Microscopic algae are an important part of the Gulf of Mexico's
natural makeup as they serve as food for fish and other
organisms. Algae do not have to be toxic to be considered
harmful. Nontoxic algae can reproduce, or bloom, at such a high
rate that they rob the water of available oxygen, which can
result in fish kills. Likewise, some algae have spines or other
protrusions that may cause fish kills simply by getting caught
in or otherwise irritating fishes' gills. Following are some
examples of both toxic and nontoxic HABs that have been found in
Texas waters. Akashiwo sanguinea is a dinoflagellate that caused
a large fish kill along Bolivar Peninsula in September 2007.
Whether or not this species is toxic has yet to be determined,
but it is thought that fish kills most likely occur because of
large-scale blooms that result in low oxygen levels in the
water. Alexandrium monilatum is a dinoflagellate that forms
chains of cells attached to each other. A. monilatum has caused
red tides and fish kills along the