Photosynthesis is expected to rise with ocean CO2 levels, and corals contain photosynthesizing algae, so won corals benefit from rising CO2?
The photosynthesis of some, but not all, algae increases when CO2 rises to levels projected for the end of this century (700-800 ppm). The single-celled algae called zooxanthellae that live within coral animals’ cells are some of the algae whose photosynthesis does not significantly increase at projected future CO2 levels. Normally, zooxanthellae and corals maintain a delicately balanced symbiosis, in which the zooxanthellae transfer photosynthetically formed carbon-based nutrition to the coral host and provide an important source of carbon for the coral and for coral calcification (skeleton building). If the algae within the corals’ cells do too well and their numbers greatly increase, the transfer of nutrition to the coral host can be disrupted. So even if zooxanthellae photosynthesis were to increase under high CO2, this does not necessarily benefit the corals. In the great majority of experiments, coral calcification rate decreases when the CO2 level increases, so it is clear that
Related Questions
- What is the correlation between human activity and the rise in CO2 levels? Is there a correlation between CO2 levels and global temperatures?
- If photosynthesis increases with ocean CO2 levels, won?t phytoplankton and seagrasses do better?
- If photosynthesis increases with ocean CO2 levels, wont phytoplankton and seagrasses do better?
