ORCID Profile
0000-0002-4861-6563
Current Organisation
Københavns Universitet
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Publisher: Wiley
Date: 22-03-2016
DOI: 10.1111/PCE.12658
Abstract: Photosynthesis of most seagrass species seems to be limited by present concentrations of dissolved inorganic carbon (DIC). Therefore, the ongoing increase in atmospheric CO2 could enhance seagrass photosynthesis and internal O2 supply, and potentially change species competition through differential responses to increasing CO2 availability among species. We used short-term photosynthetic responses of nine seagrass species from the south-west of Australia to test species-specific responses to enhanced CO2 and changes in HCO3 (-) . Net photosynthesis of all species except Zostera polychlamys were limited at pre-industrial compared to saturating CO2 levels at light saturation, suggesting that enhanced CO2 availability will enhance seagrass performance. Seven out of the nine species were efficient HCO3 (-) users through acidification of diffusive boundary layers, production of extracellular carbonic anhydrase, or uptake and internal conversion of HCO3 (-) . Species responded differently to near saturating CO2 implying that increasing atmospheric CO2 may change competition among seagrass species if co-occurring in mixed beds. Increasing CO2 availability also enhanced internal aeration in the one species assessed. We expect that future increases in atmospheric CO2 will have the strongest impact on seagrass recruits and sparsely vegetated beds, because densely vegetated seagrass beds are most often limited by light and not by inorganic carbon.
Publisher: Inter-Research Science Center
Date: 1998
DOI: 10.3354/MEPS169283
Publisher: Elsevier BV
Date: 04-1999
Publisher: Wiley
Date: 19-11-2004
Publisher: Elsevier BV
Date: 02-2003
Publisher: Wiley
Date: 03-2004
Publisher: Elsevier BV
Date: 11-2005
Publisher: Elsevier BV
Date: 05-1998
Publisher: Oxford University Press (OUP)
Date: 18-07-2005
DOI: 10.1093/AOB/MCI214
Publisher: Elsevier BV
Date: 11-2002
Publisher: Elsevier BV
Date: 11-2003
Publisher: Wiley
Date: 2003
Publisher: Springer Science and Business Media LLC
Date: 12-10-2014
Publisher: Wiley
Date: 23-02-2016
DOI: 10.1111/NPH.13900
Abstract: Seagrasses grow submerged in aerated seawater but often in low O 2 sediments. Elevated temperatures and low O 2 are stress factors. Internal aeration was measured in two tropical seagrasses, Thalassia hemprichii and Enhalus acoroides , growing with extreme tides and diel temperature litudes. Temperature effects on net photosynthesis ( P N ) and dark respiration ( R D ) of leaves were evaluated. Daytime low tide was characterized by high p O 2 (54 kP a), pH (8.8) and temperature (38°C) in shallow pools. As P N was maximum at 33°C (9.1 and 7.2 μmol O 2 m −2 s −1 in T. hemprichii and E. acoroides , respectively), the high temperatures and reduced CO 2 would have diminished P N , whereas R D increased (Q 10 of 2.0–2.7) above that at 33°C (0.45 and 0.33 μmol O 2 m −2 s −1 , respectively). During night‐time low tides, O 2 declined resulting in shoot base anoxia in both species, but incoming water containing c . 20 kP a O 2 relieved the anoxia. Shoots exposed to 40°C for 4 h showed recovery of P N and R D , whereas 45°C resulted in leaf damage. These seagrasses are ‘living near the edge’, tolerant of current diel O 2 and temperature extremes, but if temperatures rise both species may be threatened in this habitat.
Publisher: Springer Science and Business Media LLC
Date: 10-2003
Publisher: Elsevier BV
Date: 11-1999
No related grants have been discovered for Jens Borum.