Silty Bottom Research Articles

Wolffia globosa (Araceae s. l. / Lemnaceae s. str.), a new aquatic alien species in the flora of Ukraine

In Europe, Wolffia globosa was first recorded in 2002 in the RF, and not in Bulgaria, as it was previously believed. Over the past 20 years, the species has expanded its secondary range. As of 2023, it is known from seven European countries. In Ukraine, W. globosa was first found in 2023 in two localities in Zhytomyr Region (Zhytomyr Polissia). The plant communities with W. globosa in Ukraine belong to the association Lemno-Spirodeletum polyrhizae of the alliance Lemnion minoris of the class Lemnetea. In the reported localities W. globosa occurs in eutrophic stagnant waterbodies with depths of 0.2–0.5 m and weakly flowing waterbodies with depths of 1.2–1.5 m; silty bottom is covered by a silt layer 5–20 cm thick, lighting is full. It is suggested that due to the observed climate warming, further migrations of W. globosa to other regions of Ukraine are possible.

РАСПРЕДЕЛЕНИЕ И ЭКОЛОГИЧЕСКИЕ ОСОБЕННОСТИ МОЛЛЮСКА HYDROBIA ACUTA (DRAPARNAUD, 1805) У ПОБЕРЕЖЬЯ КРЫМА

Background. The distribution of the gastropod mollusc Hydrobia acuta in relation to seasons, temperature, depth, salinity and biotopes along the Crimean coast from Karkinit Bay to the Cape Kazantyp for the period from 2001 to 2023 has been considered. This species is abundant and wide-spread in the Black and Azov Seas; however, there have been no papers dedicated to it specifically since 1976. Some biotopes, in particular the epiphyton of some Chlorophyta, have not been previously investigated. It contributes to the relevance of this work, which is aimed at providing the summary of the data on the ecology of H. acuta. Sampling was carried out according to the generally accepted benthic methods with special consideration for the biotopes. According to the results, this mollusc was the most abundant (39,625 ind./m2) in the Crimean coastal area at the mouth of the Chernaya (Black) River on loose substrates in August 2011, and its highest biomass (28.48 g/m2) was recorded in the same area and substrate in September 2022. On macrophytes, the highest abundance and biomass were recorded in the associations of algae Cladophora sp.+ Chaetomorpha sp. in the Kazantyp area in July 2009—23,333 ind./kg and 23.33 g/kg, respectively. The conclusion is that the mollusc H. acuta is distributed along the Crimean coast non-uniformly; it has been found to prefer silty bottoms and thickets of green algae, shallow-water sites at the heads of bays and in Karkinit Bay itself (sometimes with increased salinity), as well as in the river estuary (mostly with reduced salinity).

El Bentos del Parana Media en el tramo Corrientes-Esquina

Quali-quantitative variations of the benthos from the Middle Paraná river course, were studied. Spatial and temporal distribution was analyzed in relation with the main environmental factors.
 Studies were monthly carried out during March 1981-March 1982 in four stations near the localities of Comentes, Bella Vista, Coya and Esquina. In each of them, four sampling points were stablished in the cross sections of the river. Samples were obtained with a Dietz-LaFond dredge and fíltered through 500 and 150 µm mesh opening screens. The predominant sandy bottoms are inhabited by a specialized psammophilous fauna. The community structure was similar along all the studied stretch. Abundánce was very fluctuant, with maximun valúes of 160.000 ind/m2 with a strong numerical dominance of a species of Oligochaeta: Narapa bonettoi Correlations análysis showed a positive association between the mean grain size and the total abundance. These coeflcients were signiñcatives in all the stations for microturbellarians but only in Goya and Esquina for N. bonettoi
 Clay bank substraía from the river margins had a richer but less abundant fauna (maximun valúes of 29.000 ind/m2) with predominance of Xenochironomus sp. The benthos of the soft silty bottoms was the least diversé and abundant.
 Seasonal changes in the abundance were observed. There was an increment in spring and the early summer with a tendency to decrease during summer floods. This pattem was similar in the thxee kinds of bottoms, but more evident in the soft silty ones.

Exotic Polychaetes of a Sewage Pollution Influenced Lagoon (Çardak Lagoon, Turkish Straits)

This paper includes three exotic polychaeta species, Hydroides dianthus (Verrill, 1873), Polydora cornuta Bosc, 1802, and Pseudopolydora paucibranchiata (Okuda, 1937), found during benthic samplings in Çardak Lagoon (Turkish Straits). The sampling was collected from the sandy and silty bottoms known to be polluted by sewage discharges. A total of 45 specimens of exotic polychaetes (H. dianthus: 1; P. cornuta: 4; P. paucibranchiata: 40) were found. The correlation values between the annual average values of the nutrients and the polychaeta abundance showed that the highest positive relationships with the abundance were between sand content, total phosphate, and pH. P. cornuta was the most observed species with a frequency index value of 75%, while H. dianthus was represented with a single species in the study area. Albeit the previous studies, P. paucibranchiata was observed most abundantly in the sampling station having low organic matter amounts. The study showed that opportunistic polychaetes observed in Çardak Lagoon mostly preferred organically poor sediments.

Донная фауна и оценка экологического состояния нижнего участка р. Ангары

On the Angara River there is a reservoirs cascade of four hydroelectric power stations, and in the lower reaches it is planned to build the Nizhneboguchanskaya HPS. On the other hand, at present there is a significant gap in the studies of the Angara lower section, especially in zoobenthos. The material for the study was zoobenthos samples taken in the coastal zone in August 2022 at 11 river stations in a section from 445 km to 9 km from the mouth. Biotopes of zoobenthos are represented mainly by pebble-sandy soil with varying degrees of silting. The benthic fauna of the Angara River was gammarid-chironomid in nature; oligochaetes were found everywhere, but in small numbers. 87 species and taxa of a higher rank had been identified, the largest number of species (37) was noted among the chironomid larvae of Orthocladiinae and Chironominae. The quantitative advantage (more than 60% of the abundance and biomass) belonged to amphipods. Chironomids predominated over amphipods only on silty bottoms; in the river section, in general, they accounted for 24% of the abundance and 10% of the biomass of benthic communities. The Shannon species diversity index was relatively low and amounted to 2.3 bit/ind. general in the section. The lower reaches of the river were characterized by the highest species diversity, but the lowest number of benthic invertebrates. The total number of zoobenthos in the studied area was 2,9 thousand ind/m2, biomass – 14,6 g/m2, in the lower reaches of the river the number decreased to 1.7 thousand ind/m2, biomass – up to 4 g/m2. An integrated approach was used to assess the water quality of the Angara benthic communities, that includes the analysis of 8 bioindication indices: Goodnight (G), Woodiwiss (TBI) and saprobity (S) indices (recommended by the Russian regulatory document); indices FBI, BMWP, ASPT (recommended by the European Water Framework Directive); the Balushkina chironomid index (K) and the Shannon species diversity index. The fundamental criterion for the selection of indices was the level of development of indicator taxa. The complex assessment revealed the trend of improving water quality to the mouth of the river. This trend is expressed in the consistent dynamics of the TBI, BMWP, ASPT indices, which can be recommended for assessing the ecological state of the Angara River and other watercourses in the region. The water quality corresponded to Class III (Polluted) with a tendency to improve at the mouth to Class II (Slightly polluted).

Deterioration of Fisheries and Improvement Procedure of Fisheries: the Improvement Procedure of Inland and Marine Fisheries throughout the World

Deterioration of Fisheries and Improvement Procedure of Fisheries: the Improvement Procedure of Inland and Marine Fisheries throughout the World

The Influence of Environmental Conditions on the Distribution and Size Composition of the Gastropod Boreotrophon candelabrum (Reeve, 1848) (Muricidae) in Vostok Bay, Sea of Japan

The distribution and size composition of the gastropod Boreotrophon candelabrum in Vostok Bay of the Sea of Japan were investigated in 2014–2019. Mollusks occurred on different bottom types and biogenic substrates, except clean washed sands of open coves and wave-exposed rocky–boulder shores. The highest abundance of B. candelabrum was observed at the head of the bay, where the density and biomass were up to 5 ind./m2 and approximately 30 g/m2, respectively. This is in agreement with the density and biomass estimates obtained in the first quantitative survey of macrobenthos in Vostok Bay in 1971–1975 [6]. In the summer, mollusks with a shell height of 10 to 62 mm were found in the bay. The size composition of B. candelabrum significantly varied in different areas of the bay. A relatively narrow range of shell sizes and low number or the absence of individuals larger than 44–50 mm were observed at the head of the bay on a silty bottom and in a wave-exposed area. In the B. candelabrum population, there was a tendency for the proportion of large mollusks with a shell height of more than 40 mm to increase between 2014 and 2017 and to decrease in subsequent years. The reasons for the variations in population composition are discussed.

Revision of Fauveliopsidae Hartman, 1971 (Annelida, Sedentaria).

Revision of Fauveliopsidae Hartman, 1971 (Annelida, Sedentaria).

Reproductive Strategies and the Origin of Parapatric and Sympatric Forms of Arctic Charr Salvelinus alpinus (Salmonidae) in the System of Lakes Bol’shoe Leprindo and Maloe Leprindo (Northern Transbaikalia)

In the system of lakes Bol’shoe Leprindo and Maloe Leprindo (Lena basin, Transbaikalia), spawning of two isolated populations of the dwarf form of Arctic charr Salvelinus alpinus was studied. The results supplemented with the data about the exterminated large form from these lakes, demonstrate a unique combination of sympatric and parapatric charr forms with autumn (large form), summer (dwarf form, Bol’shoe Leprindo) and first recorded in Russia winter-spring (dwarf form, Maloe Leprindo) spawning peaks. In both lakes, the dwarf form spawns in the profundal zone at silty bottom at the depth 25–58 m: in Bol’shoe Leprindo, from late June to October with peak in July-August when water temperature is 5–6°С, in Maloe Leprindo from January to July, with peak in January–March when temperature is 2.5–3.0°С. Eggs laid in July–August in Bol’shoe Leprindo develop for 3.0–3.5 months, eggs laid in January–March in Maloe Leprindo, for about 4.0–4.5 month; in both lakes they are actively consumed by burbot Lota lota. Due to smaller egg size the dwarf form has twice as high individual relative fecundity as the large form, which compensates for high egg mortality. It is supposed that the differences in spawning strategies were formed as the result of outcompeting of the dwarf form by the large form from the littoral to the profundal zone, where perennial low temperature favoured the prolongation and displacement of their spawning time. These differences determined reproductive isolation and genetic divergence between three charr populations.

Taxonomic diversity of benthic invertebrates of the Moskva River in the Moscow area: diversity and distribution

<p>Biological diversity and distribution of benthic invertebrates in the Moskva River within the frames of Moscow are studied. Totally, 72 invertebrate taxa were found including 8 invasive species with amphipod <em>Gmelinoides fasciatus </em>(Stebbing, 1899), an invader from the Lake Baikal. A number of observed species are characterized with high abundance and biomass while most of observed taxa are represented by a small number of individuals. The greatest species diversity was revealed for insect larvae, mainly due to Chironomidae. The main species on the investigated section of the river are various crustaceans, mainly amphipods and decapods (when present in samples) showing more than 70-90% of all biomass of zoobenthos at all stations (sites). Multivariate cluster analysis allowed concluding that bottom communities in Moskva River, the degree of their quantitative development, species richness and diversity are mainly influenced by the structure of bottom substrates rather than other factors. The most diverse benthic communities are presented on silty bottom with mixture of shells of mollusks and plant remains. The lowest diversity of benthic communities is characteristic for sites with relatively strong water and well washed sand as the main bottom substrate. Obtained data starts annual monitoring of the river at indicated stations using biological indicators, namely native amphipod <em>Gammarus lacustris</em> and invasive <em>G. fasciatus</em>.</p>

Biodiversity and functioning of a subtropical coastal ecosystem: a contribution to an integrated managment

Biodiversity and functioning of a subtropical coastal ecosystem: a contribution to an integrated managment

Relative sea level change in Olbia Gulf (Sardinia, Italy), a historically important Mediterranean harbour

Olbia Gulf, located in northeastern Sardinia, is bordered by granite, metamorphic rock, and limestones (Capo Figari and Tavolara Island). It has been an important merchant harbour for three thousand years. Tidal notches in limestone, considered one of the best sea level markers, are present between 5.1 and 8.6 m a.s.l. A fossil beach deposit on Tavolara Island is of Tyrrhenian age (MIS 5.5, 125 ka). Between 1999 and 2001, during the building of a new Olbia harbour tunnel, many shipwrecks hidden under recent fine sediments have been discovered. The archaeological excavation (380 x 20 m, to the surface of the carbonate bedrock at 4 m depth) was done by the Soprintendenza per i Beni Archeologici per le provincie di Sassari e Nuoro (Olbia branch). During the archaeological excavation campaign, thousands of ceramics, other materials which were not in situ, and 24 shipwrecks of different age and size were recovered. Eleven of these wrecks were sunk while they were still in the harbour during an attack by the Vandals in the middle of the fifth century. This attack determined the beginning of a sharp decline of Olbia, and gives a clear picture of one of the turning points of the Mediterranean cultural evolution: the end of the Roman Empire. Considering −1.4 m as the average altitude of the shipwrecks on the silty bottom of the Olbia Harbour and comparing this value with the predicted sea level curve from the Lambeck model calculated for northern Sardinia (−1 m ca. 1500 cal BP), it appears clear that the ships were at the margin of the harbour in water depth of less than 0.5 m. This confirms: a) the previous archaeological interpretation; and b) that the northern Sardinian coast was stable during the last millennia. Due to the tectonic stability of the coastal area, the evolution of the shoreline from the Bronze age (4 ka cal BP) up to 21.5 ka cal BP (LGM, last glacial maximum) is reconstructed.

8-kHz bottom backscattering measurements at low grazing angles in shallow water

8-kHz bottom backscattering measurements at low grazing angles (6 degrees -31 degrees ) are presented. The experiment was performed at a very shallow water site with a silty bottom on the south coast of Korea. Backscattering strengths between -42 and -30 dB were obtained and were compared to a theoretical backscattering model and Lambert's law. The fit of the theoretical model to the measurements suggests that sediment volume scattering is dominant over scattering from bottom interface roughness. Combining these results with previous measurements found in the published literature implies that backscattering strengths from silty sediment increase slightly as the frequency increases.

The zebra mussel (Dreissena polymorpha) and the benthic community in a coastal Baltic lagoon: another example of enhancement?

AbstractThe zebra mussel (Dreissena polymorpha), a sessile suspension feeder, has been known to enhance the benthos in the sediment around mussel beds and druses. The enhancement is mainly due to biodepositing activity of the mussel and the resultant organic enrichment of the sediment. In addition, mussel beds increase habitat complexity. In June 2007, we studied the distribution of D. polymorpha beds and their effects on the benthos in Kleines Haff, the western part of the Szczecin Lagoon, a Southern Baltic coastal water body. We expected that: (i) the sediment near a Dreissena bed will support meio‐ and macrobenthic assemblages more abundant than those living away from the bed, and (ii) the meio‐ and macrobenthic assemblages close to the Dreissena bed will show a stronger dominance of the taxa relying on the organic enrichment (nematodes among the meiofauna; oligochaetes and chironomids among the macrobenthos). Meiobenthos was sampled at two localities, one (MB4) featuring D. polymorpha druses and the other (MB5) supporting a distinct zebra mussel bed. The two localities differed in their meiobenthic communities: whereas no difference in abundance and composition was observed between the sets of samples collected at MB4, MB5 showed a distinctly more abundant meiobenthos in the uppermost sediment layer near the zebra mussel bed, but the overall abundance was lower than that away from the bed. We conclude that the meiobenthic response to the presence of D. polymorpha was, at least in part, mediated by site‐specificity of sediment characteristics. Macrozoobenthos was sampled at four stations in the vicinity of MB5 and around another Dreissena locality (MB10), and was also identified in the sediment samples collected for the meiobenthos. The macrobenthic abundance was higher by a factor of 2.4 (sandy sediment) to 4.9 (silty bottom) near the Dreissena beds than away from them. Irrespective of their situation relative to Dreissena aggregations, both meio‐ and macrobenthos were dominated by the taxa associated with organic enrichment. The macrobenthos associated with Dreissena beds included Gammarus tigrinus, a non‐indigenous amphipod, whereas another non‐native species, the polychaete Marenzelleria neglecta, was present in the macrobenthos of sandy sediments of the area.

Hard- and soft-bottom thanatofacies from the Santa Maria di Leuca deep-water coral province, Mediterranean

Thanatofacies and the skeletonized components of the living facies, from which they originate have been studied from the Santa Maria di Leuca (SML) deep-water coral mound province. Faunal analysis was carried out by means of bottom sampling and underwater video observations, taking into account all benthic taxonomic groups, mostly corals, molluscs, serpulids, bryozoans, ostracods, foraminifers and barnacles, which permitted recognition of six different facies. These thanatofacies are easily distinguishable and appear to be largely corresponding and overlapping with related living facies. Some occur in mound areas, others in the intermound ones. They are as follows: the Framework-building Coral facies (FC), characterised by colonial corals, mostly Madrepora oculata; the Coral Rubble facies (CR), with proximal and distal aspects, characterised by large- to small-sized and densely to loosely packed coral fragments; the Solitary Coral facies (SC), dominated by different species depending on the availability and dimensions of hard exploitable surfaces; the Gryphus and Isidella facies (GI) in relatively coarse-grained bottoms; the Mollusc Mud facies (MM) and the Foraminifer Mud facies (FM) in comparably homogeneous silty bottoms. Facies distribution and spatial variability are discussed, in relation to hydrology and sea-floor topography. Furthermore, the SML facies are compared with living facies from the present-day Mediterranean and Pleistocene sediments of the same area. Data on bioclastic assemblages can serve for comparison with other recent aphotic, non-tropical carbonates.

Five years of field hydrographic research in the Large Aral Sea (2002–2006)

The paper is intended to provide a summarizing account of hydrographic research activities on the Large Aral Sea since 2002. To date of the writing (August, 2006), 6 field surveys have been accomplished, some of which consisted of separate legs covering different parts of the lake. The 3D thermohaline structure was investigated by means of surface-to-bottom profiling from motor boats at various hydrographic stations. In a part of the cruises, direct observations of water velocity and lake surface height were also conducted from mooring stations at specific locations. The measurements were accompanied by water sampling and collection of meteorological data. Over the period of the observations, the surface salinity in the western, relatively deep basin has increased from about 82 g∙kg − 1 in November 2002 to over 99 g∙kg − 1 in March 2006. Because the lake surface level remained nearly constant during this period, spanning only slightly between 30.1 and 30.7 m above the ocean level, and the fluvial and groundwater inputs of salts are likely negligible at the temporal scale of a few years, this continuing salinity build-up in the western basin must be associated with water exchanges with the shallow and saltier eastern basin. In the latter, salinity has decreased from up to 160 g∙kg − 1 as previously reported for 2002 [Mirabdullaev, I.M., I.M. Joldasova, Z.A. Mustafaeva, S. Kazakhbaev, S.A. Lyubimova, and B.A. Tashmukhamedov, 2004. Succession of ecosystems of the Aral Sea during its transition from oligohaline to polyhaline waterbody. J. Marine Systems, 47(1–4), 101–108.] to only about 130 g∙kg − 1 in 2005. The denser eastern basin water sinking down the slope of the western trench is responsible for enhanced vertical stratification observed in 2002 and 2003. Such stratification greatly damped vertical mixing, which resulted in hypoxia and sulfide contamination in the bottom layer. However, the water column was ventilated in spring of 2004, presumably, following deep winter convection, thus suggesting that stratification and hypoxia are intermittent rather than permanent features. A recently formed deep (up to 7 m) channel has been discovered in the otherwise shallow strait between the two basins, presumably associated with erosion of the silty bottom by currents. This means that the expectations of imminent separation of the two basins must be revisited. Water velocity values 20–50 cm∙s − 1 have been observed in the channel. The lake surface level in the western basin responded energetically to wind-controlled inter-basin flow through the strait.

Adaptive radiation of thalassoid gastropods in Lake Tanganyika, East Africa: morphology and systematization of a paludomid species flock in an ancient lake

The paludomid gastropods of Lake Tanganyika are one of the most spectacular examples of species flocks among molluscs. However, whether they provide an example of intralacustrine speciation and truly adaptive radiation still remains unresolved, with their monophyly and phylogenetic relationships within freshwater Cerithioidea still to be rigorously evaluated. In the course of providing the data for a future comprehensive phylogenetic analysis, this paper using SEM technique describes and documents the morphology of the adult and particularly the embryonic shell (ornamentation and size) as well as the radular anatomy (including cusp pattern), with remarks on the ontogeny and ecology, for 19 species belonging to 10 genera, mainly from a collection from Kigoma Bay, East shore of Lake Tanganyika, Tanzania. The species studied live either on soft sandy and silty bottoms or on primary or secondary hard substrata, representing two ecological guilds, with rocky substrata supporting a richer species assemblage (including five taxa of Lavigeria) than soft substrata. In addition, a systematic framework for these gastropods is suggested, with protoconch and radular morphology found to be most useful to characterize and differentiate genera and species, while teleoconch and opercular features correspond to three distinct lineages corroborated also by molecular data, viz. the Paramelaniinae with paludomid-like concentric operculum with spiral nucleus, the viviparous Nassopsinae Kesteven, 1903 (= Lavigeriinae Thiele, 1925) with subspiral to paucispiral operculum, and the minute sand-dwelling Syrnolopsinae with paucispiral operculum. Oviparity was found in 70% of the 32 thalassoid species from 17 genera and represents the most common and presumably ancestral reproductive mode within Tanganyikan gastropods, while two different viviparous strategies can be differentiated in 20% of the species (in four other species the reproductive mode is unknown). Finally, some standard hypotheses as to the question of relationships with Thiaridae, monophyly, in situ radiation and viviparity as a key innovation for this radiation are briefly reviewed and discussed. It is concluded that all studied species of the thalassoid species flock are actually members of the Paludomidae instead of the true Thiaridae, representing an evolutionary lineage of ancient, and most likely originally riverine Cerithioidea that predated the formation of the East African Rift system. Consequently, neither the broad spectrum of phenotypes nor the unique morphological features should be viewed as adaptations during the course of exclusively intralacustrine speciation and adaptive radiation within Lake Tanganyika. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

A walk around the pond: insects in and over the water

A water strider darts across a pond, its feet dimpling the surface tension; a giant water bug dives below, carrying his mate's eggs on his back; hidden among plant roots on the silty bottom, a dragonfly larva stalks unwary minnows. Barely skimming the surface, in the air above the pond, swarm mayflies with diaphanous wings. Take this walk around the pond with Gilbert Waldbauer and discover the most amazingly diverse inhabitants of the freshwater world. In his hallmark companionable style, Waldbauer introduces us to the aquatic insects that have colonised ponds, lakes, streams and rivers, especially those in North America. Along the way we learn about the diverse forms these arthropods take, as well as their remarkable modes of life - how they have radiated into every imaginable niche in the water environment, and how they cope with the challenges such an environment poses to respiration, vision, thermoregulation and reproduction. We encounter the caddis fly larva building its protective case and camouflaging it with stream detritus; green darner dragonflies mating midair in an acrobatic wheel formation; ants that have adapted to the tiny water environment within a pitcher plant; and insects whose adaptations to the aquatic lifestyle are furnishing biomaterials engineers with ideas for future applications in industry and consumer goods. While learning about the evolution, natural history and ecology of these insects, readers also discover more than a little about the scientists who study them.

구멍갈파래(Ulva pertusa Kjellman)의 생태생리에 대한 생육기질의 효과

Seashore joining with land and sea, which is typical habitat for marine macroalgae, is classified two types of shore as soft- and hard-bottom shore according to topographical (geological) and ecological features. We compared two of Ulva pertusa Kjellman from two contrasting habitats, sandy (soft-bottom, Haenam) and rocky shore (hard-bottom, Hadong) in terms of chlorophyll-a fluorescence and its parameters, and various photosynthetic pigment and nutrient content in the tissue of those. Both of habitats were different in the light environment such as light attenuation coefficient and even in nutrient concentration of ambient seawater. Electron transport rate (ETR) of Ulva from sandy shore was higher than from rocky shore. The range of photosynthetic pigment content in the tissue of U. pertusa was significantly much more in from sandy shore, and also nitrogen and phosphorus content were significantly higher except for carbon content. However, there were no significant differences in the ratio of among photosynthetic pigments, and N:P ratio was similar between each other, even though significantly different. Our result implied on the reason of why most of green tides in the worldwide concentrated and frequently occurred at sites with sandy, muddy and silty bottoms, being classified as soft-bottom shore.

The first finding of the unattached form ofLaminaria gurjanovae in Pos’eta Bay, Sea of Japan

The unattached form ofLaminaria gurjanovae A. Zin. inhabiting silty and sandy bottoms at depths of 10–30 m in the area of the Tumen River mouth (Pos’eta Bay) is described for the first time. Laminarian thalli interlace their long (up to 50-cm) stipes and form dense aggretations.