SoundHAB: Akashiwo bloom in Puget Sound

[Rita Horner]

A lot of information is going out about this bloom and some needs a little 
clarification.  Akashiwo sanguinea and another dinoflagellate, Ceratium 
fusus, have been known from blooms in South Sound for as long as I can 
remember (30-40 y).  The blooms often occur in late summer and into the 
fall and the two species often occur together.  Fish kills and 
invertebrate larvae kills have been reported along with the blooms, but to 
my knowledge, no toxin has yet been identified.  Mortality is apparently 
due to clogging of gills and low oxygen as the blooms decay.

Akashiwo is of interest because of the bird kills in Monterey Bay a couple 
of years ago and on the Washington coast last fall.  It produces a 
surfactant-like protein that coats feathers and neutralizes water 
repellancy and insulation.  To my knowledge, bird kills have not been 
reported in the Sound and dead birds have not been seen with the current 
bloom in the Sound according to Teri King of WA Sea Grant.

After the bloom last fall, I queried a number of phytoplankton experts 
throughout the world and checked the literature about the possibility that 
Akashiwo produced cysts.  No one reported cyst formation except one paper 
from Esquimalt, BC, that suggested recurrent blooms there must have been 
caused by cysts.  However, the authors had no real evidence to prove this. 
(Robinson, M.G., Brown, L.N.  1983.  A recurrent red tide in a British 
Columbian coastal lagoon.  Can J. Fish. Aquat. Sci. 40:2135-2143.)  My 
guess, and it is just that, a guess, is that Akashiwo is like many other 
phytoplankton species that produce recurrent blooms without producing 
cysts.  Or maybe it forms resting cells that just aren't recognized as 
such.

The possibility that Akashiwo has become more abundant the last few years 
has been raised.  I wonder if it just seems more abundant because more 
people are looking, are more aware of blooms now and reporting them, and 
more sampling is occurring.

Just some thoughts ....

Rita






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Rita A. Horner                        373 Marine Science Bldg
School of Oceanography
Box 357940                            Phone:  206-543-8599
University of Washington              Fax:  206-543-0275
Seattle, WA  98195-7940               rita at ocean.washington.edu

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