Didymosphenia geminata in two Alberta headwater rivers: an emerging invasive species that challenges conventional views on algal bloom development.

The diatom Didymosphenia geminata (Bacillariophyceae) has garnered increased attention as a nuisance and invasive species in freshwater systems. Historically described as rare yet cosmopolitan, a suspected new variant of D. geminata has the capacity to inundate kilometres of river bottom during a bloom. Unlike most other bloom-forming algae, D. geminata proliferates under high water quality (i.e., low turbidity and low nutrient) conditions. To inform management strategies, the environmental factors and conditions that promote bloom events must be ascertained. Our study of the Bow and Red Deer rivers in southern Alberta, Canada, provides supporting evidence that the mean flow regime is associated with bloom development, based on a significant negative relationship detected between D. geminata biomass and mean discharge (r2 = 0.30). While flow regulation by dams can create the stable flow environment preferred by D. geminata, our results indicate that flow regime (rather than just proximity to dam outflows)...

[1]  P. Dillon,et al.  A diatom-based index for the biological assessment of eastern Canadian rivers : an application of correspondence analysis (CA) , 2006 .

[2]  B. Kawecka,et al.  Didymosphenia geminata in running waters of southern Poland – symptoms of change in water quality? , 2003, Hydrobiologia.

[3]  B. Biggs,et al.  Taxonomic richness of stream benthic algae: Effects of flood disturbance and nutrients , 2002 .

[4]  J. Lord.  The naturalist in Vancouver Island and British Columbia , 2001 .

[5]  E. Mccauley,et al.  Under‐ice blooms and source‐water odour in a nutrient‐poor reservoir: biological, ecological and applied perspectives , 2001 .

[6]  S. Hawkins,et al.  Problems in extraction and spectrophotometric determination of chlorophyll from epilithic microbial biofilms: towards a standard method , 1999, Journal of the Marine Biological Association of the United Kingdom.

[7]  B. Biggs,et al.  SUBSIDY AND STRESS RESPONSES OF STREAM PERIPHYTON TO GRADIENTS IN WATER VELOCITY AS A FUNCTION OF COMMUNITY GROWTH FORM , 1998 .

[8]  C. Richards,et al.  Relating Diatom Assemblage Structure to Stream Habitat Quality , 1996, Journal of the North American Benthological Society.

[9]  J. F. Brewster,et al.  Growth characteristics of bloom-forming filamentous green algae in the littoral zone of an experimentally acidified lake , 1995 .

[10]  R. Wetzel.  Microcommunities and microgradients: Linking nutrient regeneration, microbial mutualism, and high sustained aquatic primary production , 1993, Netherland Journal of Aquatic Ecology.

[11]  K. Hoagland,et al.  Influences of Canopy Cover on Spectral Irradiance and Periphyton Assemblages in a Prairie Stream , 1992, Journal of the North American Benthological Society.

[12]  S. Spaulding,et al.  Increase in Nuisance Blooms and Geographic Expansion of the Freshwater Diatom Didymosphenia geminata , 2007 .

[13]  C. Kilroy,et al.  Likely environments in which the non- indigenous freshwater diatom, Didymosphenia geminata, can survive, in New Zealand , 2005 .

[14]  B. Biggs,et al.  Ecological studies on Didymosphenia geminata , 2005 .

[15]  Awwa,et al.  Standard Methods for the examination of water and wastewater , 1999 .

[16]  R. J. Stevenson,et al.  Algal ecology: freshwater benthic ecosystems , 1996 .

[17]  R. J. Stevenson,et al.  11 – The Stimulation and Drag of Current , 1996 .

[18]  A. E. Greenberg,et al.  Standard methods for the examination of water and wastewater : supplement to the sixteenth edition , 1988 .

[19]  E. Arnold,et al.  Standard methods for the examination of water and wastewater. 16th ed. , 1985 .

[20]  R. Patrick,et al.  The diatoms of the United States. , 1966 .