The Roles of Algae in Biogeochemistry

Phycologists know that we humans wouldn't be here if the algae hadn't come first,
filling the atmosphere with oxygen (and providing a protective layer of
stratospheric ozone), drawing down carbon dioxide levels sufficiently to reduce global
heating, supplying our metazoan ancestors with plenty of fixed carbon, and
evolving into the higher plants upon which we now depend. But many people
are not aware of the significant services that algae provide. This chapter
describes important past and present biogeochemical impacts of algae, including
roles of algae in carbon cycling, algal utilization of nitrogen, the roles of
nutrient enrichment in the formation of nuisance algal blooms, and sulfur cycle
impacts on climate. This chapter will particularly interest students who
are majoring in geological and atmospheric sciences and water chemistry.