Abyssal polymetallic nodule fields constitute an unusual deep-sea habitat. The mix of soft sediment and the hard substratum provided by nodules increases the complexity of these environments. Hard substrata typically support a very distinct fauna to that of seabed sediments, and its presence can play a major role in the structuring of benthic assemblages. We assessed the influence of seafloor nodule cover on the megabenthos of a marine conservation area (area of particular environmental interest 6) in the Clarion Clipperton Zone (3950-4250 m water depth) using extensive photographic surveys from an autonomous underwater vehicle. Variations in nodule cover (1-20%) appeared to exert statistically significant differences in faunal standing stocks, some biological diversity attributes, faunal composition, functional group composition, and the distribution of individual species. The standing stock of both the metazoan fauna and the giant protists (xenophyophores) doubled with a very modest initial increase in nodule cover (from 1% to 3%). Perhaps contrary to expectation, we detected little if any substantive variation in biological diversity along the nodule cover gradient. Faunal composition varied continuously along the nodule cover gradient. We discuss these results in the context of potential seabed-mining operations and the associated sustainable management and conservation plans. We note in particular that successful conservation actions will likely require the preservation of areas comprising the full range of nodule cover and not just the low cover areas that are least attractive to mining.

Ecology of a polymetallic nodule occurrence gradient: Implications for deep-sea mining

We present data from a DNA taxonomy register of the abyssal benthic Echinodermata collected as part of the Abyssal Baseline (ABYSSLINE) environmental survey cruise 'AB01' to the UK Seabed Resources Ltd (UKSRL) polymetallic-nodule exploration claim 'UK-1' in the eastern Clarion-Clipperton Zone (CCZ), central Pacific Ocean abyssal plain. Morphological and genetic data are presented for 17 species (4 Asteroidea, 4 Crinoidea, 2 Holothuroidea and 7 Ophiuroidea) identified by a combination of morphological and genetic data. No taxa matched previously published genetic sequences, but 8 taxa could be assigned to previously-described species based on morphology, although here we have used a precautionary approach in taxon assignments to avoid over-estimating species ranges. The Clarion-Clipperton Zone is a region undergoing intense exploration for potential deep-sea mineral extraction. We present these data to facilitate future taxonomic and environmental impact study by making both data and voucher materials available through curated and accessible biological collections.

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Abyssal fauna of the UK-1 polymetallic nodule exploration claim, Clarion-Clipperton Zone, central Pacific Ocean: Echinodermata.

This paper discusses and illustrates the 23 primnoid species collected by the R/V Okeanos Explorer in the US marine protected areas in the central and western Pacific, ranging from the Musician Seamounts in the north to American Samoa to the south, and the northern Mariana Islands to the west (CAPSTONE expeditions, 2015-2017). In situ photographs are provided for most species. Thirteen of the 23 species are described as new, as well as two new genera. One new genus, Macroprimnoa, possesses some of the largest polyps in the family. A dichotomous key is provided to facilitate comparisons among the 27 species of Calyptrophora. An update of the abyssal octocorallian species occurring deeper than 3000 m is provided, increasing that number from 39 to 49 species. The character of the articulating ridge, found on the distal edge of the basal body wall scales, is re-evaluated, resulting in four genera having this character state, and requiring the description of the new genus Pseudonarella.

Primnoidae (Cnidaria: Octocorallia: Calcaxonia) of the Okeanos Explorer expeditions (CAPSTONE) to the central Pacific.

The concept of “vulnerable marine ecosystem” (VME) was included in United Nations (UN) General Assembly Resolution 61/105 as part of an international effort to minimize the effects of benthic fisheries on the high seas. However, defining a VME was left to be developed by technical guidance to the UN Food and Agricultural Organization. In that venue certain categories of organisms were deemed to be indicator species, suggesting that areas with those species would be considered VMEs with subsequent management measures implemented to conserve those ecosystem attributes. We note that on seamounts VME indicator species can be distributed widely, in dense clusters or sparse. A dense cluster, for example, of scleractinian corals or sponges, is most often referred to as a VME, but we argue that any such dense cluster is not an ecosystem, rather it is a community, likely one of many that make up the ecosystem. Other communities on the seamount that are not part of that dense cluster could include many small species (some yet to be discovered) who are also part of the ecosystem because they are part of the web of interactions and flow of materials/energy on the seamount. We also suggest that a seamount ecosystem might extend over several or many seamounts in a biogeographic area. We conclude that the term “ecosystem” in the VME concept outlined by the United Nations needs to be re-evaluated from a classical ecological perspective.

/pdf/vulnerable-marine-ecosystems-communities-and-indicator-c72r7l65y1.pdf

Vulnerable Marine Ecosystems, Communities, and Indicator Species: Confusing Concepts for Conservation of Seamounts

Dense cold-water coral garden of Paragorgia johnsoni suggests the importance of the Mid-Atlantic Ridge for deep-sea biodiversity

Using a combination of data obtained from high-definition still images, video, and specimens collected during human-occupied submersible and remotely-operated vehicle dives spanning the period 2003 to 2014, we provide the first detailed characterization of the megabenthic assemblages in the lower bathyal on the New England and Corner Rise Seamounts in the Northwest Atlantic. Over all, the New England Seamounts east from Retriever to Nashville have a more diverse megabenthic fauna than Corner Rise, but the lowest diversity was observed on the three seamounts located closest to the continental margin. The megabenthic assemblage structure varies both within and across seamounts, and hierarchical cluster analysis revealed groups dependent on location (as measured by longitude) and depth, with substrate composition an additional but less significant factor at the regional scale. We conclude that the megabenthos assemblages in the bathyal Northwest Atlantic are determined, at the regional scale, by the water masses in which they reside.

Megabenthic assemblages in the lower bathyal (700-3000 m) on the New England and Corner Rise Seamounts, Northwest Atlantic

The Lower Bathyal (approximately 700–800 to 3000–3500 m depth) of the deep sea, until recently, had only been explored in areas of continental slopes. With the advent of remotely operated vehicles (ROVs), seamounts and ridges, which comprise the bulk of the seafloor at those depths, have been increasingly sampled, at least for megafaunal species. We compiled records of cnidarians obtained from the Ocean Biogeographic Information System (OBIS) along with records of octocorals identified during ROV dives in the NW Atlantic and Central Pacific among other places, and used them to test the validity of the Watling et al. (2013) lower bathyal provinces which were proposed on the basis of hydrography. In addition, all records were used to independently determine the presence of biogeographic provinces using the Infomap Bioregions network analysis approach. Both methods have their shortcomings, but the combined results suggest that most of the provinces proposed by Watling et al. (2013) were reasonably well delineated; some changes were needed, especially in the North Atlantic. Specifically, the North Atlantic province needs to be divided into eastern and western units and the boundaries of the Boreal NW Atlantic (=Northern Atlantic Boreal) should be extended southward. Several name changes for various provinces are also proposed. Apparent endemism for those provinces where sufficient records exist was at least 33%, much higher than the 10% normally used when evaluating shallow water biogeographic provinces. 

Global biogeography of the lower bathyal (700–3000 m) as determined from the distributions of cnidarian anthozoans

Deep-sea bamboo corals (Family Isididae: subfamily Keratoisidinae) are a widely distributed group of gorgonian octocorals, commonly found in the deep sea below 200 m, with the deepest specimen to date collected at 4700 m. Two specimens were collected from the seamounts off Tasmania at depths of 3065 to 3950 m. In situ high-definition images, compound microscopy of preserved specimens, and Scanning Electron Microscopy (SEM) provided morphological data on distinguishing morphological characters such as colony shape and branching pattern, polyp arrangement, composition of the axial skeleton, and shape and arrangement of the sclerites. The genus Bathygorgia Wright, 1885 is resurrected and distinguished from Keratoisis, and two new species, B. abyssicola and B. tasmaniensis are added.

Bamboo corals from the abyssal Pacific: Bathygorgia

Four new genera and six new species of deep-sea bamboo corals (Family: Keratoisididae) from the seamounts off the eastern and southern coast of Tasmania are described and illustrated. In situ high-definition images from remotely operated vehicles, compound microscopy, and Scanning Electron Microscopy (SEM) of 29 specimens collected at depths of 729 to 3950 m were used to provide data on distinguishing morphological characters. The species described include two new species in the genus Keratoisis, two species in the newly described genus Adinisis, and one species each in the new genera Tanyostea and Dokidisis. The species Keratoisis magnifica and Lepidisis solitaria are re-assigned to the newly described genus Onkoisis due to the shape and design of the polyp arrangement and sclerites, which differ considerably from that of the type species of Keratoisis.

Abby E. Lapointe

Papers

Megabenthic assemblages in the lower bathyal (700-3000 m) on the New England and Corner Rise Seamounts, Northwest Atlantic

Global biogeography of the lower bathyal (700–3000 m) as determined from the distributions of cnidarian anthozoans

Bamboo corals from the abyssal Pacific: Bathygorgia

Towards a revision of the bamboo corals (Octocorallia): Part 5, new genera and species of Keratoisididae from the Tasmanian deep sea.

Abby E. Lapointe

Papers

Megabenthic assemblages in the lower bathyal (700-3000 m) on the New England and Corner Rise Seamounts, Northwest Atlantic

Global biogeography of the lower bathyal (700–3000 m) as determined from the distributions of cnidarian anthozoans

Bamboo corals from the abyssal Pacific: Bathygorgia

Towards a revision of the bamboo corals (Octocorallia): Part 5, new genera and species of Keratoisididae from the Tasmanian deep sea.

Global biogeography of the lower bathyal (700–3000 m) as determined from the distributions of cnidarian anthozoans