Deep penetrating benthic oxygen profiles measured in situ by oxygen optodes

Wenzhöfer, Frank; Holby, Ola; Kohls, Oliver

doi:10.1016/s0967-0637(00)00108-4

Cited by 55 publications

(39 citation statements)

References 40 publications

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“…Work in this area has focussed on sediment (e.g. Jørgensen & Des Marais 1990, Holst et al 1997, Wenzhöfer et al 2001), but has also included some investigations of boundary layers adjacent to aquatic plants and animals (e.g. Searcy-Bernal 1996, Rink et al 1998, Ploug et al 1999, Kohler-Rink & Kuhl 2000.…”

Section: Discussionmentioning

confidence: 99%

Hyperoxic boundary layers inhabited by the epiphytic meiofauna of Fucus serratus

Irwin

Davenport²

2002

Mar. Ecol. Prog. Ser.

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Opto-chemical microsensors were used to gather information about oxygen levels close to the thallus surface of Fucus serratus L. Oxygen tensions as high as 560% air saturation were recorded at the seaweed surface in seawater under static conditions at a light intensity of 229.5 µmol photon m -2 s -1. This level of oxygen supersaturation was restricted to a thin layer directly above the seaweed surface and a steep oxygen gradient was observed through the boundary layer, which extended to a distance of 1 to 2 mm in a static water body. Although remaining considerably elevated relative to the oxygen tension in the surrounding water, oxygen tensions at the seaweed surface were reduced under flow conditions. The thickness of the oxygen-supersaturated boundary layer decreased to less than 1 mm under flow conditions. However, flow rate itself did not have a significant effect on oxygen tensions at the seaweed surface or on the depth of the boundary layer. A rapid reaction of oxygen tension within the boundary layer was observed in response to initiation or cessation of flow. In darkness, under static conditions, the oxygen tension at the seaweed surface decreased to as little as 40% air saturation. Under these conditions, oxygen tension increased through the boundary layer, reaching levels similar to the surrounding water in less than 1 mm. These data indicate that small epiphytic animals (copepods, nematodes etc.) encounter highly hyperoxic conditions during daytime, even when there is water flow over seaweed. They are therefore exposed to the possibility of hyperoxic/free radical damage, even though living in an apparently benign environment.

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Section: Discussionmentioning

confidence: 99%

Hyperoxic boundary layers inhabited by the epiphytic meiofauna of Fucus serratus

Irwin

Davenport²

2002

Mar. Ecol. Prog. Ser.

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“…O 2 penetration depth was determined in situ with a profiling lander equipped with four O 2 microelectrodes and two deep-penetrating optical O 2 microsensors (optodes) 25 . Enrichment experiments were carried out with three identical benthic chamber landers, each equipped with three chambers (0.2 £ 0.2 m) 26 .…”

Section: Methods Experimental Designmentioning

confidence: 99%

“…After taxonomic identification, all specimen were freeze-dried in vacuo for the subsequent determination of 12 C/ 13 C ratios with an ANCA 20-20 (Europe Scientific) isotope ratio mass spectrometer (IRMS) 25 . For Foraminifera, 15-40 cm 3 of surficial sediment (0-1 cm) was sieved over 30 mm and stored frozen.…”

Section: Sample Processingmentioning

confidence: 99%

In situ experimental evidence of the fate of a phytodetritus pulse at the abyssal sea floor

Witte

Wenzhöfer

Sommer

et al. 2003

Nature

232

186

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“…The optodes were calibrated on board at in situ temperature using a 2-point calibration at zero oxygen and air saturation as well as the constant reading in the bottom water before lid closure. The on board calibration was compensated for pressure in accordance with Glud et al (1999) and Wenzhöfer et al (2001). Oxygen penetration depth (OPD) and diffusive oxygen uptake (DOU) were determined by shipboard microelectrode measurements in recovered sediment cores with undisturbed sediment surfaces.…”

Section: Methodsmentioning

confidence: 99%

Rapid response of a deep-sea benthic community to POM enrichment: an in situ experimental study

Witte¹,

Aberle²,

Sand³

et al. 2003

Mar. Ecol. Prog. Ser.

155

118

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A series of in situ enrichment experiments was carried out at 1265 m water depth in the Sognefjord on the west coast of Norway in order to follow the short-term fate of freshly settled phytodetritus in a deep-sea sediment. For all experiments, a deep-sea benthic chamber lander system was used. In the lander chambers, a settling spring bloom was simulated by the injection of 0.2 g of freeze-dried Thalassiosira rotula, an equivalent of 1 g organic C m -2 . The algae were 98% 13 C-labeled, thus enabling us to follow the processing of the carbon by bacteria and macrofauna. Experiment duration varied from 8 h to 3 d. The total oxygen consumption of the sediments increased by approximately 25% due to particulate organic matter (POM) enrichment. Macrofauna organisms became immediately labeled with 13 C. After 3 d, 100% of the individuals sampled down to 10 cm sediment depth had taken up 13 C from the phytodetritus added. Bacterial uptake of the tracer was fast too, and even bacteria in deeper sediment layers had incorporated the fresh material within 3 d. Our study documents the rapid downward mixing of labile organic matter and the importance of macrofauna for this process. We present the first evidence for the immediate breakdown and incorporation of POM by bacteria even in deep sediment layers. Surprisingly, the initial processing of carbon was dominated by macrofauna, although the group comprises < 5% of the benthic biomass.Altogether, approximately 5% of the carbon added had been processed within 3 d, with the majority being released from the sediment as CO 2 . Due to the good comparability of our study site with midslope settings at continental margins, in general, we propose that the processes we observed are widespread at continental margins and are significant for the biogeochemical cycling of particulate matter on the slope.

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Deep penetrating benthic oxygen profiles measured in situ by oxygen optodes

Cited by 55 publications

References 40 publications

Hyperoxic boundary layers inhabited by the epiphytic meiofauna of Fucus serratus

Hyperoxic boundary layers inhabited by the epiphytic meiofauna of Fucus serratus

In situ experimental evidence of the fate of a phytodetritus pulse at the abyssal sea floor

Rapid response of a deep-sea benthic community to POM enrichment: an in situ experimental study

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