Research that had already been done suggests that if seawater carbon concentrations drop below a quarter of their normal levels, photosynthesis by marine plants and algae my be impacted, and that the upper pH (measure of acidity) limit for growth of seaweeds and seagrass is around 9. We have been releasing water at pH 9.5, but this is instantly diluted on entering the sea (information on dilution of the released water is linked earlier in page and linked here).
We ran experiments at the Plymouth Marine Laboratory to better understand how some marine plants and animals respond to low-carbon seawater. The short-term experiments (2-5 days) studied phytoplankton, zooplankton and blue mussels exposed to different concentrations of low-carbon seawater.
Our experiments showed that short term exposure to low-carbon seawater can impact marine organisms. This is expected as many marine organisms use carbon for growth, and the amount of carbonic acid (from dissolved CO2) influences various biological processes. However, when low-carbon seawater was diluted with ambient seawater, the impacts diminished quickly.
More research is needed as current data cover only a handful of marine species and conditions. To determine whether this kind of technology should be undertaken at commercial scales, much more research is needed - and the Weymouth facility could play a very important role here.