Vol 44, No 2 (2018)

The activity of microorganisms is a decisive factor in the transformation of the essential and, at the same time, toxic selenium (Se) in marine waters. This review provides an analysis of the literature data on the microbiological regulation of the state of Se in marine waters: the role of microorganisms in eliminating toxic Se from marine waters through precipitation of reduced Se forms and in the reverse process, transformation of Se into a form available to be taken up by organisms and involvement of this element in the biogeochemical cycle. The processes of transformation of the oxidized and reduced Se forms with the participation of microorganisms in marine waters are considered. It has been shown that in anaerobic conditions bacteria use the oxidized Se forms as electron acceptors (reduction). Bioavailable selenite and selenate ions are formed in the case of aerobic oxidation. Biotransformation of dissolved Se is a key mechanism for the formation of methylated gaseous Se forms in marine waters as one of the ways to remove this element from the aquatic environment.

The parasitic fauna of common species of hermit crabs was investigated in Vostok Bay (the northwestern Sea of Japan). Pagurus proximus and Areopaguristes hirsutimanus had no parasites. The average prevalence of rhizocephalan infestation in other five species of hermit crabs ranged from 5.67 to 20.83%. The prevalence of the isopod Parapseudione lata on hermit crabs did not exceed 1%, the prevalence of infestation with the isopod Athelges takanoshimensis was significantly higher, reaching 14.58% in Pagurus middendorffii. Parasitism by the isopod P. lata on the hermit crabs Pagurus minutus and P. ochotensis, as well as parasitism by the rhizocephalan Peltogaster reticulata on P. minutus were recorded for the first time. Several variants of simultaneous infestation with two parasitic species were found. The decline in the abundance of P. middendorffii accompanied by the high prevalence of parasites, primarily the colonial rhizocephalan Peltogasterella gracilis, suggests that parasite invasion may play a more significant role in regulating the abundance of hermit crabs than was previously assumed.

The taxonomic status of the horse mackerel, Trachurus mediterraneus ponticus (Aleev, 1956), which inhabits the Black Sea, has been clarified based on the analysis of variation in the nucleotide sequence of the mtDNA cytochrome b (Cyt-b) locus. A comparison of this species with the horse mackerel from the Mediterranean basin and the World Ocean has shown that the Black Sea horse mackerel is neither an independent species nor a subspecies and can only be qualified as the species Trachurus mediterraneus (Steindachner, 1868) distributed throughout the Mediterranean Sea basin. A hypothesis has been made about the possible cause of the origin and existence of two forms, “large” and “small”, of the horse mackerel. By using the technique of calculating ontogenetic trajectories, it has been found that these are two morpho-ecological forms, whose differentiation is most likely determined by the type of feeding.

The effect of pentacyclic guanidine alkaloids monanchomycalin B, monanchocidin A and normonanchocidin A isolated from the Far-Eastern marine sponge Monanchora pulchra was investigated towards the activity of exo-β-1,3-D-glucanase from the filamentous marine fungus Chaetomium indicum and endo-β-1,3-D-glucanase L_IV from the marine bivalve mollusk Spisula sachalinensis. All compounds were shown to be slow irreversible inhibitors of exo-β-1,3-D-glucanase and significantly activated endo-β-1,3-Dglucanase. The equilibrium inhibition constants (K_i, μM) and the inactivation rate constants (k_inact, min^–1) were determined for each compound. The inhibitory capacities of alkaloids were shown to depend on the structure of the “anchor” part of the molecule of the compounds. Normonanchocidin A was the best inhibitor of exo-β-1,3-D-glucanase from fungi. A possible biological role of these compounds in the life of sponges and their microbial symbionts is discussed here.

Red Sea’s goatfish (Mullidae), locally referred as ‘Sultan Ibrahim’, are a popular recreational fish that also supports neighboring commercial markets. The present study compares spermatogenesis, oogenesis and gonad structure, in two species of goatfish from Jeddah coast. The reproductive parameters including changes in gonado-somatic index (GSI),and spawning seasons were analyzed for Parupeneus heptacanthus (cinnabar goatfish) and Parupeneus cyclostomus (goldsaddle goatfish). P. heptacanthus spawn from February to June and P. cyclostomus spawning season begins from August to September. Remarkable difference in the egg size has been observed P. heptacanthus had the egg diameter (325.9 μm), while the smallest one is P. cyclostomus (209.6 μm) when compared to other species of Mullidae. P. heptacanthus was observed with largest flagellum length (8.7 ± 0.2 μm). The ultrastructure revealed some common features in both species like oval ova; further the ovarian follicular epithelium consists of two layers, an inner granulosa layer with zona radiata under them and an outer theca layer. Centrioles of both species consist of the typically arranged nine triplets (9 + 0) of microtubules. The external lay of zona radiata is thinner than internal one. Disparity in protein patterns of muscle and gonads were observed in the present study. There was also variation in the number of specific bands for each species in both protein soluble muscle and gonads. The histology results reported gonads to be typically gonochoristic and exhibited asynchronous development of oocytes in the ovary. The outcome of this study has yielded essential information of some of the imperative reproductive biology of P. heptacanthus and P. cyclostomus.

Some examples of marine animal and plant communities with a structure determined by competitive inter-species relationships are discussed. It has been shown that the ranked species structure of these communities obeys a geometric progression, whose coefficient does not differ significantly from the constant exp(–1) = 0.368. A relationship between a certain parameter of this progression and the species diversity of a community has been found.

The recent data on the breeding abundance and distribution of the great cormorant, Phalacrocorax carbo (Linnaeus, 1758), on the Peter the Great Bay coast, Sea of Japan, are provided. A total of 1715 inhabited nests have been recorded, including 1255 nests on Furugelm Island and 460 nests on Lisii Island.