Ecosystems are highly complex webs of species that mix in space and time, creating intricate relationships and feedbacks that are difficult to study, regardless of changes in acidification. Shell-forming species seem to be highly sensitive to changes in pH, in fact some species have been directly and negatively impacted by acidification – there is a vast and growing body of literature on this including responses like metabolic changes in fish and subsequent behavioral or generational impacts. On the other hand, photosynthesizing plants in the ocean (algae and seagrasses) use CO2, so they stand to benefit. In the case of algae, it is possible that elevated CO2 will help boost growth. In fact, as more and more research is done on the effects of elevated CO2 and decreased pH on marine organisms, the results can differ depending on what species is being studied and how the studies are done.
Understanding the influence of acidification on entire ecosystems is difficult due to both the complexity of the chemistry and the complexity of marine ecosystems themselves. Very specific and technical experiments must be performed to recreate the acidified carbonate chemistry conditions of the Mid-Atlantic ocean. The problem is exacerbated by the interactions of changes in pH with changes in other environmental characteristics such as temperature, eutrophication and increases in UV radiation. These interactions, or multiple stressors, can sometimes exacerbate the impacts of changes in pH; or in other cases buffer against those impacts or even reverse them. Careful and extensive experiments are necessary to tease these apart.