A H2S microsensor for profiling biofilms and sediments: application in an acidic lake sediment

Kühl, Michael; Steuckart, Carsten; Eickert, Gabriele; Jeroschewski, Paul

doi:10.3354/ame015201

Cited by 172 publications

(102 citation statements)

References 22 publications

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“…At each sampling time microsensor measurements were conducted in the sediment layers of two coral fragments per treatment (one per tank). O 2 , H 2 S, pH, and light microsensors were prepared as described previously (51)(52)(53)(54). The pH sensors were modified for field measurements as described by Weber et al (55).…”

Section: Methodsmentioning

confidence: 99%

Mechanisms of damage to corals exposed to sedimentation

Weber

Beer

Lott

et al. 2012

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

202

139

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We investigated the mechanisms leading to rapid death of corals when exposed to runoff and resuspended sediments, postulating that the killing was microbially mediated. Microsensor measurements were conducted in mesocosm experiments and in naturally accumulated sediment on corals. In organic-rich, but not in organic-poor sediment, pH and oxygen started to decrease as soon as the sediment accumulated on the coral. Organic-rich sediments caused tissue degradation within 1 d, whereas organic-poor sediments had no effect after 6 d. In the harmful organic-rich sediment, hydrogen sulfide concentrations were low initially but increased progressively because of the degradation of coral mucus and dead tissue. Dark incubations of corals showed that separate exposures to darkness, anoxia, and low pH did not cause mortality within 4 d. However, the combination of anoxia and low pH led to colony death within 24 h. When hydrogen sulfide was added after 12 h of anoxia and low pH, colonies died after an additional 3 h. We suggest that sedimentation kills corals through microbial processes triggered by the organic matter in the sediments, namely respiration and presumably fermentation and desulfurylation of products from tissue degradation. First, increased microbial respiration results in reduced O 2 and pH, initiating tissue degradation. Subsequently, the hydrogen sulfide formed by bacterial decomposition of coral tissue and mucus diffuses to the neighboring tissues, accelerating the spread of colony mortality. Our data suggest that the organic enrichment of coastal sediments is a key process in the degradation of coral reefs exposed to terrestrial runoff.

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Section: Methodsmentioning

confidence: 99%

Mechanisms of damage to corals exposed to sedimentation

Weber

Beer

Lott

et al. 2012

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

202

139

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“…Electrode response was linear and for each profile a two-point calibration was performed in air-saturated medium and anoxic sediment, respectively. Dissolved hydrogen sulphide was measured with a new amperometric H,S microelectrode (Jeroschewski et af., 1996;Kuhl et al, 1998). The electrodes had a tip diameter of 10-20 pm, a stirring sensitivity of < 1-2 % and a 90 ' / o response time <1-2 s. The measuring circuit was composed of a picoammeter using a polarization voltage of +85 mV.…”

Section: Methodsmentioning

confidence: 99%

Growth of green sulphur bacteria in experimental benthic oxygen, sulphide, pH and light gradients

et al. 1998

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The green sulphur bacterium Prosthecochloris aestuarii (strain CE 2401) was cultured in a benthic gradient chamber to study its growth and photosynthetic activity in experimental gradients of oxygen, sulphide and light. An axenic biofilm was obtained within evenly inoculated artificial sediment after 5 weeks of incubation. The phototrophic biofilm was located 2.2-3.5 mm below the sediment surface, i.e. below the maximal penetration depth of oxygen, thus confirming that growth of P. aestuarii was restricted to strictly anoxic sediment layers. The activity was limited by the diffusive flux of sulphide, showing the role of molecular diffusion in growth of this benthic species. Scalar irradiance was attenuated strongly in the biofilm, with distinct attenuation maxima at 750 nm corresponding to bacteriochlorophyll c (Bchl c) absorption and at 800 nm corresponding to bacteriochlorophyll a (Bchl a) absorption. Using radiance attenuation data as a proxy for photopigment contents it was shown that the ratio Bchl a/Bchl c changed with depth. This indicates chromatic adaptation to changing light climates in the sediment. Total sulphide oxidation was estimated from the sulphide fluxes from below into the reaction zone. Measurements of sulphide oxidation as a function of scalar irradiance in the reaction zone showed that anoxygenic photosynthesis of the biofilm was saturated at a scalar irradiance (430-830 nm)>2 μmol photons m-2 s-1.

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“…Total dissolved sulfide concentrations were calculated using a simultaneously measured pH profile according to Kü hl et al (1998). The flux of total sulfide was calculated as the sum of the H 2 S and the HS À fluxes according to Fick's first law of diffusion:…”

Section: Sulfide Profilesmentioning

confidence: 99%

Sulfide induces phosphate release from polyphosphate in cultures of a marine Beggiatoa strain

2010

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Sulfur bacteria such as Beggiatoa or Thiomargarita have a particularly high capacity for storage because of their large size. In addition to sulfur and nitrate, these bacteria also store phosphorus in the form of polyphosphate. Thiomargarita namibiensis has been shown to release phosphate from internally stored polyphosphate in pulses creating steep peaks of phosphate in the sediment and thereby inducing the precipitation of phosphorus-rich minerals. Large sulfur bacteria populate sediments at the sites of recent phosphorite formation and are found as fossils in ancient phosphorite deposits. Therefore, it can be assumed that this physiology contributes to the removal of bioavailable phosphorus from the marine system and thus is important for the global phosphorus cycle. We investigated under defined laboratory conditions which parameters stimulate the decomposition of polyphosphate and the release of phosphate in a marine Beggiatoa strain. Initially, we tested phosphate release in response to anoxia and high concentrations of acetate, because acetate is described as the relevant stimulus for phosphate release in activated sludge. To our surprise, the Beggiatoa strain did not release phosphate in response to this treatment. Instead, we could clearly show that increasing sulfide concentrations and anoxia resulted in a decomposition of polyphosphate. This physiological reaction is a yet unknown mode of bacterial polyphosphate usage and provides a new explanation for high phosphate concentrations in sulfidic marine sediments.

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A H2S microsensor for profiling biofilms and sediments: application in an acidic lake sediment

Cited by 172 publications

References 22 publications

Mechanisms of damage to corals exposed to sedimentation

Mechanisms of damage to corals exposed to sedimentation

Growth of green sulphur bacteria in experimental benthic oxygen, sulphide, pH and light gradients

Sulfide induces phosphate release from polyphosphate in cultures of a marine Beggiatoa strain

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