Is Red Tide Dangerous?

There are many creatures and plants that live in the ocean, but sometimes it's the smallest things that can cause the most trouble. The tiny, microscopic organisms called phytoplankton live in the oceans and are a vital part of the food chain. These plankton have certain photosynthetic pigments within them that can cause color changes and when they are collected together in large quantities, it makes the water cloudy. Scientists have given the name algal bloom to the times when the phytoplankton are found in large numbers.

When there is an algal bloom, it doesn't always change the color of the water, but an actual 'red tide' is when a particular type of phytoplankton in the Gulf of Mexico become very dense and make the water red. This phytoplankton is a dinoflagellate called Karenia brevis. Because there are millions and millions of the plankton crowded together, the water becomes a very deep red. This is the time when the other animals in the water die off in massive amounts. The reason is because the Karenia brevis secretes a toxin, a neurotoxin, that paralyzes and kills fish, animals and birds.

Some scientists have speculated that red tide is caused when the Gulf of Mexico becomes loaded up with extra nutrients. The main cause of the nutrients is from human related activities like runoff from agricultural fields. Fertilizers that wash into the water can cause a nutrient loading that allows the plankton to over populate. In addition to algal blooms in theGulf, other areas of the world have had incidences also. The Pacific Ocean can have algal blooms due to increased water temperature from storm events like El Nino. This is a case when human activity didn't really have much involvement. Researchers study the causes of algal blooms in other waters around the world to see if they could also be from human causes or natural events. Some think that with the advent of better and more effective technological monitoring, the frequencies may not be more common, but simply better observed.

Whenever there is a dangerous level of phytoplankton and an algal bloom occurs, health agencies warn consumers not to eat seafood and shellfish from the area of the bloom due to the absorption of the neurotoxin that the plankton give off. Humans can become sick or even die if they eat enough of the poisoned fish or shell fish. There is medical treatment available if the person gets to the hospital in time. They may need to be placed on a respirator if their breathing is affected. Since there isn't any cure to the toxin, the doctors have to make sure the patient is able to breathe until the poison wears off.