Many of you may have noticed the brownish-red discoloration of our usually beautiful bluish-green colored ocean. You may also have noticed the unpleasant smell along the coast or even around town. Please know that this is nothing more than a natural occurrence, commonly known as a “red tide.” It is caused by a phytoplankton bloom from a mixture of microalgae when the upwelling of deeper water brings nutrients to the sunny surface layer of the ocean. Although most red tides in California usually last only a couple of weeks, this year, the bloom has been very dense and lingering longer than usual. Additionally, the process was exacerbated by the above-normal rainfall and warmer temperatures that we experienced this spring. The freshwater from the rain likely made the ocean’s surface waters more welcoming to a specific alga that prefers a less saline-dense environment. 

As the waters warmed in early April and winds were very low, conditions were perfect for the development of a widespread bloom. The bloom can even be seen in satellite imagery extending from Los Angeles to Baja. The red tide can also bring bioluminescence, causing the waves to glow at night. This red tide was particularly noted for that effect. However, red tides are erratic, and not all of them yield this bioluminescence. While red tides are usually not a public health concern, some people may be sensitive to the aerosols from the ocean during a red tide event. Some surfers and beach patrons have reported respiratory and allergic irritations. Towards the end of a red tide bloom, there is usually so much organic material in the ocean that it reduces oxygen levels, which can suffocate fish and other sea life. This has been documented by our lifeguards over the last couple of days along our local coastline. This also indicates that we are (hopefully) nearing the end of this overextended cycle of red tide. 

Please see the following links for additional information on this phenomenon: