New paper on ocean acidification: Ocean Acidification-Induced Food Quality Deterioration Constrains Trophic Transfer by Rossoll et al., PLoS One.
OA is expected to have far-reaching consequences for marine communities and ecosystems. To date, however, our understanding of the possible impacts of OA is based almost exclusively on single species responses. Here we investigate whether OA can affect trophic interactions by changing the nutritional quality of primary producers and how that translates to higher trophic levels. Our results show that OA can indirectly affect zooplankton growth through its impact on the nutritional quality of phytoplankton, their major food source. We found that the amount of total fatty acids (FAs) and FAs essential for copepod growth and reproduction declined in the food source at increasing levels of OA. Because copepods must obtain these macromolecules from their diet, the shift in algal FA directly transferred to copepods and caused a significant decrease in copepod egg production.
The classic diatom-copepod-fish link in the ocean supports some of the most productive ecosystems in the world and is an important source of highly nutritious food for fish and humans. While previous experiments showed no direct effect of elevated CO2 on copepod growth and reproduction when fed with unmanipulated CO2 diet, our study demonstrates that OA can have far-reaching consequences for ocean food webs by changing the nutritional quality of essential macromolecules in primary producers, cascading up the food web.