Sergey Galkin

Endemism and Biodiversity of Hydrothermal Vent Fauna

Hydrothermal vent fauna represents a unique source for scientists who are involved in investigations of ecology, zoology, and biochemistry of extremophyles . However, exoskeletal and biomineral-containing structures located within these organisms are of large scientific interest for bioinspired material science and especially for extreme biomimetics . Here, we report about biodiversity, endemism, and trophic specialization and the food web of animals which habituate in these extreme environmental conditions. Numerous underwater images represented in this chapter should help for better understanding of the life near hydrothermal vents.

Methane as an Organic Matter Source and the Trophic Basis of a Laptev Sea Cold Seep Microbial Community

ABSTRACT An area of cold methane seeps at the bottom of the Laptev Sea was investigated. High rates of methane oxidation were revealed in the sediments and in the water column. Anaerobic methane oxidation carried out by the ANME-2 a/b consortium was coupled to sulfate reduction. Bacteria of the genera Sulfurovum and Arcobacter were the agents of the sulfur cycle. Methane unconsumed in the sediments diffused into the near-bottom water, where it was oxidized by methanotrophic bacteria. Methanotrophic activity was essential for development of symbiotrophic tubeworms of the upper sediment layers, which were responsible for the process of bioturbation.

Trace Metal Biogeochemistry and Ecology of Deep-Sea Hydrothermal Vent Systems

Over a period of time after discovery in 1977 of the extraordinary abundant faunal assemblages functioning at the deep-sea hydrothermal vent systems, a new knowledge has been gained of highly dynamic and extreme conditions in their habitats. Hydrothermal vent communities have to survive in habitats which are exposed to high heavy metal load, emitting from vents and dispersing into ambient water and changing physicochemical parameters. All these processes are reflected in the distribution pattern of bottom communities along the gradients of reduced substances that serve a basement for chemosynthetic primary productivity. In the book we aimed to summarize available data, which are of fundamental interest for understanding the trace metal biogeochemistry and ecology of biological communities of deep-sea vent systems. Along with, some interesting aspects of the subseafloor biosphere are considered. This book is addressed to the specialists working in various fields of environmental problems, especially in marine biogeochemistry and ecology.

Geologic-Geochemical and Ecological Characteristics of Selected Hydrothermal Areas

In this paper we consider geologic-geochemical and ecological characteristics of the areas where the material for biogeochemical study (Demina, Trace metals in water in the hydrothermal biotope. Hdb Env Chem. doi: 10.1007/698_2016_1; Demina, Galkin, Factors controlling the trace metal distribution in hydrothermal vent. Hdb Env Chem. doi: 10.1007/698_2016_5) has been collected. In the Atlantic Ocean five hydrothermal areas (Menez Gwen, Rainbow, Lost City, Broken Spur, and Snake Pit) have been investigated. In the Pacific Ocean the 9°50′N vent area at the East Pacific Rise and hydrothermal manifestations in Guaymas Basin (Gulf of California) were studied. Observations and sampling were provided in 1996–2005 during numerous cruises of RV “Akademik Mstislav Keldysh” using deep-sea manned submersibles “Mir.” Explored vent areas exhibit a wide range of environmental conditions, including great variation in depth (particularly on the MAR), associated physical parameters, and different geologic setting and underlying rocks. Faunal communities also vary greatly in taxonomic composition and spatial structure. Short characteristic of abiotic environment and structure of benthic communities is given for each explored area. With all the variety of hydrothermal manifestations, in the spatial structure of communities a number of general patterns can be revealed. At the analysis of bioaccumulation function of vent organisms in the case of each area particular habitat conditions and characteristics of spatial structure of communities (microdistribution of animal’s populations, their association with a specific temperature zone and a particular type of substrate) must be taken into account.

Factors Controlling the Trace Metal Distribution in Hydrothermal Vent Organisms

Despite the numerous published data, the evaluation of the various conditions, influencing the trace metal distribution and accumulation in the different hydrothermal organisms, is not completed up till now. In this chapter we aimed to clear out the influence of the main factors, affecting the trace metal bioaccumulation in the deep-sea hydrothermal vent biota: environmental factors, acting outside the organisms, and biological ones, acting inside the organisms and within the biological communities. Among the environmental conditions there are such site-specific differences as depth, temperature, and fluid chemical composition that control trace metal concentrations in water of the biotope, as well as mineralogical features of substratum. Meanwhile the biogenic factors include stage of ontogenesis, species differences, trophic level and feeding type, and etc. For this purpose we consider data on the Fe, Mn, Zn, Cu, Cd, Pb, Ag, Ni, Co, Cr, As, Se, Sb, and Hg concentrations in the benthic organisms inhabiting the following hydrothermal vent fields at the Mid-Atlantic Ridge (MAR): Menez Gwen, Rainbow, Lost City, Broken Spur, as well at the 9°50′N at the East Pacific Rise (EPR), and the Guaymas Basin (Gulf of California). To clarify some of the influencing factors, we have aimed to summarize the available data on factors that control the trace metal distribution in hydrothermal vent organisms, including not only Bathymodiolus mussels, but also other dominant organisms, such as Rimicaris shrimps, vestimentiferan tube worms Riftia pachyptila, whose feeding strategy relies on microbial symbiotrophy. Distribution patterns of some trace metals studied in different taxa gave an evidence of the influence of environmental and biological parameters on their bioaccumulation in the hydrothermal vent organisms.

A synopsis of the vestimentiferan system

This paper presents a review of the vestimentiferan system and provides amended diagnoses for all the taxons. The class of vestimentiferans comprises two orders. Lamellibrachiida and Tevniida. The family Alaysiidae is considered to be a group of uncertain systematic position. A map of the geographical distribution of the vestimentiferans is presented.

Annelid Brain and Nerve Cord in Siboglinid Riftia pachyptila

Vestimentifera is a peculiar group of marine gutless siboglinids which has uncertain position in annelid tree. The detailed study of the fragmentary explored central nervous system of vestimentiferans and other siboglinids is requested to trace the evolution of the siboglinid group. Among all siboglinids the vestimentiferans preserve the gut rudiment what makes them a key group to homologize main cerebral structures with the ones of typical annelids, such as supra- and subesophageal commissures, cirsumesophageal connectives etc. Histologically we revealed main annelid brain structures in the compact large brain of Riftia pachyptila: circumesophageal connectives (longitudinal nerve tracts) and commissures (dorsal, supra- and subenteral commissures). Innervation of tentacles makes them homologous to peristomial palps of the rest annelids. The single nerve cord is represented by paired intraepidermal longitudinal strands associated with the ventral ciliary field in vestimentum and bearing giant axons originating from at least four pairs of perikarya. The absence of regularly positioned ganglia and lateral nerves in the nerve cord in vestimentum and trunk and presence of them in the opisthosome segments. Among siboglinids, the vestimentiferans distinguished by a large and significatly differentiated brain which is reflection of the high development of the palp apparatus. Osedax, frenulates and Sclerolinum have less developped brain. Frenulates and Sclerolinum have good ganglionization in the opisthosome, which probably indicates its high mobility. Comparative neuroanatomical analysis of the siboglinids and annelid sister clades allows us to hypothesize that the last common ancestor of siboglinids might had brain with a dorsal commissure giving rise neurite bundles to palps and paired ventral nerve cord.

The anatomy of the blood vascular system of the giant vestimentiferan tubeworm Riftia pachyptila (Siboglinidae, Annelida): Rimskaya-Korsakova et al.

The giant dimensions of vestimentiferan Riftia pachyptila (Jones, ) are achieved thanks to the well‐developed vascular system. In the vestimentum, there is a complicated net of lacunae, including the brain blood supply and the ventral lacuna underlying the ciliary field. The trunk region has an extensive network of blood vessels feeding the gonads («rete mirabile»). The thick muscular lining of the mesenterial vessels in the trunk and the dorsal vessel in the opisthosome serves as an additional pump, pushing blood into numerous vessels in the segments. It was hypothesized that the blood envelope of the ventral blood vessel in the trunk provides the blood supply to the trophosome. The 3D reconstruction has revealed that there are two vascular systems of the tentacular crown of R. pachyptila. Blood runs into the tentacles via axial afferent vessels, as described earlier only for Riftia, and also via basal ones, as described for other vestimentiferans except Riftia. The basal ones are poorly developed, and the number of lamellar blood vessels is small, indicating a lack of demand for these within huge R. pachyptila. It appears that the presence of these vessels is the preserved ancestral state of Vestimentifera. In different portions of the dorsal vessel, the morphology of the intravasal body varies, depending on function.