Planktons are on move towards colder waters, consequences to be devastating

Scientist Clare Ostle uses a PCR (Continuous Plankton Recorder), which are torpedo-like devices designed to capture plankton samples over huge areas of the Ocean. For 90 years they have been towed by merchant vessels and fishing boats on a vast network of routes. What they have seen now is that as climate change heats the seas, planktons are on the move -- with potentially profound consequences for both ocean life and humans.




What are Planktons?

Ocean organisms have been photosynthesizing for billions of years -- long before land plants - thanks to these large groups of organisms encompassing everything from photosynthesizing bacteria many times smaller than the width of a human hair, to jellyfish with long trailing tendrils.

There are two main types: phytoplankton, diverse plant-like cells commonly called algae; and zooplankton, animals like krill and the larvae of fish, crabs, and other marine creatures.


These organisms carried on the tides -- are the foundation of the marine food web. It passes through the food web, with phytoplankton consumed by zooplankton which, in turn, are eaten by creatures from birds to whales.

They are also crucial to the ocean's "biological carbon pump", which helps the sea lock away at least a quarter of C02 emitted by burning fossil fuels and produce half the oxygen on Earth.

While trees store carbon in wood and leaves, phytoplankton store it in their bodies.

"Pretty much everything you can think of in the sea at some stage of its life cycle will eat plankton," says CPR Survey head David Johns.

Climate Change Impact on the Planktons.

"The big thing that we're seeing is warming," Ostle, the coordinator of the Pacific CPR Survey, tells AFP as she demonstrates the plankton recorder off the coast of Plymouth in Britain.

The CPR Survey has documented a decisive shift of plankton towards both the poles in recent decades, as ocean currents change and many marine animals head for cooler areas.

Smaller warm water plankton is also replacing more nutritious cold-water ones, often also with differing seasonal cycles, meaning the species that feed on the need to adapt or move too.

"The big worry is when change happens so quickly that the ecosystem can't recover," says Ostle, adding that dramatic temperature spikes can lead "whole fisheries to collapse".

With nearly half of humanity reliant on fish for some 20 per cent of their animal protein, this could be devastating.

Climate change has "exposed ocean and coastal ecosystems to conditions that are unprecedented over centuries to millennia with consequences for ocean-dwelling plants and animals around the world," says the UN's Intergovernmental Panel on Climate Change (IPCC) in a leaked draft report on climate impacts, due to be published next year, which predicts "escalating impacts on marine life".

Average global phytoplankton biomass -- a measure of total weight or quantity -- is predicted to fall by around 1.8 to six percent, depending on the level of emissions.

But because of its outsized importance, even modest reductions can "amplify up the marine food web", eventually leading to reductions in marine life by roughly five to 17 percent.

In the past, conservation has focused on "the big things, the cute things, or the things that are directly worth money" -- like whales, turtles, and cod.

But all rely on planktons.


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