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| activités | bourse | liens | membres | contact | ||
date |
Vendredi, 17 novembre 2006 |
lieu |
INRS-ETE
(salle 2417) |
| heure
|
12h15 |
| Max
Bothwell Chercheur à Environment
Canada, Colombie Britanique
Professeur au départment de Biologie de l'Université de Victoria |
|
Blooms
of Didymosphenia geminata in rivers on Vancouver Island 1990
to present:
A sign of environmental change or a new invasive species?
|
Starting
in 1989 heavy blooms of Didymosphenia geminata began appearing in
the Heber River on Vancouver Island. Within 5 years D. geminata had
spread to 12 catchments on Vancouver Island and was abundant in pristine,
nutrient-poor rivers previously known to have very low algal biomass.
Investigations to determine the environmental cause of the blooms
during the early 1990's proved inconclusive. Studies on the impact
of solar ultraviolet radiation on D. geminata community development
also failed to find any significant species selective effect. Provincial
fishing license data were analyzed to explore the possibility that
the blooms of D. geminata on Vancouver Island in the 1990's might
have resulted from an invasion by a new strain of D. geminata to
Vancouver Island streams associated with intense recreational fishing
pressure on the Island in the late 1980's. |
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