According to new research, for nations that have outlying coral reefs, better land use of the mainland is crucial in order to prevent further damage to these ocean habitats.
A recent study reveals important implications for Madagascan and Australian reefs based on deforestation scenarios.
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So how can one deforestation event on land affect coral reefs which can be located miles off-shore? Well, trees prevent runoff by holding and storing water. If trees are cut down, there are less roots and leaves to absorb that water and thus rain events can cause increased water flow into rivers. Erosion causes increased sedimentation which leads to poor water quality and compromises resistance of corals to thermal stress and their potential to recover from bleaching events. This results in deterioration of their structure and ability to sustain their ecological interactions.
The study – ‘Human deforestation outweighs future climate change impacts of sedimentation on coral reefs’ – looked at the effects of future climate change on the hydroclimate of reefs and how preventing soil erosion and sediment pollution inland will indirectly benefit these reefs.
“The findings are very relevant for Australia since intense land use and past deforestation have transformed the river catchments tremendously and are seen as a major threat to coral reefs in the Great Barrier Reef and elsewhere,” said Dr Jens Zinke, of UWA’s Oceans Institute.
Dr Zinke said the study looked at four watersheds near coral reef ecosystems in Madagascar, which has different climate zones that mimic most of the world’s coral reef climate and a range of different land uses.
“With Madagascar, we wanted to understand how soil erosion and sediment discharges into coral reefs adjacent to river catchments are going to change with these two factors,” he said.
“Curbing sediment pollution to coral reefs is one of the major recommendations to buy time for corals to survive ocean warming and bleaching events in the future.
“Our results clearly show that land use management is the most important policy action needed to prevent further damage and preserve the reef ecosystem.
“The major question is: how do we manage the sedimentation through reforestation efforts and proper coastal management?
“Our study clearly shows that we need to have specific reforestation goals/targets for specific regions and make sure that the amount of land allocated for reforestation is enough to reduce sediments significantly.
“Until we precisely understand these relationships, reforestation as a tool for coral reef conservation might not meet its objective of sediment and pollution reduction.”
The study is published online in the science journal Nature Communications.
See more at The University of Western Australia.
Coral reef image via Shutterstock.