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Title: mid May & June 2009 Noctiluca blooms
Author: Jan Newton, Dan Hannafious, Rita Horner
Category: bloom
Data Source: HCDOP IAM Study
File Size: 841 kb
File Type: Image (JPG or GIF)
Date Catalogued: Thursday, June 18, 2009
Comments: Several sightings of a reddish-orangish-yellowish discoloration or "bloom" were noted in Hood Canal and Puget Sound during the sunny period in mid May 2009 and again throughout Hood Canal during mid June.
On 16 May there was an orange rust colored bloom on the north shore from Cherokee beach to almost Sisters Point in Lower Hood Canal. The bloom was noticeable along the shore line 10 to 20 yards wide. On 17 May there was a similar bloom on the south shore from Twanoh to Sunset Beach. Several sightings were noted in other areas of Puget Sound as well. Starting June 14th, sightings reported were mostly from southern Hood Canal, around Union to Twanoh. Sampling and positive ID was done on 15 June. Subsequent sighting later that week were from Belfair, Hoodsport, Lilliwaup, Seabeck and Big Beef areas.

The cause of this coloration is an organism called Noctiluca. It is not harmful to fish or humans, but it tends to bloom when we have sunny days. We have documented its occurrence in Hood Canal in similar locations during May 2007 and July 2005 posted on this website. We are continuing to monitor conditions in Hood Canal, and especially its oxygen concentration. You can track oxygen conditions from the ORCA buoys, with near real-time data available from this website HERE

If you see blooms, fish kills, or other suspicious environmental conditions, call the Ecology's Emergency Response Number: 1-800-OILS-911.

Below are answers to common questions about Noctiluca by Dr. Rita Horner (UW-Oceanography).

1. What causes the red (tomato soup) bloom in Hood Canal and in other inland waters of western Washington?
The bloom is caused by a single-celled organism, a dinoflagellate called Noctiluca. It is a large, balloon-shaped cell about the size of a pinhead. It occurs commonly in warm and cold coastal waters around the world and is especially common here in summer.

2. Is the bloom toxic?
No. This organism produces no toxin and is not harmful to humans or other large animals. However, when it (or any) dense bloom dies, it can cause oxygen depletion. It is not known to be toxic to other marine life.

3. Why is the bloom red?
Noctiluca is not photosynthetic, that is, it has no pigments of its own but obtains them from the food it eats. It grazes (eats) on phytoplankton and even fish eggs. This kind of nutrition is called heterotrophy.

4. Why do the blooms form at the surface?
The cells are not good swimmers, but are buoyant so come to the surface. If you collect a sample (just scoop some water into a clean jar) and let it sit for a few minutes, the Noctiluca cells will float to the surface and form a layer at the top of the water. The cells are large enough to see with the unaided eye and the layer will appear grayish.

5. Why are the blooms mostly close to shore? Is it because there are more nutrients nearshore?
The blooms are close to shore because the cells are moved there by the winds and might disappear quickly if the winds change only to be found elsewhere, again depending on the winds. More nutrients nearshore probably has nothing to do with where the Noctiluca blooms are found.

6. What is Noctiluca?
It is an obligate, heterotrophic dinoflagellate, meaning it is a flagellated organism that has to consume other organisms in order to live (just like us). Although it is commonly considered "phytoplankton", it does not photosynthesize. Many dinoflagellates are photosynthetic. For a picture, click HERE. Noctiluca is buoyant, largely filled with fluid and whatever it's been eating.