Bathymetric Distribution Research Articles

The diversity, distribution and status of deep-water elasmobranchs in the Rockall Trough, north-east Atlantic Ocean.

Data from a scientific deep-water trawl fisheries survey in the north-east Atlantic were analysed to determine the spatial and bathymetric distribution of elasmobranch species and assess the change in relative abundance over the period 1998-2013. During this period, commercial fisheries for deep-water sharks went from being entirely unregulated, to being briefly managed, to being completely prohibited. A total of 22 species of shark and 10 species of skate were recorded between depths of 300 and 2030 m. All showed strong species-specific depth-related trends in abundance. Out of the 11 more common species, five showed no change in relative abundance over time, two (Centrophorus squamosus and Centroselachus crepidater) declined significantly and four increased in relative abundance (Apristurus aphyodes, Apristurus microps, Galeus melastomus and Deania calcea). Assuming these populations were depleted by fisheries in the past, the current data do not suggest there has been an overall recovery. Positive signs for some species in the most recent years suggest movement or recruitment back into the area; however, it is of concern that two species continued to decline. There is a continued need to have precautionary management of these elasmobranch species, and the current ban on landing these species in European waters remains appropriate.

A review of the Munidopsidae Ortmann, 1898 (Decapoda, Galatheoidea)in Chilean waters, including new records for the Southeastern Pacific.

The information about the family Munidopsidae in Chile is scarce and sparse, making identification of new material. difficult. Due to this we lack precise information about the number and accurate distribution of Chilean species. Recent expeditions to Chile have collected specimens of this group, allowing an exhaustive review of the registers and collections in four museums in the country. A total of 93 specimens from six expeditions were analyzed, belonging to twelve species, of which five represent first records for the Chilean waters. The family in Chile is now composed by 19 bathyal and abyssal species; three belong to the genus Galacantha and 16 to Munidopsis. Only three species have distributions restricted to southeastern Pacific waters (M. cochlearis, M. follirostris and M. opalescens). Three other species are widely distributed along the eastern Pacific from Alaska or from Oregon to Chile (M. aspera, M. quadrata and M. verrucosus). No relationships were observed between the extensive geographical distribution of species and the bathymetric distribution.

Into the depth of population genetics: pattern of structuring in mesophotic red coral populations

Deep-sea reef-building corals are among the most conspicuous invertebrates inhabiting the hard-bottom habitats worldwide and are particularly susceptible to human threats. The precious red coral (Corallium rubrum, L. 1758) has a wide bathymetric distribution, from shallow up to 800 m depth, and represents a key species in the Mediterranean mesophotic reefs. Several studies have investigated genetic variability in shallow-water red coral populations, while geographic patterns in mesophotic habitats are largely unknown. This study investigated genetic variability of C. rubrum populations dwelling between 55 and 120 m depth, from the Ligurian to the Ionian Sea along about 1500 km of coastline. A total of 18 deep rocky banks were sampled. Colonies were analyzed by means of a set of microsatellite loci and the putative control region of the mitochondrial DNA. Collected data were compared with previous studies. Both types of molecular markers showed high genetic similarity between populations within the northern (Ligurian Sea and Tuscan Archipelago) and the southern (Tyrrhenian and Ionian seas) study areas. Variability in habitat features between the sampling sites did not affect the genetic variability of the populations. Conversely, the patchy distribution of suitable habitats affected populations’ connectivity within and among deep coral banks. Based on these results and due to the emphasis on red coral protection in the Mediterranean Sea by international institutions, red coral could be promoted as a ‘focal species’ to develop management plans for the conservation of deep coralligenous reefs, a reservoir of marine biodiversity.

Species composition and distribution of Agonidae in Peter the Great Bay (sea of Japan) in the summer period

In the Peter the Great Bay, there are 16 species of sea poachers (Agonidae), 13 of which occur in catches regularly. According to results of summer bottom trawl surveys, spatial and bathymetric distribution of six of the most mass species are considered and data on their size composition and biomass are presented. As the main factor determining distribution of most species, hydrological conditions of the bay and aquatic environmental inhomogeneity are considered.

On some sea cucumbers (Echinodermata: Holothuroidea) from off the south and west coasts of South Africa collected by the South African Environmental and Observation Network (SAEON).

Twenty four specimens of holothuroids recently received from the South African Environmental and Observation Network (SAEON), collected from off the south and west coasts of South Africa, are herein recorded and/or described. The specimens comprise eight nominal and one indeterminate species and represent both shallow-water and deep-sea forms, distributed from Plettenberg Bay to just north of Lambert's Bay in the Western Cape Province. There are no new species but two new records for the South African region and extensions of horizontal and bathymetric distributions of the other species. Additions to the South African fauna are Zygothuria lactea (Théel, 1886) and Synallactes cf. challengeri (Théel, 1886). The paper also contains the first definite record of Thyone venusta Selenka, 1868, originally described from the Red Sea. Distribution ranges of the following species have been altered Synallactes viridilimus Cherbonnier, 1952; S. mollis Cherbonnier, 1952 and Psuedostichopus langeae Thandar, 2009.

Distribution and population structure of deep‐dwelling red coral in the Northwest Mediterranean

AbstractCommercially harvested since ancient times, the highly valuable red coral Corallium rubrum (Linnaeus, 1758) is an octocoral endemic to the Mediterranean Sea and adjacent Eastern Atlantic Ocean, where it occurs on rocky bottoms over a wide bathymetric range. Current knowledge is restricted to its shallow populations (15–50 m depth), with comparably little attention given to the deeper populations (50–200 m) that are nowadays the main target of exploitation. In this study, red coral distribution and population structure were assessed in three historically exploited areas (Amalfi, Ischia Island and Elba Island) in the Tyrrhenian Sea (Western Mediterranean Sea) between 50 and 130 m depth by means of ROV during a cruise carried out in the summer of 2010. Red coral populations showed a maximum patch frequency of 0.20 ± 0.04 SD patches·m−1 and a density ranging between 28 and 204 colonies·m−2, with a fairly continuous bathymetric distribution. The highest red coral densities in the investigated areas were found on cliffs and boulders mainly exposed to the east, at the greatest depth, and characterized by medium percentage sediment cover. The study populations contained a high percentage (46% on average) of harvestable colonies (>7 mm basal diameter). Moreover, some colonies with fifth‐order branches were also observed, highlighting the probable older age of some components of these populations. The Ischia population showed the highest colony occupancy, density and size, suggesting a better conservation status than the populations at the other study locations. These results indicate that deep dwelling red coral populations in non‐stressed or less‐harvested areas may diverge from the inverse size‐density relationship previously observed in red coral populations with increasing depth.

Genetic population structure of four hydrothermal vent shrimp species (Alvinocarididae) in the Okinawa Trough, Northwest Pacific

Understanding the formative factors of connectivity among deep-sea chemosynthetic communities may clarify the biogeographic mechanisms that facilitate the establishment and development of vent/seep fauna. This study identified interspecific differences in the geographical distribution and genetic population structure of 4 alvinocaridid shrimp species inhabiting hydrothermal vents in the Okinawa Trough, Northwest Pacific. Shinkaicaris leurokolos populations were widely distributed at 580 to 1651 m depth, with partial nucleotide sequences of the mitochondrial COI gene revealing extremely high genetic diversity (haplotype diversity: 0.98 to 1.00). In contrast, local populations of Alvinocaris dissimilis and A. longirostris, both of which have narrower bathymetric distributions, were characterised by low haplotype diversity (0.29 to 0.52). In the Okinawa Trough, Alvinocaris sp. only occurs at the Irabu Knoll, but this species also inhabits the Suiyo Seamount on the volcanic front of the Izu-Bonin Arc (Northwest Pacific). This undescribed species had relatively high haplotype diversity (0.70 to 0.82), with no genetic differentiation between the 2 sites. Certain factors may allow this species to occur at both sites (e.g. a chemical environment derived from similar substratum), despite geological differences in hydrothermal circulation (i.e. a back-arc basin versus an arc volcanic front, respectively). The findings of this study indicate that (1) the wide geographical and bathymetrical distributional ranges of the vent shrimp species cause high genetic diversity associated with stable population connectivity and (2) certain environmental features (e.g. depth and substratum) and life-history traits (e.g. feeding habitat and larval characteristics) represent important formative factors in the connectivity of alvinocaridids in the Northwest Pacific.

Revisión de la familia Phyllophoridae (Holothuroidea: Dendrochirotida) de las aguas mexicanas.

The fauna of the echinoderms of Mexico is represented by 643 species. Within these, 113 belong to the class Holothuroidea (sea cucumbers). The phyllophorids (Holothuroidea: Phyllophoridae) are characterized by the presence of more than 10 tentacles and a calcareous ring prolonged posteriorly with small pieces forming a mosaic-like appearance. Their cryptic habits have made them difficult to record during the many years of taxonomic studies regarding this group in Mexico. This paper aims to raise awareness of the state of knowledge on the diversity of the Phyllophoridae family in Mexican territorial waters. We present 16 species belonging to six genera, living in shallow (0 - 200 m) to deep (> 200 m) waters in the Mexican Pacific, Gulf of California, Mexican Caribbean and Gulf of Mexico. Within these, three new records are included. A taxonomic identification catalog was obtained for each species, providing information about external and internal morphology; the material was examined and recorded with information from type material and locality, all previous reports for Mexico, the geographic and bathymetric distribution as well as photographs taken with Scanning Electron Microscopy (SEM) of the shape and combination of the spicules. The work is complemented with a dichotomous key for identification.

Redescription of Hemieuryale pustulata von Martens, 1867 (Echinodermata, Ophiuroidea) based on Brazilian specimens, with notes on systematics and habitat association.

We redescribe Hemieuryale pustulata on the basis of 325 specimens obtained from the continental shelf off northeastern and southeastern Brazil. This is the first record of the species for Brazil. We illustrate for the first time details of the dental plate, oral plate, and vertebrae. Few morphological variations were observed in our extensive material. All specimens were associated with the gorgonian Nicella guadalupensis, suggesting an obligatory association in the Brazilian littoral. H. pustulata did not reveal a particular pattern of distribution on its host gorgonian, but larger gorgonians tend to support a larger number of ophiuroids. In addition to expanding the knowledge on morphology and ecology, we extend the known bathymetric distribution of the species, which is now known from 18 to 330 m.

Distribution and biological characteristics of Antarctic toothfish Dissostichus mawsoni in the Weddell Sea

Based on the materials from a longline survey carried out in 2013 in the Weddell Sea, the bathymetric distribution of the Antarctic toothfish Dissostichus mawsoni, its size/weight and age composition, the maturity degree of its gonads, and its nutrition are analyzed. Individuals with a length of 63–170 cm and a weight of 3–59 kg, aged from 6 to 32 years, are recorded in the surveyed range of depths (786–1552 m). Compared with other Antarctic seas, small Antarctic toothfish (with a length of up to 70 cm) occur at deeper layers. The weight of large fish in the Weddell Sea (>100 cm) is lower than that of the individuals with the same size in the Ross Sea. It is assumed that this is due to a lower abundance and diversity of items of nutrition (four vs. ten fish species).

A new bathyal mysid of the family Petalophthalmidae (Crustacea: Mysida) from the Bismarck Sea (Western Tropical Pacific Ocean).

A new species of the genus Petalophthalmus (Crustacea: Mysida: Petalophthalmidae) is described, based on one specimen collected from the Bismarck Sea (Papua New Guinea, Western Pacific Ocean). This species can be distinguished from the other species of the genus Petalophthalmus by the globular cornea and the armature of the telson. This new species lives between 800 and 1065 m depth. A discussion on the geographic and bathymetric distribution and an identification key to world species of Petalophthalmus are provided.

Reproductive biology of NW Mediterranean tonguefish Symphurus nigrescens and Symphurus ligulatus

The population structure and reproductive biology of deep-water continental margin Cynoglossidae is poorly known. Here, we focused on two highly abundant species of the upper slope of the NW Mediterranean Sea, Symphurus nigrescens and S. ligulatus. Megafaunal sampling of 37 hauls was conducted between April 2003 and May 2004 in the Blanes canyon and the adjacent open slope between 300–1500 m depth. The differential bathymetric distribution between the two species was surveyed by standardizing catch data per unit of swept surface and by pooling resulting densities by 100 m depth interval. Females of both species were classified into a five-stage maturity scale according to their external appearance and their gonads dissected for histological analysis. The analysis of the species' bathymetric distribution revealed a differential and only partial overlap. In both species, an increase in size with depth was observed coinciding with the dominance of females in deeper depth strata. The shallower species, S. nigrescens showed a marked spawning period with a peak in summer. In contrast, the deeper-living species, S. ligulatus, presented a longer spawning period ranging from spring to autumn. Moreover, histological examination demonstrated that the ovaries of both species had an asynchronous organization. Present results on spatial-temporal size frequency distribution, spawning temporality and oocyte size are discussed assuming interspecific competition and the different environmental conditions related to their bathymetric distribution.

Prevalent endosymbiont zonation shapes the depth distributions of scleractinian coral species.

Bathymetric distributions of photosynthetic marine invertebrate species are relatively well studied, however the importance of symbiont zonation (i.e. hosting of distinct algal endosymbiont communities over depth) in determining these depth distributions still remains unclear. Here, we assess the prevalence of symbiont zonation in tropical scleractinian corals by genotyping the Symbiodinium of the 25 most common species over a large depth range (down to 60 m) on a Caribbean reef. Symbiont depth zonation was found to be common on a reef-wide scale (11 out of 25 coral species), and a dominant feature in species with the widest depth distributions. With regards to reproductive strategy, symbiont zonation was more common in broadcasting species, which also exhibited a higher level of polymorphism in the symbiont zonation (i.e. number of different Symbiodinium profiles involved). Species with symbiont zonation exhibited significantly broader depth distributions than those without, highlighting the role of symbiont zonation in shaping the vertical distributions of the coral host. Overall, the results demonstrate that coral reefs can consist of highly structured communities over depth when considering both the coral host and their obligate photosymbionts, which probably has strong implications for the extent of connectivity between shallow and mesophotic habitats.

Distribution patterns in Antarctic and Subantarctic echinoderms

Echinoderms are the dominant megafaunal taxa in Antarctic and Subantarctic waters in terms of abundance and diversity, having a predominant role in structuring communities. The current study presents new data on the asteroids, holothuroids, and ophiuroids (three of the five extant classes of echinoderms) collected in seven scientific campaigns (1995–2012) from Bouvet Is., South Shetland Is., and the Eastern Weddell Sea, from a wide bathymetric range (0–1,525 m). Among the 316 echinoderms collected, we extended the bathymetric ranges of 15 species and expanded the geographic distribution of 36 of them. This novel dataset was analyzed together with previous reports in order to establish general patterns of geographic and bathymetric distribution in echinoderms of the Southern Ocean (SO). Nearly 57 % of the assembled-data species resulted endemic of the SO, although further taxonomic efforts in less accessible areas are needed. Interestingly, some islands presented high levels of species richness even comparable to large geographic areas. While generally exhibiting a wide range of eurybathy, there were differences in species composition across depths corresponding to sublittoral, upper and lower bathyal, and abyssal. Bathymetric distribution was analyzed considering biological aspects for each class. As expected, circumpolar trends were found, although hydrographic currents may be the cause of differences in species composition among SO areas. Our analyses suggest zoogeographic links between Antarctica and the adjacent ocean basins, being the Scotia Arc the most remarkable. This study contributes to the knowledge of large-scale diversity and distribution patterns in an Antarctic key group.

Deep down on a Caribbean reef: lower mesophotic depths harbor a specialized coral-endosymbiont community.

The composition, ecology and environmental conditions of mesophotic coral ecosystems near the lower limits of their bathymetric distributions remain poorly understood. Here we provide the first in-depth assessment of a lower mesophotic coral community (60–100 m) in the Southern Caribbean through visual submersible surveys, genotyping of coral host-endosymbiont assemblages, temperature monitoring and a growth experiment. The lower mesophotic zone harbored a specialized coral community consisting of predominantly Agaricia grahamae, Agaricia undata and a “deep-water” lineage of Madracis pharensis, with large colonies of these species observed close to their lower distribution limit of ~90 m depth. All three species associated with “deep-specialist” photosynthetic endosymbionts (Symbiodinium). Fragments of A. grahamae exhibited growth rates at 60 m similar to those observed for shallow Agaricia colonies (~2–3 cm yr−1), but showed bleaching and (partial) mortality when transplanted to 100 m. We propose that the strong reduction of temperature over depth (Δ5°C from 40 to 100 m depth) may play an important contributing role in determining lower depth limits of mesophotic coral communities in this region. Rather than a marginal extension of the reef slope, the lower mesophotic represents a specialized community, and as such warrants specific consideration from science and management.

Descriptive and illustrated diagnosis of Ophiuroidea fauna (Echinodermata) in the shallow waters of North-eastern Brazil

In this study, we present descriptions, illustrations, comments, and bathymetric and geographic distributions of the brittle star species related to the estuary region of Camamu Bay, located in the State of Bahia, Brazil. The brittle star fauna lives on biological substrates, sand bottoms, mud and rubble in the Camamu Bay and comprises 12 species divided into five families. Almost all of them are common in the tropical and subtropical fauna of the regions of shallow water.Ophiophragmus filograneusis reported for the first time in Bahia, and nine other species are recorded for the first time in Camamu Bay:Amphipholis januarii, Amphipholis squamata, Ophiophragmus filograneus, Ophiostigma isocanthum,Ophioderma cinerea, Ophioderma januarii, Ophiactis lymani, Ophiactis savignyi andOphiocoma echinata.The results suggest that the ophiuroid assemblages are strongly affected by marine currents as well as by different kinds of bottom substrate.

First record of genus Coenocyathus Milne Edwards & Haime, 1848 (Cnidaria: Anthozoa: Scleratinia) in the Bay of Biscay (northeastern Atlantic)

During the Fauna II expedition by the National Museum of Natural History (Madrid, Spain), two specimens of Coenocyathus cylindricus Milne Edwards & Haime, 1848 (Cnidaria: Scleractinia) were collected off Ribadeo (Lugo, Spain), in the Bay of Biscay, at a depth of 114-116 m. This is an uncommon coral, cited only once before in the Iberian Peninsula, in the south of Portugal. The genus Coenocyathus Milne Edwards & Haime, 1848 has been, thus, first recorded in the Bay of Biscay, being also the northernmost occurrence in the Eastern Atlantic. In this paper, the specimens are described and depicted, and the geographic and bathymetric distributions of the species are updated. With this new record, there are 46 scleractinian species recorded up to now in the southern sector of the Bay of Biscay, which is herein considered of high species richness within the northeastern Atlantic fauna. Forty-two out of this 46 species are deep-sea corals living below than 50 m deep.

Water temperature and characteristics of thermal stratification in Nam Co, Tibet

水温变化是湖泊的重要物理特性,对湖泊的水质特征、湖水能量循环、水生生态系统研究具有重要意义.基于不同季节的实地观测资料,分析青藏高原高海拔、深水大湖纳木错的水温变化特征及季节差异,并着重分析湖水热力学分层的季节变化.结果显示纳木错中部、东部两个湖盆冬季封冻,夏季存在稳定分层,春、秋季混合,是一个典型双季对流、完全混合型湖泊.但两个湖盆水温变化与热力学分层又有各自的特征,东部浅湖盆湖水在春季升温快,夏季分层与秋季翻转均比中部湖盆早,且秋季翻转时水温也比中部湖盆高.初步分析认为两个湖盆不同的湖盆形状及水深分布可能是造成其热力学特征差异的主要原因.;Variation of water temperature is a critical physical property of a lake, which has great significance for other research, such as lake water quality, energy cycle, aquatic ecosystem. Illustrated by Nam Co, characteristics and seasonal differences of lake water temperature distribution were studied in a high altitude deep lake on the Tibetan Plateau, with in-situ monitoring data from different seasons. Then, seasonal variability of thermal stratification was emphatically analyzed. Results imply that in Nam Co, both the middle and eastern parts are frozen up in winter, completely mixed in spring and autumn, and steadily stratified in summer. Thus, Nam Co is a typical dimictic lake, and a holomictic lake at the same time. However, the two parts of Nam Co have unique characteristics in season variability of water temperature and thermal stratification respectively. In spring, temperature rises faster in the relatively shallow basin than that in the middle lake. Meanwhile, the date of summer stratification and autumn overturn is earlier in the shallow basin, in which water temperature is higher when circulated in autumn as well. By preliminary analysis, different topography under water and bathymetric distribution of the two basins probably contribute the most to the difference in the thermodynamic characteristic.

Acute combined pressure and temperature exposures on a shallow-water crustacean: Novel insights into the stress response and high pressure neurological syndrome

Little is known about the ecological and physiological processes governing depth distribution limits in species. Temperature and hydrostatic pressure are considered to be two dominant factors. Research has shown that some marine ectotherms are shifting their bathymetric distributions in response to rapid anthropogenic ocean surface warming. Shallow-water species unable to undergo latitudinal range shifts may depend on bathymetric range shifts to seek refuge from warming surface waters. As a first step in constraining the molecular basis of pressure tolerance in shallow water crustaceans, we examined differential gene expression in response to acute pressure and temperature exposures in juveniles of the shallow-water shrimp Palaemonetes varians. Significant increases in the transcription of genes coding for an NMDA receptor-regulated protein, an ADP ribosylation factor, β-actin, two heat shock protein 70kDa isoforms (HSP70), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were found in response to elevated pressure. NMDA receptors have been implicated in pathways of excitotoxic damage to neurons and the onset of high pressure neurological syndrome (HPNS) in mammals. These data indicate that the sub-lethal effects of acute barotrauma are associated with transcriptional disturbances within the nervous tissue of crustaceans, and cellular macromolecular damage. Such transcriptional changes lead to the onset of symptoms similar to that described as HPNS in mammals, and may act as a limit to shallow water organisms' prolonged survival at depth.

Complementary distribution of two sympatric serranids in a NATURA 2000 site in the Northern Aegean Sea (Eastern Mediterranean)

The present work aimed to investigate possible spatial and seasonal patterns in the distribution of two sympatric serranids, the painted comber, Serranus scriba and the comber, Serranus cabrilla. The research took place at a NATURA 2000 site located at Sithonia peninsula, N. Greece. Underwater visual census was used for data collection; specifically, individuals from each species were recorded along four isobathic transects of 200 m2 each, placed every 5 m and ranging from 5 to 20 m depth. A total of 27 samplings were conducted between September 2010 and August 2011. The results clearly demonstrated complementary bathymetric distributions for S. scriba and S. cabrilla, the former mostly occurring until 10 m depth, and the latter in deeper layers. This pattern was maintained during the whole season. In addition the two species exhibited differences in their preferred substrate type and their pattern of association to the sea bottom. Our results were viewed under the light of resource portioning between the two sympatric species.