Scientists pioneer method to predict environmental collapse

Terra Daily via SPX: Scientists at the University of Southampton are pioneering a technique to predict when an ecosystem is likely to collapse, which may also have potential for foretelling crises in agriculture, fisheries or even social systems.

The researchers have applied a mathematical model to a real world situation, the environmental collapse of a lake in China, to help prove a theory which suggests an ecosystem 'flickers', or fluctuates dramatically between healthy and unhealthy states, shortly before its eventual collapse.

Head of Geography at Southampton, Professor John Dearing explains: "We wanted to prove that this 'flickering' occurs just ahead of a dramatic change in a system - be it a social, ecological or climatic one - and that this method could potentially be used to predict future critical changes in other impacted systems in the world around us."

A team led by Dr Rong Wang extracted core samples from sediment at the bottom of Lake Erhai in Yunnan province, China and charted the levels and variation of fossilised algae (diatoms) over a 125-year period. Analysis of the core sample data showed the algae communities remained relatively stable up until about 30 years before the lake's collapse into a turbid or polluted state.

However, the core samples for these last three decades showed much fluctuation, indicating there had been numerous dramatic changes in the types and concentrations of algae present in the water - evidence of the 'flickering' before the lake's final definitive change of state. Rong Wang comments: "By using the algae as a measure of the lake's health, we have shown that its eco-system 'wobbled' before making a critical transition - in this instance, to a turbid state....

Géza Maróti's plan of Atlantis mock-up, around 1941 -- public domain

Seal cull will not revive Canada's cod stocks, say scientists

Stephen Leahy in the Guardian (UK): Canada's multimillion dollar proposal to cull grey seals will not bring back the ravaged stocks of Atlantic cod it is intended to help, scientists have said. In October, the Canadian Senate approved a controversial plan to kill 70,000 grey seals in the Gulf of St Lawrence under a bounty system next year, ostensibly to revive the cod stocks that the seals were eating.

But a group of marine scientists at Dalhousie University in Halifax, Nova Scotia, have said in a recent open letter: "There is no credible scientific evidence to suggest a cull of grey seals in Atlantic Canada would help depleted fish stocks recover.

"Seals are being used as a scapegoat, just like whales were once blamed for fishery declines," said Hal Whitehead, marine biologist at Dalhousie, told the Guardian. He called the proposed cull an abuse of the science. "I don't like the idea of slaughtering all these animals for no reason."

Canada's Atlantic cod stocks, once estimated at 1.5-2.5 billion fish of reproductive age, collapsed in the early 1990s from overfishing. Despite a nearly total ban on cod fishing for the past 20 years, stocks have not recovered.

That's not the case for grey seals. Similarly depleted by hunting, numbers stood at just a few thousand in the 1970s. Following the collapse of markets for seal fur, mainly due to bans by European countries, their numbers increased dramatically. Grey seals are now estimated at 300,000 to 400,000....

A grey seal photographed by Andreas Trepte, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 2.5 Generic license