAS One of the proofs of this assumption is the discovery of two new deep-sea species of Adontorhina inflata and Adontorhina diaphana during the study of the fauna of bivalve mollusks of Kuriles at depths of 788-3432 m (the results of this study were published in the journal Zoologischer Anzeiger).

Species of the genus Adontorhina are interesting because they have a small shell (no more than 4 mm long) with numerous tubercles on the inner side of the shell edge, the number, shape and location of which are unique to each specimen, like human fingerprints. When describing new species, a comparative analysis of shell morphology of all Pacific species of Adontorhina was carried out for the first time. In addition to describing two new species, the authors also provided a detailed description of the widespread Adontorhina cyclia species in the North Pacific Ocean, supplemented with new information about its shell morphology, body anatomy, and distribution in the Pacific Ocean. As a result of this work, the morphological feature of larval shell sculpture was shown to be of great importance for the diagnosis of species of the genus Adontorhina. It is noteworthy that the photographs of the new species given by the authors in the article were used by the editorial board of the journal to design the cover of the volume of the journal where this article was published. The research of the Far Eastern scientists was supported by the Russian Science Foundation (project No. 24-17-00321).

Source of information and photo: NSCMB FEB RAS

The information is taken from the Scientific Russia portal (https://scientificrussia.ru /)