Seamount Region Research Articles

Possibility and quality assessment in seafloor modeling relative to the sea surface using hybrid data

Possibility and quality assessment in seafloor modeling relative to the sea surface using hybrid data

Recovery of 1887 metagenome-assembled genomes from the South China Sea

The South China Sea (SCS) is a marginal sea characterized by strong land-sea biogeochemical interactions. SCS has a distinctive landscape with a multitude of seamounts in its basin. Seamounts create “seamount effects” that influence the diversity and distribution of planktonic microorganisms in the surrounding oligotrophic waters. Although the vertical distribution and community structure of marine microorganisms have been explored in certain regions of the global ocean, there is a lack of comprehensive microbial genomic surveys for uncultured microorganisms in SCS, particularly in the seamount regions. Here, we employed a metagenomic approach to study the uncultured microbial communities sampled from the Xianbei seamount region to the North Coast waters of SCS. A total of 1887 non-redundant prokaryotic metagenome-assembled genomes (MAGs) were reconstructed, of which, 153 MAGs were classified as high-quality MAGs based on the MIMAG standards. The community structure and genomic information provided by this dataset could be used to analyze microbial distribution and metabolism in the SCS.

Observed 10–20-Day Deep-Current Variability at 5°N, 90.5°E in the Eastern Indian Ocean

Abstract In the eastern off-equatorial Indian Ocean, deep current intraseasonal variability within a typical period of 10–20 days was revealed by a mooring at 5°N, 90.5°E, accounting for over 50% of the total bottom subtidal velocity variability. The 10–20-day oscillations were more energetic in the cross-isobathic direction (STD = 3.02 cm s−1) than those in the along-isobathic direction (STD = 1.50 cm s−1). The oscillations were interpreted as topographic Rossby waves (TRWs) because they satisfied the TRWs dispersion relation that considered the smaller Coriolis parameter and stronger β effect at low latitude. Further analysis indicated significant vertical coupling between the deep cross-slope oscillations and cross-isobathic 10–20-day perturbations at the depth of 300–950 m. The 10–20-day TRWs were generated by cross-isobathic motions under the potential vorticity conservation adjustment. The Mercator Ocean output reproduced the generation of kinetic energy (KE) of deep current variability. The associated diagnostic analysis of multiscale energetics showed that the KE of TRWs was mainly supplied by vertical pressure work. In the seamount region (2°–10°N, 89°–92°E), vertical and horizontal pressure works were identified to be the dominant energy source (contributing to 94% of the total KE source) and sink (contributing to 98% of the total KE sink) of the deep current variability, transporting energy downward and redistributing energy horizontally, respectively.

Vertical distribution of epibenthic megafauna of a large seamount west of Cape Verde islands (tropical North Atlantic)

Seamounts are thought to function as hotspots of megafauna diversity due to their topology and environmental characteristics. However, assessments of megafauna communities inhabiting seamounts, including diversity and density, are scarce. In this study, we provide megafauna diversity and density estimates for a recently discovered, not yet characterized seamount region (Boetius seamounts) west of Cape Verde (N17° 16′, W29° 26′). We investigated the distribution of epibenthic megafauna over a large depth gradient from the seamount’s summit at 1400 m down to 3200 m water depth and provided qualitative and quantitative analyses based on quantified video data. In utilizing an ocean floor observation system (OFOS), calibrated videos were taken as a horizontal transect from the north-eastern flank of the seamount, differentiating between an upper, coral-rich region (−1354/−2358 m) and a deeper, sponge-rich region (−2358/−3218 m). Taxa were morphologically distinguished, and their diversity and densities were estimated and related to substrate types. Both the upper and deeper seamount region hosted unique communities with significantly higher megafauna richness at the seamount’s summit. Megafauna densities differed significantly between the upper (0.297 ± 0.167 Ind./m2) and deeper community (0.112 ± 0.114 Ind./m). The seamount showed a vertical zonation with dense aggregations of deep-sea corals dominating the seamount’s upper region and colonies of the glass sponges Poliopogon amadou dominating the deeper region. The results are discussed in light of detected substrate preferences and co-occurrence of species and are compared with findings from other Atlantic seamounts.

Bathymetry Refinement over Seamount Regions from SAR Altimetric Gravity Data through a Kalman Fusion Method

Seafloor topography over seamount areas is crucial for studying plate motions, seafloor seismicity, and seamount ecosystems. However, seamount bathymetry modeling is difficult due to the complex hydrodynamic environment, biodiversity, and scarcity of shipborne echo sounding data. The use of satellite altimeter-derived gravity data is a complementary way of bathymetry computation; in particular, the incorporation of synthetic aperture radar (SAR) altimeter data may be useful for seamount bathymetry modeling. Moreover, the widely used filtering method may have difficulty in combing different bathymetry data sets and may affect the quality of the computed bathymetry. To mitigate this issue, we introduce a Kalman fusion method for weighting and combining gravity-derived bathymetry data and the reference bathymetry model. Numerical experiments in the seamount regions over the Molloy Ridge show that the use of SAR-based altimetric gravity data improves the local bathymetry model, by a magnitude of 14.27 m, compared to the result without SAR data. In addition, the developed Kalman fusion method outperforms the traditionally used filtering method, and the bathymetry computed from the Kalman fusion method is improved by a magnitude of 9.34 m. Further comparison shows that our solution has improved quality compared to a recently released global bathymetry model, namely, GEBCO 2022 (GEBCO: General Bathymetric Chart of the Oceans), by a magnitude of 34.34 m. The bathymetry model in this study may be substituted for existing global bathymetry models for geophysical investigations over the target area.

Diversity and Distribution of Harmful Algal Bloom Species from Seamount to Coastal Waters in the South China Sea.

Mount Xianbei is one of the largest shallow seamounts located in the middle of the South China Sea (SCS), which might play a role in shaping the biodiversity of surrounding continental coastal waters, particularly the diversity of phytoplankton species causing frequent harmful algal blooms (HABs) in northern SCS. However, the diversity, composition, and distribution of phytoplankton species in the seamount regions of Xianbei remain largely unexplored. In this study, samples around and outside the seamount regions were collected during a late summer cruise of 2021 to test whether seamounts play a role in HAB species propagation. In total, we identified 19 HAB species across all samples using the ASV-based DNA metabarcoding approach, 6 of which had not been reported previously in the SCS, suggesting a diverse HAB species in the SCS. Specifically, 16 HAB species were found in the seamount region of Xianbei, and 5 of them were also found in the coastal waters, indicating a close connection between seamount and coastal waters. This study was the first attempt to explore HAB species' spatial diversity and vertical distribution in the seamount region of Xianbei at single-nucleotide resolution, which provides a novel explanation for the coastal HAB occurrence in the northern SCS. IMPORTANCE There are a number of seamounts under the water of the South China Sea (SCS). The seamounts might play a role in shaping the biodiversity of surrounding continental coastal waters. However, there is no direct evidence revealing the relationship of the biodiversity of phytoplankton between seamounts and coastal waters in the SCS, especially those species having the potential to form harmful algal blooms (HABs). Some HAB species might proliferate in certain geographic locations, while others may be broadly distributed across oceanic provinces. In this study, we provided a detailed analysis of phytoplankton composition and molecular detection of HAB species from seamount to coastal waters in the SCS, which suggested a strong interaction in the HAB species between the two areas. This finding provides new insights into the diversity and distribution of HABs in seamounts and their role in shaping the composition and the occurrence of HABs in coastal water.

Provenance and paleoenvironmental significance of sediments in the Beipo seamount of the northern South China Sea during the last deglaciation

The sedimentary processes of seamount regions are closely related to climate change and ocean evolution. The clay minerals, grain size and 14C ages of core SCS18-1, which was collected from the Beipo seamount in the northern South China Sea (SCS) were analyzed to discuss the provenance and paleoenvironmental conditions during the last deglaciation. The sediments of core SCS18-1 are dominated by clayey silt, which is mainly composed of illite (55.2~62.1%) and chlorite (17.1~22.5%), with subordinate kaolinite (9.5~12.6%) and smectite (7.3~15.1%). The illite chemical index and illite crystallinity indicate strong physical weathering conditions. The results of the end-member modeling algorithm (EMMA) suggest that the sediments of core SCS18-1 consist of three end-members containing EM1 (0.98 μm), EM2 (9.29 μm) and EM3 (44.19 μm), with average contents of 3%, 66% and 31%, respectively. The finest endmember represents fluvial mud, the middle and coarsest endmembers are considered fluvial fine silt and eolian dust, respectively. The mean grain size is mainly controlled by the coarser fraction EM3. Based on the clay minerals, grain size and SEM analysis, we can conclude that since the onset of the last deglaciation (16.1 ka BP), the sediments of core SCS18-1 mainly originate from fluvial input, and eolian material also contributed to the sediments. The clay mineral assemblages of core SCS18-1 are stable and originate mainly from Taiwan. Additionally, the Pearl River appears to be a secondary contributor of clay minerals. Further, the Luzon Islands only account for a small proportion. Major kaolinite and moderate illite and chlorite are thought to originate from the Pearl River, predominant illite and chlorite from Taiwan, and principal smectite from the Luzon Islands. Both the relative content of EM1+ EM2 and the illite chemical index effectively represent the variation of East Asia summer monsoon (EASM) strength. Meanwhile, the relative content of EM3 effectively represents the East Asian winter monsoon (EAWM) change. The material supply of core SCS18-1 is mainly controlled by solar radiation in the Northern Hemisphere.

Caldera-like features located over the Panikkar Seamount and adjacent regions in the Laxmi Basin, eastern Arabian Sea

Caldera-like features located over the Panikkar Seamount and adjacent regions in the Laxmi Basin, eastern Arabian Sea

Metabarcoding Analysis of Harmful Algal Bloom Species in the Western Pacific Seamount Regions.

The Western Pacific is the most oligotrophic sea on Earth, with numerous seamounts. However, the plankton diversity and biogeography of the Western Pacific in general and the seamount regions in particular remains largely unexplored. In this project, we quantitatively analyzed the composition and distribution patterns of plankton species in the Western Pacific seamount regions by applying metabarcoding analysis. We identified 4601 amplicon sequence variants (ASVs) representing 34 classes in seven protist phyla/divisions in the Western Pacific seamount regions, among which Dinoflagellata was by far the most dominant division. Among the 336 annotated phytoplankton species (including species in Dinoflagellata), we identified 36 harmful algal bloom (HAB) species, many of which displayed unique spatial distribution patterns in the Western Pacific seamount regions. This study was the first attempt in applying ASV-based metabarcoding analysis in studying phytoplankton and HAB species in the Western Pacific seamount regions, which may facilitate further research on the potential correlation between HABs in the Western Pacific seamount regions and coastal regions.

Geomorphology of a bended submarine canyon in Wanhu Seamount region, northern South China Sea: Insights from manned submersible observation and measurement

Submarine canyons can transport large volumes of terrigenous material from the continent to the deep-sea environment and are the primary conduits of source-to-sink systems. The large-scale morphologic features of canyons have been well studied using seismic reflection and the bathymetry data. However, detailed analyses of the small-scale elements of canyon morphology are relatively few because of the limited resolution of traditional field investigations. In this paper, the multi-scaled geomorphology of a bended submarine canyon (canyon C4) located in Wanhu Seamount region (northern South China Sea) is described and discussed based on the in-situ high-definition video data, high-precision near-bottom acoustic data, and push-cores obtained using the manned submersible vehicle. The NNW-trending submarine canyon diverted to 122.5° at the foot of Wanhu Seamount, and the fresh erosional surfaces were recorded using the video data at the canyon axis bend. A total of eight sediment waves were generated at the overbank of the bending region. These waves contain wavelengths and wave heights decreasing in an upslope direction from the canyon axis towards the Wanhu Seamount. The C-M pattern (coarsest one percentile grain size versus median grain size values), grain cumulative probability curves, and grain size gradations derived from the sediment cores suggested that these sediment waves were induced by a turbidity current. The bending of the canyon resulted from the deflection and reflection of the turbidity currents, which were constrained by Wanhu Seamount. The abnormal geomorphologies of some sediment waves were related to the back-squeezed underflow of the turbidity currents. The turbidity current behavior was compared and found to be in agreement with the experimental and modeling simulation results mentioned in the literature. However, the morphologic setting in the natural case was more complex than that observed from the experiments, with the flow behaviors being more complicated. Future studies are required for more detailed comparison between the natural case and simulations to better understand the turbidity current behavior in a bended submarine canyon.

Topographic Rossby Waves in the Abyssal South China Sea

AbstractTopographic Rossby waves (TRWs) in the abyssal South China Sea (SCS) are investigated using observations and high-resolution numerical simulations. These energetic waves can account for over 40% of the kinetic energy (KE) variability in the deep western boundary current and seamount region in the central SCS. This proportion can even reach 70% over slopes in the northern and southern SCS. The TRW-induced currents exhibit columnar (i.e., in-phase) structure in which the speed increases downward. Wave properties such as the period (5–60 days), wavelength (100–500 km), and vertical trapping scale (102–103 m) vary significantly depending on environmental parameters of the SCS. The TRW energy propagates along steep topography with phase propagation offshore. TRWs with high frequencies exhibit a stronger climbing effect than low-frequency ones and hence can move further upslope. For TRWs with a certain frequency, the wavelength and trapping scale are dominated by the topographic beta, whereas the group velocity is more sensitive to the internal Rossby deformation radius. Background circulation with horizontal shear can change the wavelength and direction of TRWs if the flow velocity is comparable to the group velocity, particularly in the central, southern, and eastern SCS. A case study suggests two possible energy sources for TRWs: mesoscale perturbation in the upper layer and large-scale background circulation in the deep layer. The former provides KE by pressure work, whereas the latter transfers the available potential energy (APE) through baroclinic instability.

The community structure of hyperiid amphipods associated with two seamount regions in the South-east Pacific

AbstractOceanic islands and seamounts are considered biodiversity hotspots. Here, we present a taxonomy and community analyses of hyperiid amphipods collected near oceanic islands and over seamounts of the Juan Fernández Archipelago and Desventuradas Archipelago in the South-east Pacific. Both archipelagos are separated by about 800 km over the meridional gradient, suggesting the existence of different hyperiid communities because of apparent geographic isolation and distinctive oceanographic characteristics between regions. To test this hypothesis, zooplankton samples were collected from 19 stations during the CIMAR 22 ‘Oceanic Island’ cruise in October–November 2016. In total, 56 species of hyperiids were found, of whichPhrosina semilunata,Lestrigonus schizogeneios,Hyperietta stephenseni,Hyperioides longipes,Phronimella elongataandPrimno latreilleiwere the most abundant and recurrent species. The species richness (S), Shannon–Wiener diversity (H’) and dominance (D) of both the archipelagos were not significantly different. Additionally, except for a small group of rare species, the species composition was similar in both areas. Most species showed greater abundances than those observed in the coastal upwelling zone off Chile, whereas shared species between regions suggested the presence of a single biogeographic unit comprising the coastal transition zone and oceanic area off Chile within which both archipelagos are included. Correlation analysis indicated that salinity was the best predictor for the community structure, which provides evidence that the contributions of previously described water masses of the South-east Pacific may influence the spatial distribution and composition of the hyperiid community.

Using multibeam backscatter strength to analyze the distribution of manganese nodules: A case study of seamounts in the Western Pacific Ocean

Multibeam backscatter strength can be used to characterize seafloor acoustic characteristics, and classify seabed substrate types. Herein, we use acoustic reflectance data to examine the distribution of manganese nodules in deep-sea substrates in a seamount region of the Western Pacific Ocean. Based on the multibeam backscatter strength, the backscatter mosaic image is firstly corrected by a series of error corrections, and then a size-insensitive integrity-based Fuzzy C-Means (siib-FCM) technique is used to analyze the distribution of manganese nodules. The results show that the method can reveal the distribution of deep-sea manganese nodules and is suitable for the classification of seabed substrates with few sampling points. The distribution of manganese nodules has two characteristics: (1) In basin and plain areas with relatively flat terrain, manganese nodules are associated with sediment, occur in patches and their distribution is relatively sparse. (2) In seamount areas with complex terrain, manganese crusts are distributed mainly at mid-slope elevations displaying a circular distribution around the seamount. The processing technique and results of the present study form a basis for future investigations into the occurrence and distribution of manganese nodule resources in the deep oceans.

Microplastic abundance, distribution and composition in the mid-west Pacific Ocean

Microplastic pollution is widespread across most ocean basins around the world. Microplastics (MPs) are small plastic particles that have a significant impact on the marine environment. Various research on plastic pollution have been conducted in several regions. However, currently, there is limited data on the distribution and concentration of MPs in the mid-west Pacific Ocean. Therefore, this study we investigated the abundance, distribution, characteristics, and compositions of MPs in this region. Sea surface water samples collected from 18 stations showed a microplastic concentration range of 6028–95,335 pieces/km2 and a mean concentration of 34,039 ± 25,101 pieces/km2. Highest microplastic concentrations were observed in the seamount region of western Pacific. We observed a significant positive correlation between microplastic abundance and latitude across the study region. It was observed that microplastic concentrations decreased with increasing offshore distance at sites located on a 154° W transect. Fibres/filaments were the dominant microparticles observed in this study (57.4%), followed by fragments (18.3%). The dominant particle size range was 1–2.5 mm (35.1%), followed by 0.5–1 mm (28.5%), and the dominant particle colour was white (33.8%), followed by transparent (31.0%) and green (24.6%). The most common polymer identified by μ-Raman was polypropylene (39.1%), followed by polymethyl methacrylate (16.2%), polyethylene (14.1%) and polyethylene terephthalate (14.2%). The possible sources and pathways of microplastics in the study area were proposed based on the morphological and compositional characteristics of particles, their spatial distribution patterns, and shipboard current profiling (ADCP). Our study contributes to the further understanding of MPs in remote ocean areas.

Two new species of Geodiidae (Porifera, Demospongiae, Astrophorina)from the Emperor Seamounts, North Pacific Ocean.

Two new species of Geodiidae from the Emperor Seamounts, North Pacific Ocean are described and compared to congeners. Erylus imperator n. sp. differs from all other species of Erylus from the region in having large oxyasters, present in only one other species from which it differs in several other characters. Furthermore these oxyasters most often display the tendency to reduce the number of rays to a degree that they appear as triods, microxeas or even microtylostyles, depending on the number of retained rays. The second new species, Geodia arma n. sp. is a Geodia without triaenes, a group formerly described under the genus Geodinella. We compared G. arma n. sp. with all congeners lacking triaenes and determined that it is the only known species with a cortex of up to 6 mm in thickness and also the only species with oxeas up to 6 mm in length Which range from thin and sinuous to thick and straight. To our knowledge these are the first descriptions of sponge species from the Emperor Seamount region.

The Atlantic Meridional Overturning Circulation as productivity regulator of the North Atlantic Subtropical Gyre

AbstractSpatially extensive and intense phytoplankton blooms observed off Iberia, in satellite pictures, are driven by significant nutrient supply by upper-ocean vertical mesoscale activity rather than by horizontal advection by coastal upwelling. Productivity of oligotrophic regions is still poorly depicted by discrete instrumental and model data sets. The paleoproductivity reconstructions of these areas represent the mean productivity over long periods, bringing new insights into the total biomass fluxes. Here, we present paleoproductivity records from the oceanic Tore Seamount region, covering the period from 140 to 60 ka. They show higher nutrient supplies during Termination II, Marine Oxygen Isotope Stage (MIS) 4, MIS 6, and warming transitions of the MIS 5 sub-stages. The highest nutrient content (higher productivity) in phase with tracers of bottom-water ventilation (benthic δ13C,231Pa/230Th) establishes a strong linkage with variability of Southern Ocean-sourced waters. Low productivity and ventilation over warm sub-stages of MIS 5 respond instead to North Atlantic Deep Water. Assuming that the Tore Seamount is representative of oligotrophic regions, the glacial-interglacial relationship observed between paleoproductivity and Atlantic Meridional Overturning Circulation strength opens new insights into the importance of estimating the total biomass in these regions. The subtropical gyres might play a considerable role in the carbon cycle over (sub-)glacial-interglacial time scales than previously thought.

Mesozooplankton respiration and community structure in a seamount region of the eastern South Pacific

Seamounts in the Juan Fernandez Ridge, as well as in other seamount regions in the eastern South Pacific and in the world oceans, remain poorly studied ecosystems in terms of structure and functioning. Here, community respiration by epipelagic mesozooplankton in three seamounts of the Juan Fernandez Ridge, including the O`Higgins Seamount close to the coastal upwelling zone and two oceanic seamounts near the Juan Fernandez Archipelago (~33°S–78°W), was assessed. Oxygen consumption by mixed assemblages was estimated using continuous measurements of dissolved oxygen concentration under controlled temperature during onboard, short-term incubations (2–4 h). Mesozooplankton composition was analyzed with a ZooScan device and expressed in terms of community normalized size spectra, and taxa and size diversity (Shannon-Wiener index). Carbon-specific community respiration rates in the upper 100 m layer were in the range of 0.3–1.9 mg O2 m−2 d−1, indicating that up to 3.1% of the mesozooplankton biomass can be respired on a daily basis. The mesozooplankton community was dominated by small-size copepods but the proportions of small copepods, large copepods, and gelatinous zooplankton (mostly salps) changed between the seamounts, in association with modifications in taxa composition, size diversity, and the slope of the size spectrum. Community respiration was significantly correlated to these community descriptors, suggesting the composition of the pelagic community has a direct impact on the total amount of respired-C. Connectivity between the coastal upwelling zone and the Juan Fernandez Ridge region mediated by mesoscale activity, interacting with the seamounts, is suggested as a most important process in controlling zooplankton community structure and in turn community metabolism.

Expanding the conceptual framework of the spatial population structure and life history of jack mackerel in the eastern South Pacific: an oceanic seamount region as potential spawning/nursery habitat

AbstractJuvenile jack mackerel were found in 2009 in the Challenger break and the East Pacific ridge (CHAEPR). This seamount region is ∼3500 km from the coastal historic jack mackerel nursery grounds off Chile (north of 30°S). We reviewed historic evidence of juveniles around this seamount and data on several local environmental conditions: sea surface temperature, chlorophyll-a, wind, turbulence levels, and Eddy kinetic energy (EKE). A Lagrangian model for the early life stages of jack mackerel in the eastern South Pacific was used to assess the potential of the seamount region as a permanent nursery ground. Transport/retention mechanisms were assessed by releasing virtual particles coupled to a growth model into the flow simulated by an eddy-resolving ocean model. Model simulations showed high inter-annual variability for particle retention in the seamount region; high retention levels were associated with low EKE such that the particles were retained for several months. Satellite altimetry has shown a local minimum in eddy activity in the region where the juveniles were observed; this minimum was consistent with the above temporal relationship. The inclusion of the CHAEPR oceanic seamount region as a potential nursery ground for jack mackerel expands the current conceptual framework for the spatial population structure of this species in the South Pacific off central Chile proposed by Arcos et al. (The jack mackerel fishery and El Niño 1997–98 effects off Chile. Progress in Oceanography 49: 597–617, 2001). Finally, we discuss the relevance of seamounts playing a double role (spawning and nursery grounds) from the standpoint of conservation and biodiversity.

The past, present and future distribution of a deep-sea shrimp in the Southern Ocean.

Shrimps have a widespread distribution across the shelf, slope and seamount regions of the Southern Ocean. Studies of Antarctic organisms have shown that individual species and higher taxa display different degrees of sensitivity and adaptability in response to environmental change. We use species distribution models to predict changes in the geographic range of the deep-sea Antarctic shrimp Nematocarcinus lanceopes under changing climatic conditions from the Last Glacial Maximum to the present and to the year 2100. The present distribution range indicates a pole-ward shift of the shrimp population since the last glaciation. This occurred by colonization of slopes from nearby refugia located around the northern part of Scotia Arc, southern tip of South America, South Georgia, Bouvet Island, southern tip of the Campbell plateau and Kerguelen plateau. By 2100, the shrimp are likely to expand their distribution in east Antarctica but have a continued pole-ward contraction in west Antarctica. The range extension and contraction process followed by the deep-sea shrimp provide a geographic context of how other deep-sea Antarctic species may have survived during the last glaciation and may endure with projected changing climatic conditions in the future.

Geochemical characteristics and metal element enrichment in crusts from seamounts of the Western Pacific

Elemental geochemistry is an essential part of understanding mineralization mechanisms. In this paper, a data set of 544 cobalt crust samples from seamounts of the Western Pacific are used to study the enrichment characteristics of metal elements. REE normalization is utilized to reveal the origin of the crusts; effects of water depth on Co enrichment and impacts of phosphatization on mineral quality are discussed to obtain the evolution of these marine mineral deposits, which gives support to further resource assessment. Conclusions are reached as follows: 1) Elemental abundances, inter-element relationships, and shale-normalized REE patterns for phosphate-poor crusts from different locations reflect hydrogenetic origin of the crusts. EFs (enrichment coefficients) of REE exhibit exponential increase from surface sediments to phosphorite to polymetallic nodules to crusts, suggesting that the improved degree of hydrogeneous origin induces the enrichment of REE. 2) The crusts in the Western Pacific, formed through hotspot produced guyots trails, have relatively lower REE than those in the Mid-Pacific. The latter could be attributed to the peculiar submarine topography of seamounts formed by intraplate volcanism. 3) The non-phosphatized younger crust layers have 40% higher Co than the phosphatized older layers. This indicates the modification of the elemental composition in these crusts by phosphatization. A general depletion of hydroxide-dominated elements such as Co, Ni, and Mn and enrichment of P, Ca, Ba, and Sr is evident in phosphatized crusts, whereas non-phosphatized younger generation crusts are rich in terrigenous aluminosilicate detrital matter. 4) Co increases above the carbonate compensation depth (CCD) from less than 0.53% to over 0.65% in seamount regions with water depth of less than 2,500 m, suggesting the significance of the dissolution of carbonate in the sea water column to the growth and composition of crusts.