Latitudinal variations in benthic processes in the abyssal equatorial Pacific: control by biogenic particle flux

Smith, Craig R.; Berelson, W.; DeMaster, David J.; Dobbs, Fred C.; Hammond, Douglas; Hoover, Daniel J.; Pope, Robert H.; Stephens, Mark

doi:10.1016/s0967-0645(97)00022-2

Cited by 162 publications

(124 citation statements)

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“…The positive relationship between L and POC flux is likely driven by the influence of food availability on both infaunal body sizes and feeding strategies. In the quiescent deep sea, POC flux appears to be positively correlated with body size of those animals thought to control mixing, i.e., the deposit feeders (e.g., Hessler 1974;Thiel 1979;Jumars and Gallagher 1982;Wheatcroft et al 1990;Smith 1992); larger body sizes in turn should increase the particle step lengths and mixing depths of biogenic reworking (Wheatcroft et al 1990;Smith 1992). Higher POC fluxes may also cause a shift in deposit-feeding strategies by enhancing the food availability, abundances, and feeding rates of subsurface deposit feeders at given depths within the sediment (Rice and Rhoads 1989).…”

Section: Discussionmentioning

confidence: 99%

“…The strength of the relationship between POC flux and L highlights the importance of organic-carbon availability in controlling community-level processes in much of the deep sea (e.g., Hessler 1974;Smith et al 1997). Apparently, mixed-layer depth, along with community respiration, benthic community biomass, and biogenic mixing intensity (Smith and Hinga 1983;Smith et al 1997), become food limited as one moves into the oligotrophic abyss.…”

Section: Discussionmentioning

confidence: 99%

“…For the EUMELI-Eutro site, the POC flux was estimated using the oxidant flux at the sedimentwater interface (Rabouille et al 1993). At those stations where both sediment-trap and seafloor oxidant-flux data exist (e.g., the BOFS stations at ϳ33Њ and 48ЊN, and the EQPAC transect), they agree to within 30% (Shimmield et al 1995;Smith et al 1997). Regression analyses were conducted with SigmaStat (1994) and the significance of product-moment correlation coefficients (r) was determined from Rohlf and Sokal (1969).…”

Section: The Data Set and Methodsmentioning

confidence: 99%

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What controls the mixed‐layer depth in deep‐sea sediments? The importance of POC flux

Smith

Rabouille

2002

Limnology & Oceanography

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The depth of biogenic particle mixing, i.e., the mixed-layer depth (L), is fundamental in models of organic-matter recycling and paleoreconstructions for deep-sea sediments. Factors postulated to control L in the oxygenated deep sea include particulate organic carbon (POC) flux, oxygen penetration into the sediment, and a balance between the downward mixing and decay of labile POC. We explore the dependence of L on biogeochemical characteristics by compiling, from 36 sites in three oceans, an internally consistent set of deep-sea estimates of L, POC flux, biogenic mixing intensity (D b ), and POC reactivity. We use excess 210 Pb as a tracer for L and D b to avoid the confounding effects of tracer-dependent mixing. We find that L, estimated from the penetration depth of excess 210 Pb, varies systematically with POC flux, with an asymptotic function explaining 88% of the variance in L. Stepwise multiple regression suggests that the penetration depth of excess 210 Pb (and estimated L) is much more likely to be controlled by POC flux than by (1) the sediment inventory of excess 210 Pb or (2) biogenic mixing intensity (D b ). In addition, L is negatively related to oxygen penetration into the sediment (r ϭ Ϫ0.629) and not significantly related to predictions of L from a recent mixing/POC-decay model. We conclude that in the food-poor deep sea, POC flux substantially controls the size and activities of the sediment-mixing benthos and, in turn, the thickness of the biogenic mixed layer. Thus, in contrast to previous suggestions, average mixed-layer depth is not environmentally invariant but rather responds predictably to ecologically important parameters such as POC flux.The mixing of sediment grains by animal activity (i.e., biogenic particle mixing) profoundly influences the structure and geochemistry of marine sediments. In particular, the recycling and burial of organic carbon, nutrients, and pollutants, as well as the resolution of the stratigraphic record, depend substantially on the rates and depths of biogenic sediment mixing (e.g., Aller 1982;Wheatcroft et al. 1990; Smith et al. 1993).In deep-sea regions characterized by low current velocities, low sedimentation rates, and well-oxygenated bottom water, biogenic mixing is thought to control the movement of particles in near-surface sediments. Under these conditions, biogenic mixing is usually parameterized as eddy diffusion, described by an intensity coefficient D b (units of length 2 time Ϫ1 ) that operates over a sediment depth interval, L, called the mixed-layer depth (e.g., Guinasso and Schink 1975;Boudreau 1998). Based on this formulation, at steady

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: The Data Set and Methodsmentioning

confidence: 99%

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What controls the mixed‐layer depth in deep‐sea sediments? The importance of POC flux

Smith

Rabouille

2002

Limnology & Oceanography

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“…The quantities of benthic (seabed) organisms and sediment community oxygen consumption (SCOC) rates in the deep sea all correlate positively with the flux of particulate organic carbon (Smith et al, 1997;Ruhl et al, 2008), suggesting that biogeochemical processes in this environment are controlled by the quantity of available resources. Nevertheless, circumstantial evidence strongly suggests that the biochemical makeup of organic material, that is, 'resource quality', also affects the structure and functioning of deep-sea benthic communities (see, for example, Wolff et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Resource quality affects carbon cycling in deep-sea sediments

et al. 2012

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Deep-sea sediments cover B70% of Earth's surface and represent the largest interface between the biological and geological cycles of carbon. Diatoms and zooplankton faecal pellets naturally transport organic material from the upper ocean down to the deep seabed, but how these qualitatively different substrates affect the fate of carbon in this permanently cold environment remains unknown. We added equal quantities of 13 C-labelled diatoms and faecal pellets to a cold water (À0.7 1C) sediment community retrieved from 1080 m in the Faroe-Shetland Channel, Northeast Atlantic, and quantified carbon mineralization and uptake by the resident bacteria and macrofauna over a 6-day period. High-quality, diatom-derived carbon was mineralized 4300% faster than that from low-quality faecal pellets, demonstrating that qualitative differences in organic matter drive major changes in the residence time of carbon at the deep seabed. Benthic bacteria dominated biological carbon processing in our experiments, yet showed no evidence of resource qualitylimited growth; they displayed lower growth efficiencies when respiring diatoms. These effects were consistent in contrasting months. We contend that respiration and growth in the resident sediment microbial communities were substrate and temperature limited, respectively. Our study has important implications for how future changes in the biochemical makeup of exported organic matter will affect the balance between mineralization and sequestration of organic carbon in the largest ecosystem on Earth.

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“…Detailed studies of macrofauna, a major component of the sediment community, have been conducted at various locations and depths worldwide and have generally found higher abundances below areas with greater surface production (10)(11)(12)(13)(14)(15)(16). Abyssal food supply varies with distance from shore, depth, and surface productivity at basin scales.…”

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confidence: 99%

Connections between climate, food limitation, and carbon cycling in abyssal sediment communities

Ruhl

Ellena

Smith

2008

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

129

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Diverse faunal groups inhabit deep-sea sediments over much of Earth's surface, but our understanding of how interannual-scale climate variation alters sediment community components and biogeochemical processes remains limited. The vast majority of deep-sea communities depend on a particulate organic carbon food supply that sinks from photosynthetically active surface waters. Variations in food supply depend, in part, on surface climate conditions. Proposed ocean iron fertilization efforts are also intended to alter surface production and carbon export from surface waters. Understanding the ecology of the abyssal sediment community and constituent metazoan macrofauna is important because they influence carbon and nutrient cycle processes at the seafloor through remineralization, bioturbation, and burial of the sunken material. Results from a 10-year study in the abyssal NE Pacific found that climate-driven variations in food availability were linked to total metazoan macrofauna abundance, phyla composition, rank-abundance distributions, and remineralization over seasonal and interannual scales. The long-term analysis suggests that broad biogeographic patterns in deep-sea macrofauna community structure can change over contemporary timescales with changes in surface ocean conditions and provides significant evidence that sediment community parameters can be estimated from atmospheric and upper-ocean conditions. These apparent links between climate, the upper ocean, and deep-sea biogeochemistry need to be considered in determining the long-term carbon storage capacity of the ocean.biogeochemistry ͉ community structure ͉ deep sea ͉ ecology ͉ macrofauna A ppreciating how climate can influence deep-sea communities and biogeochemical cycles is essential in evaluating how they may vary in the future. Current evidence suggests that climate change is resulting in significant alterations of oceanographic conditions worldwide including increased sea-surface temperatures, stronger stratification, and increased acidity (1, 2). The changing climate will likely also impact net primary production (1, 3-7) and the export of particulate organic carbon (POC) to the deep sea. Life on the seafloor depends upon this sinking POC and has a fundamental influence on the amount of carbon and nutrients that are remineralized or buried there. Ocean iron fertilization plans also project increases in surface production and POC export from surface waters, but fertilization impacts are poorly constrained (8, 9), especially for the deep-sea sediment community.Detailed studies of macrofauna, a major component of the sediment community, have been conducted at various locations and depths worldwide and have generally found higher abundances below areas with greater surface production (10-16). Abyssal food supply varies with distance from shore, depth, and surface productivity at basin scales. Previous studies that covered adequate spatial areas, however, understandably lacked long-term temporal perspective. Most spatial studies have effectively compa...

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Latitudinal variations in benthic processes in the abyssal equatorial Pacific: control by biogenic particle flux

Cited by 162 publications

References 44 publications

What controls the mixed‐layer depth in deep‐sea sediments? The importance of POC flux

What controls the mixed‐layer depth in deep‐sea sediments? The importance of POC flux

Resource quality affects carbon cycling in deep-sea sediments

Connections between climate, food limitation, and carbon cycling in abyssal sediment communities

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