This section defines harmful algal blooms and red tides.

Find answers to frequently asked questions about red tide and other harmful algal blooms (HABs), how HABs can affect the environment, and more.

Harmful algal bloom (HAB) research occurs all over the world. Select any of the numerous links in this section to read about ongoing HAB research.

This section contains technical and general information about numerous species of harmful algae.

Are you confused by HAB terminology? Find definitions for difficult terms and abbreviations.

Marine and terrestrial animals, such as manatees and shorebirds, can all be affected by exposure to red tide. The information in this section describes how these animals may be affected and what symptoms they may display.

Toxic shellfish can cause human illnesses. Learn about types of shellfish poisoning, symptoms, and the United States locations of these incidents.