Biodiversity improves water quality in streams through a division of labour
08 Apr 2011
Biologically diverse streams are better at cleaning up pollutants than less rich waterways, and a University of Michigan ecologist says he has uncovered the long-sought mechanism that explains why this is so.
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| Ecologist Bradley Cardinale, an assistant professor at the U-M School of Natural Resources and Environment. Credit: Bradley Cardinale |
Bradley Cardinale used 150 miniature model streams, which use recirculating water in flumes to mimic the variety of flow conditions found in natural streams.
He grew between one and eight species of algae in each of the mini-streams, then measured each algae community's ability to soak up nitrate, a nitrogen compound that is a nutrient pollutant of global concern.
He found that nitrate uptake increased linearly with species richness. On average, the eight-species mix removed nitrate 4.5 times faster than a single species of algae grown alone. Cardinale reports his findings in the April 7 edition of the journal Nature.
"The primary implication of this paper is that naturally diverse habitats are pretty good at cleaning up the pollutants we dump into the environment, and loss of biodiversity through species extinctions could be compromising the ability of the planet to clean up after us," said Cardinale, an assistant professor at the University of Michigan School of Natural Resources and Environment.
Why are more diverse streams better pollutant filters? Niche partitioning, Cardinale said.
