Conservation projects to reverse current deforestation could also benefit coastal coral reef ecosystems. This new finding could potentially extend the impacts of limited conservation resources, as reported in Nature Communications this week. Led by Joseph Maina, the work suggests that in order to reduce coral reef sedimentation, regional land-use management is more important than mediating climate change. Forest cover up-river is known to affects the sediments that are washed down to the coast. Near-shore coral reef systems, such as those in Madagascar and Australia’s Great Barrier Reef are experiencing increased sediment supply due to the conversion of forests to other land uses. However, translating land use into the actual amount of sediments reaching reefs, and understanding how these amounts are influenced by climate change, has until now been lacking. “Efforts to set conservation goals have been hampered, because managers have no data on how reforestation will benefit reefs,” explains lead author, Joseph Maina. “Our study not only captures this important relationship, but also demonstrates that watersheds can behave very differently to one another, and so conservation goals should be tailored accordingly.”
Maina and colleagues simulated river flow and sediment supply in four watersheds that are linked to Madagascar’s major coral reef ecosystems for a range of future climate change projections and land-use change scenarios. They find that the adverse effects of climate-change, such altered temperature and rainfall, are outweighed by the impact of deforestation up river. “We initially expected climate change to aggravate the sedimentation problems,” Maina says. “However, climate projections suggest overall decreases in rainfall and increases in temperature, which creates a negative water balance. This places far more emphasis on land use.” The study’s authors suggest that resources spent tackling the environmental issue of deforestation may therefore also aid in preserving the coral reef ecosystems at the coast.