Contemporary reliance on bicarbonate acquisition predicts increased growth of seagrass Amphibolis antarctica in a high-CO2 world

Burnell, Owen W.; Connell, Sean D.; Irving, Andrew D.; Watling, Jennifer R.; Russell, Bayden D.

doi:10.1093/conphys/cou052

Cited by 20 publications

(17 citation statements)

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“…Studies had indicated that greater availability of DIC under future OA conditions may benefit seagrasses [ 13 – 15 ]. An increase in photosynthesis and growth following exposure to increased DIC in both tropical and temperate species was previously demonstrated [ 16 – 22 ]. Moreover, since tropical and temperate seagrasses displayed a higher photosynthetic affinity for CO 2 than HCO 3 - , an increased availability of CO 2 can further boost productivity [ 23 , 24 ].…”

Section: Introductionmentioning

confidence: 90%

“…At natural CO 2 vent sites, growth and areal cover of seagrasses were observed to be much greater than at adjacent non-CO 2 enriched sites [ 15 , 25 ]. Hence, given sufficient light and nutrient availability, seagrasses could utilise the extra provisioning of DIC to enhance productivity [ 9 , 22 , 23 , 26 ].…”

Section: Introductionmentioning

confidence: 99%

“…Another uptake pathway involves H + extrusion-driven co-transport of H + and HCO 3 - [ 30 ]. In general, active extrusion of H + into localized regions of the leaf boundary layer (acidic zones) for HCO 3 - utilisation is energetically costly compared to passive CO 2 uptake, and thus could be limited by low light levels [ 22 ].…”

Section: Introductionmentioning

confidence: 99%

“…Fluctuating light availability [ 31 – 33 ] could vary the carbon demand for the downstream carbon fixation cycle. On the other hand, elevated DIC (with CO 2 as substrate) increased photosynthetic efficiency and reduced light requirements of seagrasses [ 19 , 22 ]. So far, the interaction of light and DIC availability on seagrass photosynthesis has only been explored in a few studies [ 16 , 19 , 34 – 36 ].…”

Section: Introductionmentioning

confidence: 99%

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Light Levels Affect Carbon Utilisation in Tropical Seagrass under Ocean Acidification

Uthicke

Collier

2016

PLoS ONE

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Under future ocean acidification (OA), increased availability of dissolved inorganic carbon (DIC) in seawater may enhance seagrass productivity. However, the ability to utilise additional DIC could be regulated by light availability, often reduced through land runoff. To test this, two tropical seagrass species, Cymodocea serrulata and Halodule uninervis were exposed to two DIC concentrations (447 μatm and 1077 μatm pCO2), and three light treatments (35, 100, 380 μmol m-2 s-1) for two weeks. DIC uptake mechanisms were separately examined by measuring net photosynthetic rates while subjecting C. serrulata and H. uninervis to changes in light and addition of bicarbonate (HCO3-) use inhibitors (carbonic anhydrase inhibitor, acetazolamide) and TRIS buffer (pH 8.0). We observed a strong dependence on energy driven H+-HCO3- co-transport (TRIS, which disrupts H+ extrusion) in C. serrulata under all light levels, indicating greater CO2 dependence in low light. This was confirmed when, after two weeks exposure, DIC enrichment stimulated maximum photosynthetic rates (Pmax) and efficiency (α) more in C. serrulata grown under lower light levels (36–60% increase) than for those in high light (4% increase). However, C. serrulata growth increased with both DIC enrichment and light levels. Growth, NPP and photosynthetic responses in H. uninervis increased with higher light treatments and were independent of DIC availability. Furthermore, H. uninervis was found to be more flexible in HCO3- uptake pathways. Here, light availability influenced productivity responses to DIC enrichment, via both carbon fixation and acquisition processes, highlighting the role of water quality in future responses to OA.

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Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Light Levels Affect Carbon Utilisation in Tropical Seagrass under Ocean Acidification

Uthicke

Collier

2016

PLoS ONE

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“…Lower CR during exposed condition may increase the overall community production of exposed Z. noltei compared to submerged conditions where CR rates are higher. As well, during submersion Z. noltei favors the utilization of bicarbonate directly or indirectly to increase its production (Hellblom et al, 2001), but this process is energy intensive (Burnell et al, 2014), whereas the air exposed community during exposure, because of its high affinity and high availability of CO 2 in future conditions, can easily use the CO 2 from the atmosphere for community production (Touchette and Burkholder, 2007). The other factors that can contribute to the higher production of air-exposed Z. noltei community under CO 2 enriched conditions can be high light intensity and low turbidity.…”

Section: Co 2 Enrichmentmentioning

confidence: 99%

Short Term CO2 Enrichment Increases Carbon Sequestration of Air-Exposed Intertidal Communities of a Coastal Lagoon

2018

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In situ production responses of air-exposed intertidal communities under CO 2 enrichment are reported here for the first time. We assessed the short-term effects of CO 2 on the light responses of the net community production (NCP) and community respiration (CR) of intertidal Z. noltei and unvegetated sediment communities of Ria Formosa lagoon, when exposed to air. NCP and CR were measured in situ in summer and winter, under present and CO 2 enriched conditions using benthic chambers. Within chamber CO 2 evolution measurements were carried out by a series of short-term incubations (30 min) using an infra-red gas analyser. Liner regression models fitted to the NCP-irradiance responses were used to estimate the seasonal budgets of air-exposed, intertidal production as determined by the daily and seasonal variation of incident photosynthetic active radiation. High CO 2 resulted in higher CO 2 sequestration by both communities in both summer and winter seasons. Lower respiration rates of both communities under high CO 2 further contributed to a potential negative climate feedback, except in winter when the CR of sediment community was higher. The light compensation points (LCP) (light intensity where production equals respiration) of Z. noltei and sediment communities also decreased under CO 2 enriched conditions in both seasons. The seasonal community production of Z. noltei was 115.54 ± 7.58 g C m −2 season −1 in summer and 29.45 ± 4.04 g C m −2 season −1 in winter and of unvegetated sediment was 91.28 ± 6.32 g C m −2 season −1 in summer and 25.83 ± 4.01 g C m −2 season −1 in winter under CO 2 enriched conditions. Future CO 2 conditions may increase air-exposed seagrass production by about 1.5-fold and unvegetated sediments by about 1.2-fold.

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Photobiology of Seagrasses: A Systems Biology Perspective

Buapet

2017

Systems Biology of Marine Ecosystems

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Contemporary reliance on bicarbonate acquisition predicts increased growth of seagrass Amphibolis antarctica in a high-CO2 world

Cited by 20 publications

References 64 publications

Light Levels Affect Carbon Utilisation in Tropical Seagrass under Ocean Acidification

Light Levels Affect Carbon Utilisation in Tropical Seagrass under Ocean Acidification

Short Term CO2 Enrichment Increases Carbon Sequestration of Air-Exposed Intertidal Communities of a Coastal Lagoon

Photobiology of Seagrasses: A Systems Biology Perspective

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