Nicola Jones writes:

Across the world’s oceans, an invisible army of tiny organisms has a supersized impact on the planet. Plankton are at the base of the ocean food chain, feeding fish that feed billions of people. They are responsible for half of the world’s oxygen supply and half of our planet’s annual carbon sink. Miniscule but powerful, their presence can help or hinder ecosystems — by soaking up greenhouse gas, for example, or by spewing toxins. Where plankton live, how many there are, when they bloom and which species dominate each play a huge role in this delicate balance. And our changing climate is spurring a sea change in all of it.

“We’re headed into an ocean and, for that matter, a world that we’re not going to recognize because it’s changing so fundamentally,” says David Hutchins, a marine microbiologist at the University of Southern California, who has charted plankton’s future.

Climate change is hitting our oceans hard, making them warmer and more acidic, while radically altering currents. The outlook for plankton is mixed. Some studies report overall plankton numbers dropping, while others show them rising in some major ocean basins. As the planet warms, the diversity of the menagerie in many spots is increasing, says Clare Ostle, a marine biogeochemist at the University of Plymouth. But certain species are losing out, she adds, including big juicy plankton thought to be important for food webs and carbon sequestration. And, in the long term, plankton numbers may plummet as climate change starves them of nutrients. [Continue reading…]