Abstract
Background
There been increasing interest in polymetallic nodule mining within the Clarion-Clipperton Zone (CCZ). Polymetallic nodule mining within NORI-D will release a sediment plume within the water column and a previous mining collector test within the Nauru Ocean Resources Inc. (NORI-D) contract area released surface pollution from mining tailings. The mid-water plume, as well as accidental surface pollution, indicate that polymetallic nodule mining could impact surface plankton. Although the ichthyoplankton within the eastern tropical Pacific have been well-studied, recent data from within polymetallic nodule mining licence areas is lacking. Environmental Expedition C5e conducted an environmental baseline assessment of both pelagic and benthic fauna within the NORI-D region of the CCZ, which included the opportunistic collection of ichthyoplankton.
New information
Ichthyoplankton were collected within NORI-D from November–December 2021 using two plankton nets and a Remotely Operated Vehicle (ROV). Here, we present a checklist of ichthyoplankton within the NORI-D licence area during this winter campaign. Eighteen samples were collected and identified through morphology, with a limited number identified through genetic sequencing. Specimens were from five orders, including Argentiniformes, Stomiiformes, Myctophiformes, Beloniformes and Scombriformes. This checklist will aid contractors and scientists conducting work within the CCZ to examine how wastewater discharge from polymetallic nodule mining could impact fish reproduction and ichthyoplankton survival.
Keywords: DNA barcoding, environmental baseline assessment, fish checklist, plankton survey, polymetallic nodule mining
Introduction
The Clarion-Clipperton Zone (CCZ), an abyssal area in the northeast Pacific, is of particular economic interest due to the high abundance of seafloor polymetallic nodules which contain large quantities of manganese, nickel, copper, cobalt and rare earth elements (Hein et al. 2013, Hein et al. 2020). Nodule mining using tethered vehicles and initial at-sea mineral separation produces a sediment plume which can extend tens of kilometres from the original mining site (Spearman et al. 2020, Muñoz-Royo et al. 2022, Ouillon et al. 2022). Part of Annex 1 to ISBA/19/LTC/8, which provides recommendations on assessing environmental impacts within deep-sea mining areas, states that plankton communities in the upper 200 m should be characterised ‘if there is potential for surface discharge’ (International Seabed Authority 2015). During the pilot mining collector test in the NORI-D area of the eastern CCZ, there was overflow of water and nodule fragments onboard the collector ship (ISA Secretariat 2023, Yin et al. 2024). An initial assessment deemed that there was ‘no risk of serious harm to the marine environment from the event’ (ISA Secretariat 2023), yet this event indicates that there is potential for accidental surface waste discharge during polymetallic nodule mining operations.
Sediment released from polymetallic nodule mining contains copper, which is known to interefere with reproduction and survival across numerous taxa. In fishes, copper exposure has been shown to interfere with spermatogenesis, induce atresia and T4 and T3 hormone levels in the ovaries, inhibit spawning, reduce the mean diameter and weight of eggs, lower survival rate and slow hatchling growth (Benoit 1975, Kumar and Pant 1984, Johnson et al. 2007, James et al. 2008, Suvi et al. 2019). Copper can also accumulate within the reproductive organs (James et al. 2008), indicating that short-term exposure (96 hours) could affect reproduction and development even after leaving the impacted area. Other potential impacts to reproduction and larval survival from mining sediment release include reduced illumination due to turbidity, temperature shock from the release of cold bottom water and changes in salinity and oxygen levels (Matsumoto 1984).
To assess how polymetallic nodule mining and sediment release could impact fish populations, the ichthyoplankton in mining licence areas must be examined. Overall, the ichthyoplankton of the eastern tropical Pacific have been well-studied (Ahlstrom 1971, Ahlstrom 1972, Loeb 1984, León-Chávez et al. 2010). The majority of ichthyoplankton in the region are from the families Myctophidae and Phosichthyidae, with Diogenichthyslaternatus (Garman 1899) (family Myctophidae) and Vinciguerrialucetia (Garman 1899) (family Phosichthyidae) often dominating the ichthyoplankton captured in plankton net surveys and showing seasonal changes in abundance (Ahlstrom 1971, Ahlstrom 1972, Loeb 1984, León-Chávez et al. 2010). Although considerably less abundant, larvae from the family Scombridae (including the genus Thunnus South 1845) have also been collected from the eastern tropical Pacific (Ahlstrom 1971, Ahlstrom 1972, Matsumoto 1984, Reglero et al. 2014). The effects of deep-sea mining on nearby tuna fisheries, including affecting migratory routes and bioaccumulation of metals within muscle tissue, have been hypothesised as potentially major environmental impacts of polymetallic nodule mining (Van Der Grient and Drazen 2021, Amon et al. 2023, Tilot et al. 2024).
Although ichthyoplankton within the eastern tropical Pacific have already been characterised (Ahlstrom 1971, Ahlstrom 1972, Loeb 1984, León-Chávez et al. 2010), recent data with DNA barcoding from within polymetallic nodule licence areas is lacking. Here, we report the fish larvae and eggs collected during plankton net tows from the NORI-D area of the eastern Clarion-Clipperton Zone. Eighteen samples from NORI-D were opportunistically collected during November–December 2021 and identified through morphology, with eight supported by DNA sequences. Although limited, these data provide valuable information about which fishes are reproducing adjacent to or within this mining licence area, which can be used for future management considerations for this region.
Materials and methods
Location and Survey
As part of an baseline environmental impact assessment conducted by The Metals Company Inc., the NORI-D mining licence area was surveyed by the Maersk Launcher in 2021. Two survey areas were sampled within NORI-D (Fig. 1), which include the Collector Test Area (CTA) and the Preservation Reference Zone (PRZ). The CTA is expected to be the site of seafloor polymetallic nodule mining, while the PRZ is a designated no-mining area. All specimens were opportunistically collected during Environmental Expedition C5e from 11 November though 19 December 2021.
Figure 1.
A Map of the eastern Clarion-Clipperton Zone, with NORI-D as a black polygon; B Map of NORI-D, with the Collector Test Area (CTA) and Preservation Reference Zone (PRZ) in white and red polygons, respectively; C Map of the CTA, with net tows (PN and PTN) shown in black triangles and ROV dives (OY) shown in white circles; D Map of the PRZ, with net tows (PN and PTN) shown in black triangles.
Three different collection methods were used to capture fish larvae for this survey. They were conducted as a supplement to a formal environmental impact assessment (Table 1). The first method was a ring plankton net dubbed PN which was manually deployed and towed horizontally behind the ship. The mouth diameter was 20 cm with a mesh diameter of 330 μm and the cod end measured 3 cm diameter by 10 cm length. Nine surface tows were conducted in the CTA, which varied between 6.9 and 36.9 m wire out. A circular, open-mouthed plankton net dubbed PTN was used for vertical tows and deployed from the A-frame of the ship. The net had a mouth diameter of 70.5 cm with a mesh diameter of 330 μm and the cod end measured 30.8 long by 10.0 cm diameter. Seventeen tows were completed in the PRZ, all between 6:54–15:46 UTC on 16/12/2021 and varied between 50 and 226 m depth. Each tow spent 15–20 minutes at its target depth, with the maximum tow depth varying between 40 and 231 m. Some larvae were also accidentally captured in a concurrent ROV survey. The ROV Odysseus (Pelagic Research Services) dubbed OY was equipped with a 6-canister suction sampler with a variable-speed hydraulic pump. Each suction canister had an internal diameter of 152 mm and an internal height of 175 mm. The flexible hose through which specimens passed was 90 mm in internal diameter and the narrowest diameter in the piping system was 81 mm. The ROV was not aiming to sample larval fishes; therefore, all captures were incidentally collected by the sampling canister as bycatch during targeted sampling and their precise location and depth of capture were estimated.
Table 1.
Summary of plankton net tows and ROV dives where larval fishes were captured within NORI-D. The event (dive/tow number), event time (UTC datetime), decimal latitude, decimal longitude and the maximum depth in metres are given. Exact depth readings from an Ultra-short baseline (USBL) acoustic positioning beacon are indicated by *.
| Event | Event Time | Decimal Latitude | Decimal Longitude | Maximum Depth in Metres |
| PN_001 | 22/11/2021T00:45–01:31Z | 10.24754 | -117.33147 | 36.9 |
| PN_002 | 23/11/2021T19:32–20:32Z | 10.38729 | -117.12619 | 36.9 |
| PN_003 | 23/11/2021T20:56–21:04Z | 10.39116 | -117.12285 | 36.9 |
| PN_004 | 24/11/2021T02:50–03:04Z | 10.32901 | -117.17761 | 36.9 |
| PN_005 | 25/11/2021T15:22Z | 10.33147 | -117.19842 | 19.9 |
| PN_006 | 28/11/2021T21:11–21:30Z | 10.36106 | -117.15286 | 19.9 |
| PN_007 | 30/11/2021T19:08–19:37Z | 10.33085 | -117.17343 | 6.9 |
| PN_008 | 30/11/2021T23:00–23:27Z | 10.33119 | -117.17298 | 6.9 |
| OY34 | 05/12/2021 | 10.36704 | -117.18901 | 1500 |
| OY35 | 06/12/2021 | 10.33715 | -117.18589 | 1500 |
| PN_009 | 09/12/2021T13:00Z | 10.33073 | -117.18839 | 6.9 |
| PNT_002 | 16/12/2021T06:54–07:13Z | 10.95791 | -116.26127 | 40 |
| PNT_003 | 16/12/2021T07:18–07:38Z | 10.95477 | -116.26357 | 60 |
| PNT_004* | 16/12/2021T08:02–08:26Z | 10.94963 | -116.26874 | 200 |
| PNT_005* | 16/12/2021T08:27–08:48Z | 10.94725 | -116.27097 | 100 |
| PNT_006* | 16/12/2021T08:52–09:14Z | 10.94449 | -116.27217 | 75 |
| PNT_007* | 16/12/2021T09:18–09:43Z | 10.9414 | -116.27346 | 50 |
| PNT_008* | 16/12/2021T09:44–10:11Z | 10.93723 | -116.27464 | 200 |
| PNT_009* | 16/12/2021T10:14–0:40Z | 10.93209 | -116.27428 | 200 |
| PNT_010* | 16/12/2021T10:42–11:07Z | 10.92663 | -116.27487 | 200 |
| PNT_011* | 16/12/2021T11:12–11:40Z | 10.92172 | -116.27643 | 200 |
| PNT_012* | 16/12/2021T11:43–12:08Z | 10.91555 | -116.2783 | 200 |
| PNT_013* | 16/12/2021T12:11–12:37Z | 10.90867 | -116.28005 | 218 |
| PNT_014* | 16/12/2021T12:43–13:10Z | 10.90199 | -116.28403 | 206 |
| PNT_015* | 16/12/2021T13:11–13:40Z | 10.89612 | -116.28816 | 221 |
| PNT_016* | 16/12/2021T13:44–14:07Z | 10.88937 | -116.29373 | 231 |
| PNT_017* | 16/12/2021T14:11–14:40Z | 10.88694 | -116.29856 | 226 |
| PNT_018* | 16/12/2021T15:31–15:46Z | 10.9228 | -116.2959 | 70 |
DNA Extraction and Identification
After collection, all samples were preserved in 99% ethanol and stored in -40℃. Images of the preserved samples were taken using a stereo dissecting microscope (Leica M165C) with a camera attachment (Canon EOS Kiss X7i with NY1S Micronet lens). Total DNA was extracted using the Promega Wizard ® HMW DNA Extraction Kit following the manufacturer's instructions, but adding 23 μl of sodium acetate (3 Molar at pH 5.2) and 3 μl of Ethachinmate (cat. 312-01791, FUJIFILM Wako) in step 11 to facilitate the DNA precipitation (Montenegro et al. 2023). Either metazoan or vertebrate CO1-mtDNA and 12S-rDNA primers were used to ensure the amplication of fish DNA.
CO1-mtDNA sequences were amplified using the universal metazoan primer set LCO1490 (5’-GGT CAA CAA ATC ATA AAG ATA TTGG-3’) and HCO2198 (5’-TAA ACT TCA GGG TGA CCA AAA AAT CA-3’) (Folmer et al. 1994), with the following PCR conditions; 5 cycles of 94°C x 30 sec, 47°C x 45 sec, 72°C x 1 min, 30 cycles of 94°C x 30 sec, 52°C x 45 sec, 72°C x 1 min and final extension of 72°C x 5 min. Positive amplifications were selected using 1.5% agarose electrophoresis and purified using Shrimp Alkaline Phosphatase (cat. 2660A, SAP, TaKaRa) and Exonuclease I (cat. 2650A, Exo-I, TaKaRa). The resulting amplicons were sent for Sanger sequencing to FASMAC Co. Ltd (Kanagawa, Japan).
12S-rDNA sequences were amplified using the vertebrate primer set 12SL (5’-AAA GCA CGG CAC TGA AGA TGC-3’) and 12SR (5’-TTT CAT GTT TCC TTG CGG TAC-3’) (Wang et al. 2000) with the following touchdown PCR conditions; 27 cycles of 94°C x 1 min, 46°C - 54°C x 1 min, 72°C x 1 min 30 sec and final extension of 72°C x 10 min. Pre-amplification of the primers above were tailed for nanopore sequencing and sequencing libraries were prepared following the protocol “SQK-LSK109 with EXP-PBC096” for amplicon sequencing with barcoding. The library was sequenced using a nanopore flow cell R9.4.1 and MinION Mk1C device. Resultant reads were basecalled using a Super Accurate model (SUP) and demultiplexed using Dorado v.0.7.2 (https://github.com/nanoporetech/dorado). The resultant reads were later filtered by size (1500 bp) and average quality (Q = 12) using Chopper v.0.8.0 (De Coster and Rademakers 2023; https://github.com/wdecoster/chopper). Finally, consensus sequences were generated per amplicon using the script amplicons_sorter (r2024/03/20) (Vierstraete and Braeckman 2022; https://github.com/avierstr/amplicon_sorter) with default settings. It is worth noting that despite multiple attempts to amplify the 12S-rDNA region using the standard MiFish-U-F/R primers (Miya et al. 2015), all PCR reactions were unsuccessful.
Fishes were visually identified using identification guides (Miller et al. 1979, Ahlstrom and Moser 1980, Moser 1996, Okayama 2014) prior to destruction for DNA extraction. DNA sequences were searched against publicly available sequences on the NCBI GenBank database using nucleotide BLAST (megablast algorithm) (Altschul et al. 1990, Zhang et al. 2000). The evaluation of BLAST matches is discussed below for each sample. Although there is no universal genetic metric for species delimitation and, even in fishes, there is no clearly delineated "barcoding gap" between intraspecific and interspecific variation (Ward 2009), commonly accepted thresholds for species-level identification are > 98% sequence identity for Cytochrome c oxidase I (COI) (Ward 2009, Ko et al. 2013, Zhang et al. 2021, Xing et al. 2022) and > 99% sequence identity for 12S (Milan et al. 2020). Specimens, their identities and GenBank accession numbers are given in the checklist below. An overview of the number of taxa and how they were identified is given in Table 2.
Table 2.
Summary of specimens, including the total number collected, the number identified through morphology and the number identified through Cytochrome c oxidase I (COI) or 12S genetic sequencing.
| Taxa | Number of specimens | Number from CTA | Number from PRZ | Identified from morphology | Identified from DNA sequencing |
| Unidentified Teleostei | 5 | 4 | 1 | 5 | 0 |
| Order Argentiniformes | 1 | 0 | 1 | 1 | 1 |
| Cyclothone sp. Goode & Bean, 1883 | 1 | 1 | 0 | 1 | 0 |
| Vinciguerrialucetia (Garman 1899) | 6 | 4 | 2 | 6 | 5 |
| Diogenichthyslanternatus (Garman 1899) | 1 | 1 | 0 | 1 | 0 |
| Oxyporhamphusmicropterus (Valenciennes 1847) | 2 | 1 | 1 | 2 | 1 |
| Thunnus sp. South, 1845 | 1 | 1 | 0 | 1 | 0 |
| Gempylusserpens Cuvier 1829 | 1 | 0 | 1 | 1 | 1 |
| Total | 18 | 12 | 6 | 18 | 8 |
Checklists
Ichthyoplankton of NORI-D
Chordata
Haeckel, 1866
9C1389E6-2E83-501F-9925-D23E5930582C
Teleostei
Müller, 1845
A4CCEB29-A733-5183-9507-0D43B8DB8CAA
Materials
Type status: Other material. Occurrence: catalogNumber: DL311; recordedBy: Leah A. Bergman; individualCount: 1; lifeStage: egg; otherCatalogNumbers: 211123z_6; occurrenceID: CCZ_NORID_C5e_DL311; Location: waterBody: Pacific Ocean; stateProvince: Clarion-Clipperton Zone; locality: The Metals Company Ltd exploration contract area (NORI-D); verbatimLocality: NORI-D, CTA; maximumDepthInMeters: 36.9; locationRemarks: Environmental Expedition C5e; decimalLatitude: 10.95477; decimalLongitude: -116.26357; geodeticDatum: WGS84; Identification: identifiedBy: Leah A. Bergman, Bruce C. Mundy; Event: samplingProtocol: PN; eventDate: 23/11/2021; eventTime: 20:56–21:04Z; fieldNumber: PTN_003; Record Level: collectionID: DL311
Type status: Other material. Occurrence: catalogNumber: DL318; recordedBy: Leah A. Bergman; individualCount: 1; lifeStage: yolk-sac; otherCatalogNumbers: ML20211123SP-2; occurrenceID: CCZ_NORID_C5e_DL318; Location: waterBody: Pacific Ocean; stateProvince: Clarion-Clipperton Zone; locality: The Metals Company Ltd exploration contract area (NORI-D); verbatimLocality: NORI-D, CTA; maximumDepthInMeters: 36.9; locationRemarks: Environmental Expedition C5e; decimalLatitude: 10.387288; decimalLongitude: -117.126187; geodeticDatum: WGS84; Identification: identifiedBy: Leah A. Bergman, Bruce C. Mundy; Event: samplingProtocol: PN; eventDate: 23/11/2021; eventTime: 20:56–21:04Z; fieldNumber: PN_003
Type status: Other material. Occurrence: catalogNumber: DL317; recordedBy: Leah A. Bergman; individualCount: 1; lifeStage: preflexion; otherCatalogNumbers: PITA_14-3; occurrenceID: CCZ_NORID_C5e_DL317; Location: waterBody: Pacific Ocean; stateProvince: Clarion-Clipperton Zone; verbatimLocality: NORI-D, PRZ; maximumDepthInMeters: 221; locationRemarks: Environmental Expedition C5e; verbatimCoordinateSystem: WGS84; decimalLatitude: 10.89612; decimalLongitude: -116.28816; geodeticDatum: WGS84; Identification: identifiedBy: Leah A. Bergman, Bruce C. Mundy; Event: samplingProtocol: PNT; eventDate: 16/12/2021; eventTime: 13:11–13:40Z; fieldNumber: PNT_015
Type status: Other material. Occurrence: catalogNumber: DL326; recordedBy: Leah A. Bergman; individualCount: 1; lifeStage: preflexion; otherCatalogNumbers: SP20211209; occurrenceID: CCZ_NORID_C5e_DL326; Location: waterBody: Pacific Ocean; stateProvince: Clarion-Clipperton Zone; locality: The Metals Compary Ltd exploration contract area (NORI-D); verbatimLocality: NORI-D, CTA; maximumDepthInMeters: 6.9; locationRemarks: Environmental Expedition C5e; decimalLatitude: 10.330728; decimalLongitude: -117.188378; geodeticDatum: WGS84; Identification: identifiedBy: Leah A. Bergman, Bruce C. Mundy; Event: samplingProtocol: PN; eventDate: 30/11/2021; eventTime: 19:08–19:37Z; fieldNumber: PN_007
Type status: Other material. Occurrence: catalogNumber: DL325; recordedBy: Leah A. Bergman; individualCount: 1; lifeStage: preflexion; otherCatalogNumbers: SP20211130-13; occurrenceID: CCZ_NORID_C5e_DL325; Location: waterBody: Pacific Ocean; stateProvince: Clarion-Clipperton Zone; locality: The Metals Compary Ltd exploration contract area (NORI-D); verbatimLocality: NORI-D, CTA; maximumDepthInMeters: 6.9; locationRemarks: Environmental Expedition C5e; decimalLatitude: 10.330728; decimalLongitude: -117.188378; geodeticDatum: WGS84; Identification: identifiedBy: Leah A. Bergman, Bruce C. Mundy; Event: samplingProtocol: PN; eventDate: 30/11/2021; eventTime: 19:08–19:37Z; fieldNumber: PN_007
Notes
Fig. 2
Unidentified ichthyoplankton from NORI-D. A DL311 captured with PN during PN_003; B DL318 captured with PN during PN_003; C DL317 captured with PTN during PNT_015; D DL326 captured with PN during PN_007; E DL325 captured with PN during PN_007.
Figure 2a.
Figure 2b.
Figure 2c.
Figure 2d.
Figure 2e.
Argentiniformes
29F9A79E-6175-5B63-A8E5-23F0BA0526EE
Materials
Type status: Other material. Occurrence: catalogNumber: DL314; recordedBy: Leah A. Bergman; individualID: 1; lifeStage: preflexion; otherCatalogNumbers: PITA_11-2; associatedSequences: GenBank (12S): PQ351602; occurrenceID: CCZ_NORID_C5e_DL314; Location: waterBody: Pacific Ocean; stateProvince: Clarion-Clipperton Zone; locality: The Metals Company Ltd exploration contract area (NORI-D); verbatimLocality: NORI-D, PRZ; maximumDepthInMeters: 200; locationRemarks: Environmental Expedition C5e; decimalLatitude: 10.91555; decimalLongitude: -116.2783; geodeticDatum: WGS84; Identification: identifiedBy: Leah A. Bergman, Bruce C. Mundy, Javier Montenegro; Event: samplingProtocol: PTN; eventDate: 16/12/2021; eventTime: 11:43–12:08Z; fieldNumber: PTN_012
Notes
Fig. 3
DL314 captured with PTN during PTN_012. Top: whole body. Bottom: right side of the head of the same specimen.
Figure 3a.
Figure 3b.
The closest 12S sequence match was 95.02% with Lipolagusochotensis (Schmidt 1938) family Bathylagidae (NC_004591.1). However, < 99% identity match is typically considered too broad for species-level identification (Milan et al. 2020, Kumar et al. 2022). Therefore, conservative identification to order Argentiniformes using morphology follows Bruce C. Mundy (July 2024, personal communication)
Stomiiformes
AFCA1D71-A805-519C-9B04-631F12F4BBFA
Gonostomatidae
Cocco, 1838
7A3BB697-355F-514C-A2D1-C96A4641DBFF
Cyclothone
Goode & Bean, 1883
5F53B6B4-449F-5A78-819F-018A313329D9
Materials
Type status: Other material. Occurrence: catalogNumber: DL387; recordedBy: Leah A. Bergman; lifeStage: postflexion; otherCatalogNumbers: OY35SS1-1; 211208z-SS1-1; occurrenceID: CCZ_NORID_C5e_DL387; Location: waterBody: Pacific Ocean; stateProvince: Clarion-Clipperton Zone; locality: The Metals Company Ltd exploration contract area (NORI-D); verbatimLocality: NORI-D, CTA; minimumDepthInMeters: 75; maximumDepthInMeters: 1500; locationRemarks: Environmental Expedition C5e; decimalLatitude: 10.31731; decimalLongitude: -117.20236; geodeticDatum: WGS84; Identification: identifiedBy: Leah A. Bergman, Bruce C. Mundy; Event: samplingProtocol: ROV Odysseus; eventDate: 08/12/2021; fieldNumber: OY35
Notes
Fig. 4
Figure 4.
DL387 captured with the ROV Odysseus suction sampler during OY35.
Phosichthyidae
Weitzman, 1974
D3A458FD-7BE5-53D0-A041-170E42172FF9
Vinciguerria
Jordan & Evermann, 1896
CA9771B0-B4FB-5424-8356-27CBF5B01544
Vinciguerria lucetia
(Garman, 1899)
1D47DEED-0632-5E4D-8B66-98E4EA2ACAFA
Materials
Type status: Other material. Occurrence: catalogNumber: DL320; recordedBy: Leah A. Bergman; lifeStage: flexion; otherCatalogNumbers: SP20211123Z-3; associatedSequences: GenBank: PQ327500; occurrenceID: CCZ_NORID_C5e_DL320; Location: waterBody: Pacific Ocean; stateProvince: Clarion-Clipperton Zone; locality: The Metals Company Ltd exploration contract area (NORI-D); verbatimLocality: NORI-D, CTA; maximumDepthInMeters: 37; locationRemarks: Environmental Expedition C5e; decimalLatitude: 10.39116; decimalLongitude: -117.12285; geodeticDatum: WGS84; Identification: identifiedBy: Leah A. Bergman, Bruce C. Mundy, Javier Montenegro; Event: samplingProtocol: PN; eventDate: 23/11/2021; eventTime: 20:56–21:04Z; fieldNumber: PN_003
Type status: Other material. Occurrence: catalogNumber: DL321; recordedBy: Leah A. Bergman; individualCount: 1; lifeStage: preflexion; otherCatalogNumbers: SP20211125-5; associatedSequences: GenBank (CO1): PQ327501; occurrenceID: CCZ_NORID_C5e_DL321; Location: waterBody: Pacific Ocean; stateProvince: Clarion-Clipperton Zone; locality: The Metals Company Ltd exploration contract area (NORI-D); verbatimLocality: NORI-D, CTA; maximumDepthInMeters: 20; locationRemarks: Environmental Expedition C5e; decimalLatitude: 10.331383; decimalLongitude: -117.198422; geodeticDatum: WGS84; Identification: identifiedBy: Leah A. Bergman, Bruce C. Mundy, Javier Montenegro; Event: samplingProtocol: PN; eventDate: 25/11/2021; eventTime: 15:22Z; fieldNumber: PN_005
Type status: Other material. Occurrence: catalogNumber: DL324; recordedBy: Leah A. Bergman; individualCount: 1; lifeStage: preflexion; otherCatalogNumbers: SP20211130-12; associatedSequences: GenBank (CO1): PQ327503; Genbank (12S): PQ351600; occurrenceID: CCZ_NORID_C5e_DL324; Location: waterBody: Pacific Ocean; stateProvince: Clarion-Clipperton Zone; locality: The Metals Company Ltd exploration contract area (NORI-D); verbatimLocality: NORI-D, CTA; maximumDepthInMeters: 7; locationRemarks: Environmental Expedition C5e; decimalLatitude: 10.33119; decimalLongitude: -117.172982; geodeticDatum: WGS84; Identification: identifiedBy: Leah A. Bergman, Bruce C. Mundy, Javier Montenegro; Event: samplingProtocol: PN; eventDate: 30/11/2021; eventTime: 19:08–19:37Z; fieldNumber: PN_007
Type status: Other material. Occurrence: catalogNumber: DL322; recordedBy: Leah A. Bergman; individualCount: 1; lifeStage: flexion; otherCatalogNumbers: SP20211130-10; associatedSequences: GenBank (CO1): PQ327502; occurrenceID: CCZ_NORID_C5e_DL322; Location: waterBody: Pacific Ocean; stateProvince: Clarion-Clipperton Zone; locality: The Metals Company Ltd exploration contract area (NORI-D); verbatimLocality: NORI-D, CTA; maximumDepthInMeters: 7; locationRemarks: Environmental Expedition C5e; decimalLatitude: 10.33119; decimalLongitude: -117.172982; geodeticDatum: WGS84; Identification: identifiedBy: Leah A. Bergman, Bruce C. Mundy, Javier Montenegro; Event: samplingProtocol: PN; eventDate: 30/11/2021; eventTime: 19:08–19:37Z; fieldNumber: PN_007
Type status: Other material. Occurrence: catalogNumber: DL313; recordedBy: Leah A. Bergman; individualCount: 1; lifeStage: flexion; otherCatalogNumbers: PITA_2-7; associatedSequences: GenBank (CO1): PQ327504; occurrenceID: CCZ_NORID_C5e_DL313; Location: waterBody: Pacific Ocean; stateProvince: Clarion-Clipperton Zone; locality: The Metals Company Ltd exploration contract area (NORI-D); verbatimLocality: NORI-D, PRZ; maximumDepthInMeters: 60; locationRemarks: Environmental Expedition C5e; decimalLatitude: 10.951607; decimalLongitude: -117.266673; geodeticDatum: WGS84; Identification: identifiedBy: Leah A. Bergman, Bruce C. Mundy, Javier Montenegro; Event: samplingProtocol: PTN; eventDate: 16/12/2021; eventTime: 07:18–07:38Z; fieldNumber: PNT_003
Type status: Other material. Occurrence: catalogNumber: DL388; recordedBy: Leah A. Bergman; individualCount: 1; lifeStage: postflexion; otherCatalogNumbers: P20211216-2; occurrenceID: CCZ_NORID_C5e_DL388; Location: waterBody: Pacific Ocean; stateProvince: Clarion-Clipperton Zone; locality: The Metals Company Ltd exploration contract area (NORI-D); verbatimLocality: NORI-D, PRZ; maximumDepthInMeters: 60; locationRemarks: Environmental Expedition C5e; decimalLatitude: 10.951607; decimalLongitude: -117.266673; geodeticDatum: WGS84; Identification: identifiedBy: Leah A. Bergman, Bruce C. Mundy, Javier Montenegro; Event: samplingProtocol: PTN; eventDate: 16/12/2021; eventTime: 07:18–07:38Z; fieldNumber: PNT_003
Notes
Fig. 5
A DL320 captured with PN during PN_003; B DL321 captured with PN during PN_005; C DL324 captured with PN during PN_007; D DL322 captured with PN during PN_007; E DL322 captured with PTN during PTN_003; F DL388 captured with PTN during PTN_003.
Figure 5a.
Figure 5b.
Figure 5c.
Figure 5d.
Figure 5e.
Figure 5f.

The COI sequences for five specimens (DL313, DL320, DL321, DL322, DL324) matched a reference sequence of V.lucetia (HQ010067, voucher SIO 09-204) with 100.0% identity and all other BLAST hits showed < 95% identity. DL388 was identified through morphology only (Moser 1996). This mesopelagic Pacific species (Fricke et al. 2024) has been previously recorded from Clipperton Atoll (Fourriére et al. 2014) and it is dominant in the larval fish assemblages of the eastern tropical Pacific off Mexico (León-Chávez et al. 2010). V.lucetia larvae are elongate and slender with ovoid eyes and usually possess a large melanophore ventrally near end of the caudal peduncle (Moser 1996).
Myctophiformes
4D44673F-9396-5F2F-9654-AEF24AAB82A0
Myctophidae
Gill, 1893
F2C39BE7-14AF-5130-9734-AA835419C6BF
Diogenichthys
Bolin, 1939
AABA6734-9842-5B8D-83FC-7947C3F2050C
Diogenichthys laternatus
(Garman, 1899)
5F333C7B-E3BB-55E9-BC08-E0A84AF64338
Materials
Type status: Other material. Occurrence: catalogNumber: DL312; recordedBy: Leah A. Bergman; lifeStage: postflexion; otherCatalogNumbers: OY34-SS1; occurrenceID: CCZ_NORID_C5e_DL312; Location: waterBody: Pacific Ocean; stateProvince: Clarion-Clipperton Zone; locality: The Metals Company Ltd exploration contract area (NORI-D); verbatimLocality: NORI-D, CTA; minimumDepthInMeters: 75; maximumDepthInMeters: 1500; locationRemarks: Environmental Expedition C5e; decimalLatitude: 10.37227; decimalLongitude: -117.17892; geodeticDatum: WGS84; Identification: identifiedBy: Leah A. Bergman, Bruce C. Mundy, Javier Montenegro; Event: samplingProtocol: ROV Odysseus; eventDate: 06/12/2021; fieldNumber: OY34
Notes
Fig. 6
Figure 6.
DL312 captured with the ROV Odysseus suction sampler during OY34.
This abundant mesopelagic species occurs in the central and eastern Pacific (Evseenko 2006, Fricke et al. 2024). Adults have been recorded from Clipperton Atoll (Fourriére et al. 2014) and it is dominant in the larval fish assemblages of the eastern tropical Pacific off Mexico, Ecuador, Peru and Chile (Evseenko 2006, León-Chávez et al. 2010). D.lanternatus larvae are characterised by elliptical eyes, moderately-sized head and a melanophore on trunk above pre-anal arch of gut (Moser 1996).
Beloniformes
0A3CCCEA-AEDC-5C90-AA04-B0750CAE4FAA
Hemiramphidae
Gill, 1859
6C2B8E7B-9754-59DD-9553-D3A01E6EAE9C
Oxyporhamphus
Gill, 1864
6428D2F2-CA14-50AF-9BA3-67AADE763A9A
Oxyporhamphus micropterus
(Valenciennes, 1847)
322DEF83-F590-575F-BF34-EABBDA6B54A7
Materials
Type status: Other material. Occurrence: catalogNumber: DL319; recordedBy: Leah A. Bergman; individualCount: 1; lifeStage: egg; otherCatalogNumbers: SP20211122T01300-5; associatedSequences: GenBank (CO1): PQ327499; occurrenceID: CCZ_NORID_C5e_DL319; Location: waterBody: Pacific Ocean; stateProvince: Clarion-Clipperton Zone; locality: The Metals Company Ltd exploration contract area (NORI-D); verbatimLocality: NORI-D, CTA; maximumDepthInMeters: 37; locationRemarks: Environmental Expedition C5e; decimalLatitude: 10.247537; decimalLongitude: -117.3303; geodeticDatum: WGS84; Identification: identifiedBy: Leah A. Bergman, Bruce C. Mundy, Javier Montenegro; Event: samplingProtocol: PN; eventDate: 22/11/2021; eventTime: 15:31–16:45Z; fieldNumber: PN_001
Type status: Other material. Occurrence: catalogNumber: DL315; recordedBy: Leah A. Bergman; individualCount: 1; lifeStage: egg; otherCatalogNumbers: PITA_12-2; occurrenceID: CCZ_NORID_C5e_DL315; Location: waterBody: Pacific Ocean; stateProvince: Clarion-Clipperton Zone; locality: The Metals Company Ltd exploration contract area (NORI-D); verbatimLocality: NORI-D, PRZ; maximumDepthInMeters: 200; locationRemarks: Environmental Expedition C5e; decimalLatitude: 10.90867; decimalLongitude: -116.28005; geodeticDatum: WGS84; Identification: identifiedBy: Leah A. Bergman, Bruce C. Mundy; Event: samplingProtocol: PTN; eventDate: 16/12/2021; eventTime: 04:11–04:37Z; fieldNumber: PNT_013
Notes
Fig. 7
A DL319 captured with PN during PN_001; B DL315 captured with PTN during PTN_013.
Figure 7a.
Figure 7b.
The COI sequence for DL319 was 99.83% identical to sequences of Oxyporhamphusmicropterus (Valenciennes 1847) (MZ892547.1; MZ050602.1, voucher FIFP2021-seq16; MZ028360.1), corroborating morphological identification of the egg. DL315 was identified, based on morphological similarity to DL319. This genus is widespread in the surface waters of the Atlantic, Pacific and Indo-Pacific Oceans, O micropterus occurring in Western Atlantic, Eastern Pacific and Indo-Pacific Oceans and Oxyporhamphussimilis Bruun 1935 occurring in Western and Eastern Atlantic Oceans (Collette 2004, Fricke et al. 2024). Adults have been recorded from Clipperton Atoll (Fourriére et al. 2014). Based on COI sequences, eggs and larvae have been recorded from the Ninety East Ridge of the eastern Indian Ocean (Zhang et al. 2021) and larvae have been recorded from Hawaiian waters (Xing et al. 2022). Eggs are characterised by short, numerous, pointed spines on the chorion (Ahlstrom and Moser 1980).
Scombriformes
7F235C85-3D05-57B7-861D-0831CDCEF140
Scombridae
Rafinesque, 1815
FE20913B-AC6F-56E8-BFD4-86AD8A308E95
Thunnus
South, 1845
55C7CAD8-D676-59A6-8F10-1D1E2C8FE009
Materials
Type status: Other material. Occurrence: catalogNumber: DL323; recordedBy: Leah A. Bergman; lifeStage: preflexion; otherCatalogNumbers: SP20211130-11; occurrenceID: CCZ_NORID_C5e_DL323; Location: waterBody: Pacific Ocean; stateProvince: Clarion-Clipperton Zone; locality: The Metals Company Ltd exploration contract area (NORI-D); verbatimLocality: NORI-D, CTA; maximumDepthInMeters: 7; locationRemarks: Environmental Expedition C5e; decimalLatitude: 10.33119; decimalLongitude: -117.172982; geodeticDatum: WGS84; Identification: identificationID: Leah A. Bergman, Bruce C. Mundy; Event: samplingProtocol: PN; eventDate: 30/11/2021; eventTime: 11:08–11:38Z; fieldNumber: PN_007
Notes
Fig. 8
Figure 8.
DL323 captured with PN in the CTA during PN_007.
Gempylidae
Gill, 1862
292048AF-C48C-5EE9-AC1F-41202DCA78E9
Gempylus
Cuvier, 1829
49B4160C-C368-54F5-AD51-1BB67677F3F3
Gempylus serpens
Cuvier, 1829
0F680948-B169-56B5-ABBE-434BEBC318FF
Materials
Type status: Other material. Occurrence: catalogNumber: DL316; recordedBy: Leah A. Bergman; lifeStage: preflexion; otherCatalogNumbers: PITA_13-4; associatedSequences: GenBank (CO1): PQ351601; occurrenceID: CCZ_NORID_C5e_DL316; Location: waterBody: Pacific Ocean; stateProvince: Clarion-Clipperton Zone; locality: The Metals Company Ltd exploration contract area (NORI-D); verbatimLocality: NORI-D, PRZ; maximumDepthInMeters: 200; locationRemarks: Environmental Expedition C5e; decimalLatitude: 10.90199; decimalLongitude: -116.28403; geodeticDatum: WGS84; Identification: identificationID: Leah A. Bergman, Bruce C. Mundy; Event: samplingProtocol: PTN; eventDate: 16/12/2021; eventTime: 04:43–05:10Z; fieldNumber: PTN_014
Notes
Fig. 9
Figure 9.
DL316 captured with PTN during PTN_014.
This mesopelagic predatory species is widespread in tropical oceans (Choy et al. 2013, Mthethwa et al. 2023, Fricke et al. 2024). Its larvae are commonly captured nearshore in the Hawaiian Archipelago (Miller et al. 1979). Adults have been recorded from Clipperton Atoll (Fourriére et al. 2014). Based on COI sequences, eggs and larvae have been recorded from the Ninety East Ridge of the eastern Indian Ocean (Zhang et al. 2021) and larvae have been recorded from Hawaiian waters (Xing et al. 2022). G. serpens larvae are characterised by strong pre-opercular spines, well-developed dorsal and pelvic fin ray spines, with pigmentation on the brain, dorsal surface of the gut, the mid-body and along the body margin under the first dorsal fin (Moser 1996).
Discussion
This report details ichthyoplankton opportunistically collected from November through December 2021 within a polymetallic nodule mining licence area in the eastern tropical Pacific. Of the three sampling methodologies from this report, the majority of samples were collected using PN, the net used for horizontal tows. Although the mouth diameter and cod end of PN were smaller than PTN, conducting horizontal tows near the surface (maximum wire out: 36.9 m) yielded more ichthyoplankton samples during the survey period. Consequently, more were collected from the CTA, where both PN and OY collected ichthyoplankton. Due to the CTA and PRZ being less than 100 km apart from each other, the difference in the amount of ichthyoplankton captured between the two regions was likely due to the difference in survey methodology.
One potential impact of polymetallic nodule mining within the Clarion-Clipperton Zone includes the release and suspension of copper. The majority of copper within seafloor sediment is confined to the upper 10 cm, with up to 120 ppm within the upper 20 cm of sediment in the eastern CCZ (Callender and Bowser 1980). In simulated polymetallic nodule mining experiments, the upper 15–20 cm of sediment were removed and resuspended (Vonnahme et al. 2020), indicating that sediment plumes may suspend a considerable amount of copper and have the potential to affect reproduction across taxa. Although more work is needed to quantify the impacts of polymetallic nodule mining, including modelling the impacts of sedimentation, trace metal release and shifts in the thermocline, creating an updated checklist of ichthyoplankton within polymetallic nodule mining licence areas is valuable for considering the potential impacts of mining on the fish community.
All taxa within this survey have been previously collected in the Clarion-Clipperton Zone and the eastern tropical Pacific, both as adults and larvae (Ahlstrom 1971, Ahlstrom 1972, Fourriére et al. 2014). The most abundant taxon within this survey was Vinciguerrialucetia, with six specimens captured. Previous work has also quantified this species as one of the most abundant in ichthyoplankton surveys within the region (Ahlstrom 1971, Ahlstrom 1972, Loeb 1984, León-Chávez et al. 2010). Adult V.lucetia comprise nearly 10% of the diet of tuna in the eastern tropical Pacific and are a key trophic link between the surface and the mesopelagic (Alverson 1963, Olson et al. 2014); therefore, any impact on their reproduction and development could affect a wide variety of taxa.
Although this survey only reported a single Thunnus sp. specimen and Thunnus sp. larvae are less common within the eastern tropical Pacific than Vinciguerria spp. (Ahlstrom 1971, Ahlstrom 1972, Matsumoto 1984), the presence of larval tuna within a polymetallic nodule mining licence area is noteworthy. This supports previous hypotheses suggesting that tuna are reproducing near polymetallic nodule licence areas and that polymetallic nodule mining could potentially impact their reproduction (Reglero et al. 2014, Van Der Grient and Drazen 2021). However, the importance of NORI-D as a spawning area for tuna remains unclear.
This report details eighteen ichthyoplankton samples captured within a polymetallic nodule mining licence area from November–December 2021. Several of these species also occur in recent DNA-based ichthyoplankton checklists from Hawaiian waters (Xing et al. 2022) and the eastern Indian Ocean (Zhang et al. 2021). The eastern Pacific sequences generated in this work thereby represent an important geographic data point for baseline studies of population connectivity. Sampling within NORI-D in this survey occurred only during wintertime, therefore more work is needed throughout the year to quantify seasonal shifts in fish reproduction. As polymetallic nodule mining is an emerging industry, the content of wastewater and sediment plumes is largely unknown. Examining both the contents and spread of mining discharge are critical in determining the impact polymetallic nodule mining will have on fish reproduction and ichtyoplankton survival.
Supplementary Material
Acknowledgements
We thank the crew and scientists aboard the Maersk Launcher and the ROV team of the ROV Odysseus, without whom this work would not have been possible. We thank Bruce C. Mundy for his help with specimen identification and for his comments on the manuscript. We also thank two reviewers for their helpful comments on improving the manuscript. This project was partially supported by a Monbukagakusho (MEXT) Scholarship to LAB. Research in the NORI-D area in the eastern CCZ was partly funded by The Metals Company Inc. (TMC) in a joint collaboration between the University of Hawaii and JAMSTEC. The authors received support from TMC through its subsidiary Nauru Ocean Resources Inc. (NORI). NORI holds exploration rights to the NORI-D contract area in the CCZ regulated by the International Seabed Authority and sponsored by the government of Nauru. All funders were not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit it for publication. This is contribution TMC/NORI/D/019.
Author contributions
Conceptualisation, LAB; Data curation, LAB, JM, CAS, TB, DJL and JCD; Formal analysis, LAB, JM, CAS; Funding acquisition LAB, DJL, and JCD; Investigation, LAB, JM, CAS, TB, EVT, DJL and JCD; Methodology, LAB, JM, DJL; Project administration, EVT, DJL and JCD; Resources, FM, DJL and JCD; Supervision, DJL and JCD; Validation, JM, CAS; Visualisation, LAB; Writing - original draft, LAB, JM, CAS; Writing - review and editing, LAB, JM, CAS, TB, EVT, FM, DJL and JCD.
References
- Ahlstrom E. H. Kinds and abundance of fish larvae in the eastern tropical Pacific, based on collections made on EASTROPAC I. Fishery Bulletin. 1971;69(1):3–77. [Google Scholar]
- Ahlstrom E. H. Kinds and and abundance of fish larvae in the eastern tropical Pacific on the second multivessel EASTROPAC Survey, and observations on the annual cycle of larval abundance. Fishery Bulletin. 1972;70(4):1163. [Google Scholar]
- Ahlstrom E. H., Moser H. G. Characters useful in identification of pelagic marine fish eggs. CalCOFI Reports. 1980;21:121–131. [Google Scholar]
- Altschul S. F., Gish W., Miller W., Myers E. W., Lipman D. J. Basic local alignment search tool. Journal of Molecular Biology. 1990;215(3):403–410. doi: 10.1016/S0022-2836(05)80360-2. [DOI] [PubMed] [Google Scholar]
- Alverson F. G. The food of yellowfin and skipjack tunas in the eastern tropical Pacific Ocean. http://hdl.handle.net/1834/20403 Inter-American Tropical Tuna Commission Bulletin. 1963;7(5):293–396. [Google Scholar]
- Amon D. J., Palacios-Abrantes J., Drazen J. C., Lily H., Nathan N., Grient J. M.A., McCauley D. Climate change to drive increasing overlap between Pacific tuna tisheries and emerging deep-sea mining industry. npj Ocean Sustainability. 2023;2(1):9. doi: 10.1038/s44183-023-00016-8. [DOI] [Google Scholar]
- Benoit D. Chronic effects of copper on survival, growth, and reproduction of the bluegill (Lepomismacrochirus) Transactions of the American Fisheries Society. 1975;104:353–358. doi: 10.1577/1548-8659(1975)1042.0.CO;2. [DOI] [Google Scholar]
- Callender E., Bowser C. J. Manganese and copper geochemistry of interstitial fluids from manganese nodule-rich pelagic sediments of the northeastern equatorial Pacific Ocean. American Journal of Science. 1980;280(10):1063–1096. doi: 10.2475/ajs.280.10.1063. [DOI] [Google Scholar]
- Choy C. Anela, Portner Elan, Iwane Mia, Drazen Jeffrey C. Diets of five important predatory mesopelagic fishes of the central North Pacific. Marine Ecology Progress Series. 2013;492:169–184. doi: 10.3354/meps10518. [DOI] [Google Scholar]
- Collette Bruce B. Family Hemiramphidae Gill 1859 — Halfbeaks. https://www.calacademy.org/scientists/annotated-checklists-of-fishes California Academy of Sciences Annotated Checklists of Fishes. 2004;22:1–35. [Google Scholar]
- De Coster W., Rademakers R. NanoPack2: population-scale evaluation of long-read sequencing data. Bioinformatics. 2023;39(5) doi: 10.1093/bioinformatics/btad311. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Evseenko S. A. On species composition and distribution of lanternfish larvae (Myctophidae) in the eastern outh Pacific. Journal of Ichthyology. 2006;46(Supplement 1):S110–S115. doi: 10.1134/s0032945206100080. [DOI] [Google Scholar]
- Folmer O., Black M., Hoeh W., Lutz R., Vrijenhoek R. DNA primers for amplification of mitochondrial cytochrome c oxidase subunit I from diverse metazoan invertebrates. Molecular Marine Biology and Biotechnology. 1994;3(5):294–299. [PubMed] [Google Scholar]
- Fourriére Manon, Reyes-Bonilla Héctor, Rodríguez-Zaragoza Fabián A., Crane Nicole. Fishes of clipperton atoll, eastern Pacific: checklist, endemism, and analysis of completeness of the inventory. Pacific Science. 2014;68(3):375–395. doi: 10.2984/68.3.7. [DOI] [Google Scholar]
- Fricke Ron, Eschmeyer William N., Van der Laan Richard., editors. Eschmeyer's catalog of fishes: genera, species, references. https://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp. [2024-08-20T00:36:32+00:00]. https://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp
- Hein J. R., Mizell K., Koschinsky A., Conrad T. A. Deep-ocean mineral deposits as a source of critical metals for high-end green-technology applications: comparison with land-based resources. Ore Geology Reviews. 2013;51:1–14. doi: 10.1016/j.oregeorev.2012.12.001. [DOI] [Google Scholar]
- Hein J. R., Koschinsky T., Kuhn A. Deep-ocean polymetallic nodules as a resource for critical materials. Nature Reviews Earth & Environment. 2020;1:158–169. doi: 10.1038/s43017-020-0027-0. [DOI] [Google Scholar]
- Authority International Seabed. ISA consolidated regulations and recommendations on prospecting and exploration. Revised. The International Seabed Authority; Kingston, Jamaica: 2015. [Google Scholar]
- Secretariat ISA. CARMU Inspection Report 01/2023, Doc.No: INSP/2023/NRU/001, Version 1. 2023. https://www.isa.org.jm/wp-content/uploads/2023/02/ISA_inspection_report_NORI_mining_collector_system_test.pdf https://www.isa.org.jm/wp-content/uploads/2023/02/ISA_inspection_report_NORI_mining_collector_system_test.pdf
- James R., Sampath K., Jothilakshmi S., Vasudhevan I., Thangarathinam R. Effects of copper toxicity on growth, reproduction and metal accumulation in chosen ornamental fishes. Ecohydrology & Hydrobiology. 2008;8:89–97. doi: 10.2478/v10104-009-0007-y. [DOI] [Google Scholar]
- Johnson A., Carew E., Sloman K. A. The effects of copper on the morphological and functional development of zebrafish embryos. Aquatic Toxicology. 2007;84:431–438. doi: 10.1016/j.aquatox.2007.07.003. [DOI] [PubMed] [Google Scholar]
- Ko Hui-Ling, Wang Yu-Tze, Chiu Tai-Sheng, Lee Ming-An, Leu Ming-Yih, Chang Kuang-Zong, Chen Wen-Yu, Shao Kwang-Tsao. Evaluating the accuracy of morphological identification of larval fishes by applying DNA barcoding. PLOS ONE. 2013;8(1):e53451. doi: 10.1371/journal.pone.0053451. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kumar Girish, Reaume Ashley M., Farrell Emily, Gaither Michelle R. Comparing eDNA metabarcoding primers for assessing fish communities in a biodiverse estuary. PLOS ONE. 2022;17(6):e0266720.. doi: 10.1371/journal.pone.0266720. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kumar S., Pant S. Comparative effects of the sublethal poisoning of zinc, copper and lead on the gonads of the teleost Puntiusconchonius. Toxicology Letters. 1984;23:189–194. doi: 10.1016/0378-4274(84)90125-5. [DOI] [PubMed] [Google Scholar]
- León-Chávez Cristina A., Sánchez-Velasco Laura, Beier Emilio, Lavín Miguel F., Godínez Victor M., Färber-Lorda Jaime. Larval fish assemblages and circulation in the eastern tropical Pacific in autumn and winter. Journal of Plankton Research. 2010;32(4):397–410. doi: 10.1093/plankt/fbp138. [DOI] [Google Scholar]
- Loeb V. J. Vertical distribution and composition of ichthyoplankton and invertebrate zooplankton assemblages in the eastern tropical Pacific. Biología Pesquera. 1984;13:39–66. [Google Scholar]
- Matsumoto W. M. US Department of Commerce; 1984. Potential impact of deep seabed mining on the larvae of tunas and billfishes. NOAA Technical Memorandum NMFS-SWFC-44. [Google Scholar]
- Milan David T., Mendes Izabela S., Damasceno Júnio S., Teixeira Daniel F., Sales Naiara G., Carvalho Daniel C. New 12S metabarcoding primers for enhanced neotropical freshwater fish biodiversity assessment. Scientific Reports. 2020;10(1):17966. doi: 10.1038/s41598-020-74902-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Miller J. M., Watson W., Leis J. M. An atlas of the common nearshore marine fish larvae of the Hawaiian Islands. MR-80-02. University of Hawaii Sea Grant College Program; Honolulu: 1979. 79 [Google Scholar]
- Miya M., Sato Y., Fukunaga T., Sado T., Poulsen J. Y., Sato K., Minamoto T., Yamamoto S., Yamanaka H., Araki H., Kondoh M. MiFish, a set of universal PCR primers for metabarcoding environmental DNA from fishes: detection of more than 230 subtropical marine species. Royal Society Open Science. 2015;2(7):150088. doi: 10.1098/rsos.150088. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Montenegro J., Collins A. G., Hopcroft R. R., Questel J. M., Thuesen E. V., Bachtel T. S., Bergman L. A., Sangekar M. N., Drazen J. C., Lindsay D. J. Heterogeneity in diagnostic characters across ecoregions: a case study with Botrynema (Hydrozoa: Trachylina: Halicreatidae. Frontiers in Marine Science. 2023;9:1101699. doi: 10.3389/fmars.2022.1101699. [DOI] [Google Scholar]
- Moser H. G., editor. The early stages of fishes in the California Current Region. California Cooperative Oceanic Fisheries Investigations Atlas no. 33. National Oceanographic and Atmospheric Administration; La Jolla, CA: 1996. 1505 [Google Scholar]
- Mthethwa Siphesihle, Bester‐van der Merwe Aletta E., Roodt‐Wilding Rouvay. Addressing the complex phylogenetic relationship of the gempylidae fishes using mitogenome data. Ecology and Evolution. 2023;13(6):e10217. doi: 10.1002/ece3.10217. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Muñoz-Royo C., Ouillon R., El Mousadik S., Alford H. M., Peacock T. An in situ study of abyssal turbidity-current sediment plumes generated by a deep seabed polymetallic nodule mining preprototype collector vehicle. Science Advances. 2022;8(38):eabn1219. doi: 10.1126/sciadv.abn1219. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Okayama M. An atlas of early stage fishes in Japan. 2nd edition. Tokai University Press.; 2014. [Google Scholar]
- Olson R. J., Duffy L. M., Kuhnert P. M., Galvan-Magana F., Bocanegra-Castillo N., Alatorre-Ramírez V. Decadal diet shift in yellowfin tuna Thunnusalbacares suggests broad-scale food web changes in the eastern tropical Pacific Ocean. Marine Ecology Progress Series. 2014;497:157–178. doi: 10.3354/meps10609. [DOI] [Google Scholar]
- Ouillon R., Muñoz-Royo C., Alford M. H., Peacock T. Advection-diffusion-settling of deep-sea mining sediment plumes. part 1: midwater plumes. Flow. 2022;2:E22. doi: 10.1017/flo.2022.20. [DOI] [Google Scholar]
- Reglero P., Tittensor D. P., Álvarez-Berastegui D., Aparicio-González A., Worm B. Worldwide distributions of tuna larvae: revisiting hypotheses on environmental requirements for spawning habitats. Marine Ecology Progress Series. 2014;501:207–224. doi: 10.3354/meps10666. [DOI] [Google Scholar]
- Spearman J., Taylor J., Crossouard N., Cooper A., Turnbull M., Manning A., Lee M., Murton B. Measurement and modelling of deep sea sediment plumes and implications for deep sea mining. Scientific Reports. 2020;10(1):5075. doi: 10.1038/s41598-020-61837-y. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Suvi R., Giovanna M., Katja A. Transgenerational endocrine disruption? Experimental copper exposure, but not heat stress, leads to elevated egg thyroid hormone levels. bioRxiv. 2019;717157 doi: 10.1101/717157. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tilot V., Fourchault L., Grissac A. J., Mallefet J., Navas J. M. In: Ocean Deep-Sea Mining and the Water Column: Advances, Monitoring and Related Issues. Sharma Rahul., editor. Springer, Cham; 2024. Multilevel assessment and options for the management of cumulative impacts on pelagic ecosystems in the north-eastern tropical Pacific. [DOI] [Google Scholar]
- Van Der Grient J. M.A., Drazen J. C. Potential spatial intersection between high-seas fisheries and deep-sea mining in international waters. Marine Policy. 2021;129:104564. doi: 10.1016/j.marpol.2021.104564. [DOI] [Google Scholar]
- Vierstraete A. R., Braeckman B. P. Amplicon_sorter: a tool for reference‐free amplicon sorting based on sequence similarity and for building consensus sequences. Ecology and Evolution. 2022;12(3):8603. doi: 10.1002/ece3.8603. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Vonnahme T. R., Molari M., Janssen F., Wenzhöfer F., Haeckel M., Titschack J., Boetius A. Effects of a deep-sea mining experiment on seafloor microbialcommunities and functions after 26 years. Science Advances. 2020;6(18):eaaz5922. doi: 10.1126/sciadv.aaz5922. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wang H. Y., Tsai M. P., Tu M. C., Lee S. C. Universal primers for amplification of the complete mitochondrial 12S rRNA gene in vertebrates. Zoological Studies. 2000;39(1):61–66. [Google Scholar]
- Ward Robert D. DNA barcode divergence among species and genera of birds and fishes. Molecular Ecology Resources. 2009;9(4):1077–1085. doi: 10.1111/j.1755-0998.2009.02541.x. [DOI] [PubMed] [Google Scholar]
- Xing Bingpeng, Wang Chunguang, Wu Qiong, Wang Yanguo, Chen Xiaoyin, Sun Rouxin, Zhang Zhilan, Xiang Peng. Species identification of larval fish in Hawaiian waters using DNA barcoding. Frontiers in Marine Science. 2022;9:825395. doi: 10.3389/fmars.2022.825395. [DOI] [Google Scholar]
- Yin Z., Lu Y., Liu Y., Zhan W., Zhang H., Dou C., Wu C., Sun D., Liu Z., Wang C., Wang Y. Monitoring discharge from deep-sea mining ships via optical satellite observations. Journal of Oceanology and Limnology. 2024:1–12. doi: 10.1007/s00343-024-3264-0. [DOI]
- Zhang Liyan, Zhang Jing, Liu Shigang, Wang Rui, Xiang Jiali, Miao Xing, Zhang Ran, Song Puqing, Lin Longshan. Characteristics of ichthyoplankton communities and their relationship with environmental factors above the ninety east ridge, eastern Indian Ocean. Frontiers in Marine Science. 2021;8:764859. doi: 10.3389/fmars.2021.764859. [DOI] [Google Scholar]
- Zhang Z., Schwartz S., Wagner L., Miller W. A greedy algorithm for aligning DNA sequences. Journal of Computational Biology. 2000;7(1-2):203–214. doi: 10.1089/10665270050081478. [DOI] [PubMed] [Google Scholar]
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