Oxygen Movement in Seagrasses

Borum, Jens; Sand‐Jensen, Kaj; Binzer, Thomas; Pedersen, Ole; Grève, T.

doi:10.1007/978-1-4020-2983-7_10

Cited by 70 publications

(107 citation statements)

References 65 publications

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“…Such H 2 S intrusion into the below-ground tissue of seagrasses has mainly been related to inadequate internal aeration during night-time, as a result of a low water-column O 2 content and thus a decrease in the diffusive O 2 supply from the surrounding water-column (Pedersen et al, 2004;Borum et al, 2005). The amount of O 2 passively diffusing into the leaves from the water-column during darkness, is thus highly dependent on the water-column O 2 content, but is also strongly affected by other factors such as the DBL thickness (Binzer et al, 2005;Borum et al, 2006) and the leaf surface area. The DBL surrounds all aquatic surfaces, such as seagrass leaves, and functions as a diffusive barrier to the exchange of gasses and nutrients with the surrounding water-column by impeding water motions toward the leaf tissue surface (Jørgensen and Revsbech, 1985).…”

Section: Introductionmentioning

confidence: 99%

“…Sinks encompass the total O 2 demand of the surrounding sediment, including bacterial respiration and chemical reactions with reduced compounds, as well as the plants own respiratory needs. The amount of O 2 produced or passively diffusing into the leaves is affected by external physical factors such as the light availability for underwater photosynthesis, the flow-dependent thickness of the DBL and the water-column O 2 content, whereas the sinks are highly affected by elevated seawater temperatures and the quantity of accessible organic matter in the rhizosphere (Pedersen et al, 2004;Binzer et al, 2005;Borum et al, 2006;Raun and Borum, 2013).…”

Section: Introductionmentioning

confidence: 99%

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Epiphyte-cover on seagrass (Zostera marina L.) leaves impedes plant performance and radial O2 loss from the below-ground tissue

et al. 2015

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The O 2 budget of seagrasses is regulated by a complex interaction between several sources and sinks, which is strongly regulated by light availability and mass transfer over the diffusive boundary layer (DBL) surrounding the plant. Epiphyte growth on leaves may thus strongly affect the O 2 availability of the seagrass plant and its capability to aerate its rhizosphere as a defense against plant toxins. We used electrochemical and fiber-optic microsensors to quantify the O 2 flux, DBL, and light microclimate around leaves with and without filamentous algal epiphytes. We also quantified the below-ground radial O 2 loss (ROL) from roots (∼1 mm from the root-apex) to elucidate how this below-ground oxic microzone was affected by the presence of epiphytes. Epiphyte-cover on seagrass leaves (∼21% areal cover) resulted in reduced light quality and quantity for photosynthesis, thus leading to reduced plant fitness. A ∼4 times thicker DBL around leaves with epiphyte-cover impeded gas (and nutrient) exchange with the surrounding water-column and thus the amount of O 2 passively diffusing down to the below-ground tissue through the aerenchyma in darkness. During light exposure of the leaves, radial oxygen loss from the below-ground tissue was ∼2 times higher from plants without epiphyte-cover. In contrast, no O 2 was detectable at the surface of the root-cap tissue of plants with epiphyte-cover during darkness, leaving the plants more susceptible to sulfide intrusion. Epiphyte growth on seagrass leaves thus has a negative effect on the light climate during daytime and O 2 supply in darkness, hampering the plants performance and thereby reducing the oxidation capability of its below-ground tissue.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Epiphyte-cover on seagrass (Zostera marina L.) leaves impedes plant performance and radial O2 loss from the below-ground tissue

et al. 2015

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“…9). This behavior could be related to the pressurization of the aerenchyma at sunrise (Borum et al, 2006), and it might suggest that photosynthetic activity affects the acoustic signal even in the absence of conditions that allow the release of free bubbles. The validation of such a hypothesis would require a further experiment to be conducted in lower productivity conditions.…”

Section: Discussionmentioning

confidence: 99%

Acoustic monitoring of O2 production of a seagrass meadow

Felisberto

Jesus

Zabel

et al. 2015

Journal of Experimental Marine Biology and Ecology

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a b s t r a c t a r t i c l e i n f oAcoustic data were acquired in October 2011 over a Posidonia oceanica meadow in the Bay of la Revellata, Calvi, Corsica. The purpose was to develop an acoustic system for monitoring the oxygen (O 2 ) production of an entire seagrass meadow. In a shallow water area (b38 m), densely covered by P. oceanica, a sound source transmitted signals in 3 different bands (400-800 Hz, 1.5-3.5 kHz and 6.5-8.5 kHz) toward three self-recording hydrophones at a distance of 100 m, over the period of one week. The data show a high correlation between the diel cycle of the acoustic signals' energy received by the hydrophones and the temporal changes in water column O 2 concentration as measured by optodes. The results thus show that a simple acoustic acquisition system can be used to monitor the O 2 -based productivity of a seagrass meadow at the ecosystem level with high temporal resolution. The finding of a significant production of O 2 as bubbles in seagrass ecosystems suggests that net primary production is underestimated by methods that rely on the mass balance of dissolved O 2 measurements.

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“…The samples retrieved by the box corer were immediately sieved through a 1mm mesh sieve in situ to obtain the >1 mm fractions of the OCbio, OCdead and OCcsed. Seagrass bodies have air-filled lacunae so that they float; thus, we considered buoyant seagrass bodies captured by the sieve to be OCbio (Borum et al, 2006). We merged any dead plant structures attached to live seagrass bodies into OCbio because their mass was usually very small.…”

Section: However 15mentioning

confidence: 99%

Contributions of the direct supply of belowground seagrass detritus and trapping of suspended organic matter to the sedimentary organic carbon stock in seagrass meadows

Tanaya¹,

Watanabe²,

Yamamoto³

et al. 2017

Preprint

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Abstract. Carbon captured by marine living organisms is called "blue carbon", and seagrass meadows are a dominant blue carbon sink. However, our knowledge of how seagrass increases sedimentary organic carbon (OC) stocks is limited. We investigated two pathways of OC enrichment: trapping of organic matter in the water column and the direct supply of belowground seagrass detritus. We developed a new type of box corer to facilitate the retrieval of intact cores that preserve the structures of both sediments (including coarse sediments and dead plant structures) and live seagrass bodies. We measured 5 seagrass density, total OC mass (OCtotal) [= live seagrass OC biomass (OCbio) + sedimentary OC mass (OCsed)], and the stable carbon isotope ratio (δ 13 C) of OCsed at back-reef and estuarine sites in the tropical Indo-Pacific region. OCbio accounted for 19% and OCsed for 81% of OCtotal; this contribution of OCbio to OCtotal is the highest in globally compiled data. Belowground detritus accounted for ~90% of the OC mass of dead plant structures (>2 mm in size) (OCdead). At the back-reef site, belowground seagrass biomass, OCdead, and δ 13 C of OCsed (δ 13 Csed) were positively correlated with OCsed, indicating that the 10 direct supply of belowground seagrass detritus is a major mechanism of OCsed enrichment. At the estuarine site, aboveground seagrass biomass was positively correlated with OCsed but δ 13 Csed did not correlate with OCsed, indicating that trapping of suspended OC by seagrass leaves is a major mechanism of OCsed enrichment there. We inferred that the relative importance of these two pathways may depend on the supply (productivity) of belowground biomass. Our results indicate that belowground biomass productivity of seagrass meadows, in addition to their aboveground morphological complexity, is an important factor 15 controlling their OC stock. Consideration of this factor will improve global blue-carbon estimates.Biogeosciences Discuss., https://doi

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Oxygen Movement in Seagrasses

Cited by 70 publications

References 65 publications

Epiphyte-cover on seagrass (Zostera marina L.) leaves impedes plant performance and radial O2 loss from the below-ground tissue

Epiphyte-cover on seagrass (Zostera marina L.) leaves impedes plant performance and radial O2 loss from the below-ground tissue

Acoustic monitoring of O2 production of a seagrass meadow

Contributions of the direct supply of belowground seagrass detritus and trapping of suspended organic matter to the sedimentary organic carbon stock in seagrass meadows

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