Calcareous green alga Halimeda tolerates ocean acidification conditions at tropical carbon dioxide seeps
Nikolas Vogel
Katharina Elisabeth Fabricius
Julia Strahl
Sam Hamilton Croft Noonan
Christian Wild
Sven Uthicke
Abstract
We investigated ecological, physiological, and skeletal characteristics of the calcifying green alga Halimeda grown at CO2 seeps (pHtotal ∼ 7.8) and compared them to those at control reefs with ambient CO2 conditions (pHtotal ∼ 8.1). Six species of Halimeda were recorded at both the high CO2 and control sites. For the two most abundant species Halimeda digitata and Halimeda opuntia we determined in situ light and dark oxygen fluxes and calcification rates, carbon contents and stable isotope signatures. In both species, rates of calcification in the light increased at the high CO2 site compared to controls (131% and 41%, respectively). In the dark, calcification was not affected by elevated CO2 in H. digitata, whereas it was reduced by 167% in H. opuntia, suggesting nocturnal decalcification. Calculated net calcification of both species was similar between seep and control sites, i.e., the observed increased calcification in light compensated for reduced dark calcification. However, inorganic carbon content increased (22%) in H. digitata and decreased (−8%) in H. opuntia at the seep site compared to controls. Significantly, lighter carbon isotope signatures of H. digitata and H. opuntia phylloids at high CO2 (1.01‰ [parts per thousand] and 1.94‰, respectively) indicate increased photosynthetic uptake of CO2 over HCO3− potentially reducing dissolved inorganic carbon limitation at the seep site. Moreover, H. digitata and H. opuntia specimens transplanted for 14 d from the control to the seep site exhibited similar δ13C signatures as specimens grown there. These results suggest that the Halimeda spp. investigated can acclimatize and will likely still be capable to grow and calcify in P CO 2 conditions exceeding most pessimistic future CO2 projections.
Vogel N., Fabricius K.E., Strahl J., Noonan S.H.C., Wild C. and Uthicke S. (2015) Calcareous green alga Halimeda tolerates ocean acidification conditions at tropical carbon dioxide seeps. 60(1): 263-275. 10.1002/lno.10021
@article{Vogel2015,
Title = {Calcareous green alga Halimeda tolerates ocean acidification conditions at tropical carbon dioxide seeps},
Author = {Vogel, Nikolas and Fabricius, Katharina Elisabeth and Strahl, Julia and Noonan, Sam Hamilton Croft and Wild, Christian and Uthicke, Sven},
Editor = {},
Year = {2015},
Pages = {263-275},
Volume = {60},
Doi = {10.1002/lno.10021},
Abstract = {We investigated ecological, physiological, and skeletal characteristics of the calcifying green alga Halimeda grown at CO2 seeps (pHtotal ∼ 7.8) and compared them to those at control reefs with ambient CO2 conditions (pHtotal ∼ 8.1). Six species of Halimeda were recorded at both the high CO2 and control sites. For the two most abundant species Halimeda digitata and Halimeda opuntia we determined in situ light and dark oxygen fluxes and calcification rates, carbon contents and stable isotope signatures. In both species, rates of calcification in the light increased at the high CO2 site compared to controls (131% and 41%, respectively). In the dark, calcification was not affected by elevated CO2 in H. digitata, whereas it was reduced by 167% in H. opuntia, suggesting nocturnal decalcification. Calculated net calcification of both species was similar between seep and control sites, i.e., the observed increased calcification in light compensated for reduced dark calcification. However, inorganic carbon content increased (22%) in H. digitata and decreased (−8%) in H. opuntia at the seep site compared to controls. Significantly, lighter carbon isotope signatures of H. digitata and H. opuntia phylloids at high CO2 (1.01‰ [parts per thousand] and 1.94‰, respectively) indicate increased photosynthetic uptake of CO2 over HCO3− potentially reducing dissolved inorganic carbon limitation at the seep site. Moreover, H. digitata and H. opuntia specimens transplanted for 14 d from the control to the seep site exhibited similar δ13C signatures as specimens grown there. These results suggest that the Halimeda spp. investigated can acclimatize and will likely still be capable to grow and calcify in P CO 2 conditions exceeding most pessimistic future CO2 projections.},
}
TY - JOUR
AU - Vogel, Nikolas
AU - Fabricius, Katharina Elisabeth
AU - Strahl, Julia
AU - Noonan, Sam Hamilton Croft
AU - Wild, Christian
AU - Uthicke, Sven
TI - Calcareous green alga Halimeda tolerates ocean acidification conditions at tropical carbon dioxide seeps
PY - 2015
SP - 263-275
VL - 60
DO - 10.1002/lno.10021
AB - We investigated ecological, physiological, and skeletal characteristics of the calcifying green alga Halimeda grown at CO2 seeps (pHtotal ∼ 7.8) and compared them to those at control reefs with ambient CO2 conditions (pHtotal ∼ 8.1). Six species of Halimeda were recorded at both the high CO2 and control sites. For the two most abundant species Halimeda digitata and Halimeda opuntia we determined in situ light and dark oxygen fluxes and calcification rates, carbon contents and stable isotope signatures. In both species, rates of calcification in the light increased at the high CO2 site compared to controls (131% and 41%, respectively). In the dark, calcification was not affected by elevated CO2 in H. digitata, whereas it was reduced by 167% in H. opuntia, suggesting nocturnal decalcification. Calculated net calcification of both species was similar between seep and control sites, i.e., the observed increased calcification in light compensated for reduced dark calcification. However, inorganic carbon content increased (22%) in H. digitata and decreased (−8%) in H. opuntia at the seep site compared to controls. Significantly, lighter carbon isotope signatures of H. digitata and H. opuntia phylloids at high CO2 (1.01‰ [parts per thousand] and 1.94‰, respectively) indicate increased photosynthetic uptake of CO2 over HCO3− potentially reducing dissolved inorganic carbon limitation at the seep site. Moreover, H. digitata and H. opuntia specimens transplanted for 14 d from the control to the seep site exhibited similar δ13C signatures as specimens grown there. These results suggest that the Halimeda spp. investigated can acclimatize and will likely still be capable to grow and calcify in P CO 2 conditions exceeding most pessimistic future CO2 projections.
ER -
