Photos: Red tide at Surfers Beach


Posted by
Thu, August 20, 2009


Keith Mangold
Red tide at Surfers Beach on Thursday. Click for larger image.
Lana Ellis
Lana Ellis

Interesting that the red tide has recently shown up.  Just two days ago, we saw two groups of three dolphins playing along Poplar Beach.  They were practically surfing the waves!

I’ve added a couple of photos from another photographer with a closer view, but not quite so red.

My family and I were at Francis Beach (Half Moon Bay) yesterday (Aug. 22) and the red algae was very abundant.  It looked like the waves were made of rust and was very strange.  When I got home I was interested to find more and found your site.  So this is what the famous “Red Tide” is. I’ve never actually seen it before.  Very interesting.  Have sent a photo for you to use if you want.


Description of red tide from wikipedia:

Red tide is a common name for a phenomenon more correctly known as an algal bloom, an event in which estuarine, marine, or fresh water algae accumulate rapidly in the water column. These algae, more specifically phytoplankton, are single-celled protists, plant-like organisms that can form dense, visible patches near the water’s surface. Certain species of phytoplankton, such as Dinoflagelate, contain photosynthetic pigments that vary in colour from green to brown to red.

When the algae are present in high concentrations, the water appears to be discoloured or murky, varying in colour from purple to almost pink, normally being red or green. Not all algal blooms are dense enough to cause water discolouration, and not all discoloured waters associated with algal blooms are red. Additionally, red tides are not typically associated with tidal movement of water, hence the preference among scientists to use the term algal bloom.

Some red tides are associated with the production of natural toxins, depletion of dissolved oxygen or other harmful effects, and are generally described as harmful algal blooms. The most conspicuous effects of red tides are the associated wildlife mortalities among marine and coastal species of fish, birds, marine mammals and other organisms.

Red tide also turns the water phosphorescent when disturbed. You might try some night photography.

Is red tide harmful to humans?  My family and I swam in the red tide at surfers beach on Friday and my son now is sick - fever, sinus and stomach aches. Thanks.

It’s not clear whether swimming in a red tide is harmful. From the CDC:

The human health effects associated with eating brevetoxin-tainted shellfish are well documented. However, scientists know little about how other types of environmental exposures to brevetoxin—such as breathing the air near red tides or swimming in red tides—may affect humans. Anecdotal evidence suggests that people who swim among brevetoxins or inhale brevetoxins dispersed in the air may experience irritation of the eyes, nose, and throat, as well as coughing, wheezing, and shortness of breath. Additional evidence suggests that people with existing respiratory illness, such as asthma, may experience these symptoms more severely.

http://www.cdc.gov/hab/redtide/about.htm