SoundHAB: Alexadrium catenella observations from around Puget Sound, 25 August 2006

[Jack Rensel]

Here is some recent observations I compiled concerning the ongoing bloom.
I encourage others of you to provide observations as you see fit. 

 

 

Scott Ridgeway provides the following general information as of the morning
of 25 August 2006.  

 

Scott is a fish farm technician with 18 years experience observing and
quantifying harmful algae in Central Puget Sound for the fish farming
company, American Gold Seafoods. 

 

-  Presently their daily observations (net tows and discrete water bottle
samples) show highest concentrations in the restricted channels and bays
west of Bainbridge Island including Brownsville, Illahee, Sinclair Inlet and
Dyes Inlet.  

 

- Notable but lower densities are being seen in the main body of CPS at the
sampling location east of Bainbridge Island near Blakely Rocks. 

 

- Interestingly, the Clam Bay area (site of NOAA and EPA laboratories and 3
farm sites) remains somewhat free of A. catenella.   During the Heterosigma
bloom of early August it was also relatively free of that alga and in both
cases experiences cooler, clearer water than that of CPS and the associated
backwaters mentioned above.   This morning near surface DO was 4.2 mg/L,
typical of mixed, upwelled water often seen there in the late summer. Water
visibility is very high, as measured by Secchi disk.

 

-  Scott notes that cell densities of A. catenella were the highest he has
ever seen (in 18 years) about 4 weeks ago but have declined since then.  

 

-  I collected a series of CTD casts and other data in the area 4 weeks ago
and noted some unusually warm near surface water temperatures in the areas
mentioned above, extending across the sound to Seattle.   I have preserved
samples from throughout the area at that time. 

 

Bill Clark, manager of the Cypress Island sites in North Puget Sound with
experience in that area since the 1980s added observations in NPS:

 

-  Mixed diatom and dinoflagellate assemblages continue to be present as
they have since the cessation of the late June and early July 2006
Heterosigma bloom. 

 

-  A. catenella has been observed periodically during this time period but
not at high densities. 

 

-  Water temperatures have remained near 12°C except for a few days of 13°C
since the Heterosigma bloom there.   Dissolved oxygen is somewhat higher
than seen near Manchester, mid 5 to 6 mg/L.  Secchi disk is moderate. 

 

Randy Hodgin, manager of the Port Angeles site near the Strait of Juan de
Fuca and phytoplankton technician Brett Raemer report only occasional A.
catenella cells and typically cool water temperatures of 10.5 to 11.5 in
that area.

 

 

There is a working conceptual model of what causes Heterosigma blooms in
Puget Sound and approaches that can be developed into a numerical model.
This model was developed first by fish farmers and they use it in their
management every year.   Laurie Connell and I have written about this in the
past and this year’s experience is being used to refine the model a bit
more. 

 

Hopefully as monitoring increases and recording or real time moorings are
placed in Puget Sound we can develop such models for other species that
increasingly are shown to affect both fish and shellfish, wild and cultured
as well as the entire food web.  

 

Today’s local media story about the PSP bloom, complete with a picture of
Noctiluca blooming in Penn Cove at
http://seattlepi.nwsource.com/local/282565_redtide25.html

 

 

++++++++++++++++++++++++++

J.E. Jack Rensel Ph.D.

Rensel Associates Aquatic Sciences

4209 234th Street N.E.

Arlington Wa 98223

jackrensel at att.net

360-435-3285

Cell  360-631-6538

 

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