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Meiobenthos of the Oxic/Anoxic Interface in the Southwestern Region of the Black Sea: Abundance and Taxonomic Composition

Meiobenthos of the Oxic/Anoxic Interface in the Southwestern Region of the Black Sea: Abundance and Taxonomic Composition
Meiobenthos of the Oxic/Anoxic Interface in the Southwestern Region of the Black Sea: Abundance and Taxonomic Composition
The Black Sea contains the World’s largest body of anoxic water. Based on new and published data, we describe trends among selected protozoan and metazoan meiofaunal taxa at water depths of 120–240 m in the northwestern part of the Black Sea near the submarine Dnieper Canyon. This transect spans the transition between increasingly hypoxic but non-sulfidic bottom water and the deeper anoxic/sulfidic zone, the boundary between these two domains being located at approximately 150–180 m depth. This transition zone supports a rich rose-Bengal-stained fauna. Among the protozoans, gromiids are common only at 120 and 130 m. All other groups exhibit more or less distinct abundance maxima near the base of the hypoxic zone. Foraminifera peak sharply at ?160 m while ciliates are most abundant at 120, 160–190, and 240 m, where they are possibly associated with concentrations of bacterial cells. The three most abundant metazoan taxa also exhibit maxima in the hypoxic zone, the nematodes and polychaetes at 160 m, and the harpacticoid copepods at 150 m. Most of the polychaetes belong to two species, Protodrilus sp. and Vigtorniella zaikai, the larvae of which are widely distributed in severely hypoxic water just above the anoxic/sulfidic zone of the Black Sea. Both protozoans and metazoans are usually concentrated in the 0–1 cm layer of the sediment, except at the shallowest (120–130 m) site where deeper layers may yield a substantial proportion of the assemblage. The concentration of nematodes in the 3–5 cm layer at 120 m is particularly notable. Our data suggest that some benthic species can tolerate anoxic/sulfidic conditions in the Black Sea. An important caveat is that anoxia or severe hypoxia may lead to the corpses of nonindigenous organisms being preserved in our samples. However, we argue that the morphological integrity of specimens, the high population densities (associated with high bacterial concentrations in the case of ciliates), the presence of taxa often found in hypoxic settings, and the presence of all life stages (including gravid females) among nematodes and harpacticoids, suggests that at least some of the organisms are indigenous. Further comparative studies of shallow- and deep-water meiobenthic communities in the Black Sea are necessary in order to establish which species are characteristic and indicative of hypoxic/anoxic conditions.
978-94-007-1895-1
369-401
Springer
Sergeeva, Nelli G.
b8309e63-f99f-457d-8a26-8514266fd1ab
Gooday, Andrew J.
d9331d67-d518-4cfb-baed-9df3333b05b9
Mazlumyan, Sofia A.
d5fd3574-65dc-4a9f-800b-69c67babae10
Kolesnikova, Elena A.
090de399-04ca-45b3-b1e3-7ea9180e4213
Lichtschlag, Anna
be1568d9-cc63-4f85-bd38-a93dfd7e245f
Kosheleva, Tetiana N.
7f69d1ba-5cbc-40a4-a1d7-563de2e81aed
Anikeeva, Oksana V.
6ecf2635-59b1-4d04-86fc-1cd29769754d
Altenbach, Alexander V.
Bernhard, Joan M.
Seckbach, Joseph
Sergeeva, Nelli G.
b8309e63-f99f-457d-8a26-8514266fd1ab
Gooday, Andrew J.
d9331d67-d518-4cfb-baed-9df3333b05b9
Mazlumyan, Sofia A.
d5fd3574-65dc-4a9f-800b-69c67babae10
Kolesnikova, Elena A.
090de399-04ca-45b3-b1e3-7ea9180e4213
Lichtschlag, Anna
be1568d9-cc63-4f85-bd38-a93dfd7e245f
Kosheleva, Tetiana N.
7f69d1ba-5cbc-40a4-a1d7-563de2e81aed
Anikeeva, Oksana V.
6ecf2635-59b1-4d04-86fc-1cd29769754d
Altenbach, Alexander V.
Bernhard, Joan M.
Seckbach, Joseph

Sergeeva, Nelli G., Gooday, Andrew J., Mazlumyan, Sofia A., Kolesnikova, Elena A., Lichtschlag, Anna, Kosheleva, Tetiana N. and Anikeeva, Oksana V. (2012) Meiobenthos of the Oxic/Anoxic Interface in the Southwestern Region of the Black Sea: Abundance and Taxonomic Composition. In, Altenbach, Alexander V., Bernhard, Joan M. and Seckbach, Joseph (eds.) Anoxia: Evidence for Eukaryote Survival and Paleontological Strategies. (Cellular Origin, Life in Extreme Habitats and Astrobiology, 21) Hamburg, DE. Springer, pp. 369-401.

Record type: Book Section

Abstract

The Black Sea contains the World’s largest body of anoxic water. Based on new and published data, we describe trends among selected protozoan and metazoan meiofaunal taxa at water depths of 120–240 m in the northwestern part of the Black Sea near the submarine Dnieper Canyon. This transect spans the transition between increasingly hypoxic but non-sulfidic bottom water and the deeper anoxic/sulfidic zone, the boundary between these two domains being located at approximately 150–180 m depth. This transition zone supports a rich rose-Bengal-stained fauna. Among the protozoans, gromiids are common only at 120 and 130 m. All other groups exhibit more or less distinct abundance maxima near the base of the hypoxic zone. Foraminifera peak sharply at ?160 m while ciliates are most abundant at 120, 160–190, and 240 m, where they are possibly associated with concentrations of bacterial cells. The three most abundant metazoan taxa also exhibit maxima in the hypoxic zone, the nematodes and polychaetes at 160 m, and the harpacticoid copepods at 150 m. Most of the polychaetes belong to two species, Protodrilus sp. and Vigtorniella zaikai, the larvae of which are widely distributed in severely hypoxic water just above the anoxic/sulfidic zone of the Black Sea. Both protozoans and metazoans are usually concentrated in the 0–1 cm layer of the sediment, except at the shallowest (120–130 m) site where deeper layers may yield a substantial proportion of the assemblage. The concentration of nematodes in the 3–5 cm layer at 120 m is particularly notable. Our data suggest that some benthic species can tolerate anoxic/sulfidic conditions in the Black Sea. An important caveat is that anoxia or severe hypoxia may lead to the corpses of nonindigenous organisms being preserved in our samples. However, we argue that the morphological integrity of specimens, the high population densities (associated with high bacterial concentrations in the case of ciliates), the presence of taxa often found in hypoxic settings, and the presence of all life stages (including gravid females) among nematodes and harpacticoids, suggests that at least some of the organisms are indigenous. Further comparative studies of shallow- and deep-water meiobenthic communities in the Black Sea are necessary in order to establish which species are characteristic and indicative of hypoxic/anoxic conditions.

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Published date: 2012
Organisations: Marine Biogeochemistry, Marine Geoscience

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Local EPrints ID: 340763
URI: http://eprints.soton.ac.uk/id/eprint/340763
ISBN: 978-94-007-1895-1
PURE UUID: 691da2c1-c955-4c4f-9895-d7eff15656bb

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Date deposited: 02 Jul 2012 13:41
Last modified: 11 Dec 2021 00:40

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Contributors

Author: Nelli G. Sergeeva
Author: Andrew J. Gooday
Author: Sofia A. Mazlumyan
Author: Elena A. Kolesnikova
Author: Anna Lichtschlag
Author: Tetiana N. Kosheleva
Author: Oksana V. Anikeeva
Editor: Alexander V. Altenbach
Editor: Joan M. Bernhard
Editor: Joseph Seckbach

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