Red tide still killing dolphins off the coast of Florida

It's been six months since Florida was officially red tide free, but the effects of the last breakout can still be seen in an increased dolphin mortality rate, according to a report by the National Oceanic Atmospheric Administration.

Ocean circulation likely to blame for severity of 2018 red tide

The harmful algae that causes red tide is currently at near undetectable levels in Florida waters compared with the much higher concentrations at this time last year. The red tide algae, Karenia brevis, causes respiratory ...

Dead dolphins, diseased seals wash up on US shores

Over the past two months, dozens of dead dolphins have washed ashore in Florida and hundreds of diseased seals have died in the northeastern United States, officials said Friday.

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Red tide

Red tide is a common name for a phenomenon more correctly known as an algal bloom, an event in which estuarine, marine, or fresh water algae accumulate rapidly in the water column. These algae, more specifically phytoplankton, are single-celled protists, plant-like organisms that can form dense, visible patches near the water's surface. Certain species of phytoplankton, such as Dinoflagelate, contain photosynthetic pigments that vary in colour from green to brown to red.

When the algae are present in high concentrations, the water appears to be discoloured or murky, varying in colour from purple to almost pink, normally being red or green. Not all algal blooms are dense enough to cause water discolouration, and not all discoloured waters associated with algal blooms are red. Additionally, red tides are not typically associated with tidal movement of water, hence the preference among scientists to use the term algal bloom.

Some red tides are associated with the production of natural toxins, depletion of dissolved oxygen or other harmful effects, and are generally described as harmful algal blooms. The most conspicuous effects of red tides are the associated wildlife mortalities among marine and coastal species of fish, birds, marine mammals and other organisms. In the case of Florida red tides, these mortalities are caused by exposure to a potent neurotoxin called brevetoxin which is produced naturally by the marine algae Karenia brevis.

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