The importance of slime: does living in a community matrix save algal cells from the toxic effects of copper?

Microscopic algae are often used to assess the toxic effects of chemicals to the environment. They are good indicators of ecosystem health because they form the basis of the aquatic food chain and many algal species are sensitive to metals, like copper, at concentrations which occur naturally in the environment. Most toxicity tests with algae use planktonic species, that is, alga that live in the water as free-living species. To date, little research has been done on the toxicity of metals to attached algal species living in a community matrix known as biofilms, because of the difficulties in quantifying changes in such a complex community.