scholarly journals Larval assemblages over the abyssal plain in the Pacific are highly diverse and spatially patchy

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7691 ◽  
Author(s):  
Oliver Kersten ◽  
Eric W. Vetter ◽  
Michelle J. Jungbluth ◽  
Craig R. Smith ◽  
Erica Goetze
Keyword(s):  
Human Impacts ◽  
Abyssal Plain ◽  
Benthic Boundary Layer ◽  
Parasitic Copepods ◽  
Polymetallic Nodule ◽  
Disturbed Areas ◽  
Pelagic Larvae ◽  
The Pacific ◽  
Clarion Clipperton Fracture Zone ◽  
Nodule Mining

Abyssal plains are among the most biodiverse yet least explored marine ecosystems on our planet, and they are increasingly threatened by human impacts, including future deep seafloor mining. Recovery of abyssal populations from the impacts of polymetallic nodule mining will be partially determined by the availability and dispersal of pelagic larvae leading to benthic recolonization of disturbed areas of the seafloor. Here we use a tree-of-life (TOL) metabarcoding approach to investigate the species richness, diversity, and spatial variability of the larval assemblage at mesoscales across the abyssal seafloor in two mining-claim areas in the eastern Clarion Clipperton Fracture Zone (CCZ; abyssal Pacific). Our approach revealed a previously unknown taxonomic richness within the meroplankton assemblage, detecting larvae from 12 phyla, 23 Classes, 46 Orders, and 65 Families, including a number of taxa not previously reported at abyssal depths or within the Pacific Ocean. A novel suite of parasitic copepods and worms were sampled, from families that are known to associate with other benthic invertebrates or demersal fishes as hosts. Larval assemblages were patchily distributed at the mesoscale, with little similarity in OTUs detected among deployments even within the same 30 × 30 km study area. Our results provide baseline observations on larval diversity prior to polymetallic nodule mining in this region, and emphasize our overwhelming lack of knowledge regarding larvae of the benthic boundary layer in abyssal plain ecosystems.

scholarly journals Recovery of Paleodictyon patterns after simulated mining activity on Pacific nodule fields

2021 ◽  
Vol 51 (6) ◽  
Author(s):  
Lilian Boehringer ◽  
Sofia P. Ramalho ◽  
Yann Marcon ◽  
Antje Boetius ◽  
Daphne Cuvelier ◽  
...  
Keyword(s):  
Deep Sea ◽  
Image Data ◽  
Camera System ◽  
Polymetallic Nodule ◽  
Disturbed Areas ◽  
The Pacific ◽  
Mode Of Life ◽  
Irregular Form ◽  
The Pacific Ocean ◽  
Clarion Clipperton Fracture Zone

AbstractSince the late 1980s, various experiments have been conducted in polymetallic nodule fields of the Pacific Ocean to assess the potential environmental impacts of future mining, specifically in two areas: the Peru Basin and the Clarion-Clipperton Fracture Zone (CCZ). Two expeditions, SO242/2 in 2015 (Peru Basin) and SO268/1 + 2 in 2019 (CCZ), deployed a towed camera system to collect imagery from both areas. These expeditions aimed to assess recovery of fauna in the short (few weeks) and long term (several years) following physical seafloor disturbance actions designed to mimic potential mining, by ploughs, dredges and epibenthic sleds. Within the collected image data, several strikingly hexagonal hole patterns were observed and identified as Paleodictyon nodosum, and an irregular form of Paleodictyon traces, both on undisturbed and disturbed areas of seafloor. Recent forms occur abundantly in various deep-sea regions, but their origin, and how they represent the mode of life of the forming organism, remains unknown. In this study, the imaged occurrences of Paleodictyon traces on disturbed seafloor sheds light on the lifecycle of the forming organism, demonstrating that they can recolonize disturbed habitat and produce the trace network in a few weeks. Nevertheless, the density of these patterns on disturbed substrates was lower than observed on undisturbed substrates in both nodule regions. We therefore hypothesize that, along with other benthic deep-sea fauna, these structures and the forming organism are impacted by physical seafloor disturbance, and even 26 years after disturbance, densities on disturbed sediments have not recovered to undisturbed levels.

scholarly journals Physical and hydrodynamic properties of deep sea mining-generated, abyssal sediment plumes in the Clarion Clipperton Fracture Zone (eastern-central Pacific)

Elem Sci Anth ◽  
2019 ◽  
Vol 7 ◽  
Author(s):  
Benjamin Gillard ◽  
Kaveh Purkiani ◽  
Damianos Chatzievangelou ◽  
Annemiek Vink ◽  
Morten H. Iversen ◽  
...  
Keyword(s):  
Fracture Zone ◽  
Deep Sea ◽  
Transport Model ◽  
Dry Weight ◽  
In Situ Tests ◽  
Central Pacific ◽  
Polymetallic Nodule ◽  
Clipperton Fracture Zone ◽  
Clarion Clipperton Fracture Zone ◽  
Nodule Mining

The anthropogenic impact of polymetallic nodule harvesting in the Clarion-Clipperton Fracture Zone is expected to strongly affect the benthic ecosystem. To predict the long-term, industrial-scale impact of nodule mining on the deep-sea environment and to improve the reliability of the sediment plume model, information about the specific characteristics of deep-sea particles is needed. Discharge simulations of mining-related fine-grained (median diameter ≈ 20 μm) sediment plumes at concentrations of 35–500 mg L–1 (dry weight) showed a propensity for rapid flocculation within 10 to 135 min, resulting in the formation of large aggregates up to 1100 μm in diameter. The results indicated that the discharge of elevated plume concentrations (500 mg L–1) under an increased shear rate (G ≥ 2.4 s–1) would result in improved efficiency of sediment flocculation. Furthermore, particle transport model results suggested that even under typical deep-sea flow conditions (G ≈ 0.1 s–1), rapid deposition of particles could be expected, which would restrict heavy sediment blanketing (several centimeters) to a smaller fall-out area near the source, unless subsequent flow events resuspended the sediments. Planning for in situ tests of these model projections is underway.

scholarly journals From sea surface to seafloor: a benthic allochthonous eDNA survey for the abyssal ocean

2020 ◽  
Author(s):  
Olivier Laroche ◽  
Oliver Kersten ◽  
Craig R. Smith ◽  
Erica Goetze
Keyword(s):  
Water Column ◽  
Deep Sea ◽  
Anthropogenic Impacts ◽  
Spatial Scales ◽  
Deep Ocean ◽  
Environmental Dna ◽  
Benthic Boundary Layer ◽  
Large Sample Size ◽  
Polymetallic Nodule ◽  
Nodule Mining

AbstractDiverse and remote deep-sea communities are critically under-sampled and increasingly threatened by anthropogenic impacts. Environmental DNA (eDNA) metabarcoding could facilitate rapid and comprehensive biotic surveys in the deep ocean, yet many aspects of the sources and distribution of eDNA in the deep sea are still poorly understood. In order to examine the influence of the water column on benthic eDNA surveys in regions targeted for deep-sea polymetallic nodule mining, we investigated the occurrence of pelagic eDNA across: (1) two different deep-sea habitat types, abyssal plains and seamounts, (2) benthic sample types, including nodules, sediment, and seawater within the benthic boundary layer (BBL), and (3) sediment depth horizons (0-2 cm, 3-5 cm). Little difference was observed between seamounts and the adjacent abyssal plains in the proportion of legacy pelagic eDNA sampled in the benthos, despite an > 1000 m depth difference for these habitats. In terms of both reads and amplicon sequence variants (ASVs), pelagic eDNA was minimal within sediment and nodule samples (< 2%), and is unlikely to affect benthic surveys that monitor resident organisms at the deep seafloor. However, pelagic eDNA was substantial within the BBL (up to 13 % ASVs, 86% reads), deriving both from the high biomass upper ocean as well as deep pelagic residents. While most pelagic eDNA found in sediments and on nodules could be sourced from the epipelagic for metazoans, protist legacy eDNA sampled on these substrates appeared to originate across a range of depths in the water column. Some evidence of eDNA degradation across a vertical sediment profile was observed for protists, with higher diversity in the 0-2 cm layer and a significantly lower proportion of legacy pelagic eDNA in deeper sediments (3-5 cm). Study-wide, our estimated metazoan sampling coverage ranged from 40% to 74%, despite relatively large sample size. Future deep-sea eDNA surveys should examine oceanographic influences on eDNA transport and residence times, consider habitat heterogeneity at a range of spatial scales in the abyss, and aim to process large amounts of material per sample (with replication) in order to increase the sampling coverage in these diverse deep ocean communities.

scholarly journals Extent of impact of deep-sea nodule mining midwater plumes is influenced by sediment loading, turbulence and thresholds

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Carlos Muñoz-Royo ◽  
Thomas Peacock ◽  
Matthew H. Alford ◽  
Jerome A. Smith ◽  
Arnaud Le Boyer ◽  
...  
Keyword(s):  
Fracture Zone ◽  
Deep Sea ◽  
Environmental Concern ◽  
Field Studies ◽  
Research Activity ◽  
Polymetallic Nodule ◽  
Commercial Scale ◽  
Clipperton Fracture Zone ◽  
Clarion Clipperton Fracture Zone ◽  
Nodule Mining

AbstractDeep-sea polymetallic nodule mining research activity has substantially increased in recent years, but the expected level of environmental impact is still being established. One environmental concern is the discharge of a sediment plume into the midwater column. We performed a dedicated field study using sediment from the Clarion Clipperton Fracture Zone. The plume was monitored and tracked using both established and novel instrumentation, including acoustic and turbulence measurements. Our field studies reveal that modeling can reliably predict the properties of a midwater plume in the vicinity of the discharge and that sediment aggregation effects are not significant. The plume model is used to drive a numerical simulation of a commercial-scale operation in the Clarion Clipperton Fracture Zone. Key takeaways are that the scale of impact of the plume is notably influenced by the values of environmentally acceptable threshold levels, the quantity of discharged sediment, and the turbulent diffusivity in the Clarion Clipperton Fracture Zone.

scholarly journals Using Habitat Classification to Assess Representativity of a Protected Area Network in a Large, Data-Poor Area Targeted for Deep-Sea Mining

2020 ◽  
Vol 7 ◽  
Author(s):  
Kirsty A. McQuaid ◽  
Martin J. Attrill ◽  
Malcolm R. Clark ◽  
Amber Cobley ◽  
Adrian G. Glover ◽  
...  
Keyword(s):  
Deep Sea ◽  
Large Data ◽  
Area Network ◽  
Equatorial Pacific Ocean ◽  
Environmental Correlates ◽  
Polymetallic Nodule ◽  
Organic Carbon Flux ◽  
Habitat Classification ◽  
Clarion Clipperton Fracture Zone ◽  
Nodule Mining

Extractive activities in the ocean are expanding into the vast, poorly studied deep sea, with the consequence that environmental management decisions must be made for data-poor seafloor regions. Habitat classification can support marine spatial planning and inform decision-making processes in such areas. We present a regional, top–down, broad-scale, seafloor-habitat classification for the Clarion-Clipperton Fracture Zone (CCZ), an area targeted for future polymetallic nodule mining in abyssal waters in the equatorial Pacific Ocean. Our classification uses non-hierarchical, k-medoids clustering to combine environmental correlates of faunal distributions in the region. The classification uses topographic variables, particulate organic carbon flux to the seafloor, and is the first to use nodule abundance as a habitat variable. Twenty-four habitat classes are identified, with large expanses of abyssal plain and smaller classes with varying topography, food supply, and substrata. We then assess habitat representativity of the current network of protected areas (called Areas of Particular Environmental Interest) in the CCZ. Several habitat classes with high nodule abundance are common in mining exploration claims, but currently receive little to no protection in APEIs. There are several large unmanaged areas containing high nodule abundance on the periphery of the CCZ, as well as smaller unmanaged areas within the central CCZ, that could be considered for protection from mining to improve habitat representativity and safeguard regional biodiversity.

scholarly journals Copper-binding ligands in deep-sea pore waters of the Pacific Ocean and potential impacts of polymetallic nodule mining on the copper cycle

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sophie A. L. Paul ◽  
Rebecca Zitoun ◽  
Ann Noowong ◽  
Mythili Manirajah ◽  
Andrea Koschinsky
Keyword(s):  
Pacific Ocean ◽  
Deep Sea ◽  
Organic Ligand ◽  
Copper Binding ◽  
Pore Waters ◽  
Potentially Toxic Metals ◽  
Polymetallic Nodule ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Nodule Mining

AbstractThe release of potentially toxic metals, such as copper (Cu), into the water column is of concern during polymetallic nodule mining. The bioavailability and thus toxicity of Cu is strongly influenced by its speciation which is dominated by organic ligand (L) complexation in seawater, with L-complexes being considered less bioavailable than free Cu2+. The presence of CuL-complexes in deep-sea sediments has, however, not been systematically studied in the context of deep-sea mining. We thus analyzed the Cu-binding L concentration ([L]) in deep-sea pore waters of two polymetallic nodule provinces in the Pacific Ocean, the Peru Basin and the Clarion-Clipperton-Zone, using competitive ligand equilibration–adsorptive stripping voltammetry. The pore-water dissolved Cu concentration ([dCu]) ranged from 3 to 96 nM, generally exceeding bottom water concentrations (4–44 nM). Based on fitting results from ProMCC and Excel, Cu was predominantly complexed by L (3–313 nM) in bottom waters and undisturbed pore waters. We conclude that processes like deep-sea mining are unlikely to cause a release of toxic Cu2+ concentrations ([Cu2+]) to the seawater as > 99% Cu was organically complexed in pore waters and the [Cu2+] was < 6 pM for 8 of 9 samples. Moreover, the excess of L found especially in shallow pore waters implied that even with a Cu release through mining activities, Cu2+ likely remains beneath toxic thresholds.

scholarly journals Estimation Accuracy and Classification of Polymetallic Nodule Resources Based on Classical Sampling Supported by Seafloor Photography (Pacific Ocean, Clarion-Clipperton Fracture Zone, IOM Area)

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 263 ◽  
Author(s):  
Jacek Mucha ◽  
Monika Wasilewska-Błaszczyk
Keyword(s):  
Pacific Ocean ◽  
Estimation Accuracy ◽  
Relative Standard Error ◽  
Polymetallic Nodule ◽  
The Pacific ◽  
Relative Standard ◽  
International Seabed Authority ◽  
Clarion Clipperton Fracture Zone ◽  
Small Parts

The amount and accuracy of nodule resources estimation in the Pacific Ocean are among the main factors conditioning the future exploitation. The estimates are based on the results of classical, direct seafloor sampling. Due to the large distance between sampling sites, the accuracy of assessing nodule resources in small parts of the deposit is low. The accuracy can be increased by using a large number of seafloor photographs taken along the route of the research vessel performing classic sampling. The study conducted for a part of the area administered by Interoceanmetal Joint Organization (IOM) included: (i) determining a model of the relationship between nodule abundance and seafloor nodule coverage using statistical methods, (ii) assessing the accuracy of nodule resources estimation using a geostatistical kriging procedure, (iii) proposing a preliminary classification of resources referring to International Seabed Authority (ISA) classification standards as material for further discussion. It was found that achievement of high accuracy in the estimation of nodule resources (with relative standard error <5%) in blocks planned for annual exploitation based on direct sampling is difficult. While the use of seafloor photographs increases the accuracy of estimating nodule resources, this improvement is not radical due to the unfavorable, preferential arrangement of photographic data.

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