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Conservation Science for a Healthy Planet

Mass Mortality Events: The terrifying phenomenon that is pushing species towards extinction

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February 25 2018 Read the full Guardian UK article here

….The saiga – whose migrations form one of the great wildlife spectacles – were victims of a mass mortality event (MME), a single, catastrophic incident that wipes out vast numbers of a species in a short period of time. MMEs are among the most extreme events of nature. They affect starfish, bats, coral reefs and sardines. They can push species to the brink of extinction, or throw a spanner into the complex web of life in an ecosystem. And according to some scientists, MMEs are on the rise and likely to become more common because of climate change….

…[Scientists] concluded that a rise in temperature to 37C and an increase in humidity above 80% in the previous few days had stimulated the bacteria to pass into the bloodstream where it caused haemorrhagic septicaemia, or blood poisoning…

…Untangling the causes – and working out the role of climate change in MMEs is difficult. “In many cases, there are multiple stressors – such as, in the case of the saiga, a low-lying bacterial infection, slightly higher humidity and higher temperatures,” says Siepielski….

…An MME can push a species closer to extinction. But it can also have knock-on effects elsewhere in the fragile food web. In tidal pools on the west coast, where once there was a healthy mix of species, mussels – food for starfish – are starting to dominate. Off California, another source of starfish food, sea urchins, are also on the rise – causing a fall in the availability of kelp, the sea urchins’ main food source. That decline could hit species that depend on it for shelter, food and protection. A paper published last year in the Philosophical Transactions of the Royal Society concluded that the die-off was probably linked to warmer seas….

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