Deep Water Off Research Articles

Renewed occurrence of schooling scalloped hammerhead (Sphyrna lewini) and of great hammerhead (S. mokarran) sharks in the Cayman Islands

The scalloped hammerhead shark (Sphyrna lewini), a critically endangered species with a decreasing global population, is characterised by its occurrence in large schools. Such schools are still observed today in the Pacific Ocean, but this is generally not the case in the Atlantic Ocean, and in the Cayman Islands not since the 1970s. Here we report a recent record of a school of S. lewini in deep water off Grand Cayman, and describe a recent, concomitant increase in numbers of the species, and its critically endangered congener, the great hammerhead (Sphyrna mokarran), around the Cayman Islands. Relative population trends and seasonal patterns were assessed using data from shallow and deep-water BRUVS, scientific longlining, citizen science projects including the Sharklogger Network and REEF, and social media reports. It appears that S. lewini may be slowly re-occupying the area, selecting and using deeper waters to school, while S. mokarran has also become less scarce than hitherto.

Malakichthys formosus, a new species of small seabass (Acropomatiformes: Malakichthyidae) from southwestern Taiwan.

A new species of Malakichthys is described based on six specimens collected from deepwaters off southwestern Taiwan, northwestern Pacific Ocean. The new species, M. formosus sp. nov., exhibits distinct morphological characters, primarily characterized by the absence of chin spines, distinguishing it from other congeners with the exception of M. levis and M. mochizuki. It differs from the two species by having more lateral-line scales, a shorter distance between the snout and dorsal-fin origin, a shallower head, fewer scale rows below the lateral line, and the structure of the first anal-fin pterygiophore. Eight species are now recognized in Malakichthys.

New species of Cirratulidae (Annelida) from continental slope and abyssal depths off eastern Australia

Seven new species of Cirratulidae are described from deep waters off the east coast of Australia. Samples were collected as part of the RV Investigator voyage IN2017_V03 in May/June 2017 using a Brenke sledge and 0.25 m2 box core. Sample depths reported in the present study were from the lower continental slope of about 2100 m to abyssal depths up to 4170 m. These collections provide the first cirratulid polychaetes to be described from deep water off Australia. The new species of Cirratulidae are in the genera Aphelochaeta (2), Chaetocirratulus (2), Chaetozone (2), and Kirkegaardia (1). Each of the new species is compared and contrasted with their known congeners. The bitentaculate Cirratulidae known from abyssal depths of 3000 m and greater are reviewed and discussed.

New species of Scalibregmatidae (Annelida) from slope and abyssal depths off eastern Australia

Seven new species of Scalibregmatidae are described from deep waters off the east coast of Australia. Samples were collected as part of the RV Investigator voyage IN2017_V03 in May/June 2017 using a Brenke sledge and 0.25 m2 box core. Sample depths reported in the present study were from the lower continental slope of about 2450 m to abyssal depths up to 4280 m. These collections provide the first scalibregmatid polychaetes to be described from deep water off Australia. The new species of Scalibregmatidae are in the genera Asclerocheilus (1), Axiokebuita (1), Oligobregma (4), and Pseudoscalibregma (1). Each of the new species is compared and contrasted with their known congeners. Asclerocheilus and Oligobregma are the largest genera of the family in terms of numbers of species; the known species of each of these genera are tabulated and compared. The Scalibregmatidae known from abyssal depths of about 3000 m and greater are reviewed and discussed.

New species and records of Heterospio (Annelida, Longosomatidae) from continental shelf, slope and abyssal depths of the Atlantic Ocean, Pacific Ocean, Indian Ocean and adjacent seas.

Nineteen species of the rare polychaete genus Heterospio are reported, 15 of which are new to science. The status of H. longissima Ehlers, 1874, the type-species, is reviewed. The specimens examined are from several locations in the North Atlantic Ocean, Gulf of Mexico, Caribbean Sea, off Br azil, the Indian Ocean, the Pacific Ocean off California, New Zealand, Australia, and the South China Sea. Deep-water samples from the western North Atlantic Ocean collected by the late Drs. H.L. Sanders and R.R. Hessler that were reported by Hartman as H. longissima were re-examined and referred to two new species, H. hartmanae n. sp. (abyssal depths, New England to Bermuda transect) and H. guiana n. sp. (bathyal depths off Suriname). Other materials from the Sanders/Hessler North Atlantic collections were also examined and referred to two additional species, H. canariensis n. sp. (deep water off Canary Islands) and H. southwardorum n. sp. (Bay of Biscay) as well as H. cf. reducta from off SW Ireland in bathyal depths. New collections from the North Atlantic region include additional materials of H. hartmanae n. sp. (deep water off the Mid-Atlantic and SE USA), H. aruba n. sp. (Caribbean Sea), H. bathyala n. sp. (deep water off SE USA), and H. dibranchiata n. sp. (deep water, Gulf of Mexico). Heterospio paulolanai n. sp. is from shelf depths off southeastern Brazil. Heterospio knoxi n. sp. is from the North Island of New Zealand, H. ehlersi n. sp. is from the Gulf of Thailand, in the South China Sea, H. bidentata n. sp. is described from deep water in the Coral Sea off eastern Australia, and H. alata n. sp. and H. brunei n. sp. are described from deep water off the Island of Borneo in the South China Sea. Heterospio africana n. sp. and H. antonbruunae n. sp. are described from off east Africa in the Mozambique Channel. New records and descriptions of H. catalinensis, H. indica, and H. peruana are presented. The 15 new species reported here nearly triple the number of previously known species of Heterospio, with 23 species now recognized. All known species are tabulated and compared.

A new species and new record of Samadinia Ng & Richer de Forges, 2013 (Crustacea: Brachyura: Epaltidae) from deepwater off north-eastern Queensland, Australia

A new species of Samadinia Richer de Forges & Ng, 2013, is described from deep-water off northeastern Queensland, Australia. Samadinia hela n. sp. is distinctive in having pseudorostral spines longer than the maximum carapace length, slender preorbital spines that are curved inwards over the base of the rostrum, and long and laterally flattened hepatic and lateral bracnchial spine plates. A new record of S. despereaux (Lee, Richer de Forges & Ng, 2019) from Queensland is also reported in this study.

A new species of deep-water tonguefish (Pleuronectiformes: Cynoglossidae: Symphurus) from the western North Pacific Ocean.

A new species of symphurine tonguefish, Symphurus oxyrhynchus sp. nov., is described from two specimens captured in deep waters (718-852 m) off Taiwan and Japan. This new species is distinguished from congeners by the following combination of characters: predominant 1-2-2-1-2 pattern of interdigitation of dorsal pterygiophores and neural spines, 14 caudal-fin rays, 93 dorsal-fin rays, 80-81 anal-fin rays, 9 abdominal and 52 total vertebrae, 5 hypurals, small eye (7.5-8.0 % HL) with relatively large pupil (78-85% ED), moderately large scales (87-89 scales in longitudinal series, 31 scales in transverse row), snout square and projecting anteriorly, ocular side uniformly yellow to dark brown with intense pigmentation on body areas overlying dorsal- and anal-fin pterygiophores, outer surface of opercle on both sides bluish black, general background coloration shared the same coloration in blind side, including more intense on body areas overlying dorsal and anal pterygiophores. Symphurus oxyrhynchus sp. nov. is a rare species, only two specimens were retrieved by research vessels. This study provides formal description of this unique new species based on these two specimens. Further investigations and expeditions are necessary for better understanding of the biodiversity of tonguefishes in the western Pacific.

Multi-factor biotopes as a method for detailed site characterization in diverse benthic megafaunal communities and habitats in deep-water off Morro Bay, California

Here we describe the methods and results for biological characterization of the benthos on a previously unexplored area of central California, USA seafloor. We conducted 40 remotely operated vehicle dives from 371 to 1173 m water depth. Seafloor habitats and megafauna (fish and invertebrates) were documented from 46.8 km of seafloor video footage. Our expanded development and analysis of biotopes from quantitative data allowed us to describe detailed biological communities, along with the physical characteristics and habitat associations within the study area. This method provides a framework for potential monitoring, detection of future environmental change (natural and anthropogenic) and comprehensive comparison to other deep water regions. From 185 h of observational video at 25 sites, nearly 120,000 annotations of organisms, habitat characters, biological detritus and anthropogenic debris were recorded and analyzed. We identified a total of 228 taxa, with 173 of them present on linear quantitative transects. Species richness for transects ranged from 0.04 to 0.28 m-2 (8–55 taxa), with densities ranging from 0.07 to 5.20 ind. m−2. Both were highest on hard substrate with greatest surface area. Densities decreased with depth. Within soft substratum zones was a large field of pockmarks, which are seafloor depressions averaging 175 m in diameter and 5 m in depth. Pockmarks have sometimes been associated with seafloor gas seepage, but here we found no biological evidence of chemosynthetic organisms. No significant differences were found in either density nor species richness at pockmark sites vs. non-pockmark sites. Mud draped greenish-black coarse sand occurred only in low oxygen areas, while hummocky, rugose mud supported somewhat different species than flat mud plains. Seventy percent of the transects occurred inside the oxygen minimum zone. We conclude that high rugosity, slope, and the presence of hard substratum were better predictors of species richness and density than oxygen concentration in this specific study. Abundant biological detritus, in the form of dead and dying pelagic pyrosomes and salps, created a large, presumably ephemeral flux of carbon to the seafloor during the study period.

A new record of a rare labrid, Suezichthys notatus (Actinopterygii: Labridae), from Taiwan, with comparison to related species from Taiwan

Three specimens of a rare labrid, Suezichthys notatus (Kamohara, 1958) were recently collected from local markets, which were captured from deep-water off northern and southwestern Taiwan, and represent a new record for Taiwan. Suezichthys notatus can be distinguished from its congeners by a combination of characters: scale rows above lateral line 2½; low scaly sheath present at base of dorsal and anal fins; dorsal-fin element IX, 11; anal-fin elements III, 10; lateral line scales 25‒26, each with simple, unbranched laterosensory canal tube; cheek scale rows behind and below eye 2 and 2‒3 respectively; a group of prominent dark blotches extending from the interorbital region dorsoposteriorly; body depth at dorsal-fin origin 3.7‒3.9 in standard length; short pelvic fin without filamentous extension, 2.2‒2.5 in head length. Suezichthys resembles the labrid genus Pseudolabrus, comparison of Taiwanese species of Suezichthys with those of Pseudolabrus are given.

New species of squat lobsters of the genus Munida from Australia

This study reports on new squat lobsters of the genus Munida collected during recent surveys of Australia’s continental margins. We report on 33 species of Munida including seven new species and 14 new range extensions for Australia. More than 500 specimens were collected, mostly from the western continental margin of Australia, but also including a new species from deep water (>2000 m) off Tasmania. We provide new data on the colour patterns of some species and include molecular data from two mitochondrial markers (16S rRNA and COI) to support the taxonomic status of the new species.

Steganoderma Stafford, 1904 (Digenea: Zoogonidae: Lepidophyllinae) from Two Species of Rockfishes from Deep Waters off Oregon Including a New Species and an Updated Key to Species of This Genus

Steganoderma eamiqtrema n. sp. and a single unidentified specimen of Steganoderma Stafford, 1904 (Zoogonidae: Lepidophyllinae) obtained from the intestine of the greenstriped rockfish, Sebastes elongatus Ayres, 1859, and the flag rockfish, Sebastes rubrivinctus (Jordan and Gilbert, 1880) (Scorpaeniformes: Sebastidae), collected from 190–200 m depths off Oregon, USA, are described. The new species is distinguished from its seven other congeners by a diagnostic combination of morphological features including an elongate oval to spindle-shaped body, a clavate to comma-shaped cirrus pouch located in the forebody and hindbody, a bipartite seminal vesicle, a bifurcal or just post-bifurcal genital pore, a larger ventral than oral sucker, and a smooth testes and ovary with a relatively small distance between them. We present an updated key to the eight species now in Steganoderma and provide a list of parasites known from Se. elongatus and Se. rubrivinctus. The discovery of S. eamiqtrema in Se. elongatus represents the second species of zoogonid known from this host, and the finding of Steganoderma sp. in Se. rubrivinctus represents the first report of a digenean from this host species. A detailed discussion also is given of the type species, S. formosum Stafford, 1904, and questions are raised as to whether this species has a worldwide distribution and infects such a wide variety of fish hosts. We present evidence including variation we observed in redescriptions of the type species, query the implausible idea that there could be gene flow between conspecific helminths geographically separated in the North Atlantic and North Pacific Oceans over such a vast geological period, and offer the possibility that some prior reports of S. formosum may, indeed, be S. eamiqtrema; all of which suggests S. formosum sensu lato may be part of a species complex and not the same worldwide species. Steganoderma is represented in the deep sea by S. eamiqtrema, S. formosum, and Steganoderma sp., and limited speculation is given as to the host specificity of this genus and life history strategies of the new species in deeper waters. Finally, molecular studies of species of Steganoderma are sorely needed (i.e., there is no DNA sequence data currently available in GenBank for any species of this genus), and we suspect that with further molecular, morphological, and life history work, this genus will be taxonomically divided up.

Discrete Pulses of Cooler Deep Water Can Decelerate Coral Bleaching During Thermal Stress: Implications for Artificial Upwelling During Heat Stress Events

Global warming is considered to be the most severe threat to coral reefs globally, which makes it important for scientists to develop novel strategies that mitigate the impact of warming on corals and associated habitats. Artificial upwelling of cooler deep water to the surface layer may be a possible mitigation/management tool. In this study, we investigated the effect of simulated artificial upwelling with deep water off Bermuda collected at 50 m (24°C) and 100 m (20°C) on coral symbiont biology of 3 coral species (Montastrea cavernosa, Porites astreoides, and Pseudodiploria strigosa) in a temperature stress experiment. The following treatments were applied over a period of 3 weeks: (i) control at 28°C (ii) heat at 31°C, (iii) heat at 31°C + deep water from 50 m depth, and (iv) heat at 31°C + deep water from 100 m depth. Artificial upwelling was simulated over a period of 25 minutes on a daily basis resulting in a reduction of temperature for 2 hours per day and the following degree-heating-weeks: 5.7°C-weeks for ii, 4.6°C-weeks for iii and 4.2°C-weeks for iv. Comparative analysis of photosynthetic rate, chlorophyll-a concentration and zooxanthellae density revealed a reduction of heat stress responses in artificial upwelling treatments in 2 of the 3 investigated species, and a stronger positive effect of 100-m water than 50-m water. These results indicate that artificial upwelling could be an effective strategy to mitigate coral bleaching during heat stress events allowing corals to adjust to increasing temperatures more gradually. It will still be necessary to further explore the ecological benefits as well as potential ecosystem impacts associated with different artificial upwelling scenarios to carefully implement an effective in-situ artificial upwelling strategy in coral reefs.

Bioluminescence potential modeling during polar night in the Arctic: impact of advection versus local sources

Bioluminescence (BL) potential observations registered high BL potential emissions during the polar night of January 2012 at the mouth of a fjord Rijpfjorden (northern Svalbard, Norway). Notably, observations of BL potential at this location were significantly higher in the upper 50 m than observed BL potential at offshore stations located on the shelf-slope areas and in the deeper water off northern Svalbard. In the present paper, we address questions as to why the values of BL potential in the fjord are higher than at offshore stations and what the role of advection is in the observed elevation of BL potential values in the fjord in comparison to offshore stations. We utilized the ensemble approach when changes in BL potential are modeled with the advection-diffusion-source (ADS) model, and the focus is on modeling and predictions of a large ensemble of averaged values of BL potential over a specific domain of interest at the fjord mouth. Results of the modeling have demonstrated increases in ensemble members with BL potential values larger than or equal to the specific threshold in comparison to corresponding ensemble members in the initial distribution. Even when we introduced mortality rates in our simulations (values from 0.1 to 0.3 day−1), increases in ensemble members with higher than the threshold value were more than 3.7 times larger in comparison to ensemble members in the initial distribution. The interpretation of our results is that during the polar night, the fjord represents an area where bioluminescent organisms from offshore aggregate through advection and mixing.

A revision of the unusual feather star genus Atopocrinus with a description of a new species (Echinodermata: Crinoidea).

Atopocrinus ojii new species, is described from deep water off Japan. The genus was previously monotypic and known only from the holotype of A. sibogae A. H. Clark, 1912, from Indonesia. Examination of all known specimens of Atopocrinus has added the following genus-level characters: cirrus sockets arising as tubes along the adoral surface of the centrodorsal, and faint, superficial, suture-like lines that cross the interradial ridges aboral to the centrodorsal/basal suture. The new species exhibits additional novel characters, some of which may be unique (e.g., deep pores around cirrus sockets) and others that may be shared with the incomplete holotype of A. sibogae (e.g., hollow pinnulars). Confusion about the structure of basal ossicles versus basal rays in Atopocrinus and other extant feather stars prompted inclusion of a review of the structure and development of these skeletal components. Video of a live specimen attributed to A. sibogae revealed that the distal half of the arms lack pinnules. The new species also shares several characters in common with Jurassic Spinimetra chesnieri Hess Thuy, 2017.

Variability of internal tide energy, mixing and nitrate fluxes in response to changes in stratification on the northeast New Zealand continental shelf

ABSTRACT A 4-month time series of water column temperature structure on the shelf of North Island New Zealand is used to calculate the energy in the internal tide as stratification evolved between spring and summer. Average total energy in the internal tidal wave was 200 J m−2, with peaks reaching 600 J m−2. Wave energy was weakly correlated with stratification (r = 0.2) and with the spring-neap cycle of tidal currents (r = 0.17). Overall there was little predictability in internal tide behaviour in response to the physical environment. Reduction in wave energy was associated with a downwelling-favourable wind event which reduced stratification by mixing and by removing deeper water off the shelf. Vertical eddy diffusivity driven by internal wave dissipation ranged between 5.6 × 10−5 and 3.2 × 10−4 m2 s−1. Combined with nitrate data this diffusivity resulted in diapycnal nitrate fluxes towards the sea surface of 1.6–2.2 mmol m−2 day−1. Strong stratification in summer reduced the eddy diffusivity but had little effect on nitrate flux as a strengthened vertical nitrate gradient compensated for the reduced diffusivity. This compensation will be important when predicting how stronger stratification in a warmer climate might alter diapycnal nutrient supplies to the upper ocean.

Molecular systematics of the heteronemertean genus Dushia (Nemertea, Pilidiophora), with descriptions of D. wijnhoffae sp. nov. and D. nigra species complex comb. nov.

The heteronemertean genus Dushia Corrêa, 1963 was established for what was identified as D. atra (Girard, 1851) (originally Meckelia atra) based on material from littoral, shallow waters in Curaçao, while the nominal species Meckelia atra was originally described from deep water off Florida Cape. In this paper, we conclude that the type species for Dushia has been misidentified. Based on specimens from the Caribbean, we establish D. wijnhoffae Schwartz Norenburg sp. nov. to represent the true identity of the genus, according to Article 70.3.2 of the International Code of Zoological Nomenclature; Meckelia atra should be regarded as a nomen dubium. While the genus has remained monotypic since its establishment, our molecular analysis discovered a second member-or rather a group of members-from the West Pacific. This 'group of members', herein termed Dushia nigra (Stimpson, 1855) species complex comb. nov., involves i) at least two genetically separated biological entities, 0.136-0.148 (p-distance) and 0.152-0.168 (K2P) apart in terms of 513-bp COI sequences, which we interpret as likely to represent cryptic species, ii) three color forms, orange, brown, and black, with the last one occurring most frequently, and iii) four nominal species, Meckelia nigra Stimpson, 1855 (now Cerebratulus niger), Meckelia rubella Stimpson, 1855 (now Cerebratulus rubellus), Micrura formosana Yamaoka, 1939, and Micrura japonica Iwata, 1952. At present, however, we have no objective ground as to which of the four potentially available names (i.e., formosana, japonica, nigra, and rubella) should be allotted to the two cryptic species discovered in the analysis, because i) a single locality can harbor two cryptic species, ii) a single cryptic species may contain three different color morphs (i.e., orange, brown, black), and iii) no data from the type localities for these four nominal species are available at the moment. Our multi-locus analysis of heteronemerteans-for which 16S rRNA, COI, 18S rRNA, 28S rRNA, histone H3 genes are available in public databases-shows that Dushia wijnhoffae sp. nov. and Dushia nigra species complex comb. nov. form a clade, which is closely related to Gorgonorhynchus albocinctus Kajihara, 2015 and an undetermined heteronemertean that has been misidentified as Cerebratulus leucopsis (Coe, 1901). Members of Dushia thus show a vicariant Caribbean-West-Pacific distribution, indicating that the lineage predates the rise of the Isthmus of Panama.

Deep-water cirripedes colonizing dead shells of the cephalopod Nautilus macromphalus from New Caledonian waters.

Fossil cephalopods are frequently encrusted by epibionts; however, determining whether encrustation occurred prior to or post‐mortem to the host, and whether the final environment of deposition corresponds to the habitat of encrustation is complex. The present paper describes cirripede epibionts, their calcareous bases and their attachment scars on 6 post‐mortem shells of Nautilus macromphalus, collected from deep water off New Caledonia. The cirripedes have left both cemented calcareous bases of Hexelasma and scars associated with bioerosion and discoloration produced by verrucomorph barnacles. Live cirripedes included a Metaverruca recta, with articulated opercular plates and organic tissue (on a shell that had been exposed on the sea floor for at least 150 years), and specimens of Hexelasma velutinum, one of which was partly attached to an internal surface of a shell. The disposition of verrucomorphs indicates that most Nautilus shells were colonized post‐mortem rather than during a floating stage. However, as cirripedes are known to have colonized living Nautilus, some Hexelasma, preserved only as calcareous eroded bases, may represent specimens that settled on a living Nautilus. The degree of bioerosion and discoloration induced by verrucomorph barnacles varies according to the surface preservation of Nautilus shells, with deeper and discolored traces preserved on old and degraded shells. Traces made by verrucomorphs described here are ellipsoidal and a new ichnotaxon, Anellusichnus ellipticus, is proposed to accommodate them. Importantly, verrucomorphs and other cirripede taxa with membranous bases that were attached to pristine shells may not leave any substantial scars, and, thus, will be difficult to detect in the fossil record.

Redescription of the rare shrimp Heterocarpus nesisi (Burukovsky, 1986 (Crustacea: Caridea: Pandalidae) rediscovered off western Mexico, with the proposal of a new genus.

A rare species of pandalid shrimp, Heterocarpus nesisi Burukovsky, 1986, is rediscovered in deep water off western Mexico. Previous to this capture, this species was known only from the holotype, a mature male captured at 800 m depth, originally described in the genus Heterocarpus and later transferred to Plesionika. A second, unconfirmed record, was provided in 1989: a female captured at 898 m near the southern tip of the Baja California Peninsula. Heterocarpus nesisi is redescribed and appendages are illustrated. The general morphology of this species makes it difficult to fit within Heterocarpus or Plesionika, and a new genus, Heteronika gen. nov., is proposed to accommodate it. Heteronika nesisi is associated with the lower boundary of the Oxygen Minimum Zone occurring off western Baja California.

Occurrence of blue whales (Balaenoptera musculus) in offshore waters of southeastern Brazil

At-sea sightings of blue whales, Balaenoptera musculus, in Brazil are rare. A mother-calf pair was observed in deep (2645 m) waters off southeastern Brazil (22°11′S 038°58′W); during a seismic survey in July 2014. It is unknown to which of the subspecies the animals sighted belong. The presence of a calf suggests that blue whales use deep waters off Brazil as calving or nursing grounds. The identification and conservation of wintering grounds for blue whale populations is important to promote the recovery of blue whales as their numbers were critically reduced as a result of commercial whaling.

A new species ofBemlosShoemaker, 1925 (Amphipoda: Aoridae) from deep water off Tanabe Bay, Japan, with a review of the deep-sea aorids and their adaptations to the deep sea

A new species of<i>Bemlos</i>Shoemaker, 1925 (Amphipoda: Aoridae) from deep water off Tanabe Bay, Japan, with a review of the deep-sea aorids and their adaptations to the deep sea