Definition - What does Red Tide mean?
A red tide is the common term used to describe a harmful algal bloom (HAB) in the sea along coastal areas. These often turn the water a dark, del red colour. A red tide occurs when colonies of algae grow out of control and produce toxins that affect humans and animal life in the ocean.
Safeopedia explains Red Tide
Not all algal blooms are harmful to the health of humans and animals, and can also contribute to the good health of ice and the environment, but a select few types of algae can cause problems in greater numbers. The harmful effects or illnesses caused by an algal bloom can be very debilitating or even life threatening for humans and various birds, shellfish, mammals, fish etc..