Mechanisms of bicarbonate use influence the photosynthetic carbon dioxide sensitivity of tropical seagrasses
Permanent Link:

Material Information

Title:
Mechanisms of bicarbonate use influence the photosynthetic carbon dioxide sensitivity of tropical seagrasses
Series Title:
Limnology and Oceanography Methods
Creator:
Campbell, Justin E.
Fourqurean, James W.
Publisher:
Association for the Sciences of Limnology and Oceanography
Publication Date:
Language:
English

Subjects

Subjects / Keywords:
Seagrasses -- Florida
Carbon dioxide -- Florida
Photosynthesis -- Florida
Genre:
article
serial ( sobekcm )
Spatial Coverage:
Florida
Coordinates:
28 x -82

Notes

Abstract:
The photosynthetic bicarbonate (HCO3) use properties of three widely distributed tropical seagrasses were compared using a series of laboratory experiments. Photosynthetic rates of Thalassia testudinum, Halodule wrightii, and Syringodium filiforme were monitored in an enclosed chamber while being subjected to shifts in pH and dissolved inorganic carbon. Specific mechanisms of seagrass use were compared by examining the photosynthetic effects of the carbonic anhydrase inhibitor acetazolamide (AZ). All seagrasses increased photosynthetic rates with reduced pH, suggesting a large effect of dissolved aqueous carbon dioxide (CO2(aq)). However, there was considerable interspecific variation in pH response. T. testudinum was highly sensitive, increasing photosynthetic rates by 100% as the pH was reduced from 8.2 to 7.4, whereas rates in H. wrightii and S. filiforme increased by only 20% over a similar range, and displayed prominent photosynthetic plateaus, indicating an increased capacity for use. Additional incubations that manipulated [] under constant [CO2(aq)] support these findings, as only H. wrightii and S. filiforme increased photosynthetic rates with increasing []. T. testudinum responded to AZ addition, indicating that carbonic anhydrase enzymes facilitate limited use. H. wrightii and S. filiforme showed no response to AZ, suggesting alternate, more efficient mechanisms of use. Estimated kinetic parameters, Ks(CO2) and Vmax, revealed interspecific variation and further support these conclusions. Variation in photosynthetic pH responses and AZ sensitivity indicate distinctions in the carbon use properties of seagrasses exposed to similar environmental conditions. These results suggest that not all seagrasses will similarly respond to future increases in CO2(aq) availability. Attention towards potential shifts in competitive interactions within multispecific seagrass beds is warranted.
General Note:
Limnology and Oceanography Methods (3), 2013, 839–848

Record Information

Source Institution:
Florida International University
Rights Management:
Please contact the owning institution for licensing and permissions. It is the users responsibility to ensure use does not violate any third party rights.
Resource Identifier:
FI14082507
10.4319/lo.2013.58.3.0839 ( doi )