Editor's Note: This is the transcript on an interview conducted by KPBS Environment Reporter Ed Joyce.
Red tide is a common name for a phenomenon also known as an algal bloom, in which large concentrations of aquatic microorganisms, such as phytoplankton, accumulate rapidly in the water, causing discoloration at the surface.
I asked Scripps Institution of Oceanography researcher Melissa Carter to tell me more about algal blooms.
MELISSA CARTER: "They're growing really fast and the conditions are right for them to grow. And then potentially you also have physical mechanisms, such as winds and currents, that are accumulating them in certain areas, and so that's why you get this discoloration in some areas and then not others."
ED JOYCE: "And when did it start?"
MELISSA CARTER: "We started seeing it in late August and then the numbers kept creeping up."
ED JOYCE: "How common is this off San Diego's Coast? It's not something that we seem to see that often?"
MELISSA CARTER: "Usually we seem to have these blooms kind of every six to seven years. We had a very small bloom in 2010 that only lasted for a couple weeks. So they can last anywhere from a couple weeks to a few months. We don't understand what causes the blooms to go away, that's something we're really interested in studying as well as what causes them in the first place. This is a little late in the year, this is the latest bloom of Lingulodinium polyedrum that we've seen. Usually they do occur in the spring and summer and not this late in fall."
ED JOYCE: "Any negative or positive effects on the health of the ocean ecosystem?"
MELISSA CARTER: "Usually blooms aren't considered bad unless there are toxins being created that are accumulating in the food web. Luckily, the toxin that it creates is not very toxic."
ED JOYCE: "During this time there's more likelihood that you could get bacteria as a swimmer in your ears, or if you have an open cut. This might be a time not to go into those discolored waters and maybe find another spot in San Diego if you want to go swimming."
MELISSA CARTER: "Right, and so that would be most likely be further offshore because it seems like right now most of the beaches have this happening at them."
Carter also said the rare blue bioluminescent at night caused by the blooms is one of nature's most spectacular shows. She encouraged people to see it before it's gone.
She said the best place to see it is at an area where you've noticed lots of red water during the day.
Carter also said the reason swimmers and surfers could be more prone to ear or other infections during red tide is because bacteria in the water feed on the algal blooms, creating a higher risk of bacterial infection. She recommended cleaning ears after swimming with a solution of isopropyl alcohol and a two-percent solution of acidic acid or vinegar.
