Jellyfish: the Ocean’s Canaries
Monday, 10 June 2013
Some may think jellyfish are simply a pesky problem when we want to take a swim or snorkel, but they are actually a sign of flagging oceanic health. We think of them as the canary in the coal mine. The difference is the canary dies when there is a problem, but jellyfish flourish in the conditions that global warming wreaks on our oceans.
Climate change heats and acidifies the planet’s oceans. Overfishing adds to the first two major problems. All three contribute to creating an ideal environment for jellyfish to thrive and multiply. So what’s the big deal if there are too many jellyfish?
The issue is that jellyfish take a bad situation and make it worse. They have a unique trait where they’re able to eat up the food chain. This is surprising considering these sea creatures don’t even have brains. However, they actually can consume animals that are bigger, smarter and faster than they are. They damage the ecosystem further by competing with large mammals, such as whales, by feeding on the same fish and plankton that these other animals need to survive.
Marine expert Lisa-ann Gershwin wrote the new book Stung! On Jellyfish Blooms and the Future of the Ocean. She points to an example where jellyfish wiped out an entire food chain simply by eating from the bottom up.
The jellyfish species Mnemiopsis leidyi was accidentally introduced into the Black Sea in the early 1980s. In just a few short years, these jellyfish comprised “95 per cent of the biomass in the Black Sea”. This means “ninety-five per cent of every living thing was this one species of jellyfish”.
Jellyfish could rule our planet’s oceans as they once did in the Precambrian era. A time when biodiversity was low, the jellyfish commanded the oceans, and mammals and reptiles did not exist. This is a scary eventuality, that our feet are firmly planted on the path towards. We need to heed the warnings that these gelatinous invertebrates provide and begin seriously reducing our carbon footprints and offsetting the rest of our carbon emissions.