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  • 18S (SSU) rRNA gene  (1)
  • Athalassohaline  (1)
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  • 1
    Publikationsdatum: 2022-05-25
    Beschreibung: © The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in BMC Biology 13 (2015): 105, doi:10.1186/s12915-015-0213-6
    Beschreibung: The deep-sea hypersaline anoxic basins (DHABs) of the Mediterranean (water depth ~3500 m) are some of the most extreme oceanic habitats known. Brines of DHABs are nearly saturated with salt, leading many to suspect they are uninhabitable for eukaryotes. While diverse bacterial and protistan communities are reported from some DHAB haloclines and brines, loriciferans are the only metazoan reported to inhabit the anoxic DHAB brines. Our goal was to further investigate metazoan communities in DHAB haloclines and brines. We report observations from sediments of three DHAB (Urania, Discovery, L’Atalante) haloclines, comparing these to observations from sediments underlying normoxic waters of typical Mediterranean salinity. Due to technical difficulties, sampling of the brines was not possible. Morphotype analysis indicates nematodes are the most abundant taxon; crustaceans, loriciferans and bryozoans were also noted. Among nematodes, Daptonema was the most abundant genus; three morphotypes were noted with a degree of endemicity. The majority of rRNA sequences were from planktonic taxa, suggesting that at least some individual metazoans were preserved and inactive. Nematode abundance data, in some cases determined from direct counts of sediments incubated in situ with CellTrackerTM Green, was patchy but generally indicates the highest abundances in either normoxic control samples or in upper halocline samples; nematodes were absent or very rare in lower halocline samples. Ultrastructural analysis indicates the nematodes in L’Atalante normoxic control sediments were fit, while specimens from L’Atalante upper halocline were healthy or had only recently died and those from the lower halocline had no identifiable organelles. Loriciferans, which were only rarely encountered, were found in both normoxic control samples as well as in Discovery and L’Atalante haloclines. It is not clear how a metazoan taxon could remain viable under this wide range of conditions. We document a community of living nematodes in normoxic, normal saline deep-sea Mediterranean sediments and in the upper halocline portions of the DHABs. Occurrences of nematodes in mid-halocline and lower halocline samples did not provide compelling evidence of a living community in those zones. The possibility of a viable metazoan community in brines of DHABs is not supported by our data at this time.
    Beschreibung: Supported by NSF grants OCE-0849578 to VPE and JMB, OCE-1061391 to JMB and VPE, and The Investment in Science Fund at WHOI.
    Schlagwort(e): Athalassohaline ; Bryozoa ; CellTrackerTM Green ; Discovery ; L’Atalante ; Loricifera ; Meiofauna ; Nematoda ; Ultrastructure ; Urania
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Format: application/pdf
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Publikationsdatum: 2022-10-26
    Beschreibung: © The Author(s), 2022]. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Suter, E. A., Pachiadaki, M., Taylor, G. T., & Edgcomb, V. P. Eukaryotic parasites are integral to a productive microbial food web in oxygen-depleted waters. Frontiers in Microbiology, 12, (2022): 764605, https://doi.org/10.3389/fmicb.2021.764605.
    Beschreibung: Oxygen-depleted water columns (ODWCs) host a diverse community of eukaryotic protists that change dramatically in composition over the oxic-anoxic gradient. In the permanently anoxic Cariaco Basin, peaks in eukaryotic diversity occurred in layers where dark microbial activity (chemoautotrophy and heterotrophy) were highest, suggesting a link between prokaryotic activity and trophic associations with protists. Using 18S rRNA gene sequencing, parasites and especially the obligate parasitic clade, Syndiniales, appear to be particularly abundant, suggesting parasitism is an important, but overlooked interaction in ODWC food webs. Syndiniales were also associated with certain prokaryotic groups that are often found in ODWCs, including Marinimicrobia and Marine Group II archaea, evocative of feedbacks between parasitic infection events, release of organic matter, and prokaryotic assimilative activity. In a network analysis that included all three domains of life, bacterial and archaeal taxa were putative bottleneck and hub species, while a large proportion of edges were connected to eukaryotic nodes. Inclusion of parasites resulted in a more complex network with longer path lengths between members. Together, these results suggest that protists, and especially protistan parasites, play an important role in maintaining microbial food web complexity, particularly in ODWCs, where protist diversity and microbial productivity are high, but energy resources are limited relative to euphotic waters.
    Beschreibung: This work was supported by the National Science Foundation (NSF) grants (OCE-1336082 to VE and OCE-1335436 and OCE-1259110 to GT). The Cyverse infrastructure and resources are supported by the NSF under Award Numbers DBI-0735191, DBI-1265383, and DBI-1743442 (www.cyverse.org). Support was also provided by the Faculty Scholarship and Academic Advancement Committee at Molloy College.
    Schlagwort(e): 18S (SSU) rRNA gene ; Oxygen-depleted environment ; Oxygen minimum zone (OMZ) ; Protist ; Syndiniales ; Parasite ; Eukaryotes ; Network analysis
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Standort Signatur Einschränkungen Verfügbarkeit
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