Resource quality affects carbon cycling in deep-sea sediments

Mayor, Daniel J.; Thornton, Barry; Hay, Steve; Zuur, Alain F.; Nicol, Graeme W.; McWilliam, Jenna M; Witte, Ursula

doi:10.1038/ismej.2012.14

Cited by 48 publications

(49 citation statements)

References 51 publications

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“…Whilst assimilation of terrigenous OM was relatively low, it was used in greater proportions than marine OM in deeper sediment layers. Terrigenous OM is less labile than marine OM, but bacterial assemblages are characterised by high metabolic and stoichiometric flexibility that allows them to process recalcitrant OM (Kristensen and Holmer, 2001;Mayor et al, 2012). These data support the hypothesis that resource-partitioning between macrofaunal and bacterial assemblages control OM recycling in marine sediments (Witte et al, 2003b;van Nugteren et al, 2009;Hunter et al, 2012b).…”

Section: Bacterial Responses and Faunal-bacterial Interactionsmentioning

confidence: 67%

Sediment community responses to marine vs. terrigenous organic matter in a submarine canyon

et al. 2013

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Abstract. The Whittard Canyon is a branching submarine canyon on the Celtic continental margin, which may act as a conduit for sediment and organic matter (OM) transport from the European continental slope to the abyssal sea floor. In situ stable-isotope labelling experiments were conducted in the eastern and western branches of the Whittard Canyon, testing short-term (3-7 days) responses of sediment communities to deposition of nitrogen-rich marine (Thalassiosira weissflogii) and nitrogen-poor terrigenous (Triticum aestivum) phytodetritus. 13 C and 15 N labels were traced into faunal biomass and bulk sediments, and the 13 C label traced into bacterial polar lipid fatty acids (PLFAs). Isotopic labels penetrated to 5 cm sediment depth, with no differences between stations or experimental treatments (substrate or time). Macrofaunal assemblage structure differed between the eastern and western canyon branches. Following deposition of marine phytodetritus, no changes in macrofaunal feeding activity were observed between the eastern and western branches, with little change between 3 and 7 days. Macrofaunal C and N uptake was substantially lower following deposition of terrigenous phytodetritus with feeding activity governed by a strong N demand. Bacterial C uptake was greatest in the western branch of the Whittard Canyon, but feeding activity decreased between 3 and 7 days. Bacterial processing of marine and terrigenous OM were similar to the macrofauna in surficial (0-1 cm) sediments. However, in deeper sediments bacteria utilised greater proportions of terrigenous OM. Bacterial biomass decreased following phytodetritus deposition and was negatively correlated to macrofaunal feeding activity. Consequently, this study suggests that macrofaunal-bacterial interactions influence benthic C cycling in the Whittard Canyon, resulting in differential fates for marine and terrigenous OM.

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Section: Bacterial Responses and Faunal-bacterial Interactionsmentioning

confidence: 67%

Sediment community responses to marine vs. terrigenous organic matter in a submarine canyon

et al. 2013

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“…We show that these trawled sediments are generally characterized by a decrease in the fraction of organic matter of algal origin (i.e., total phytopigments), which is the fraction of sedimentary organic matter that is most digestible to heterotrophic consumption, and, as such, represents the most important food source for deep-sea benthic fauna (24)(25)(26).…”

Section: Discussionmentioning

confidence: 99%

Chronic and intensive bottom trawling impairs deep-sea biodiversity and ecosystem functioning

Pusceddu

Bianchelli

Martín

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

296

228

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Bottom trawling has many impacts on marine ecosystems, including seafood stock impoverishment, benthos mortality, and sediment resuspension. Historical records of this fishing practice date back to the mid-1300s. Trawling became a widespread practice in the late 19th century, and it is now progressively expanding to greater depths, with the concerns about its sustainability that emerged during the first half of the 20th century now increasing. We show here that compared with untrawled areas, chronically trawled sediments along the continental slope of the north-western Mediterranean Sea are characterized by significant decreases in organic matter content (up to 52%), slower organic carbon turnover (ca. 37%), and reduced meiofauna abundance (80%), biodiversity (50%), and nematode species richness (25%). We estimate that the organic carbon removed daily by trawling in the region under scrutiny represents as much as 60-100% of the input flux. We anticipate that such an impact is causing the degradation of deepsea sedimentary habitats and an infaunal depauperation. With deep-sea trawling currently conducted along most continental margins, we conclude that trawling represents a major threat to the deep seafloor ecosystem at the global scale.

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“…In both approaches, phytodetritus, e.g., diatoms or coccolithophores (Jeffreys et al, 2013), or zooplankton fecal pellets (Mayor et al, 2012) that have been enriched in 13 C and/ or 15 N are added to the benthic ecosystem (pulse) to track the uptake and processing of this material by microorganisms, meiofauna, metazoan macrofauna, and foraminifera (chase). Despite the high importance of deep-sea megafauna, dominated by holothurians, as e.g., grazers of labile phytodetritus (Miller et al, 2000;Gallucci et al, 2008;Amaro et al, 2010), logistic challenges of deepsea research have so far hampered the inclusion of megafauna in these stable isotope studies.…”

Section: Introductionmentioning

confidence: 99%

Has Phytodetritus Processing by an Abyssal Soft-Sediment Community Recovered 26 Years after an Experimental Disturbance?

et al. 2018

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The potential harvest of polymetallic nodules will heavily impact the abyssal, soft sediment ecosystem by removing sediment, hard substrate, and associated fauna inside mined areas. It is therefore important to know whether the ecosystem can recover from this disturbance and if so at which rate. The first objective of this study was to measure recovery of phytodetritus processing by the benthic food web from a sediment disturbance experiment in 1989. The second objective was to determine the role of holothurians in the uptake of fresh phytodetritus by the benthic food web. To meet both objectives, large benthic incubation chambers (CUBEs; 50 × 50 × 50 cm) were deployed inside plow tracks (with and without holothurian presence) and at a reference site (holothurian presence, only) at 4100 m water depth. Shortly after deployment, 13 C-and 15 N-labeled phytodetritus was injected in the incubation chambers and during the subsequent 3-day incubation period, water samples were taken five times to measure the production of 13 C-dissolved inorganic carbon over time. At the end of the incubation, holothurians and sediment samples were taken to determine biomass, densities and incorporation of 13 C and 15 N into bacteria, nematodes, macrofauna, and holothurians. For the first objective, the results showed that biomass of bacteria, nematodes and macrofauna did not differ between reference sites and plow track sites when holothurians were present. Additionally, meiofauna and macrofauna taxonomic composition was not significantly different between the sites. In contrast, total 13 C uptake by bacteria, nematodes and holothurians was significantly lower at plow track sites compared to reference sites, though the number of replicates was low. This result suggests that important ecosystem functions such as organic matter processing have not fully recovered from the disturbance that occurred 26 years prior to our study. For the second objective, the analysis indicated that holothurians incorporated 2.16 × 10 −3 mmol labile phytodetritus C m −2 d −1 into their biomass, which is one order of Stratmann et al.Phytodetritus Processing after Experimental Disturbance magnitude less as compared to bacteria, but 1.3 times higher than macrofauna and one order of magnitude higher than nematodes. Additionally, holothurians incorporated more phytodetritus carbon per unit biomass than macrofauna and meiofauna, suggesting a size-dependence in phytodetritus carbon uptake.

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Resource quality affects carbon cycling in deep-sea sediments

Cited by 48 publications

References 51 publications

Sediment community responses to marine vs. terrigenous organic matter in a submarine canyon

Sediment community responses to marine vs. terrigenous organic matter in a submarine canyon

Chronic and intensive bottom trawling impairs deep-sea biodiversity and ecosystem functioning

Has Phytodetritus Processing by an Abyssal Soft-Sediment Community Recovered 26 Years after an Experimental Disturbance?

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