Two weeks ago, a group of sailors off the coast of New Zealand leaned over the side of their boat, dropped a contraption into the Pacific Ocean and watched it disappear. Using an app they’d downloaded to a smartphone, they logged a reading from the underwater device, along with their GPS location and the water temperature. In just a few minutes’ time, they had become the first participants in a new program launched by the UK’s Plymouth University Marine Institute which allows citizen scientists to help climatologists study the effects of climate change on the oceans.
The Kiwi sailors were measuring the concentration of phytoplankton, a microorganism that lives at the sea surface. Phytoplankton, also called microalgae, produce half of the oxygen in the air we breathe and are responsible for 50 percent of the Earth’s photosynthesis. Whales, jellyfish, shrimp and other marine life feast on it, making it a critical part of the marine food chain.
Phytoplankton require a certain water temperature to thrive (this varies regionally), and without these favored conditions, they either decrease in number or migrate in search of optimal water. As the upper levels of the Earth’s oceans have warmed by 0.59 degrees Fahrenheit in the past century, the amount of phytoplankton worldwide dips by roughly 1 percent each year, according to a 2010 study published in the journal Nature.
In fact, phytoplankton concentrations have decreased by a total of 40 percent since 1950. The decline joins coral bleaching, sea-level rise, ocean acidification and a slowing of deep-water circulation (which effects water temps and weather patterns) as the known tolls of climate change on the oceans.
This drop in phytoplankton population is troubling because of this organism’s role in the marine food web. “Despite their microscopic size, phytoplankton… are harbingers of climate change in aquatic systems,” wrote the authors of a 2011 study on phytoplankton and climate change published in the journal Proceedings of the Royal Society. So understanding how other sea creatures will fare as climate changes depends on how drastically phytoplankton levels continue to drop.