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Title: 24 May 2007 Noctiluca Bloom Info
Author: Jan Newton, Dan Hannafious, Rita Horner
Category: bloom
Data Source: UW, Ecology, HCSEG, Photo Credit: Richard Bambans
File Size: 195 kb
File Type: Image (JPG or GIF)
Date Catalogued:
Thursday, May 24, 2007
On May 24th 2007, several people reported patches of an orange-red-brown substance on the surface waters of the western shore of Hood Canal. Observations were reported from Sund Rock, Hoodsport, and Lilliwaup. It looks a bit like tomato soup floating on top of the water.
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 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 is 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 a bloom dies, it can cause oxygen depletion.
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.
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