Zoarcid Fish Research Articles

Species composition and distribution of eelpouts (Zoarcidae, Perciformes, Actinopterygii) in the northwestern Sea of Okhotsk in summer

The northern part of the Sea of Okhotsk is currently a grey area in terms of the degree of knowledge on the taxonomy and distribution of some non-commercial fish families, especially Zoarcidae, which are represented here by a large number of species. The species composition and spatial distribution of eelpouts in the northwestern Sea of Okhotsk outer shelf and adjacent upper continental slope are described based on 2013 bottom trawl survey data. A rich and diverse zoarcid fish fauna are found. A total of 3664 specimens distributed among 6 genera and 19 species are registered. The study incorporated two areas of the shelf with temperatures below and above −1 °C, both possessed a high species diversity but different species composition. A clear vertical zonation pattern was revealed in the distribution of the species.

A new species of Gymnelus (Perciformes, Zoarcidae) from Greenland, similar to G. viridis

Zoarcid fishes of the genus Gymnelus Reinhardt inhabit the shelves of the North Pacific Ocean and the Arctic. A new species, G. pseudosquamatus sp. nov., is described from trawl samples taken at depths off South-West Greenland. It is most similar to the type species of the genus, Common Fish Doctor G. viridis, inhabiting the coastal waters of Greenland. The characters of the latter are specified on materials from the type locality, including the neotype and specimens of J.C.H. Reinhardt. Both species are in the group of Gymnelus with an interrupted supratemporal commissura, two supratemporal sensory pores (1+0+1), and a dorsal fin originating above the pectoral fin. The two species differ in a complex of characters, including habitus. In G. viridis, the trunk is roundish in cross section, highest above the beginning of the anal fin; the anterior rays of the dorsal fin are shortened, and covered with a thick and somewhat fleshy skin. In G. pseudosquamatus, the body is compressed and deeper anteriorly, the dorsal-fin rays are evenly elongated, and the fin membrane is thin. Differences in counts and measurements are statistically significant, including the number of vertebrae and rays in the dorsal, anal and pectoral fins, the number of teeth on the jaws, as well as the length and depth of the head, predorsal length, the length of pectoral fins, eye diameter and length of the gill slit. The color of G. pseudosquamatus, with 8–16 wide brown mottled bands, is also unusual, as the skin is dotted with light speckles that create the illusion of tiny scales, which is the reason for the name “pseudosquamatus”, the Deceptive Fish Doctor. While G. viridis is found inshore in a zone of macroalgae, the new species is found in deeper waters (100–457 m) along the shelf edge of South-West Greenland. The name Ophidium stigma Lay et Bennett, 1839 (=Gymnelus stigma) should be excluded from the synonymy of G. viridis, since the original description mentions the presence of scales on the body, which are absent in Gymnelus.

Diagnostic characters of two rare zoarcids, Krusensterniella multispinosa and K. pavlovskii (Pisces: Zoarcidae), with new data for the Sea of Okhotsk

Diagnostic characters and taxonomic descriptions of two rare zoarcid fishes, Krusensterniella multispinosa Soldatov, 1922 and K. pavlovskii Andriashev, 1955 (family Zoarcidae), have been updated using the type and additional specimens. The type locality of K. multispinosa is located in the northwestern part of the Sea of Okhotsk (55°57ʹN, 138°13ʹE, depth 87 m). The lectotype (ZIN No 19961) was designated by P.Yu. Schmidt (1950). The morphological variability of the species is described, diagnosis is expanded. Additional differences from the species of related genus Gymnelopsis are specified. The distribution of K. multispinosa is limited to the Sea of Okhotsk and depths of 78–160 m. Krusensterniella pavlovskii was known by three type specimens from the Cape Africa, eastern Kamchatka (holotype ZIN No 33748, paratypes ZIN No 56576). Additional specimen derives from the north-eastern part of the Sea of Okhotsk (58°50ʹN, 157°02ʹE), which extends the known range of the species. The description of K. pavlovskii was updated, the diagnosis supplemented. Krusensterniella multispinosa and K. pavlovskii (subgenus Schantarella Andriashev, 1938) differ from other congeners in a larger number of pungent spines in the middle section of the dorsal fin D (XV–XXVI vs. I-XI). The both have 100–112 vertebrae, 95–110 dorsal-fin rays, and 81–94 anal-fin rays. In Krusensterniella pavlovskii unlike K. multispinosa, there are XXIII–XXVI pungent spines D (vs. XV–XX), 71–74 spiny rays in the anterior and middle parts of the dorsal fin (vs. 60–69), and 7 preoperculomandibular pores (vs. 6); the middle section of D with pungent spines is 83-112% of the length of the posterior section of D (43–72% in K. multispinosa) and 26–31% of the tail length, measured from the anal-fin origin to the caudal-fi n en d (vs. 17–22%); the scale cover reaching forward to the pectoral fins (in K. multispinosa not reaching the anal-fin origin.

Benthic and Demersal Scavenger Biodiversity in the Eastern End of the Clarion-Clipperton Zone – An Area Marked for Polymetallic Nodule Mining

In the Clarion-Clipperton Zone (CCZ) in the north-eastern Pacific Ocean ca. 30 billion tonnes of polymetallic nodules, rich in metals critical for frontier technologies, lay on the sediment surface over an area of 4 to 5 million square kilometres. For this reason, there is accelerating interest in deep-sea mineral mining in the CCZ. Few data exist concerning marine biodiversity in this enormous region and a solid understanding of baseline biodiversity and ecosystem function are necessary in order to inform effective management strategies, conservation and monitoring in the event that mining goes ahead in the CCZ. In this study, 10 in situ baited-camera experiments were carried out in the BGR (The Federal Institute for Geosciences and Natural Resources, Germany) license area in the eastern CCZ to document the biodiversity of scavengers and their feeding activities. Twelve different bait-attending taxa were identified. The most common of these were macrourid, ophidiid and zoarcid fishes, and dendrobranchiate shrimp. Successional patterns regarding their time of arrival were also observed. The bait consumption rate was measured, and a mean scavenging rate of 878 g d-1 ± 113 (SE, n = 9) was calculated, with the rattail Coryphaenoides spp. responsible for the majority of the bait consumption. Polymetallic nodule size did not significantly affect community structure, diversity or scavenging rates within the BGR license area, but significant differences were found in community structure between the BGR area and other areas of the eastern CCZ (the Ocean Minerals of Singapore and UK1 areas). This study increases our knowledge of deep-sea scavenging communities in an area targeted for deep-sea mining.

Complete mitochondrial genome characteristics and phylogenetic position of Lycodes brevipes Bean, 1890

Lycodes brevipes is one of the representative species of zoarcid fishes with little genetic information. The complete mitochondrial genome sequence of L. brevipes was sequenced by long PCR and primer walking methods. The mitogenome is a circular molecule of 16,537 bp in length including the structure of 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes and two non-coding regions (origin of light strand replication and control region). The present study also revealed the phylogenetic relationship of this species at the molecular level using NJ algorithm. The mitogenome of L. brevipes provides essential genetic data for further phylogenetic and evolutionary analyses.

Redescription and phylogenetic position of Myxobolus aeglefini and Myxobolus platessae n. comb. (Myxosporea), parasites in the cartilage of some North Atlantic marine fishes, with notes on the phylogeny and classification of the Platysporina

Myxobolus ‘aeglefini’ Auerbach, 1906 was originally described from cranial cartilage of North sea haddock (Melanogrammus aeglefinus), but has subsequently been recorded from cartilaginous tissues of a range of other gadoid hosts, from pleuronectids and from lumpsucker (Cyclopterus lumpus) in the North Atlantic and from a zoarcid fish in the Japan Sea (Pacific).We obtained partial small-subunit rDNA sequences of Myxobolus ‘aeglefini’ from gadoids and pleuronectids from Norway and Iceland. The sequences from gadoids and pleuronectids represented two different genotypes, showing 98.2% identity. Morphometric studies on the spores from selected gadids and pleuronectids revealed slight but statistically significant differences in spore dimensions associated with the genotypes, the spores from pleuronectids were thicker and with larger polar capsules. We identify the morpho- and genotype from gadoids with Myxobolus ‘aeglefini’ sensu Auerbach, and the one from pleuronectids with Sphaerospora platessae Woodcock, 1904 as Myxobolus platessae n. comb. The latter species was originally described from Irish Sea plaice (Pleuronectes platessa). Myxobolus albi Picon et al., 2009 described from the common goby Pomatoschistus microps in Scotland is a synonym of M. ‘aeglefini’. The Pacific Myxobolus ‘aeglefini’ represents a separate species, showing only 97.4–97.6% identity to the Atlantic species. In phylogenetic analyses based on SSU rDNA sequences, these and some related marine chondrotropic Myxobolus spp. form a distinct well supported group. This clusters with freshwater and marine myxobolids and Triangula and Cardimyxobolus species, in a basal clade in the phylogeny of the Platysporina. Members of family Myxobilatidae, Ortholinea spp. (currently Ortholineidae) and sequences of some other urinary system infecting myxosporeans form a well supported clade among members of the suborder Platysporina. Based on phylogenetic analyses, we propose the following changes to the classification of Myxosporea: i) Ortholineidae is dismantled and Ortholinea spp. transferred to Myxobilatidae, and ii) Myxobilatidae is transferred from suborder Variisporina to Platysporina.

Description of a new deep-sea eelpout Pachycara matallanasi sp. nov. from the Solomon Sea (western South Pacific Ocean)

A new species of zoarcid fish, Pachycara matallanasi, is described. During the Danish Galathea 3 expedition, on 28 December 2006, six specimens of Pachycara Zugmayer, 1911 were collected from depths of 4350–4450 m. The new species is the second member of the genus in the western South Pacific Ocean. Pachycara matallanasi sp. nov. can be distinguished from its congeners by a combination of the following characters: body without scales; pelvic fin absent; lateral line mediolateral; dorsal fin origin associated with vertebrae 5–6 with 0–1 free predorsal pterygiophores; total vertebrae 103–108; smooth ceratohyal–epihyal articulation; post-temporal with well-developed ventral ramus; coracoid with a posterior strut and a small foramen.http://zoobank.org/urn:lsid:zoobank.org:pub:B61D0421-8CF3-46E5-BCE0-20E12E3ED69A

On the colour types in Lycodes nakamurae (Tanaka, 1914) and species composition of the subgenus Furcimanus (Perciformes: Zoarcidae: Lycodes) in the sea of Japan.

Two colour types were revealed in a zoarcid fish of the subgenus Furcimanus, genus Lycodes, in the Sea of Japan. A comparison of morphometric, meristic and genetic characters in dark coloured and light coloured individuals suggests that the two colour morphs represent a single species, determined to be Lycodes nakamurae (Tanaka, 1914). Variability in colouration within L. nakamurae and a lack of morphological or molecular characters distinguishing L. nakamurae from L. nishimurai Shinohara & Shirai, 2005 suggest that the latter should be considered a synonym of L. nakamurae (Tanaka, 1914). A record of L. pectoralis in the waters of the Republic of Korea is regarded as a misidentification. Thus, we conclude that only one species of the Lycodes subgenus Furcimanus, L. nakamurae, with dark and light colour morphs as well as specimens of intermediate colouration, inhabits the Sea of Japan.

Discovery of a recent, natural whale fall on the continental slope off Anvers Island, western Antarctic Peninsula

Whale falls provide a substantial, nutrient-rich resource for species in areas of the ocean that may otherwise be largely devoid of food. We report the discovery of a natural whale fall at 1430m depth in the cold waters of the continental slope off the western Antarctic Peninsula. This is the highest-latitude whale fall reported to date. The section of the carcass we observed—the tail fluke—was more complete than any previously reported natural whale fall from the deep sea and in the early stages of decomposition. We estimate the entire cetacean to measure 5–8m in length. The flesh remained almost intact on the carcass but the skin was missing from the entire section except for the end of the fluke, clearly exposing blubber and soft tissue. The absence of skin indicates rapid and Homogeneous loss. The dominant macrofauna present were crustaceans, including most prominently the lithodid crab Paralomis birsteini, and zoarcid fish typical of the ‘mobile-scavenger’ successional stage. The density of mobile macrofauna was greatest on the carcass and declined to background levels within 100m, indicating that they were attracted to the whale fall. This whale fall offers an important opportunity to examine the decomposition of a carcass under deep-sea conditions at polar latitudes.

Phylogeny and taxonomy of Petroschmidtia teraoi (Katayama, 1943) (Osteichthyes: Perciformes: Zoarcidae).

A morphological and genetic reassessment of the phylogeny and taxonomy of the dwarf zoarcid fish Lycodes teraoi Katayama, 1943 indicated that the species, a senior synonym of Lycodes sadoensis Toyoshima & Honma, 1980, should be placed in the genus Petroschmidtia. A redescription of P. teraoi is provided, with remarks on its taxonomy. Numerous specimens revealed a wide distribution of P. teraoi in the Sea of Japan, as well as in the southern Sea of Okhotsk.

Population Structure and Demographic History of Davidijordania poecilimon (Perciformes: Zoarcidae)

The population structure and demographic history of a zoarcid fish, Davidijordania poecilimon (Jordan and Fowler, 1902), around Japan were investigated on the basis of sequence variations in the cytochrome b gene of mitochondrial DNA (440 base pairs). Among 44 specimens, 18 haplotypes were recognized. Although some were shared among individuals from different localities in the Sea of Japan or in the Pacific Ocean, no haplotypes were shared between the two regions. The haplotype network showed a rough separation of the Sea of Japan and Pacific population haplotypes, forming a dumbbell-like pattern, each half with a major haplotype. In addition, the pairwise ΦST between the Sea of Japan and Pacific populations of 0.35 was significant according to the permutation test (p < 0.01). Such evidence indicates that gene flow between the two populations is restricted by the shallow strait (Tsugaru Strait) between the Sea of Japan and the Pacific Ocean. Mismatch distribution analysis suggests that the Pacific population comprises historically older and larger populations than those in the Sea of Japan.

Moytirra: Discovery of the first known deep‐sea hydrothermal vent field on the slow‐spreading Mid‐Atlantic Ridge north of the Azores

Geological, biological, morphological, and hydrochemical data are presented for the newly discovered Moytirra vent field at 45oN. This is the only high temperature hydrothermal vent known between the Azores and Iceland, in the North Atlantic and is located on a slow to ultraslow‐spreading mid‐ocean ridge uniquely situated on the 300 m high fault scarp of the eastern axial wall, 3.5 km from the axial volcanic ridge crest. Furthermore, the Moytirra vent field is, unusually for tectonically controlled hydrothermal vents systems, basalt hosted and perched midway up on the median valley wall and presumably heated by an off‐axis magma chamber. The Moytirra vent field consists of an alignment of four sites of venting, three actively emitting “black smoke,” producing a complex of chimneys and beehive diffusers. The largest chimney is 18 m tall and vigorously venting. The vent fauna described here are the only ones documented for the North Atlantic (Azores to Reykjanes Ridge) and significantly expands our knowledge of North Atlantic biodiversity. The surfaces of the vent chimneys are occupied by aggregations of gastropods (Peltospira sp.) and populations of alvinocaridid shrimp (Mirocaris sp. with Rimicaris sp. also present). Other fauna present include bythograeid crabs (Segonzacia sp.) and zoarcid fish (Pachycara sp.), but bathymodiolin mussels and actinostolid anemones were not observed in the vent field. The discovery of the Moytirra vent field therefore expands the known latitudinal distributions of several vent‐endemic genera in the north Atlantic, and reveals faunal affinities with vents south of the Azores rather than north of Iceland.

Evolutionary force in confamiliar marine vertebrates of different temperature realms: adaptive trends in zoarcid fish transcriptomes.

BackgroundStudies of temperature-induced adaptation on the basis of genomic sequence data were mainly done in extremophiles. Although the general hypothesis of an increased molecular flexibility in the cold is widely accepted, the results of thermal adaptation are still difficult to detect at proteomic down to the genomic sequence level. Approaches towards a more detailed picture emerge with the advent of new sequencing technologies. Only small changes in primary protein structure have been shown to modify kinetic and thermal properties of enzymes, but likewise for interspecies comparisons a high genetic identity is still essential to specify common principles. The present study uses comprehensive transcriptomic sequence information to uncover general patterns of thermal adaptation on the RNA as well as protein primary structure.ResultsBy comparing orthologous sequences of two closely related zoarcid fish inhabiting different latitudinal zones (Antarctica: Pachycara brachycephalum, temperate zone: Zoarces viviparus) we were able to detect significant differences in the codon usage. In the cold-adapted species a lower GC content in the wobble position prevailed for preserved amino acids. We were able to estimate 40-60% coverage of the functions represented within the two compared zoarcid cDNA-libraries on the basis of a reference genome of the phylogenetically closely related fish Gasterosteus aculeatus. A distinct pattern of amino acid substitutions could be identified for the non-synonymous codon exchanges, with a remarkable surplus of serine and reduction of glutamic acid and asparagine for the Antarctic species.ConclusionBased on the differences between orthologous sequences from confamiliar species, distinguished mainly by the temperature regimes of their habitats, we hypothesize that temperature leaves a signature on the composition of biological macromolecules (RNA, proteins) with implications for the transcription and translation level. As the observed pattern of amino acid substitutions only partly support the flexibility hypothesis further evolutionary forces may be effective at the global transcriptome level.

Evolution of an antifreeze protein by neofunctionalization under escape from adaptive conflict

The evolutionary model escape from adaptive conflict (EAC) posits that adaptive conflict between the old and an emerging new function within a single gene could drive the fixation of gene duplication, where each duplicate can freely optimize one of the functions. Although EAC has been suggested as a common process in functional evolution, definitive cases of neofunctionalization under EAC are lacking, and the molecular mechanisms leading to functional innovation are not well-understood. We report here clear experimental evidence for EAC-driven evolution of type III antifreeze protein gene from an old sialic acid synthase (SAS) gene in an Antarctic zoarcid fish. We found that an SAS gene, having both sialic acid synthase and rudimentary ice-binding activities, became duplicated. In one duplicate, the N-terminal SAS domain was deleted and replaced with a nascent signal peptide, removing pleiotropic structural conflict between SAS and ice-binding functions and allowing rapid optimization of the C-terminal domain to become a secreted protein capable of noncolligative freezing-point depression. This study reveals how minor functionalities in an old gene can be transformed into a distinct survival protein and provides insights into how gene duplicates facing presumed identical selection and mutation pressures at birth could take divergent evolutionary paths.

Behavioral rhythms of hydrocarbon seep fauna in relation to internal tides

Behavioral rhythms in marine organisms are generally studied in coastal areas in rela- tion to day-night and tidal cycles. In contrast, the presence of these rhythms in demersal deep-sea fauna remains poorly characterized at present due to technological constraints on direct observation and sampling repeatability. In this study, our aim was to determine the presence of tidally synchro- nized behavioral rhythms of the demersal fauna at a hydrocarbon seep in Sagami Bay (1100 m depth; central Japan) using automated video-image analysis. Time series of visual counts were obtained for eelpouts (zoarcid fishes), red crabs Paralomis multispina, and snails Buccinum soyomaruae. Water pressure data were used as a marker of internal tidal action. By fitting 24-h and 12-h Fourier harmon- ics onto 24-h time series segments, a power content value was obtained as a marker of diurnal and semidiurnal fluctuations within the biological data sets. Rhythms were stronger in eelpouts and were weaker in red crabs and snails. Visual counts of eelpouts peaked during spring phases with an infra- dian periodicity of 13 d. These results are discussed, taking into consideration that animal responses may be of a reactive type (i.e. exogenous) or may be controlled by a biological clock through putative hydrodynamic entrainment. Observed differences in the magnitudes of the rhythms were related to the different modes of species locomotion (i.e. swimming in eelpouts versus walking and crawling in red crabs and snails, respectively) in relation to seabed currents.

Description of two new genera, Santelmoa and Bentartia and two new species of Zoarcidae (Teleostei, Perciformes) from the Southern Ocean

Two new genera of lycodine zoarcid fish, Santelmoa and Bentartia, and two new species, Santelmoa carmenae and Bentartia cinerea, are described from 13 specimens collected from the Gerlache Strait, Southern Ocean, at 1,056-m depth. Santelmoa can be distinguished from all other lycodine genera by the combination of the following characters: anterior portion of frontals fused; scapular foramen open; ceratohyal–epihyal articulation interdigitating; cranium narrowed; supratemporal commissure and occipital pores absent; intercalar reaching the prootic; parasphenoid wing well developed; palatal arch well developed; posterior hyomandibular ramus short; post-temporal ventral ramus well developed; six branchiostegal rays; vertebrae asymmetrical; pelvic fin rays ensheathed; scales, lateral line, pyloric caeca, palatine and vomerine teeth present. Bentartia differs from the remaining lycodine genera by the following combination of characters: basioccipital and exoccipitals fused; supraoccipital–exoccipital articulation broadly contacting; ceratohyal–epihyal articulation interdigitating; post-temporal ventral ramus weak; two posterior nasal pores; cranium narrowed; supratemporal commissure and occipital pores absent; intercalar set posteriorly; palatal arch well developed; posterior hyomandibular ramus not elongate; parasphenoid wing high; six branchiostegal rays; vertebrae asymmetrical; pelvic fin rays ensheathed; scales, lateral line, pyloric caeca, palatine and vomerine teeth present. The relationships of the two new genera are discussed.

A novel morphometry-based protocol of automated video-image analysis for species recognition and activity rhythms monitoring in deep-sea fauna.

The understanding of ecosystem dynamics in deep-sea areas is to date limited by technical constraints on sampling repetition. We have elaborated a morphometry-based protocol for automated video-image analysis where animal movement tracking (by frame subtraction) is accompanied by species identification from animals' outlines by Fourier Descriptors and Standard K-Nearest Neighbours methods. One-week footage from a permanent video-station located at 1,100 m depth in Sagami Bay (Central Japan) was analysed. Out of 150,000 frames (1 per 4 s), a subset of 10.000 was analyzed by a trained operator to increase the efficiency of the automated procedure. Error estimation of the automated and trained operator procedure was computed as a measure of protocol performance. Three displacing species were identified as the most recurrent: Zoarcid fishes (eelpouts), red crabs (Paralomis multispina), and snails (Buccinum soyomaruae). Species identification with KNN thresholding produced better results in automated motion detection. Results were discussed assuming that the technological bottleneck is to date deeply conditioning the exploration of the deep-sea.

Description of Ophthalmolycus andersoni sp. nov. (Pisces, Zoarcidae) from the Antarctic Ocean

A new species of zoarcid fish is described on the basis of three specimens collected from the Antarctic Peninsula, Antarctic Ocean. The new species can be distinguished from its congeners by its body shape and pigment pattern, and by the following combination of characters: 6 branchiostegal rays; pectoral-fin origin well below midbody, pectoral base extending ventrally to abdomen; lateral line double with ventral and medio-lateral branches; oral valve not reaching anterior edge of vomer; gill slit extending ventrally well below end of pectoral fin base; vertebrae asymmetrical 22+7074=92-96; dorsal fin origin associated with vertebrae 4 or 5 with no supraneurals; pectoral fin rays 16 or 17; 2 postorbital pores (positions 1 &amp; 4) and 2 well developed pyloric caeca. The relationships of the new species with its congeners are discussed.

Description of a new genus and species of zoarcid fish, Bellingshausenia olasoi, from the Bellingshausen Sea (Southern Ocean)

A new genus and species of zoarcid fish, Bellingshausenia olasoi, is described on the basis of five specimens collected from the Bellingshausen Sea, Southern Ocean, at depths of 602–615 m. Bellingshausenia is a lycodine that can be distinguished from all other zoarcid genera by the following combination of characters: seven branchiostegal rays, scapular foramen open, cranium narrowed, smooth ceratohyal-epihyal articulation, palatal arch well developed, supratemporal commissure and occipital pores absent, intercalar reduced and displaced backward and parasphenoid wing high. The relationships of the new genus are discussed.

Characterization of Andriashevia natsushimae, a new species of eelpout (Pisces, Perciformes: Zoarcidae) from Sagami Bay, Japan, and its phylogenic status as inferred from 16S rRNA

A new zoarcid fish, Andriashevia natsushimae (Japanese name: Natsushimachojyagenge), is described on the basis of 2 specimens collected in Sagami Bay, Japan, at the depth of 850 m. This species has no pectoral fins and no pelvic fins, indicating it to be Andriashevia. It has a round body and a moderate-sized mouth in contrast to Andriashevia aptera which has a flat body and a large mouth. Phylogenic tree based on 16S ribosomal RNA (16S rRNA) sequence indicates the species had diverted at the early stage in the evolution of eelpouts.