To all red-tides watchers! Posted July 15, 1998 to Phycotoxins
listserver
The St. Lawrence estuary on the canadian east coast is one of
the hottest spots in the world for PSP. The causative organisms
are Alexandrium tamarense, and occasionally A. ostenfeldii. Each
year, shellfish from hundreds of kilometers of coast become toxic
for several weeks. Usually, cell concentrations remain below 50,000
cells per liter, with shellfish becoming toxic (> 80 µg
STX/100 g meat) when cell concentrations reach only 1,000 cells
per liter.
Last week, a huge red tide (150 km long by 2-3 km wide of discolored
water) developed along the south shore with cell concentrations
reaching 4 million cells per liters! Several ship and helicopter
surveys showed that Alexandrium was present in high concentrations
all over the Estuary.
Although most of the coastal zone was already closed for shellfish
harvesting, the Department of Fisheries and Oceans, in collaboration
with the Canadian agency for Food Inspection sent a warning to
the media to advise people that the shellfish may be extremely
toxic this year. So far, there is no report of fish or seabird
mortallity.
A research project on the determination of the variation in the
in situ growth rate of Alexandrium spp. was on its way in our
lab when the red tide occured. It thus represents a great opportunity
to determine the importance of this parameter on the dynamics
of Alexandrium blooms in the St. Lawrence.
Maurice Levasseur, for the Toxic Algal Research Team of Maurice
Lamontagne Institute
Department of Fisheries and Ocean Canada
Maurice Lamontagne Institute
Mont-Joli, Quebec
Canada G5H 3Z4
levasseurm@dfo-mpo.gc.ca
Fax:(418) 775-0546
Tel: (418) 775-0608