Friday, March 8, 2013

Sperm whales: How plastic bags are poisoning the planet's greatest predators | Mail Online

Sperm whales: How plastic bags are poisoning the planet's greatest predators | Mail Online: In another recent and tragic case, a group of seven sperm whales stranded themselves on a Mediterranean beach. They had been driven into shallow waters, possibly by military sonar exercises. There they were unable to feed on squid. And since whales get their liquid from their food, they began to dehydrate.

Then, their starving bodies began to break down fat — to deadly effect. The pollutants they’d absorbed from the ocean and had been deposited in their fat were released.

They included heavy metals such as mercury, lead and cadmium, and organochlorines like PCBs and DDTs, even fire-retardants used on modern furnishings.

In effect, the whales were poisoning themselves. Fatally weakened, they stranded themselves together on the shore, demonstrating the unswerving loyalty to each other for which their species is renowned.

And when their carcases were dissected, it came as no surprise to discover an unusual amount of plastic, including the dreaded plastic bags, in their stomachs.

Pollution can have random or chaotic effects on the environment, if random then it can reach a normal equilibrium where it is tolerated with occasional deviations of severe harm. If chaotic then the effects can rise exponentially to a ceiling and collapse, for example some pesticides such as DDT caused mutations in animals and people leading to collapses in some populations. Here the whales encounter a tipping point where the levels of pollutants rose exponentially in their bloodstreams from being stranded. This would happen more often as this normal level of pollutants gets closer to a tipping point, random variation would increasingly push them over the edge into disaster.

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