Research project: Effects of global climate change (elevated CO2 and UVB radiation) on the physiological performance of microalgae

The microalgae that comprise the marine phytoplankton contribute up to 45% of the total global annual primary productivity and thereby fix carbon dioxide into organic matter. They thus represent a major biological sink for atmospheric CO2 (Longhurst 1991; Rau et al. 1989).

Given that phytoplankton activity is believed to have accounted for ~30% of the carbon sequestered since the onset of the Industrial Revolution, the ecological consequences of changes in phytoplankton primary production are enormous. Although it is generally accepted that global atmospheric CO2 levels will increase dramatically in the future, and the increase in UVBR at high latitudes is well documented, very little is known about the ways in which phytoplankton will react to the combined effects of such components of climate change and the effects this might have on oceanic primary productivity and the role of the oceans as a sink for anthropogenically generated CO2.

Even a small change (10-20%) in phytoplankton growth rate would represent a change in the annual global production of dry matter of ~3.5-10 x109 tonnes. This project therefore seeks to investigate the effects of global climate change on photosynthesis, nutrient acquisition and growth of marine phytoplankton.

Specifically we are investigating the following questions:

  • Will elevated CO2 levels, sufficient to partially down-regulate the CO2 concentrating mechanism (CCM), render phytoplankton cells more susceptible to UVB inhibition of photosynthesis and growth?
  • Will cells without CCM capacity show a different susceptibility to UVB under elevated CO2than under present day atmospheric CO2 concentrations.
  • Does UVB have differing effects on the physiological performance of organisms with CCMs based on CO2 vs HCO3- transport?
  • What are the effects of UVB and elevated CO2 on nutrient uptake and assimilation by algae?
  • Will elevated CO2 and UVB affect the macromolecular content of microalgae and their secretion of extracellular materials?
  • How will global climate change affect the flow of energy and elements such as C, N & P to higher trophic levels?
  • These questions are being investigated through a variety of approaches ranging from growth measurements through to biochemistry and molecular biology.

For further information see:

Beardall, J. and Raven J.A. (2004) The potential effects of global climate change on microalgal photosynthesis, growth and ecology. Phycologia 43: 31-45.
Shelly K., Heraud P. and Beardall, J. (2003) Interactive effects of PAR and UV-B radiation on PSII electron transport in the marine alga Dunaliella tertiolecta (Chlorophyceae) Journal of Phycology 39: 509-512.
Shelly, K., Heraud, P. and Beardall, J (2002) Nitrogen limitation in Dunaliella tertiolectaButcher (Chlorophyceae) leads to increased susceptibility to damage by ultraviolet-B radiation but also increased repair capacity. Journal of Phycology 38: 1-8.