For those of you who are not familiar with “red tide” here is what wikipedia had to say about them:

Red tide is a common name for a phenomenon also known as an algal bloom (large concentrations of aquatic microorganisms), an event in which estuarine, marine, or fresh water algae accumulate rapidly in the water column and results in discoloration of the surface water. It is usually found in coastal areas.^[1]

These algae, known as phytoplankton, are single-celled protists, plant-like organisms that can form dense, visible patches near the water’s surface. Certain species of phytoplankton, usually dinoflagellatesor diatoms, contain photosynthetic pigments that vary in color from green to brown to red.

When the algae are present in high concentrations, the water appears to be discolored or murky, varying in color from purple to almost pink, normally being red or green. Not all algal blooms are dense enough to cause water discoloration, and not all discolored 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.

The cool part about it is that at night you can see the blue phosphorescence that is released when the organisms are crushed by the breaking waves. Here are some really cool photos that Ingrid Dietrich took of the red tide here in La Jolla last week along with a photo of what the red tide normally looks like in the daytime.

(click to enlarge)