As regular CFZ-watchers will know, for some time Corinna has been doing a column for Animals & Men and a regular segment on On The Track... particularly about out-of-place birds and rare vagrants. There seem to be more and more bird stories from all over the world hitting the news these days so, to make room for them all - and to give them all equal and worthy coverage - she has set up this new blog to cover all things feathery and Fortean.

Sunday 21 October 2012

Dead birds trigger bio-toxin scare

A neurotoxin known as domoic acid is probably killing large numbers of birds in the Walvis Bay area. The carcasses of more than 100 Greater Flamingo and Avocets have been spotted since last week, some even as far as Long Beach. 

The number of dead birds led to scores of reports from the public to the Ministry of Fisheries and Marine Resources, bird conservation groups and even the Municipality of Walvis Bay. People initially thought it was the work of work of stray dogs targeting the birds roosting in the shallow water, especially in the Walvis Bay lagoon.

When realising only Avocet and Greater Flamingoes are killed scientists at the Ministry of Fisheries tested for bio-toxins. They almost instantly suspected it to be domoic acid, a neurotoxin that causes amnesic shellfish poisoning. Water samples were tested as well as tissue samples collected from the carcasses.

What also led scientists to suspect domoic acid to be the cause are the many reports on Greater Flamingo and Avocet behaving strangely. Telltale signs of domoic acid poisoning are that the birds show no fear of humans and move in a disorientated manner.

"We have ruled out viral infection, heavy metals in the water or pollutants from the port of Walvis Bay," John Patterson of the Coastal Environmental Trust of Namibia (CETN) told Informanté. He explained that domoic acid is a bio-toxin that originates from phytoplankton.

It is especially lethal to zoo-plankton filter feeders like the Greater Flamingo and Avocet. The Lesser Flamingo that feed on phytoplankton are unaffected.

Patterson further explained domoic acid outbreaks are natural occurrences, like red tide, and cannot be controlled nor prevented. It is also unknown how long the phenomenon lasts and where along the Namibian coast it would occur next.

In mammals, including humans, domoic acid acts as a neurotoxin, causing short-term memory loss, brain damage and, in severe cases, death.

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