This page includes recent information or images on active algal blooms or data on factors that cause them in central and northern California. Blooms are composed of one or more species of phytoplankton. Some blooms are 'red tides', appearing brown to red in color, and some of these can be harmful to people or wildlife depending on the species forming the bloom. Other blooms are not visible but can still cause health problems. Learn more about algal blooms at the CeNCOOS algal bloom education page. Note: we are not a regulatory agency, so please contact the US Coast Guard or County Environmental Health Agencies in your area for health and safety information.
Report Ongoing Blooms!
Bloom reports from the CeNCOOS region:
- A major bloom of the toxin producing dinoflagellate, Gonyaulax spinifera, was documented in coastal areas between Pt Arena and Pt Reyes in late August through September 2011. This type of bloom is very uncommon and the impacts of the toxin (called yessotoxin) on marine life and people using the ocean are uncertain. Partially coinciding with the bloom was a huge die-off of marine life from approximately 8/20 - 9/4. Apparently limited to invertebrates, dead abalone, crabs, urchins, chitons and seastars washed ashore on north coast beaches in large numbers, it is still unclear whether the algal bloom is linked to the die-off. Other potential causes for the die-off include viruses or bacteria. See more at the CeNCOOS Report on this event
- May 5th in northern Monterey Bay (near Aptos) a NON-harmful bloom developed, composed of the dinoflagellate, Noctiluca.
(Left images) Non-harmful bloom at La Selva Beach on May 5th (Photo by: Grant Matsumoto) and the same bloom from near the Capitola Wharf on May 6th (Photo by Steve Haddock - MBARI). Find out more about this bloom from this UCSB webpage.
(Left images) A Noctiluca collected by MBARI AUV Dorado operating in northern Monterey Bay in late-April (image provided by John Ryan MBARI). The other image is a MODIS satellite image showing the greyish bloom pattern in the northern Bay (image provided by Raphe Kudela UCSC).
- Month of October in Monterey Bay: An intense bloom of dinoflagellates Pseudo-nitzschia australis and Prorocentrum micans in northern Monterey Bay began in early October and continued through the month. This bloom was monitored carefully by a unique Real-time Algal Bloom Monitoring Experiment.
- September 19 at Ocean Beach (San Francisco): Joan Molitoris reported a "bright rusty-red/pink swath of water", ~10-20 yards wide paralleling the beach, beginning~ 400 yards from shore. No results as to the nature of this bloom are available at the present time.
- September 17th offshore San Gregorio Beach:
Agustus Bannan of the US Coast Guard sent us this image which he received from a pilot flying 1/2 mile offshore from Half Moon Bay area. UCSC researchers identified a water sample sent to them by the Coast Guard as dominated by Noctiluca, a heterotrophic dinoflagellate that is NOT harmful. There were some Pseudo-nitzschia mixed in at low abundance, but no more than we'd expect in central California. The bloom could persist for several days, forming red tides, but it will eventually go away when the ocean conditions change. There is no danger from skin contact, respiratory issues or consumption of sport fish associated with a bloom of this type.
- March through August on the central California coast:
A harmful algal bloom (HAB) event composed of Pseudo-nitzschia was fairly continuous in spring and summer 2010, with apparent peaks in mid-July and late-August. These diatoms produce toxins called Domoic Acid (DA) that can poison wildlife and humans that eat infected seafood. Levels of DA went up and down over the summer in shellfish samples, never getting to the regulatory limit (when shellfish are considered unsafe to eat) in Monterey, but well over the limit in Santa Barbara on several occasions.
(image at left) The bloom can be seen in NASA OBPG satellite chlorophyll images at one of its peaks in late-August with high concentrations of algae in red. Image courtesy of Dr. Raphael Kudela at UCSC.
- October 17th Stinson Beach (Marin County north of SF): A bloom was reported off by a helpful observer in our region. Pseudo-nitzschia was more abundant in the blooms at this time, this species can be harmful to wildlife and humans through shellfish poisoning etc.
- Oct 6th, 2009 in Monterey Bay:
A bloom of Ceratium (Left image) contributed by John Ryan of MBARI using imaging spectrometry onboard a Airship Ventures, Inc. airship project run by Steve Dunagan of NASA/AMES.
- September 27th: A bloom was also reported 5-7 miles W/SW of the Golden Gate by a concerned citizen. This bloom was likely dominated by Ceratium, which is non-harmful.
- Late-August 2009 Half Moon Bay:
(Left image) Photo by Lana Ellis. Half Moon Bay Review reported an intense bloom at Surfer's Beach in Half Moon Bay, CA.
We attempt to post information on current algal blooms in the CeNCOOS region on this page. If you have any information on a potential algal bloom in central or northern California, please contact us (CeNCOOS_Communications@mbari.org). In your email message, please provide as specific information as possible on the location, date and nature of the bloom you observed as well as your contact information. Thanks for you help!
Sources of further information:
- CeNCOOS Algal Bloom Education webpage
- October 2010 Monterey Bay cooperative real-time Algal Bloom Monitoring Experiment.
- To find descriptions, pictures, and differences between individual species visit the View the UCSC Kudela Lab Phytoplankton ID Gallery
- During October 2008, the Monterey Bay Aquarium Research Institute (MBARI) and other US, European, and Japanese partners institutions conducted oceanographic surveys as part of the "Monterey Bay 2008 Experiment". View results from this project.
- A significant harmful algal bloom (red tide) event occured during November 2007 in Monterey Bay (view the CeNCOOS report). 2007 Red tide event linked to large scale seabird strandings (pdf publication)
- View CeNCOOS report on 2007 algal bloom here
- View the CIMT Fact Sheet on harmful algal blooms (HABs) here
For more information contact CeNCOOS (CeNCOOS_Communications@mbari.org )