Census of Marine Life

Darlene Trew Crist , Ronald O'Dor , in Encyclopedia of Biodiversity (2d Edition), 2013

Glossary

Deep-sea plain

Large areas of flat areas referred to every bit abyssal patently from ∼4000 to 6000   thousand in water depth.

Archaea

Microorganisms that are similar to bacteria in size and simplicity of structure merely radically different in molecular organization. They are at present believed to constitute an ancient intermediate grouping betwixt the bacteria and eukaryotes.

Biodiversity

The variety of life in the globe or in a item habitat or ecosystem.

Biome

A large naturally occurring customs of flora and animal occupying a major habitat.

Ambiguous species

Morphologically duplicate but taxonomically distinct species.

Blue-green alga

A division of microorganisms that are related to the bacteria but are capable of photosynthesis. They are prokaryotic and represent the earliest known form of life on the earth.

Eukaryote

An organism consisting of a prison cell or cells in which the genetic material is Dna in the form of chromosomes contained within a distinct nucleus.

Prokaryote

A microscopic unmarried-celled organism, including the leaner and cyanobacteria, that has neither a singled-out nucleus with a membrane nor other specialized organelles.

Protist

A kingdom or large grouping that comprises mostly single-celled organisms such as the protozoa, elementary algae and fungi, slime molds, and (formerly) the bacteria.

Taxon

A taxonomic group of any rank, such as a species, family unit, or class.

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Marine Sediments

Paul V.R. Snelgrove , in Encyclopedia of Biodiversity (Second Edition), 2013

Glossary

Abyssal plains

Relatively flat areas of the sea bottom below ∼4000   one thousand depth.

Benthos

Bottom-living organisms, including those that reside on difficult and soft bottom surfaces and others that reside between sediment grains.

Continental ascension

An expanse at the base of operations of the continental slope betwixt 3000 and 4000   one thousand where the bottom slope is slight and sediments frequently accumulate.

Continental shelf

A region of ocean lesser extending from the low water mark at the edge of continents to a depth (∼200   grand) at which the incline increases markedly and the continental gradient begins.

Continental gradient

Ocean bottom extending from the border of the continental shelf at an ∼4° incline to a depth (3000–10,000   yard) at which the slope decreases and the continental rise begins.

Deposit feeders

Organisms that feed primarily past ingesting organic material occurring on or between sediment grains.

Macrofauna

Animals large enough to be retained on a 300- or 500-μm, sieve.

Megafauna

Animals those are sufficiently large to be identified from bottom photographs.

Meiofauna

Animals modest enough to pass through a 500-μm sieve but large plenty to be retained on a 44- or 63-μm sieve.

Suspension feeders

Organisms that feed primarily on particles of organic material suspended in the water above the bottom.

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Natural Reserves and Preserves

Alexander N. Glazer , in Encyclopedia of Biodiversity (2nd Edition), 2013

The Endeavor Hydrothermal Vents Marine Protected Area

Abyssal plains, underwater plains on the deep body of water floor, cover more than half of the Earth'southward surface. Abyssal food bondage are fueled by organic debris that sediments downwards to the ocean floor. This limited food source supports a sparse population of abyssal brute. A very different situation is seen in active seafloor-spreading zones where tectonic plates dissever and new oceanic crust is extruded onto the seafloor. Here, common cold seawater percolates down through the crust, and comes into contact with the underlying molten lava. The particle rich, superheated fluid emerges through the seafloor as buoyant flumes. Such hydrothermal vent fields support faunal biomass productivity, sometimes a thousand-fold higher than that of the surrounding deep ocean, and comparable to that of the most productive marine ecosystems. More than 100 vent fields have been documented along the 60,000-km global mid-body of water ridge system.

In 2003, Canada established the start marine protected surface area for the conservation of deep ocean hydrothermal vents. The 82   kmii Endeavour Hydrothermal Vents Marine Protected Area (47o  N/129o  W), 250   km southwest of Vancouver Isle, at a depth of 2250   m, is within the Endeavour Segment of the Juan de Fuca ridge organization, and encompasses five vent fields. These fields span hydrothermal venting conditions varying in h2o temperature, salt content, and mineral chimney morphology. The mineral composition at Endeavor vent sites has been extensively analyzed. Black smokers, with vigorous hydrothermal catamenia and exit temperatures typically in the range of 250–350 oC, emit black "smoke." The emissions are rich in Iron, S, Ca, Cu, and Zn. The "smoke" consists of particulate and dissolved metal-rich sulfide (anhydrite, chalcopyrite, sphalerite, barite) and sulfate minerals, products of loftier-temperature mixing between vent fluids and oxygen-containing libation seawater. The volcanic emissions from blackness smokers accept substantial amounts of dissolved CO2, HiiSouthward, H2, and minor amounts of methane. These dissolved gases and metals sustain microbial communities that, in plough, serve as the base of the food concatenation for communities of prokaryotes and eukaryotes of five hundred or more than different species of organisms, feature of these very special sites. The discovery in 1977 of vent beast, with its unique suite of organisms and boggling metabolic pathways, amazed the scientific community, and gave rise to the speculation that life may accept originated in such hydrothermal vent environments.

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The Barbados ridge

Eric Deville , Alain Mascle , in Regional Geology and Tectonics: Principles of Geologic Assay, 2012

21.2 The Atlantic abyssal plain

The Atlantic deep-sea plain east of the Barbados prism is part of the Central Atlantic sea that opened in tardily Jurassic time as Africa and N Africa drifted autonomously. This late Jurassic-Cretaceous bounding main has been almost totally subducted during late Cretaceous-Tertiary times beneath the Caribbean area plate. Pieces of this initial oceanic crust take been obducted and may be found in the allochthonous cordillera of Colombia and Venezuela to the southward, and inside the Greater Antilles terranes to the due north ( Giunta et al., 2003). A last remnant of belatedly Jurassic-early Cretaceous crust is believed to be nevertheless present in front of the southern Barbados Ridge between the South America margin to the south and the Demerara error zone to the due north (i.e., between ix°xxx′ and 12°North on the studied area; Boettcher et al., 2003). The lack of whatever magnetic anomaly and the absenteeism of wells in this surface area prevent any precise age determination of this oceanic crust and of its very thick sedimentary embrace (more than than 4 sTWT). Conversely, to the north of the Demerara error zone, well-depicted magnetic anomalies (30–34) and DSDP well 543 command permit a late Cretaceous historic period assignment for the oceanic crust facing the Barbados Ridge (Fig. 21.3).

Figure 21.3. Simplified stratigraphic log of DSDP well 543

 (from blue book leg 78A; Biju-Duval et al., 1984).

Furthermore, division of the oceanic crust into narrow strips occurs parallel to the dense network of WNW–ESE trending fracture zones, and prominent topographic ridges (particularly Tiburon and Barracuda) in the area of the lengthened plate boundary betwixt Northward and Southward America. These ridges have been interpreted equally the consequence of transpressive movements during Tertiary times (Mueller and Smith, 1993). Some of these fracture zones are certainly withal active and participate in the slight relative displacement between the North and S America plates. They accept controlled the deposition of the sedimentary clastic influxes from the south.

From this full general framework, iii E–W trending segments can be recognised in the abyssal plainly facing the Barbados Ridge, which possibly have induced some segmentation of the overriding Lesser Antilles active margin. Equally a matter of fact, the geometry and nature of the subducting plate, in terms of sedimentary thickness and location of potential décollements, and in terms of rigidity and density of the whole lithosphere (related to the historic period), have controlled the development of the accretionary prism, the volcanic arc, and the back arc area equally well.

North of the Tiburon Rise (15°Northward), a sedimentary cover less than g m thick of Campanian to present age overlies the late Cretaceous oceanic crust (Biju Duval et al., 1984). In a higher place pelagic Campanian carbonates, sediments are hemipelagic mudstones with some volcanic ash layers. Some mudstones (betwixt 171 and 209 mbsf and between 456 and 494 mbsf at DSDP well 543) include up to thirty% of radiolarians (Mascle and Moore, 1990). These intervals are characterised by loftier preserved porosity (about 20–25% above normal trend). Due to the resulting lower forcefulness of these materials, the upper interval (of early on Miocene historic period) hosts the basal décollement, above which the accretionary prism is developing at the deformation front, while the deeper interval (of early on Eocene historic period) perhaps hosts a deeper décollement (plain-featured sediments of Oligocene to Middle Eocene age have been encountered at ODP site 674 inside the accreted complex). Moreover, at DSDP well 543, between 228–332 and 332–456 m, silty Oligocene and sandy center-tardily Eocene turbidites, respectively, are present. The sandstone and the oil-bearing sandstones of like historic period nowadays on Barbados Island (cf. infra), may represent deep sea fan clastic materials originating from the northern South American continent when the volcanic arc of the Lesser Antilles was located approximately due north of the nowadays-24-hour interval Maracaïbo area (Brook et al., 1990). These characters of the oceanic foreland have led to the evolution of an active margin characterised by a relatively deep (more than five km), narrow (less than 100 km), and thin (less than 7 km) accretionary prism with short wavelength structures above the décollement, and no large mud volcanoes. The seismic resolution is of rather poor quality except for the long décollement separating tightly folded off-scraped sediments above from overpressured autochthonous sediments below (Westbrook and Smith, 1983; Westbrook et al., 1982). The characteristics of the foreland are probably responsible for a relatively low bending subduction beneath the Caribbean lithosphere, which has produced a shift of the volcanic arc to the west since centre Miocene times, a slight uplift of the eastern edge of the volcanic arc, and moderate subsidence in the back-arc area (Bouysse and Mascle, 1994; Pinet et al., 1984).

Between Tiburon Rise and the Demerara FZ, the oceanic crust is still of belatedly Cretaceous age (more recent than magnetic bibelot 34), but a regionally more pronounced subsidence and local vertical displacements related to the E–W oceanic transform faults have induced an irregular deepening of the basement to the south. Despite the lack of whatsoever well data, Sumner and Westbrook (2001) have made the reasonable supposition that pre-middle Miocene sediments were similar to those encountered farther n (DSDP-ODP wells) and that middle Miocene to Fourth sediments correspond very distal clastics from the Orinoco deep sea fan. In that area, active mud volcanoes are located in the Atlantic deep-sea patently as far 23 km e of the deformation front. They trend along basement lows side by side to oceanic fracture zones (Henry, 2000; Henry et al., 1990, 1996; Lance et al., 1998; Langseth et al., 1988; Sumner and Westbrook, 2001; Westbrook and Smith, 1983). The Lesser Antilles margin facing this oceanic foreland is a transitional between the northern area previously discussed and the southern domain presented future: decrease in h2o-depth and increase in both width and thickness of the prism, narrowing of the Tertiary volcanic arc (from Guadeloupe to Martinique), and deepening of the back-arc expanse.

Between the Demerara FZ and the South America continental margin, the oceanic crust is classically believed to be of late Jurassic and/or early on Cretaceous age from regional considerations and palinspatic reconstructions. Information technology is not yet well established whether the oceanic crust is linked with the South America continental crust either directly via one single transform error, or via a narrow zone of stretched continental crust (Boettcher et al., 2003). The Guyana margin represents a transform margin of late Jurassic age (Stephan et al., 1990). The sedimentary embrace shows a thickness in excess of 7 km in front of the Barbados Ridge (Plate 21.1). Two-thirds of this thickness may be related to the Mid-Miocene-Pleistocene time interval, that is, to the evolution of the Orinoco deep ocean fan (Boettcher et al., 2003; Jacome et al., 2003), plus additional influxes from the Guyana margin as unconfined low density turbidites (sourced by the Amazon from the southeast). The disengagement over which the southern Barbados Ridge accretionary complex has developed is believed to accept been hosted in a heart Miocene interval, that is, at a time shut to the onset of rapid distal clastic sedimentation from the Orinoco delta (Di Croce et al., 1999). Two points should exist outlined: (ane) the late Jurassic-early Cretaceous age of the oceanic crust makes the occurrence of deep marine black shale coeval with the prolific oil-decumbent late Cretaceous marine source rocks (La Luna and Naparima Hill formations) well known in Venezuela and Trinidad (Persad et al., 1993) within the tardily Cretaceous interval possible, and (two) the proximity of the continent of Southward America could have, in Cretaceous and Tertiary times, favoured the deposition of sandy basin floor fans that could be targets for oil and gas exploration in ultra-deep h2o. The volcanic arc facing this old (and consequently dense) oceanic chaff is ordinarily narrow (from Martinique to Grenada) and an increase of the angle of subduction of the slab (with respect to the northern segments) is associated with pronounced subsidence of the back-arc expanse (Grenada bowl; Pinet et al., 1984). Southward of the Demerara fault zone, the Atlantic obviously is covered at the vicinity of the prism by the braided turbidite organisation (channel-levees) of the Orinoco deep sea fan (Belderson et al., 1984; Faugères et al., 1991, 1993; Fig. 21.4). In that area, all the piston cores nerveless in the recent sediments within the abyssal evidently have found sand-rich sediments.

Effigy 21.4. Sunshaded body of water-floor topography and backscattering imagery in the frontal folds of the Barbados prism and in the Atlantic abyssal plain.

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Volume two

1000. Shanmugam , in Encyclopedia of Geology (Second Edition), 2021

Deep-sea Plains

The term 'deep-sea plain' refers to a flat region of the ocean floor, usually at the base of a continental rise, where slope is less than i:1000. It represents the deepest and flat part of the ocean floor lying between 4000 and 6500  m deep in the U.S. Atlantic Margin. A more than general term 'bowl plain' is unremarkably used in referring to aboriginal examples. In general, bowl-plainly deposits are laterally continuous and canvas similar turbidites and interbedded peladites (Fig. 12). Most common basin-plain deposits are pelagites and hemipelagites (see Glossary). However, mass-ship deposits (MTD) have been interpreted to travel from the shelf border to basin plains. MTDs have been documented in the modern basinal areas of the U. S. Atlantic margin (Embley, 1980, Shanmugam, 2018a).

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Tonga

Karen Rock , ... Ben Eliason , in World Seas: an Ecology Evaluation (2d Edition), 2019

30.four.1 The Abyssal Plain

Tonga has an all-encompassing abyssal evidently, within the Lau bowl, to the w of the Tonga ridge, lying at depths of 3000–6000  m. Its sediments my achieve one   km depth and contain areas with isolated volcanic hills or seamounts that rise steeply from it (Encyclopedia Britannica, 2014).

Many of the abyssal plainly organisms obtain their food from sinking particles (organic matter from expressionless organisms falling from the h2o column above), or past eating detritus feeders. Species constitute tend to have depression growth, reproduction, and recolonization rates (Smith, 2006), and therefore would likely be extremely slow to recover from disturbance such every bit that acquired by deep seabed mining.

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Demography of Marine Life

Ronald O'Dor , ... Andrea Ottensmeyer , in Encyclopedia of Biodiversity, 2007

2. Abyssal Apparently

Exploration of the bounding main'southward deep-sea plains has been hindered past time, distance, and the resources required to investigate this hidden realm. The Census of Diversity of Abyssal Marine Life (CeDAMar) was launched to written report the deep-sea evidently biodiversity of the endo-, epi-, and hyperbenthic organisms (those living in, on, or directly above the sediment).

CeDAMar has successfully unified significant Abyssal Plain projects in major ocean basins. Information technology has taxonomists gathering data on species assemblages of single ocean basins and on the large-calibration distribution of species. CeDAMar has completed two deep-sea plain sampling expeditions using benthic grabs and sleds in three oceans (Fig. vii). More than than 70 publications accept been produced from the results of these cruises. Hundreds of new species have been added to athenaeum and five boosted cruises are funded for the North Atlantic, Southern ocean, and Indian Sea.

Figure 7. Dots show sampling sites of CeDAMar expeditions (Andeep and Diva) comparison benthic biodiversity in the Pacific (peak, Adrian Glover and Craig Smith, unpublished) and Atlantic and Southern Oceans (bottom). Reproduced from CeDAMar (2006), with permission.

CeDAMar has established standardized sampling protocols for the study of abyssal biodiversity. Its databases are designed to serve as a benchmark well into the future. (For images of species collected, encounter CeDAMar, 2006.)

Past 2010, CeDAMar will have made one of the largest additions to known species from the subconscious realm of the Deep-sea Plain, without exhausting the potential for discovery of rare species.

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Marine Geographic and Geological Environment of Prc

Ye Yincan et al , in Marine Geo-Hazards in Prc, 2017

4.ii.ten Abyssal Ooze

Abyssal ooze is found in the abyssal patently surface area of South China Sea with h2o depth more than than 3500  m. The sediments are mainly composed of clay minerals with content of fourscore%–90%, the sand particles are mainly biogenic debris, followed by a modest corporeality of mineral debris, universe thing and volcano thing, nearly the sea bottom loma, and sand particle content increases. The boilerplate content of illite in clay minerals is 39.77%, the average content of montmorillonite is nineteen%, and the boilerplate contents of chlorite and kaolinite are fifteen% and 12%. Biological detritus are mainly radiolaria, followed by diatoms and sponge spicules, a minor corporeality of foraminifera antisolvent and bryozoans. The detrital mineral content is small, more often than not non more than 1%; they are mainly quartz, feldspar, tourmaline, and zircon, and volcanic clastic minerals have a small amount of magnetite, pyroxene, and hornblende. Authigenic minerals are mainly pyrite and glauconite; in the sediment in some areas, in that location are rich Fe and Mn particle content, with amorphous phase as the main, and the minority can be set as Na manganite; illite content in clay mineral is higher than that in sea sediments, montmorillonite content is on the contrary, which shows the continental affinity.

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Gulf of Mexico, Thermobiogenic Hydrates

Rudy Rogers , in Offshore Gas Hydrates, 2015

3.9.1 Green Canyon, GC-955

Greenish Canyon Block 955 extends into the abyssal plain of the GOM, seaward of the Sigsbee Escarpment boundary and in front of the Sigsbee's northeastern to southwestern movement. Come across Figure 3.6. Its deep reservoir sands near BGHS within the hydrate stability zone overlie a Louann salt base of operations (Hutchinson et al., 2008b).

Figure 3.six. Location of KC-151 and AT-xiii in JIP evaluation of prospects.

 Drawn by Marco D'Emidio (Lee et al., 2008).

The geologic establishment of a GC-955 hydrate-bearing organization to a large extent typifies hydrate reservoir developments throughout the northern GOM. Since Pleistocene time, channel-levee-type sands began accumulating what now serves as quality hydrate reservoirs 480 mbsf (McConnell, 2000). To complete the GC-955 hydrate organisation development, reservoirs became linked to gas sources by faults emanating from table salt diapirs below (McConnell et al., 2009; Boswell et al., 2012a).

Before JIP drilling, seismic data had revealed geologic features conducive to hydrate accumulations at GC-955. Salt uplifts nearly the Sigsbee Escarpment caused folding to disrupt strata at BGHS, generating widespread fault systems and numerous active gas chimneys that convey gas throughout the bowl. The seismic data also revealed a mud volcano on the GC-955 seafloor, resulting in a forty m diameter mound extending well-nigh 10 m above the seafloor (Heggland, 2004; McConnell and Zhang, 2011).

Manufacture drilled 2 GC-955 conventional hydrocarbon wells, which supplied historical data for hydrate endeavors, prior to JIP involvement. The first well was drilled in the block's center that verified thick reservoir sands. Subsequently, JIP drilled iii GC-955 wells at water depths of 2000–2200 m to test, among other things, hydrate content of the porous sands. The first well, designated I well, showed but minor hydrate accumulations with their thick sands seemingly plain isolated from gas sources (McConnell et al., 2012).

Quality logs from the second well, designated the H well, taken while drilling were evaluated by Zhang and McConnell (2011). They found over the interval 410–450 mbsf sonic velocity and resistance logs highlighting hydrates saturating sands to an extent of 70%. To a lesser extent, gamma ray and density logs defined hydrates in the larger interval 375–490 mbsf. The meaning results of the Zhang and McConnell logging information interpretations are presented in Table three.five.

Tabular array 3.5. Results from LWD information, GC-955H (McConnell and Zhang, 2011)

Depth interval (mbsf) Log Value Results
410–450 Resistivity 1–200 Ω m Concentrated hydrates, >70% saturation
410–450 Sonic velocity 1600–2800 m/s Full-bodied hydrates
375–490 Gamma ray Low Concentrated hydrates in sand
375–490 Density Low Hydrates

Structural traps provide reservoirs within sands sealed by shale higher up (Hutchinson et al., 2008a,b). Apparently, random impermeability of gas hydrates traps free gas within the aqueduct sands (McConnell and Zhang, 2011). The numerous interbedded sparse sand beds of loftier S gh observed in GC-955H give similar structures to Nankai Trough (Boswell et al., 2012a).

At the GC-955 I and H sites, hydrate reservoirs exist deep in thick channel sands. Existence near the BGHS, having relatively high 32 mK/m thermal gradients as a event of underlying salt bases, and demonstrating l–89% hydrate saturation, these reservoirs take high production potential (Hutchinson et al., 2008b).

The GC-955 data converge on multiple desirable features for successful gas production from its hydrate reservoirs. Volumetric calculations substantiate the data. For example, Boswell et al. (2012a) guess in-place gas in the hydrate sands intersected by I and H wells based on the following data: 40% porosity, eighty% hydrate saturation, and average net sand thickness 30 m for the H zone and 21 thou for the I zone in their calculations. Overall in-place gas for I and H hydrate sands is 5.5 × 108 m3 (19.eight bcf).

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Manganese nodule fields from the Northeast Pacific every bit benthic habitats

Thomas Kuhn , ... Pedro Martinez Arbizu , in Seafloor Geomorphology as Benthic Habitat (Second Edition), 2020

Surrogacy

Manganese nodules cover large parts of the abyssal plains in the working area and form contiguous nodule fields. However, such nodule fields are usually interspersed with low abundance regions or areas that are almost barren of nodules ( Fig. 58.five).

Multibeam acoustic imagery (backscatter) data are collected simultaneously during seafloor bathymetric mapping with multibeam echosounding systems. Backscatter data provide data on the geological atmospheric condition of the seafloor. The higher the value, the greater is the likelihood that difficult rocks outcrop on the ocean floor, while lower backscatter values signal the presence of unconsolidated, water-saturated sediments. Since the divergence in relative backscatter strength betwixt a flat, sediment-covered seafloor with and without nodules is between +xi and +13   dB for frequencies betwixt 9 and 160   kHz, it is possible to distinguish nodule fields on the seafloor from areas devoid of nodules (Weydert, 1990; Scanlon and Mason, 1992; Mitchell, 1993). Moreover, the assay of backscatter data of a 12   kHz multibeam system also allows for the discrimination between seafloor areas dominated past small-sized nodules (long centrality of the nodules <four   cm) and seafloor areas dominated by medium to big-sized nodules (>4   cm). This bigotry is based on the concrete principle that hydroacoustic pressure waves are scattered differently on the flat and sediment-covered seafloor depending on the ratio between bottom roughness (a) and acoustic wavelength (k; Clay and Medwin, 1977). The scattering of waves by a particle can be described equally

Relative frequency = 2 π r λ

where r is the particle radius and λ is the wavelength.

If the relative frequency is less than 1, the backscatter return is determined by Rayleigh scattering. If the relative frequency is greater than 1, the backscatter render is adamant by Mie scattering. At a frequency f =12   kHz (i.e., λ=12.5   cm) and a particle radius of 2   cm, the relative frequency is i. If manganese nodules are seen equally perfectly shaped spheres, nodules with a diameter of 4   cm (i.e., radius of 2   cm) would event in a relative frequency of 1. Backscatter analyses in the working surface area show that the size of nodules is characterized by a bimodal distribution with ane maximum at effectually iii   cm diameter (i.e., nodule radius a<2   cm) and another maximum betwixt 5 and half dozen   cm diameter (i.e., nodule radius a>two   cm; Fig. 58.3). Information technology was too shown that each size-class forms face-to-face nodules fields. Therefore, backscatter data can be used to map such fields. The ground truthing information conspicuously support our findings (Figs. 58.three and 58.v).

Nodule abundance and nodule size directly and indirectly impact biological communities. A direct relationship can be found for sessile organisms that attach to hard substrate, as the nodules represent the nigh common difficult substrate available in abyssal sediments. Other hard substrates may be formed by rocks and basaltic outcrops, shark teeth and whale bones, or living stalked sponges, but they are magnitudes lower in abundance compared to the nodules. According to our models, the macrofaunal-sized epifauna also seems to respond to changes in nodule size. Areas with many small nodules have a greater abundance of epifauna than the areas with fewer, larger nodules, probably due to the fact that more substrate surface is generally available. Sediment-covered areas without nodules volition obviously not have nodule-associated sessile fauna. A similar effect can be assumed for the megafauna (Vanreusel et al., 2016).

Every bit many of the sessile organisms are filter feeders, they will profit from enhanced food availability either due to pronounced exposure in elevated areas (Amon et al., 2016) and/or due to increased near-bottom currents. The presence of college abundances of epifauna in areas dominated past modest-sized nodules and the observation that minor-sized nodules are indicative of enhanced well-nigh-lesser currents support this assumption.

The same indirect relationship simply with opposite influence holds for the meiofauna. These small infaunal organisms depend on soft sediment habitat for living and their principal energy source is the POC flux from euphotic layers (Smith et al., 2008). Meiofauna are by and large more abundant in areas with no or but a low coverage of nodules on the sediment surface, that are nigh likely characterized by higher sedimentation rates than in the surrounding, nodule-covered areas.

We conclude that the backscatter signal can be used as a surrogate for relative faunal abundance. Loftier backscatter values represent a relatively low affluence of meiofauna, simply high abundance of epifauna and megafauna, whereas low backscatter values represent the opposite trend. Although quantitative data on species density and richness are scarce in the CCZ, the patterns shown hither for abundance of organisms will correlate with patterns of diversity. In abyssal areas, the species–surface area but as well species–specimens relationships rarely attain an asymptote (Rose et al., 2005). For instance, there is a significant linear relationship between the number of studied adult harpacticoid copepods and diversity, and similar patterns have been found for isopods (Ramirez-Llodra et al., 2010). More than species per unit area volition thus exist expected in areas with a loftier abundance of organisms compared to areas with very depression continuing stocks.

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