Presentability of the Utrish Nature Reserve's benthic communities for the North Caucasian Black Sea Coast

An assessment of the presentability of the biotopes and benthic communities of the northwestern part of the Utrish Nature Reserve marine area for the Caucasian Black Sea coast has been conducted. The literary and original data on the state of benthos in the area from the Kerch Strait to Adler were examined. The studied area of the Utrish Natural Reserve included habitats that are common along the coast (an active cliff, a narrow pebble beach, boulder deposits, rock bench and soft sediments). Only two of the three well-known Black Sea belt macrozoobenthic biocoenoses were observed along the northeastern Black Sea coast: the shallow-water «venus sand» and the deep-water «phaseolina silt». The third biocoenosis («mussel mud») was not noted neither in the reserve's area nor in the studied part of the shelf to the south of Novorossiysk. Of these three belts only «venus sand» was found in the Utrish Nature Reserve's marine area. The absence of the mussel belt in the studied area of the reserve is typical for the southern part of the North Caucasian coast in the current period and thus does not affect the presentability of the reserve's benthic ecosystem. The biocoenosis of the bivalves Pitar rudis – Gouldia minima was common at the muddy sand with shells in both reserve's and reference sites' middle-depths complex instead of the mussel belt which was typical for the 20th century. Its boundary was 10 m deeper in the reserve compared to the reference sites. The absence of the Modiolula phaseolina belt in the area of the reserve could be explained by the insufficient width of the protected marine area (up to 52 m depth); due to this the deep-water complex in the reserve is actually represented by a narrow strip. Extension of the reserve's boundary over the depth of 70 m will include this biocoenosis into the Protected Area, which would significantly increase the presentability of the reserve's marine part for the North Caucasian coast. The biogeographical composition of the reserve's flora, its species diversity and structure in general corresponds to that of the whole region. The macrophyte zone consists of four belts: upper (0–2 m, Dictyota fasciola f. repens + Polysiphonia opaca + Ceramium ciliatum + Ulva compressa), upper mid (2–12 m, Cystoseira crinita + Cystoseira barbata – Cladostephus spongiosus – Ellisolandia elongata), lower mid (12–18 m, Phyllophora crispa, Codium vermilara and Bonnemaisonia hamifera), and the lower belt (below 18 m) formed by a recent invader, B. hamifera. The majority of species found in the reserve's marine area are common species of the Black Sea macrophytobenthos. However, the Utrish Nature Reserve includes more favourable habitats for macrophytes than most of the North Caucasian coast, because the typical macrophyte Cystoseira spp. have been noted at greater depths in the reserve, in comparison to the remaining shelf

Meiofauna in the Gollum Channels and the Whittard Canyon, Celtic Margin—How Local Environmental Conditions Shape Nematode Structure and Function

The Gollum Channels and Whittard Canyon (NE Atlantic) are two areas that receive high input of organic matter and phytodetritus from euphotic layers, but they are typified by different trophic and hydrodynamic conditions. Sediment biogeochemistry was analysed in conjunction with structure and diversity of the nematode community and differences were tested between study areas, water depths (700 m vs 1000 m), stations, and sediment layers. The Gollum Channels and Whittard Canyon harboured high meiofauna abundances (1054–1426 ind. 10 cm−2) and high nematode diversity (total of 181 genera). Next to enhanced meiofauna abundance and nematode biomass, there were signs of high levels of organic matter deposition leading to reduced sedimentary conditions, which in turn structured the nematode community. Striking in this respect was the presence of large numbers of ‘chemosynthetic’ Astomonema nematodes (Astomonema southwardorum, Order Monhysterida, Family Siphonolaimidae). This genus lacks a mouth, buccal cavity and pharynx and possesses a rudimentary gut containing internal, symbiotic prokaryotes which have been recognised as sulphur-oxidising bacteria. Dominance of Astomonema may indicate the presence of reduced environments in the study areas, which is partially confirmed by the local biogeochemical environment. The nematode communities were mostly affected by sediment layer differences and concomitant trophic conditions rather than other spatial gradients related to study area, water depth or station differences, pointing to small-scale heterogeneity as the main source of variation in nematode structure and function. Furthermore, the positive relation between nematode standing stocks, and quantity and quality of the organic matter was stronger when hydrodynamic disturbance was greater. Analogically, this study also suggests that structural diversity can be positively correlated with trophic conditions and that this relation is tighter when hydrodynamic disturbance is greater

Ecology and Biogeography of Free-Living Nematodes Associated with Chemosynthetic Environments in the Deep Sea: A Review

Background: Here, insight is provided into the present knowledge on free-living nematodes associated with chemosynthetic environments in the deep sea. It was investigated if the same trends of high standing stock, low diversity, and the dominance of a specialized fauna, as observed for macro-invertebrates, are also present in the nematodes in both vents and seeps. Methodology: This review is based on existing literature, in combination with integrated analysis of datasets, obtained through the Census of Marine Life program on Biogeography of Deep-Water Chemosynthetic Ecosystems (ChEss). Findings: Nematodes are often thriving in the sulphidic sediments of deep cold seeps, with standing stock values ocassionaly exceeding largely the numbers at background sites. Vents seem not characterized by elevated densities. Both chemosynthetic driven ecosystems are showing low nematode diversity, and high dominance of single species. Genera richness seems inversely correlated to vent and seep fluid emissions, associated with distinct habitat types. Deep-sea cold seeps and hydrothermal vents are, however, highly dissimilar in terms of community composition and dominant taxa. There is no unique affinity of particular nematode taxa with seeps or vents. Conclusions: It seems that shallow water relatives, rather than typical deep-sea taxa, have successfully colonized the reduced sediments of seeps at large water depth. For vents, the taxonomic similarity with adjacent regular sediments is much higher, supporting rather the importance of local adaptation, than that of long distance distribution. Likely the ephemeral nature of vents, its long distance offshore and the absence of pelagic transport mechanisms, have prevented so far the establishment of a successful and typical vent nematode fauna. Some future perspectives in meiofauna research are provided in order to get a more integrated picture of vent and seep biological processes, including all components of the marine ecosystem

Amphimonhystera molloyensis Tchesunov et Mokievsky, sp. n.

<i>Amphimonhystera molloyensis</i> Tchesunov et Mokievsky sp. n. <p>(Figures 4 A–E, 5 A–D & 6A–E)</p> <p> <b>Type material:</b> Holotype male, three paratype males and two paratype females mounted in glycerin on glass slides. Type specimens is deposited in the collection of the P. P. Shirshov Institute for Oceanology, Russian Academy of Sciences, Moscow.</p> <p> <i>Labels</i>: (Holotype male ref #1­1/4): RV Polarstern, ARK XVII st. 125, B(0 – 1 cm), 63 µm, 1/44; (Paratype male 1 and paratype female 1 ref # M­1/6): RV Polarstern, ARK XVII, st. 125, C (0–1 cm), 250 µm, 2/2; (Paratype male 2, ref # M­1/5): RV Polarstern, ARK XVI, St. 251, MD 316 (0–1 cm), 125 mkmµm, 1/13; (Paratype male 3, ref # M­1/3): RV Polarstern, ARK XVI, St. 251, MD 316 (0–1 cm), 125 mkm; (Paratype female 2, ref # M­1/7): RV Polarstern, ARK XVII, st. 125, C (0–1 cm), 125 µm, 2/44.</p> <p> <b>Type locality</b>: Arctic Ocean, area between Greenland and Svalbard. Holotype: st.125, 79°12.0' N 02°34.5' E, 5416 m, (Molloy Deep), silt, 13 July, 2001; Paratypes: St.251, 79°8.2' N & 02°53.6' E, depth 5569 m (Molloy Deep), silt, 16 August, 2000; and st.125, 79°12.0' N 02°34.5' E, 5416 m, (Molloy Deep), silt, 13 July, 2001.</p> <p> <b>Etymology:</b> The species name refers to the area of its findings, Molloy Deep. <b>Morphometric data:</b> Table 5.</p> <p>Specimens Holotype Paratypes</p> <p>Label Male 1 Male 2 Male 3 Male 4 Female 1 Female 2 dist. tail portion (%) 28 34 29 36 32 28</p> <p> termin s. 6.5 6.0 5.0 6.5 7.5 6.0 <b>Description:</b> Body slender, elongated spindle­shape, near cylindrical. Cuticle rather thin and finely transversely striated. In one specimen (ɗ2), subcuticular hypodermis yellow­brownish granules irregularly distributed throughout the body; pigment granules concentrated in preneural region (especially densely just posterior to the amphidial fovea) and thereafter less densely in posterior body region and tail, predominantly in ventral position. In other specimens, males and females as well, there are no conspicuous pigment granules in the anterior hypodermis. Labial region dome­shaped and slightly set off from the rest of the body. Inner labial sensilla not observed. Six outer labial sensilla and four cephalic sensilla setiform, and united with two additional lateral setae in one circle of twelve slender setae situated at the level of the stoma base. ɗ2 distinguished with shorter outer labial setae equal to cephalic setae and lacking additional setae. Amphidial fovea very large, longitudinally oval, with distinct cuticular edging; amphidial fovea of ɗ2 with a convex central spot. The cuticular edging marked with a slight break posteriorly in some specimens. The amphidial fovea situated relatively close to the anterior end. Somatic setae scarce and short, mostly in sublateral position. Buccal cavity small, with very weakly sclerotised walls. The cheilostoma forming the major part of the buccal cavity. The posterior stoma region or esophastoma very short, narrow and slightly asymmetrical. Esophagus uniform and weakly muscular, very slender, gradually widening to the cardia. Cardia internal. There is a thick dense internal lining in the midgut lumen. No indication of a renette cell. Anterior part of the female genital branch with germinal zone and smaller oocytes in two rows situated left of the intestine. Posterior part of the female branch with larger oocytes in one row folded ventrally to the right side of the intestine. The posteriormost part of the branch filled with small rounded spermatozoa. Vagina slanting and encircled by a strong sphincter. There are two sets of granular vulvar glands associated with the vagina, the anterior vulvar glands being much smaller than posterior ones. Five transparent ejaculatory glands visible at the left side of the ejaculatory duct of ɗ1. Spicules short, twice bent, distally acute and proximally cephalated. No gubernaculum.</p> <p>Tail consisting of a proximal conical and a distal slender cylindrical part. Tail tip slightly widened and provided with two subterminal setae.</p> <p> <b>Remark:</b> ɗ2 (paratype) is noticeably distinguished from other males and females by slightly shorter outer labial setae of the cephalic circle and intensive subcuticular pigmentation in the anterior body region (Fig. 6 B–C). These differences may be connected with the locality of ɗ2, i.e. remote from the sites of other specimens.</p> <p> <b>Diagnosis</b>: Body length 810–975 µm. Outer labial and cephalic setae 4.0–8.5 µm long. Amphidial fovea large, 15.5–18.0 µm long; ratio length to width of the amphidial fovea 1.55–1.67; distance from cephalic apex to anterior rim of the amphidial fovea rather short, 9.0–11.5 µm. Spicules 27.0–32.5 µm long. Terminal caudal setae 5.0–7.5 µm long.</p> <p> <b>Differential diagnosis</b>: The new species shares with <i>A. galea</i>, <i>A. marisalbi</i> and <i>A. pallida</i> a relatively small body length (<1 mm) and tail shape with slender cylindrical portion bearing terminal setae. <i>A. molloyensis</i> sp. n. distinctly differs from both <i>A. galea</i> and <i>A. pallida</i> by very short setae of the cephalic circle and by proximal position of the amphidial fovea.</p>Published as part of <i>Tchesunov, Alexei V. & Mokievsky, Vadim O., 2005, A review of the enus Amphimonhystera Allgén, 1929 (Monhysterida: Xyalidae, Marine Freeliving Nematodes) with description of three new species, pp. 1-20 in Zootaxa 1052</i> on pages 12-16, DOI: <a href="http://zenodo.org/record/170014">10.5281/zenodo.170014</a&gt

Amphimonhystera pallida Tchesunov et Mokievsky, sp. n.

<i>Amphimonhystera pallida</i> Tchesunov et Mokievsky sp. n. <p>(Figure 7)</p> <p> <b>Type material:</b> Holotype male 1 (ref # M­1/1), paratype male 2 (ref # M­1/2) and paratype female 1 (ref # M­1/8) mounted in glycerin on glass slides. Type specimens are deposited in the collection of the P. P. Shirshov Institute for Oceanology, Russian Academy of Sciences, Moscow.</p> <p> <b>Type locality</b>: Arctic Ocean, area between Greenland and Svalbard, 79°8.2' N & 02°53.6' E, depth 5569 m (Molloy Deep), silt, 16 August, 2000.</p> <p> <b>Etymology</b>: The species name reflects the pale colouration of the species in comparison with some other brownish <i>Amphimonhystera</i> species.</p> <p> <b>Morphometric data:</b> Table 6.</p> <p> <b>Description:</b> Small nematodes with slender, near fusiform to cylindrical body. Cuticle thin, with fine transverse annulation. Subcuticular yellow­brownish granulation weakly developed (mainly in pre­amphidial and amphidial regions) in males or nearly absent in female. Pre­amphidial region more or less narrowed. Labial region slightly set off. Inner labial sensilla as poorly visible tiny papillae. Outer labial and cephalic sensilla united in one circle of ten setae of moderate length. Amphidial fovea large, longitudinally oval, with distinct unbroken cuticular edging and without a visible central spot. Somatic sensilla short, scarcely distributed laterally along the body; nearly absent in midgut region.</p> <p> Buccal cavity small; cheilostoma hemispherical; esophastoma narrow, funnel shaped, with sclerotised walls. Esophagus slender, weakly muscular, gradually widening to the posterior end. Cardia small, triangular, internal. Midgut with distinct internal lumen and peritrophic membrane. At a short distance posterior to the cardia, the midgut shifted dorsally by a cell body which may be a pseudocoelomocyte or cell body of a rudimental renette cell. Anterior portion of the female branch situated left of the intestine, posterior portion right of the intestine. Uterus with two ripe eggs. Vulva as a small transversal slit. No vulval glands discernible. Anterior strait testis poorly discernible; posterior testis not visible at all. Two ejaculatory glands left of the <i>vas deferens</i> and intestine in the paratype male. Spicules short and slender, sharply bent in the middle, distally acute and proximally cephalated. No gubernaculum. Tail with a proximal conical and a distal slender cylindrical portion. Tail tip slightly inflated, with two or three terminal setae. No other somatic setae visible in tail region.</p> <p> <b>Diagnosis:</b> Body pale, 655–740 µm long. Outer labial and cephalic setae 3.0–7.0 µm long. Amphidial fovea, 11–12 µm long; ratio length to width of the amphidial fovea 1.2– 1.4 µm; distance from cephalic apex to anterior rim of the amphidial fovea 14–21 µm. Spicules 24–26 µm long. Terminal caudal setae 4.0–9.0 µm long.</p> <p> <b>Differential diagnosis:</b> <i>Amphimonhystera palida</i> sp. n. is similar <i>to A. galea</i>, <i>A. marisalbi</i> and <i>A. molloyensis</i> in body size. However, <i>A. pallida</i> differs from <i>A. galea</i> by having a much shorter cephalic setae length and shorter spicules; from <i>A. marisalbi</i> by a greater distance apex­amphidial fovea and longer terminal caudal setae; and from <i>A. molloyensis</i> by a greater distance apex­amphidial fovea.</p>Published as part of <i>Tchesunov, Alexei V. & Mokievsky, Vadim O., 2005, A review of the enus Amphimonhystera Allgén, 1929 (Monhysterida: Xyalidae, Marine Freeliving Nematodes) with description of three new species, pp. 1-20 in Zootaxa 1052</i> on pages 16-19, DOI: <a href="http://zenodo.org/record/170014">10.5281/zenodo.170014</a&gt

Amphimonhystera

List of Amphimonhystera species 1. Amphimonhystera anechma (Southern, 1914). Literature and synonymy: Southern, 1914: 13–14, pl. III, Figs 7 A–F (Monohystera a.), Ireland; Allgén, 1928: 298–299 (Monhystera a.), west coast of Sweden. Gerlach, 1958: 81, Kiel Bay; Riemann, 1967: 218–222, Abb. 1–7, North Sea; Lorenzen, 1974: 313; North Sea and Lorenzen, 1977: 203–205, Abb. 2 a–f; North Sea. Own data: White Sea. 2. Amphimonhystera circula Guo et Warwick, 2001. Females not described. Literature: Guo & Warwick, 2001: 1579–1581, Fig. 3, Bohai Sea, China, depth 20.5–38.5 m, silt. 3. Amphimonhystera galea Fadeeva, 1984. Females not described. Literature: Fadeeva, 1984: 46–48, Figs 2 B, 3, 3B, Japan Sea, now White Sea. 4. Amphimonhystera marisalbi sp. n. White Sea, this study. 5. Amphimonhystera molloyensis sp. n. Arctic Ocean, area between Greenland and Svalbard, deep sea, this study. 6. Amphimonhystera pallida sp. n. Arctic Ocean, area between Greenland and Svalbard, deep sea, this study.Published as part of Tchesunov, Alexei V. & Mokievsky, Vadim O., 2005, A review of the enus Amphimonhystera Allgén, 1929 (Monhysterida: Xyalidae, Marine Freeliving Nematodes) with description of three new species, pp. 1-20 in Zootaxa 1052 on page 4, DOI: 10.5281/zenodo.17001

Amphimonhystera marisalbi Tchesunov et Mokievsky, sp. n.

Amphimonhystera marisalbi Tchesunov et Mokievsky sp. n. (Figure 3, A–G) Type material: Holotype male (ref # M­ 1 / 9), one paratype male (ref # M­ 1 / 10) and four paratype females (ref # M­ 1 / 11, M­ 1 / 12, M­ 1 / 13, M­ 1 / 14) mounted in glycerin on glass slides. Type specimens are deposited in the collection of the P. P. Shirshov Institute for Oceanology, Russian Academy of Sciences, Moscow.. Type locality: The White Sea, Kandalaksha Bay, Station CBB­ 20 (1 A 1), RV KARTESH, 66 ° 23.47 ’ N, 34 ° 18.71 ’ W, depth 270 m, 27.07. 1998. Etymology: Marisalbi (Latin) means "of the White Sea". Morphometric data: Table 4. ......continued on the next page Description: Body elongate fusiform. Cuticle thin, finely annulated, without any lateral field. Ψ 3 with light brownish cuticle and hypodermis with brown pigment granules; bodies of other specimens seem neither brownish nor yellowish. Cephalic end anterior to the amphidial fovea very slightly narrowed in some specimens. Inner labial sensilla hardly visible. Cephalic crown of sensilla in males and females consists of six pairs of moderatesized setae (6 outer labial setae + 4 cephalic setae + 2 additional lateral setae). In the lateral pair, a ventral seta slightly shorter than the dorsal seta. Amphidial fovea large, slightly longitudinally oval or even rounded, with distinct cuticular rim and slightly asymmetrical central spot. No cervical setae. Short somatic setae scarcely distributed along the body. Buccal cavity very small and consisting mainly of a cheilostoma and an esophastoma reduced to a flat bottom. Esophagus slender, cylindroid, gradually widening to the cardia, with even radial muscular striation along its length. Cardia internal. No indications of a renette cell. Ovary of Ψ 1 and Ψ 3 situated entirely to the left side of the intestine. In Ψ 2 and Ψ 4, anterior portion of the ovary placed to the left of the intestine while posterior half portion bent to the right of the intestine. Uterus filled with small rounded spermatozoa. No postvulvar spermatheca. There are two (?) postvulvar glands with granular content. Anterior testis situated to the left of the intestine; posterior testis not seen. Spicules small but very distinct and robust, abruptly bent in the middle. Distal ends acute, proximal ends cephalated. Gubernaculum indistinct, as a rod­like body at the spicule distal ends. Tail with proximal conical and a distal slender cylindrical portions gradually going over in one another. Tail tip slightly widened with two or three very short subventral and subdorsal setae. There are two caudal gland cell bodies discernible within the tail. There are several pairs of pre­ and postanal lateroventral setae on the tail region. Diagnosis: Body length 535–870 µm. Outer labial and cephalic setae 3.5 –5.0 µm long. Amphidial fovea 6–10 µm long; ratio length to width of the amphidial fovea 1.1–1.3; distance from cephalic apex to anterior rim of the amphidial fovea 7.0– 8.5 µm. Spicules 15–16 µm long. Terminal caudal setae 2.0–3.0 µm long. Differential diagnosis: Amphimonhystera marisalbi sp. n. is similar to A. galea in general appearance and structural characters but differs by a very small or hardly visible inner labial sensilla, fewer of setae in the cephalic crown (12 versus 20) and by a number of morphometric characters such as shorter setae of the cephalic crown (3.5 –5.0 µm versus 7–15 µm) and tail terminal setae (2.0–3.0 µm versus 6.0–9.0 µm).Published as part of Tchesunov, Alexei V. & Mokievsky, Vadim O., 2005, A review of the enus Amphimonhystera Allgén, 1929 (Monhysterida: Xyalidae, Marine Freeliving Nematodes) with description of three new species, pp. 1-20 in Zootaxa 1052 on pages 9-12, DOI: 10.5281/zenodo.17001