Global Warming Allows Crabs to March on Antarctica
The Icy cold waters that surround Antarctica are at a temperature of 0°C to -2°C making it an inhospitable place to most ocean dwelling predators such as crab, rays and sharks, who prefer the warmer, deeper waters further off the coast ranging between 0°C and 10°C.
This means that for the past 40 million years or so the native Antarctic marine species including sponges, molluscs and brittle sea stars have flourished on the continental shelf surrounding Antarctica. They have been able to survive unimpeded in the colder waters due to their bodies producing a form of antifreeze allowing them to survive in the colder water.
Now that global warming is causing the worlds oceans to heat up, the advantage of being able to survive where their predators once couldn't will soon be taken away. The giant ribbon worms, muscles and other creatures that are in abundance on the underwater shelf the will soon be facing King Crabs and other predators which they have never needed to evolve a defence against.
The expedition consisting of a US and Swedish research team that made these findings onboard the Swedish icebreaker Oden came to an end in January 2011. They used a remote sub which took more than 100,000 images of the sea bed and discovered hundreds of King crabs which grow up to 20cm (10 inches) long, not including their legs, marching south up the slope towards the sea shelf. It showed the crabs already in much shallower waters than they were in 2007 but not yet all the way up onto the shelf.
The research team are now trying to figure out how long it will be until the temperature is warm enough for the crabs and whether or not they will simply invade and leave or colonize the area permanently. The temperature of the Southern Ocean west of the Antarctic peninsula have alredy risen by 1°C since records began in the 1950's, which has expanded the region in which the king crabs are able to live. Some experts disagree with the findings and doubt whether the seawater temperature will change greatly enough at the bottom of the ocean to affect the creatures living there.
This might not seem like a big deal to those of us sat in front of the computer thousands of miles away from the land of sea urchins and this is another effect of climate change that will go by largely unseen. However it is an excellent example of how global warming can and will irreversibly change eco systems around the world including eventually our own.