Biology Reference
In-Depth Information
Chapter 19
Seaweed Responses to Ocean Acidification
Michael Y. Roleda and Catriona L. Hurd
19.1
Introduction
Since the start of the industrial revolution (~1850), burning fossil fuels, cement
manufacturing, and changes to land use have increased atmospheric carbon dioxide
(CO
2
) concentrations from ~280 to 385 ppm. For the coming decades, the 2007
IPCC report on climate change predicts a continued rapid rise in atmospheric CO
2
leading to significant temperature increases in the atmosphere and ocean (IPCC
2007). Another consequence of increasing anthropogenic CO
2
is a reduction in the
pH of the world's ocean and concomitant changes in seawater carbonate chemistry,
termed ocean acidification. Ocean acidification (OA) may have profound impact on
biogeochemical cycles, marine organisms, ecosystems, and the services they pro-
vide. In combination with warming seas and other stress factors (e.g., eutrophica-
tion, UVR), this will create multiple threats to the marine environment. This chapter
will discuss seawater chemistry and algal carbon physiology, and concentrate on
seaweed responses to OA by themselves and in synergy with other environmental
stresses. Reference to phytoplankton, seagrasses, and corals is made where
appropriate.
19.2 Anthropogenic CO
2
and Seawater Carbonate Chemistry
The world's oceans have taken up ~30% of anthropogenic CO
2
and have buffered
climate change in terrestrial systems by reducing the atmospheric concentration of
this greenhouse gas (Feely et al.
2004
). The air-sea gas exchange equilibrates
surface seawater CO
2
to atmospheric levels with a timescale of ~1 year (Doney
M.Y. Roleda (
*
) • C.L. Hurd
Department of Botany, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
