Document Type


Article Version

Publisher's PDF

Publication Date



In recent decades, the diatom Didymosphenia geminata has emerged as nuisance species in river systems around the world. This periphytic alga forms large “blooms” in temperate streams, presenting a counterintuitive result: the blooms occur primarily in oligotrophic streams and rivers, where phosphorus (P) availability typically limits primary production. The goal of this study is to examine how high algal biomass is formed under low P conditions. We reveal a biogeochemical process by which D. geminata mats concentrate P from flowing waters. First, the mucopolysaccaride stalks of D. geminata adsorb both iron (Fe) and P. Second, enzymatic and bacterial processes interact with Fe to increase the biological availability of P. We propose that a positive feedback between total stalk biomass and high growth rate is created, which results in abundant P for cell division. The affinity of stalks for Fe in association with iron-phosphorus biogeochemistry suggest a resolution to the paradox of algal blooms in oliogotrophic streams and rivers.


Copyright 2011 by the American Geophysical Union. Published by Wiley Blackwell.

Archived with the permission of the copyright holder - American Geophysical Union.

Publication Title

Geophysical Research Letters

Published Citation

Sundareshwar, PV.; Upadhayay, S.; Abessa, M.; Honomichl, S.; Berdanier, B.; Spaulding, S. A.; Sandvik, C.; Trennepohl, A. “Didymosphenia geminata: Algal blooms in oligotrophic streams and rivers” Geophysical Research Letters 38, no. L10405 (May 28 2011) DOI: 10.1029/2010GL046599



Peer Reviewed