Research Projects

Didymosphenia geminata studies at the Systems Microbial Ecology Laboratory (SMEL) in the Division of Earth and Ecosystems Sciences at the Desert Research Institute, Reno, NV

PI: Christian H. Fritsen

Keywords: Didymosphenia geminata, algae, nuisance growth, stalked diatom, SMEL

In the past two decades, the stalked diatom Didymosphenia geminata, (Lyngbye) M.Schimdt 1899 has proliferated in what was considered its historic range and invaded new ranges. This change in growth patterns has generated considerable interest and concern around the world.

In the fall of 2005, SMEL lab first found D. geminata in Lee Vining Creek in the Eastern Sierra Nevada. By early winter of 2006, Andy Rost, PhD candidate at the University of Nevada, Reno, working with Dr. Chris Fritsen and the SMEL lab, embarked on several research projects focusing on aspects of D. geminata ecophysiology and potential ecological consequences of nuisance growth.

Their research is organized into three studies;

1. Distribution of Didymosphenia geminata in Sierra Nevada streams in relation to water chemistry and watershed geology.

   We conducted a series of stream surveys in the Sierra Nevada to link presence as well as coverage of D. geminata to water chemistry and watershed geology to gain insights into aspects of D. geminata ecophysiology and add to distribution and risk assessment models.

2. Potential nutrient limitations of D. geminata with an emphasis on micro and macro nutrients.

   A series of nutrient diffusing substrate have been deployed into several streams in the Sierra Nevada in an effort to identify if D. geminata growth is limited by macro and/or micronutrients.

3. Can Didymosphenia geminata form ecologically disruptive algal blooms (EDAB)?

   We analyzed community composition, stable isotopes δ13C and δ15N signatures, grazer biomass, and carbon/nitrogen ratios in benthic algae and macroinvertebrates and fish in stream reaches with extensive D. geminata cover to determine if D. geminata can form EDABs.

D.geminata cell in Annalid gut
Images taken by C. Davis (100x and 200x)

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