Marine Phytoplankton Levels Drop Sharply

Oceanic phytoplankton – the cornerstone of the marine food chain – has dropped sharply in volume: a situation scientists potentially link to climate change in a study that’s just been published. The importance of plankton within marine ecosystems means that this drop – which has been measured at around one per cent every 12 months – could have massive implications.

Phytoplankton lives close to the surface of the world’s oceans. This isn’t out of choice – it has to, since it’s reliant on photosynthesis for energy purposes and so needs to maximise its exposure to light. The majority of phytoplankton cannot be seen by the naked eye – it’s that small – but when present collectively, it appears as a green mass.

“Phytoplankton is the fuel on which marine ecosystems run”, head study author Daniel Boyce commented, adding: “A decline affects everything up the food chain, including humans.”

Marine Phytoplankton Report

The scientists behind the marine phytoplankton report – which appears in the Nature publication – made their discovery through looking at historical archives dating back to the early 1900s.

No previous plankton report has ever assessed changes across such a wide timeframe and, overall, there is now approximately forty per cent less phytoplankton in the world’s oceans than in 1950. Sea temperature rises associated with climate change are cited as the possible source, but further studies will be needed to establish this for sure. Potentially, though, the scenario could be more significant than loss of rainforests or coral reefs, according to some members of the scientific community.

Phytoplankton Levels

Boyce and his fellow scientists blended modern hi-tech satellite data with archived records to track progressive marine phytoplankton levels. However, since satellite images are a recent innovation, they drew on other technologies to cover earlier events, including the Secchi Disk developed by Peitro Angelo Secchi almost 150 years ago. This device – which is white in colour – is simply lowered beneath the water surface until it can no longer be seen.

“I think we should all be very concerned that phytoplankton have declined over this long time period and we should be looking to the future...continually monitoring our global phytoplankton levels to ensure they don't continue to decline”, Boyce added.

See also:

Nature Affected by Climate Change - Update