Vol 44, No 5 (2018)

Information on diatoms of the genus Pseudo-nitzschia, known as producers of domoic acid (DA), from the North Pacific is summarized. The differences in the negative impact of toxic diatoms on ecosystems in the western and eastern North Pacific are shown. The possible causes that determine the degree of these different impacts are discussed: a different composition of dominant species; a difference in the intracellular DA concentration in bloom-forming species; the hydrological, climatic, and hydrochemical factors that are responsible for the formation of toxic blooms (upwelling events, patterns of water circulation, concentration of iron compounds in sea water, etc.). The conclusion is made that the prospects of further studies of toxic diatoms are based on comparative investigations into the species and genetic diversity of Pseudo-nitzschia and associated bacteria, as well as the environmental parameters that control the formation of toxic blooms and the accumulation of DA in microalgae and other marine organisms in the eastern and western North Pacific.

A new genus and new species of semnoderid kinorhynchs, Parasemnoderes intermedius gen. nov., sp. nov. collected from the abyssal plane at the south border of the Kuril-Kamchatka Trench at the depth 5348 m is described and illustrated using light and electron microscopy. This new representative of the family Semnoderidae is characterized by the structure of the first trunk segment consisting of externally closed cuticular ring with indistinct intracuticular tergosternal junctions. Cuticular ring of the first trunk segment is with deep and narrow middorsal incision and much broader midventral incision filled by midventral placid. Lateroventral spines aciculate, on trunk segments 3–9. Lateroventral accessory spines are minute, only on trunk segment 5. Laterodorsal spines on trunk segment 10. Parasemnoderes intermedius gen. nov, sp. nov. constitutes the third genus the Semnoderidae described so far (Semnoderes and Sphenoderes) and the first species of this family described from the abyssal depth. The total species number of the family Semnoderidae has been increased up to 6. A key to the species of the family Semnoderidae is proposed.

The modification of the structure of the subtidal phytocoenosis was investigated along the gradient of the concentration of nutrients brought with sewage effluents into the Sukhoputnaya Bay (Ussuriisky Bay, the Sea of Japan). It was shown that an increase in the concentration of dissolved inorganic nitrogen (DIN) from 4.2 to 16.6 μM was followed by a decrease of 1.7 times in species richness, while the relative biomass of opportunistic species increased simultaneously by more than 1.5 times and by more than 5 times for Ulva lactuca. A decrease in the number of dominant species and in the number of layers in the structure simplified the algal phytocoenoses. The complex polydominant multi-layered phytocoenosis of Stephanocystis crassipes–Laurencia nipponica + Ulva lactuca–Ahnfeltiopsis flabelliformis was first substituted for a bidominant two-layered phytocoenosis of Stephanocystis crassipes–Tichocarpus crinitus, and further by a one-layer monodominant phytocoenosis of Ulva lactuca. A comparison of our own and published data allows us to conclude that complex phytocoenoses of perennial macrophytes can develop in water areas with DIN concentrations that do not exceed 15 μM.

The levels of thyroid hormones (total thyroxine, free thyroxine, and total triiodothyronine) in the blood serum of the Caspian seal Pusa caspica are reported for the first time. The serum levels of thyroid hormones in Caspian seal were comparable to those in the harbor seal Phoca vitulina. An increased plasma level of total thyroxine was found in seals during the molting season. A tendency toward an increase in free thyroxine levels was observed in adult females in the autumn. In contrast to the data for the harbor seal, in our research there were only two cases when measured levels of thyroid hormones in the blood serum of Caspian seals dropped below the threshold.

The aim of the present study was to assess the antiviral and larvicidal property of the marine actinobacterial compound extracted from Nocardia alba KC710971. The compounds were tested against the Newcastle disease virus and infectious Brucellosis disease virus and the larvae of Aedesegypti, Culexquinquefasciatusand Anopheles stephensi. The isolated bioactive compound have showed potential to act as antiviral and anti-larval and the compound was identified as “(Z)-1-((1-hydroxypenta-2,4-dien-1-yl)oxy)anthracene-9,10-dione”.

Sex-independent characters for identification of Gymnocanthus pistilliger and G. galeatus in their cohabitation areas were revealed: the presence, position, and arrangement of rough bony plates on the interorbital space, as well as the total spine and ray count for all fins (dorsals and anal; doubled number of rays in pectoral). The interorbital space of G. galeatus is completely covered by bony plates; the spine and ray count for all fins is 82−89. In G. pistilliger, the interorbital space is naked (26%) or has only a few bony plates that never extend onto the rim of the orbit; the spine and ray count for all fins is 74−81. In the eastern part of the Sea of Okhotsk, G. galeatus is not common and perhaps might be found here only occasionally.