Vol 43, No 1 (2017)

Until recently, the general biodiversity concepts have suggested common patterns of species richness dynamics for both small planktonic and large benthic organisms in the gradients of environmental factors, including salinity, which is the major abiotic characteristic that influences the diversity of flora and fauna in coastal marine ecosystems. Recent studies discovered an extremely species-rich aquatic microworld and resulted in proposing new concepts and shifting the paradigms in biodiversity studies, including those on planktonic unicellular eukaryotes such as protists. As a result, Remane’s species-minimum concept has been revisited and the range of its application updated. This paper provides a review of the studies dedicated to establishing, developing, and analyzing the novel protistan species-maximum concept for the critical salinity zone (5–8‰), or the horohalinicum. The obtained new data contribute to the formation of the modern views on aquatic ecosystem dynamics, biodiversity conservation, and effective ecological management aimed at maintaining the environmental balance and the rational use of marine biological resources.

The benthic fauna of ostracods of the order Myodocopida of Antarctic waters is characterized by high diversity, relative species abundance, and a complicated taxonomic and ecological structure, with a simplified biogeographical structure. This fauna, which is distinguished by a high level of endemicity, although at a low taxonomic rank, includes a great share of deep-sea and subtidal elements. Ostracod populations of High and Low-Antarctic subzones differ qualitatively and quantitatively. A distinct impoverishment of fauna is observed in the region of the Antarctic divergence compared to the more northern areas. The number of species increases with depth to reach its maximum in the lower subtidal zone and on the upper continental slope at depths of 200–500 m. The number of species decreases with increasing depth. Myodocopida have not been yet found in the Antarctic waters deeper than 5000 m.

Molecular phylogenetic tools are often useful in distinguishing cryptic species with similar morphologies, but they can also be helpful in identifying morphotypes of a species, which displays completely different shapes. We performed molecular-phylogenetic analysis of supra-tidal green algae in the Kamchatka peninsula that belong to the order Prasiolales (Trebouxiophyceae, Chlorophyta). Based on rbcL sequences results, two new species were recorded for the first time in Kamchatka. Approximately 1.4% of the field-collected Rosenvingiella constricta had a unique uniseriate hood-like blade shape, although their rbcL sequences were 100% identical with typical multiseriate filamentous plants. Kamchatka’s population of R. constricta showed 99.4–99.6% identity in rbcL sequences with the populations from Canada and New Zealand. Another similar-looking Rosenvingiella species collected from the same locality had 93.5% identity of the rbcL gene sequence with R. constricta. Morphological and geographical analyses also suggested that this species might be a new species of the genus Rosenvingiella. Prasiola delicata was recorded for the first time in Kamchatka. The Kamchatka population of P. delicata showed 100% identity in rbcL gene sequence with the population from Vancouver, but differed from the Canadian population morphologically.

We examined the structure of the tegument surface of the acanthocephalan Corynosoma strumosum and its surrounding capsule in paratenic hosts: the notched-fin eelpout Zoarces elongatus (Kner, 1868) and the Pacific halibut Hippoglossus stenolepis (Schmidt, 1904). In both cases, the capsules are “leucocytic” and have, in general, a similar structure but with a few peculiarities. Some of them are evidently caused by the different ages of capsules and others may be connected with the species of the host. The tegument surface of C. strumosum from eelpout is covered with a thick layer of glycocalyx, which is absent in acanthocephalans from halibut. The results suggest that the acanthocephalan C. strumosum is more adapted to the eelpout Z. elongatus and to the sculpin Myoxocephalus stelleri than to flatfish.

Based on the changes in the species composition, abundance, and species richness of benthic foraminiferal assemblages in sediments of the northwestern Pacific, we reconstructed the paleoenvironment (paleoproductivity and near-bottom water ventilation) during the period of 8000–19000 calendar years ago (ka). A moderate seasonal productivity of the surface water, a relatively high oxygen content of the near-bottom water, and the influence of sea ice occurred during the Last Glacial Maximum in the studied area. An increased primary production and suboxic conditions in the near-bottom water were typical of the cold Heinrich 1 event (17.5–14.7 ka). A further increase in surface-water productivity and a decrease in oxygen content of the near-bottom and pore waters have been reconstructed for the second half of the Bølling/Allerød interstadial (14.7–12.8 ka) and the Pre-Boreal (11.8–9.2 ka). Surface water productivity decreased and oxygen saturation of the near-bottom water increased during the Younger Dryas (12.8–11.8 ka). In the Middle Holocene, the total decrease in productivity led to an increased oxygen content of the near-bottom and pore waters.

This study focuses on the strategy for the conservation of masu salmon, Oncorhynchus masou, in the northern part of the species range (via the masu populations in Sakhalin Oblast), based on data of its population structure. It is shown that masu populations that inhabit different rivers genetically differ from each other in allele frequencies at microsatellite markers. In the Naiba River basin, at least two genetically distinct masu populations exist: in the upper reaches and in a tributary, the Bolshoy Takoy River. The masu populations on Iturup Island significantly differ from those on Sakhalin Island; within Sakhalin, the masu salmon from the Chernaya River in the southwestern part of the island is genetically distinct from the southeastern Sakhalin and Aniva Bay populations. The genetic diversity of Iturup populations is substantially lower than that on Sakhalin, probably due to their small sizes. The measures for the conservation and recovery of masu salmon populations should be based primarily on their own genetic resources, or, in the case of a lack of spawners, on the base populations of their ecological/geographical region. In the latter case, masu populations of large rivers can be considered as base ones: for southeastern Sakhalin, this is masu salmon of the Naiba River; for Aniva Bay, this is masu salmon of the Lyutoga River. Transplantation of fish, fertilized eggs, or any other genetic material from a population that is different genetically and inhabits the waters with different ecological gradients should be strongly restricted. The formosan masu salmon from Taiwan Island is studied as an example of a strict genetic isolate.

The description of the Pacific long-nosed chimaera Rhinochimaera pacifica (length 100 cm), which was first caught in Russian waters off the Southeastern coast of Sakhalin Island, is given.