Master Naturalists: Red tide, evil princess, orange tide in 2012

By Paul and Mary Meredith
March 1, 2012 at midnight
Updated Feb. 29, 2012 at 9:01 p.m.

Noctiluca scintillans, a phytoplankton shaped like a water-lily pad, appears red-orange in the Gulf and is bio-luminescent at night.

Noctiluca scintillans, a phytoplankton shaped like a water-lily pad, appears red-orange in the Gulf and is bio-luminescent at night.

Folks sampling for harmful phytoplankton that sometimes occur during cooler months have been busy checking our Gulf waters. Texas Master Naturalists sample locations along the coast, and have detected at least two harmful types.

Samplers' data, plus other data, supplies input about harmful phytoplankton for researchers working on the problems resulting from blooms, or very large numbers of phytoplankton.

We'll share some information about two harmful phyto (as some fellow samplers refer to them) this year.

Plus, two samplers (who you happen to know) detected an intriguing phytoplankton. And we'll share a fun experience we had with it.

Red tide: Harmful phytoplankton

If you've heard about this year's red tide along much of the Texas coast, you've probably heard about the bloom's very negative economic impact on oystering.

The effects of this red tide outbreak on the oyster industry have been called some of the worst ever. Areas are gradually being re-opened as they lose their toxic condition and oysters become edible again.

Phytoplankton Karenia brevis causes the red-colored tide, plus harmful effects on humans, among others. We first encountered red tide shortly after we began phytoplankton sampling. Crew members of a work boat returning home farther south along the coast suffered symptoms including burning eyes, runny nose, coughing and wheezing. Those symptoms usually disappear after leaving the red tide area, but they indicate red tide may be the cause.

The toxin causing those symptoms and others accumulates in the tissues of molluscan shellfish (oysters, clams, mussels, whelks). The shellfishes' meat is rendered inedible by the toxin, even after cooking it.

A type of food poisoning can happen after eating red tide-affected shellfish. And the symptoms (nausea, vomiting and numbness or tingling of the lips and tongue) can persist for days.

Fish kills also can occur with red tide and are another indication of its presence. Flyovers may detect the red streaks that develop when K. brevis is present in large numbers (called a bloom).

This year's red tide comes with our ongoing drought, which is causing high salinity levels in Texas bays, resulting in disease in many shellfish. The effects of the combination of these problems result in the negative economic and health impact.

Evil princess - another harmful phytoplankton

Volunteer samplers may also find Dinophysis, or evil princess phytoplankton. The nickname helps describe how it looks when identifying phytoplankton under the microscope.

Dinophysiss phytoplankton can produce Diahrretic Shellfish Poisoning, a gastrointestinal illness. Its symptoms usually occur within 30 minutes to several hours after consuming contaminated shellfish. Symptoms may include diarrhea, nausea, vomiting and abdominal pain.

Moreover, long-term exposure may promote other problems in the digestive system. Full recovery is expected within three days, regardless of medical treatment.

Some evil princess has recently been found in areas along the Texas coast.

Updates on blooms and closures/re-openings can be found on the TPWD website. Photos of phytoplankton can be found online at

Paul and Mary Meredith are master naturalists. Contact them at



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