Rietvlei’s toxin-producing algae – but who cares?

14 December 2011

Filaments of the blue-green alga Anabaena in Rietvlei (Photo: Bill Harding)

Last week Droplets reported on algal toxins measured in South Africa’s Rietvlei Dam, located east of Pretoria.  This yielded absolutely zero interest!  This is not a report that you will see in a South African newspaper, unlike the type of algal warnings routinely followed by Droplets.  Although many dams have regular toxic blooms, warnings are hardly ever posted.  Are South African’s so wrapped up in themselves that they are happy to remain (read “be kept”) unaware of health risks?  

Toxin-producing Microcystis colonies in Rietvlei (Photo: Bill Harding)

An algal health-warning has been issued for Lake Okaro in New Zealand.

“Blue-green algae are present in Lake Okaro at levels that may result in adverse health effects and so it is advisable for people to avoid contact with the water,” says Dr Phil Shoemack, Medical Officer of Health.

Lake Okaro, near Rainbow Mountain, approximately twenty kilometres to the south of Rotorua, is prone to blooms, some of which persist for several months. Signage will be erected at Lake Okaro advising potential lake users of the algal bloom.

Over in Texas, an algal bloom has shut-down the oyster industry (Droplets readers will have seen earlier reports on this as the bloom started developing):

A monstrous bloom of toxic algae looming across the Texas coast has shut down oyster season. Fueled by Texas’ ongoing drought, the algae — known as Karenia brevis— thrives in warm, salty water and has spread through the bays and islands along Texas’ 350-mile coast, says Meridith Byrd, a marine biologist for the Texas Parks and Wildlife Department. The algae could cause nausea, vomiting and diarrhea in humans and is harmful to fish but not fatal to people, she says.

And in Australia, people involved with the tourism industry in the Gippsland Lake area are banding together to create awareness.

The bloom presently affects areas in Lakes Entrance such as Cunninghame Arm and lower North Arm as well as other areas such as Paynesville, Nungurner jetty, Chinamen’s Creek, Boxes Creek, Eagle Point, Metung wharf, and more.

A tourism response group has been formed consisting of representatives from Destination Gippsland, East Gippsland Shire Council, East Gippsland  Marketing and East Gippsland Regional Tourism Association in response to recent announcements of the algal bloom affecting the Gippsland Lakes.

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