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Bathyal zone

About: Bathyal zone is a research topic. Over the lifetime, 1652 publications have been published within this topic receiving 50094 citations. The topic is also known as: bathypelagic zone & midnight zone.


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Journal ArticleDOI
01 Apr 1983-Nature
TL;DR: In this article, a similar seasonal pulse of detrital material to bathyal and abyssal depths in temperate latitudes is presented, this material seems to be derived directly from the surface primary production and to sink rapidly to the deep-sea benthos.
Abstract: Until recently the deep sea was considered to be a particularly stable environment1, free from seasonal variations. However, atmospheric storms may cause periodicity in deep-ocean currents2 and nepheloid layers3 while seasonality in the particulate flux to the deep sea is known to occur in the Sargasso Sea4,5 and Panama Basin6. Evidence is presented here of a similar seasonal pulse of detrital material to bathyal and abyssal depths in temperate latitudes; this material seems to be derived directly from the surface primary production and to sink rapidly to the deep-sea benthos. Considerable sedimentation occurs soon after the spring bloom and continues throughout the early summer. This process acts as a pathway for the descent of carbon from the euphotic zone, providing a periodic food source for the deep pelagic and benthic communities.

922 citations

Journal ArticleDOI
01 Sep 2004
TL;DR: In this paper, the authors provided the first global quantification of naturally hypoxic continental margin floor by determining upper and lower oxygen minimum zone depth boundaries from hydrographic data and computing the area between the isobaths using seafloor topography.
Abstract: Hypoxia in the ocean influences biogeochemical cycling of elements, the distribution of marine species and the economic well being of many coastal countries Previous delineations of hypoxic environments focus on those in enclosed seas where hypoxia may be exacerbated by anthropogenically induced eutrophication Permanently hypoxic water masses in the open ocean, referred to as oxygen minimum zones, impinge on a much larger seafloor surface area along continental margins of the eastern Pacific, Indian and western Atlantic Oceans We provide the first global quantification of naturally hypoxic continental margin floor by determining upper and lower oxygen minimum zone depth boundaries from hydrographic data and computing the area between the isobaths using seafloor topography This approach reveals that there are over one million km 2 of permanently hypoxic shelf and bathyal sea floor, where dissolved oxygenis o05 ml l � 1 ; over half (59%) occurs in the northern Indian Ocean We also document strong variation in the intensity, vertical position and thickness of the OMZ as a function of latitude in the eastern Pacific Ocean and as a function of longitude in the northern Indian Ocean Seafloor OMZs are regions of low biodiversity and are inhospitable to most commercially valuable marine resources, but support a fascinating array of protozoan and metazoan adaptations to hypoxic conditions r 2004 Elsevier Ltd All rights reserved

712 citations

Book ChapterDOI
TL;DR: Mid-water oxygen minima intercept the continental margins along much of the eastern Pacific Ocean, off west Africa and in the Arabian Sea and Bay of Bengal, creating extensive stretches of sea floor exposed to permanent, severe oxygen depletion, and may preview the types of adaptations, species, and processes that will prevail with increasing hypoxia over ecological and evolution- ary time.
Abstract: Mid-water oxygen minima (� 0.5 ml l � 1 dissolved O2) intercept the continental margins along much of the eastern Pacific Ocean, off west Africa and in the Arabian Sea and Bay of Bengal, creating extensive stretches of sea floor exposed to permanent, severe oxygen depletion. These seafloor oxygen minimum zones (OMZs) typically occur at bathyal depths between 200 m and 1000 m, and are major sites of carbon burial along the continental margins. Despite extreme oxygen depletion, protozoan and metazoan assemblages thrive in these envi- ronments. Metazoan adaptations include small, thin bodies, enhanced respiratory surface area, blood pigments such as haemoglobin, biogenic structure formation for stability in soupy sedi- ments, an increased number of pyruvate oxidoreductases, and the presence of sulphide-oxidising symbionts. The organic-rich sediments of these regions often support mats of large sulphide- oxidising bacteria (Thioploca, Beggiatoa, Thiomargarita ), and high-density, low-diversity meta- zoan assemblages. Densities of protistan and metazoan meiofauna are typically elevated in OMZs, probably due to high tolerance of hypoxia, an abundant food supply, and release from predation. Macrofauna and megafauna often exhibit dense aggregations at OMZ edges, but depressed densities and low diversity in the OMZ core, where oxygen concentration is lowest. Taxa most tolerant of severe oxygen depletion ( � 0.2 ml l � 1 ) in seafloor OMZs include calcare- ous foraminiferans, nematodes, and annelids. Agglutinated protozoans, harpacticoid copepods, and calcified invertebrates are typically less tolerant. High dominance and relatively low species richness are exhibited by foraminiferans, metazoan meiofauna, and macrofauna within OMZs. At dissolved oxygen concentrations below 0.15 ml l � 1 , bioturbation is reduced, the mixed layer is shallow, and chemosynthesis-based nutrition (via heterotrophy and symbiosis) becomes important. OMZs represent a major oceanographic boundary for many species. As they expand and con- tract over geological time, OMZs may influence genetic diversity and play a key role in the evo- lution of species at bathyal depths. These ecosystems may preview the types of adaptations, species, and processes that will prevail with increasing hypoxia over ecological and evolution- ary time. However, many questions remain unanswered concerning controls on faunal standing stocks in OMZs, and the physiological, enzymatic, metabolic, reproductive and molecular adap- tations that permit benthic animals to live in OMZs. As global warming and eutrophication reduce oxygenation of the world ocean, there is a pressing need to understand the functional consequences of oxygen depletion in marine ecosystems.

702 citations

Journal ArticleDOI
Kunio Kaiho1
01 Aug 1994-Geology
TL;DR: In this paper, the foraminiferal oxygen index derived from bathyal and abyssal Holocene faunas correlates well with the dissolved-oxygen levels in overlying waters.
Abstract: Changes in oxygen concentrations at the sediment-water interface play a major role in controlling benthic foraminiferal assemblages and morphologic characteristics; such changes are reflected in size, wall thickness, porosity, and also taxa (genera and species) of foraminifera present. These morphologic and taxonomic differences have been quantified as a dissolved-oxygen index. This paper demonstrates that the foraminiferal oxygen index derived from bathyal and abyssal Holocene faunas correlates well with the dissolved-oxygen levels in overlying waters. This index is then used for paleoenvironmental interpretations.

653 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202356
2022122
202152
202064
201947
201849