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 This is a very invasive freshwater
diatom that can make large mats in waterways. It is native to temperate areas of the northern Hemisphere
including Europe, North America, and Asia.
It was found infesting freshwater rivers in the South Island of New
Zealand in 2004. The pest has also
begun to expand its range in the Northern Hemisphere.
The
covering of rocks and underwater structures disrupts habitat and harms or
eliminates other organisms living in infested waterways. Extensive accumulations associated with
didymo result from asexual reproduction.
When the diatom divides, the stalk that fixes the diatom to a rock or
some other surface divides also. As
this continues a mass of branched interconnected stalks develops. This aggregation, which is difficult to
reduce gives rize to the large.
Outbreaks may have contributed to the declines of freshwater
invertebrate and vertebrate populations, especially fish.
The
spread of the pest into new areas is believed to involve contaminated fishing
equipment. Therefore, sanitation
should be employed to reduce the spread.
Removal of all obvious clumps of didymo from boats and fishing
equipment is essential. Soaking
fishing gear in bleach or saltwater solutions, heating for prolonged periods,
or freezing for several days can sterilize fishing gear by killing
didymo. This native in the Northern
Hemisphere is expanding its range in North America and it is now found in New
England, New York, Virginia, Tennessee, Colorado, Arkansas, Wyoming, Utah, Idaho,
Montana, Washington State, North Dakota, South Dakota, Alaska, and in Canada
from British Columbia and Alberta. In
central California the pest has been found in the South Fork of the American
River.
REFERENCES:
Bothwell, Max L. &
Brad W. Taylor. 2017. Blooms of benthic diatoms in
phosphorus-poor streams. Frontiers in
Ecology and the Environment. 15 (2):
110–111.
George, Scott Daniel
& Barry Paul Baldigo. 2015. Didymosphenia
geminata in the Upper Esopus Creek: Current Status,
Variability, and Controlling Factors.
PLOS ONE 10 (7): 130-558.
Lavery, J. M., J. Kurek,
K. M. Rühland, C. A. Gillis, M. F. J. Pisaric & J. P. Smol, J. P. 2014. Exploring the
environmental context of recent Didymosphenia
geminata proliferation in Gaspésie, Quebec, using
paleolimnology. Canadian Journal of
Fisheries and Aquatic Sciences. 71 (4):
616–626.
Kirkwood, A. E., T. Shea, L. J. Jackson & E. McCauley. 2007.
Didymosphenia
geminata in two Alberta headwater rivers: an emerging
invasive species that challenges conventional views on algal bloom
development. Canadian J. Fish. Aquat. Sci. 64:
1703–9.
Kociolek, J. P. & E. F.
Stoermer. 1988. A preliminary investigation of the
phylogenetic relationships among the freshwater, apical porefield-bearing
cymbelloid and gomphonemoid diatoms (Bacillariophyceae). Journal of
Phycology 24: 377-385
Pite, D., K. Lane, A. Hermann, S. A. Spaulding & B. Finney. 2009. Historical abundance and morphology of Didymosphenia
geminata in Naknek Lake, Alaska. Proceedings of the 20th International
Diatom Symposium,
Acta Bot. Croat. 68: 183-197
Spaulding, S. A., Kilroy, C. &
Edlund, M. 2010. Diatoms as invasive species. In: Smol, J. & E.F. Stoermer (eds). The Diatoms: Applications
for the Environmental and Earth Sciences. Cambridge University Press,
Cambridge. pgs. 560-569.
Taylor, B. W. & M. I.
Bothwell. 2014. The origin of invasive microorganisms
matters for science, policy, and management: The case of Didymosphenia
geminata.
BioScience
64: 531–538
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