It is the starting point for our oceans’ food chain. But stocks of phytoplankton have decreased by 40 percent since 1950, potentially as a result of global warming. It is an astonishing collapse, say researchers, and may have dramatic consequences for both the oceans and for humans.

The forms that marine flora and fauna come in are varied and spectacular. From bizarre deep sea creatures to elegant predators and giant marine mammals, the diversity in our planet’s oceans is astounding.

But it is the microscopic organisms like diatoms, green algae, dinoflagellates and cayanobacteria that make it all possible. Phytoplankton is the first link in the oceanic food chain. It is eaten by zooplankton which is in turn eaten by other animals, which are then consumed by yet further sea creatures. Sometimes that chain can be quite short — the only thing that separates whales from phytoplankton in the food chain, for example, are the krill that come in between.

But it appears that humans may be in the process of destroying this fundamental link in the oceanic food chain. Temperatures on the surface of our oceans are rising because of climate change, resulting in a reduction of the stock of phytoplankton. Just how […]