Study demonstrates reductions in CO² could boost recovery of marine life

Making meaningful reductions in CO² emissions could help marine life damaged by increasingly acidified oceans to recover, according to new research.

An international team of scientists – world-leading experts in ocean acidification and warming from the University of Plymouth and the Shimoda Marine Research Center at the University of Tsukuba – placed a series of artificial tiles on the ocean floor off the coast of Japan.

The seafloor in the region is home to a number of volcanic seeps, which have been shown to raise the CO² in the ocean to levels predicted to occur globally over the coming decades.

Over a period of 12 months, they monitored how the tiles were colonised by different forms of algae and what effect the differing degrees of ocean acidification had on that process.

As a result of regular monitoring, the scientists found the tiles became dominated by turf algae under elevated CO² conditions and had lower biomass, diversity and complexity, a pattern consistent across seasons.

However, when those tiles were removed and placed in waters with current levels of CO², the algae which had colonised them was able to recover and display similar characteristics to that found in oceans today.

Scientists say the study highlights that without reducing atmospheric CO² emissions, we may increasingly observe the loss of large algal habitats and the spread of fast-growing, small opportunistic species that can utilise additional inorganic carbon.

However, making meaningful reductions in CO² within the oceans – the goal of many international climate agreements – can have a marked and positive effect on species living within them.

The study is the latest to result from an ongoing collaboration between scientists in Plymouth and Tsukuba. They and other collaborators have published several studies over the past decade that show ocean acidification is having a major impact on marine life, resulting in habitat degradation and a loss of biodiversity.

The full study – Harvey et al: Ocean acidification locks algal communities in a species-poor early successional stage – is published in Global Change Biology, doi: 10.1111/gcb.15455.

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