Water temperatures significantly affect the limits of phytoplankton growth rates: populations near the equator have the potential to grow much faster than strains found in cooler waters, near the poles, given sufficient nutrients. The researchers of this study believe that current models underestimate the effects of rising temperatures on ocean ecosystems. Such models focus on indirect mechanisms, such as how rising temperatures lead to fewer nutrients in surface ocean waters. This study therefore investigated the direct effect of higher temperatures on individual phytoplankton species.
The scientists used an eco-evolutionary model to investigate how phytoplankton adapts to current ocean temperatures. They also used species distribution models, to predict how ocean temperature changes would affect populations.
Rising temperatures will thus affect phytoplankton in different ways, depending on their location. Until we learn more about how phytoplankton evolves, there is significant uncertainty regarding how these organisms will respond to climate change and to what extent we can rely upon them to remove CO2 from our atmosphere. The future health of the ocean ecosystems that depend on them is also threatened.
Source: European Commission News Alert: Science for Environment Policy
Thomas, M.K., Kremer, C.T., Klausmeier, C.A., and Litchman, E. (2012) A Global Pattern of Thermal Adaptation in Marine Phytoplankton. Science. 338: 1085-1088.