Toxic algal blooms at both ends of the temperature spectrum

27 January 2013

Here’s a newcomer to Droplets CyanoAlert (and another indication of an early spring in the northern Hemisphere):  An algal warning has been posted for Wilderness Lake (Maple Valley), southeast of Seattle in Washington.  The children in that part of the world must be tough as (today) it’s 6 deg C out, yet the press report warns (correctly under ‘normal’ conditions) that children playing at the water’s edge, along with pets like dogs, are the most at risk.  Glad my parents didn’t send me out to play at the edge of the lake during winter!

From New Zealand (where it’s a lot warmer than Washington), the past week’s press has contained warnings for the Selwyn River at the Whitecliffs Domain and in Lake Ellesmere / Te Waihora.  In the Wellington area, an increase in toxic algae has been reported for the Ruamahanga River.  In both cases warmer weather has been deemed a contributing factor.  Of course, moving to cooler climes, such as the picturesque Washington State, won’t help 😉

Of course too much in the way of nutrients is a major factor underpinning blooms of unwanted algae.  This week has seen criticism of the New Zealand government approach to boosting irrigation and agriculture, without due attention to the need to protect water resources, as this statement from the Green Party suggests:

The National Government is pouring millions into subsidising irrigation for intensive farming yet failing to protect our waterways from becoming even more polluted, Green Party water spokesperson Eugenie Sage said today.

“The National Government’s announcement today of an initial $80 million for irrigation, through a new Government company, is a subsidy for intensive farming and will see our rivers, lakes and aquifers polluted even faster.

“More irrigation and more intensive agriculture with increased stocking, and more fertiliser will result in greater water pollution.

“Government irrigation subsidies will worsen our already severe water pollution problems.

“Irrigators get to pocket profits yet when the degradation inevitably happens, the taxpayer will end up having to pay for waterway clean-ups.

“The National Government is trying to hide the extent and seriousness of our water quality problems by ditching consolidated nation-wide state of the environment reporting. That reporting needs to be reinstated immediately.”

Of course. consolidated reporting is a ploy used by many governments and water resource managers to hide the true extent of the water quality crisis.  The other trick is simply to not report at all.  This is why some countries seem to have less algal blooms than in past years or even none at all!

The coastline of Tasmania has, during the past few weeks, been plagued by red tides – as if the fires and the need to evacuate holiday makers off the beaches wasn’t enough!  This time a bloom has appeared in the Huon Estuary:

The latest bloom, affecting shellfish, crabs and rock lobsters between Nine Pin Point and Huon Point, including Cygnet, is caused by Gymnodinium catenatum.

It is a different algae to Alexandrium tamarense, the culprit in the closure of East Coast fisheries in November, but produces similar toxins.

G. catenatum has been a frequent visitor to the Huon area since its first detection in 1985.

Director of Public Health Roscoe Taylor said people who ate oysters, mussels, clams/pipis, scallops with roe and crab and rock lobster guts, risked contracting paralytic shellfish poisoning.

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