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Newcastle University study sounds alarm for marine ecosystem

FINDINGS: Dr William Chivers, at Newcastle University’s Ourimbah campus. His work has shown that different plankton groups have varying responses to thermal change.RISING sea temperatures have changed the movement and reduced the numbers of some species of plankton, sounding the alarm bell for the marine ecosystem, an international study involving the University of Newcastle has found.

A team, lead by the university’s Dr William Chivers, used publicly-available data to track the movement of 35 plankton species in the north Atlantic and North Sea, resulting in the first large-scale evidence that different plankton groups have varying responses to thermal change.

They found certain species of plankton had moved substantiallyand their numbers had depleted over the past six decades, due to rising sea temperatures.

“The groups (of plankton) which form the food of fish larvae, the dinoflagellates and copepods, are the most adversely affected, moving north as the sea warmed,” Dr Chivers, from the university’s Central Coast campus,said.

He said the change in movement was substantial.

“During the period of 1984-2008, the average range change for this group was 99 kilometres per decade, while the average for less affected species was only seven kilometres per decade,” Dr Chivers said.

He said the differences were resulting in major changes to the ocean ecosystem and were likely to have severe implications for fisheries as well as biodiversity.

“Plankton are also responsible fornearly 50 per cent of the world’s photosynthesis, which maintains the atmospheric oxygen level and removes carbon dioxide, so their response to climate change is critical,” he said.

Dr Chivers employed a novel approach to analyse the data by examining the proportion of each species in relation to isotherms – lines on a map that join areas with the same temperature.

The study, a collaboration between the University of Newcastle, Deakin University and colleagues in the United Kingdom, used data dating back to 1954 from the Sir Alister Hardy Foundation for Ocean Science in Plymouth, UK.

The study has challenged previous assumptions about the sensitivity ofplankton to thermal change.

The full findings are published in the online journal Nature Communications.

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