If you look hard enough, the news is full of stories about climate change, loss of species and biodiversity, rising sea levels, the shrinkage of arctic sea ice and glaciers, increasing pollution, the destruction of forests and jungles, the depletion of earth’s natural resources, and so on. The coverage is relentless. And if you read for long enough, you might feel depressed and wonder if the human race is running out of time. Or perhaps you feel that scientists have got it wrong, and/or that humans with their limitless ingenuity can master these changes. Even if the population is projected to rise from 7,177,594,112 at the time of writing (link) to 10 billion by 2050. That’s 10,000,000,000 people.
Antarctic krill, Euphausia superba, are one of the most abundant and successful animal species on Earth. There are about 85 species of these open-ocean living crustaceans which are known as euphausiids (Photo: Stephen Brookes)
Well if that’s not enough, scientists are now warning that substantial reductions in the numbers of antarctic krill could have catastrophic consequences for marine mammals and birds in the cold oceans of the southern hemisphere. Krill? What are krill?
Krill are small crustaceans found in all the world’s oceans. In the Southern Ocean, the Antarctic krill, Euphausia superba, are the backbone of the food chain and are the primary food for penguins, seals, fish and whales. They make up an estimated biomass of over 500,000,000 tonnes, roughly twice that of humans on the planet, and may be the largest of any multi-cellular animal species on the planet. A study by the Australia’s Antarctic Division published in Nature Climate Change has found that once levels of dissolved carbon dioxide in the ocean reach about 1,250 micro-atmospheres due to the oceans becoming more acidic as a result of the burning of fossil fuels, the numbers of krill eggs hatching successfully begins to decline dramatically. Some of the areas for krill already reach 550 micro-atmospheres.
In the 2011 Australian-American 3D animated film, Happy Feet Two, Brad Pitt provides the voice of Will the Krill, and Matt Damon that of Bill the Krill. Will seeks a life outside of the swarm, with Bill following reluctantly, but they realise they are at the bottom of the food chain. Although Will tries to be a predator, they eventually return to the relative safety of the swarm. Hopefully these two cute crustaceans will raise the profile of this potentially threatened species.
As well as mammals, birds and fish being threatened, commercial fishing is currently taking around 200,000 tonnes of the crustacean from the same areas affected by the projected decline. The krill are used in food products, health supplements, and as feed for farmed fish.
These findings come as the Commission for the Conservation of Antarctic Marine Living Resources – comprising 25 countries including the European Union – is considering proposals to protect thousands of species in the Southern Ocean from exploitation. The increasing acidification of earth’s oceans due to the burning of fossil fuels however will respect no such boundaries.
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