Revealing zooplankton diversity in the midnight zone

Zooplankton diversity in the deep “midnight zone” (>1000 m), where sunlight does not reach, remains largely unknown. Uncovering such diversity has been challenging because of the major difficulties in sampling deep pelagic fauna and identifying many (unknown) species that belong to these comp...

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Main Authors: Carolina E. González, Leocadio Blanco-Bercial, Rubén Escribano, Igor Fernández-Urruzola, Reinaldo Rivera, Osvaldo Ulloa
Format: Article
Language:English
Published: Frontiers Media S.A. 2023-12-01
Series:Frontiers in Marine Science
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Online Access:https://www.frontiersin.org/articles/10.3389/fmars.2023.1252535/full
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author Carolina E. González
Leocadio Blanco-Bercial
Rubén Escribano
Rubén Escribano
Igor Fernández-Urruzola
Reinaldo Rivera
Osvaldo Ulloa
Osvaldo Ulloa
author_facet Carolina E. González
Leocadio Blanco-Bercial
Rubén Escribano
Rubén Escribano
Igor Fernández-Urruzola
Reinaldo Rivera
Osvaldo Ulloa
Osvaldo Ulloa
author_sort Carolina E. González
collection DOAJ
description Zooplankton diversity in the deep “midnight zone” (>1000 m), where sunlight does not reach, remains largely unknown. Uncovering such diversity has been challenging because of the major difficulties in sampling deep pelagic fauna and identifying many (unknown) species that belong to these complex swimmer assemblages. In this study, we evaluated zooplankton diversity using two taxonomic marker genes: mitochondrial cytochrome oxidase subunit 1 (COI) and nuclear 18S ribosomal RNA (18S). We collected samples from plankton net tows, ranging from the surface to a depth of 5000 m above the Atacama Trench in the Southeast Pacific. Our study aimed to assess the zooplankton diversity among layers from the upper 1000 m to the ultra-deep abyssopelagic zone to test the hypothesis of decreasing diversity with depth resulting from limited carbon sources. The results showed unique, highly vertically structured communities within the five depth strata sampled, with maximal species richness observed in the upper bathypelagic layer (1000–2000 m). The high species richness of zooplankton (>750 OTUS) at these depths was higher than that found in the upper 1000 m. The vertical diversity trend exhibited a pattern similar to the well-known vertical pattern described for the benthic system. However, a large part of this diversity was either unknown (>50%) or could not be assigned to any known species in current genetic diversity databases. DNA analysis showed that the Calanoid copepods, mostly represented by Subeucalanus monachus, the Euphausiacea, Euphausia mucronata, and the halocypridade, Paraconchoecia dasyophthalma, dominated the community. Water column temperature, dissolved oxygen, particulate carbon, and nitrogen appeared to be related to the observed vertical diversity pattern. Our findings revealed rich and little-known zooplankton diversity in the deep sea, emphasizing the importance of further exploration of this ecosystem to conserve and protect its unique biota.
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spelling doaj-art-35e0d9092913494ea498dcdf9119d8ae2025-08-20T03:05:45ZengFrontiers Media S.A.Frontiers in Marine Science2296-77452023-12-011010.3389/fmars.2023.12525351252535Revealing zooplankton diversity in the midnight zoneCarolina E. González0Leocadio Blanco-Bercial1Rubén Escribano2Rubén Escribano3Igor Fernández-Urruzola4Reinaldo Rivera5Osvaldo Ulloa6Osvaldo Ulloa7Instituto Milenio de Oceanografía (IMO), Universidad de Concepción, Concepción, ChileBermuda Institute of Ocean Sciences, Arizona State University, St. Georges, BermudaInstituto Milenio de Oceanografía (IMO), Universidad de Concepción, Concepción, ChileDepartamento de Oceanografía, Facultad de Ciencias Naturales y Oceanografía, Universidad de Concepción, Concepción, ChileInstituto Milenio de Oceanografía (IMO), Universidad de Concepción, Concepción, ChileInstituto Milenio de Oceanografía (IMO), Universidad de Concepción, Concepción, ChileInstituto Milenio de Oceanografía (IMO), Universidad de Concepción, Concepción, ChileDepartamento de Oceanografía, Facultad de Ciencias Naturales y Oceanografía, Universidad de Concepción, Concepción, ChileZooplankton diversity in the deep “midnight zone” (>1000 m), where sunlight does not reach, remains largely unknown. Uncovering such diversity has been challenging because of the major difficulties in sampling deep pelagic fauna and identifying many (unknown) species that belong to these complex swimmer assemblages. In this study, we evaluated zooplankton diversity using two taxonomic marker genes: mitochondrial cytochrome oxidase subunit 1 (COI) and nuclear 18S ribosomal RNA (18S). We collected samples from plankton net tows, ranging from the surface to a depth of 5000 m above the Atacama Trench in the Southeast Pacific. Our study aimed to assess the zooplankton diversity among layers from the upper 1000 m to the ultra-deep abyssopelagic zone to test the hypothesis of decreasing diversity with depth resulting from limited carbon sources. The results showed unique, highly vertically structured communities within the five depth strata sampled, with maximal species richness observed in the upper bathypelagic layer (1000–2000 m). The high species richness of zooplankton (>750 OTUS) at these depths was higher than that found in the upper 1000 m. The vertical diversity trend exhibited a pattern similar to the well-known vertical pattern described for the benthic system. However, a large part of this diversity was either unknown (>50%) or could not be assigned to any known species in current genetic diversity databases. DNA analysis showed that the Calanoid copepods, mostly represented by Subeucalanus monachus, the Euphausiacea, Euphausia mucronata, and the halocypridade, Paraconchoecia dasyophthalma, dominated the community. Water column temperature, dissolved oxygen, particulate carbon, and nitrogen appeared to be related to the observed vertical diversity pattern. Our findings revealed rich and little-known zooplankton diversity in the deep sea, emphasizing the importance of further exploration of this ecosystem to conserve and protect its unique biota.https://www.frontiersin.org/articles/10.3389/fmars.2023.1252535/fulldeep-oceanzooplanktondiversity patternAtacama TrenchSoutheast Pacific
spellingShingle Carolina E. González
Leocadio Blanco-Bercial
Rubén Escribano
Rubén Escribano
Igor Fernández-Urruzola
Reinaldo Rivera
Osvaldo Ulloa
Osvaldo Ulloa
Revealing zooplankton diversity in the midnight zone
Frontiers in Marine Science
deep-ocean
zooplankton
diversity pattern
Atacama Trench
Southeast Pacific
title Revealing zooplankton diversity in the midnight zone
title_full Revealing zooplankton diversity in the midnight zone
title_fullStr Revealing zooplankton diversity in the midnight zone
title_full_unstemmed Revealing zooplankton diversity in the midnight zone
title_short Revealing zooplankton diversity in the midnight zone
title_sort revealing zooplankton diversity in the midnight zone
topic deep-ocean
zooplankton
diversity pattern
Atacama Trench
Southeast Pacific
url https://www.frontiersin.org/articles/10.3389/fmars.2023.1252535/full
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AT igorfernandezurruzola revealingzooplanktondiversityinthemidnightzone
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