Rhodopsin containing marine bacteria don't make oxygen.
Algae and phytoplankton make oxygen and use carbon dioxide with chlorophyll like other land plants. This also means they help us survive by providing oxygen and using up the carbon dioxide that we exhale - animals and plants live in harmony. This also means they have been helping reduce the amount of greenhouse gases which add to climate change.
Another type of bacteria common in ocean water doesn't use carbon dioxide or create oxygen. They can create energy with sunlight but not in the same way as plants do with chlorophyll, they make it with rhodopsin, a light absorbing pigment that is also found in the human eye. Rhodopsin can convert a signal perceived as light in the eye into a nerve signal which will then be interpreted by other areas of the brain as to shape or color or movement of the light signal.
The ocean has been absorbing a large amount of the carbon dioxide that human civilization creates in various ways. The increase in carbon dioxide in the ocean increases the acidity of the water which is already harming some species. As the temperature and acidity of the ocean waters increase it is possible that the rhodopsin containing bacteria may become more prevalent and chlorophyll containing microbes may become less so which could add to the risk of climate change as less carbon dioxide would be used and less oxygen would be created.
The air we breathe is in a constant cycle flowing upward with the evaporation of water from the ocean and other bodies of water, and then falling downward as rain or snow. We need our air, our atmoshere, to contain enough oxygen for our survival and for all the other animals that breathe oxygen.
A marine microbe could play increasingly important role in regulating climate: A light-snatching bacteria may get its place in the sun and alter how oceans absorb carbon dioxide -- *less carbon dioxide could be used by chlorophyll containing marine microbes if the population of microbes shifted towards the rhodopsin containing bacteria. (sciencedaily.com)
Marine Bacterial and Archaeal Ion-Pumping Rhodopsins: Genetic Diversity, Physiology, and Ecology, ( mmbr.asm.org).
Disclaimer: Information provided for educational purposes within the guidelines of Fair Use.