SYDNEY, March 11 (Xinhua) -- Australian scientists on Wednesday revealed the latest details about the impact of human activities on regional Southeast Asian coral reefs, looking at how those combined with large-scale environmental pressures to affect the major marine ecosystems.

Nearly all of Southeast Asia's marine coastal ecosystems have experienced intense pressures in the past four decades, due to large-scale economic development, urbanization and deforestation, lead Australian researcher and Curtin University coral ecologist Nicola Browne said in a statement.

"The ways that humans use the land can severely impact soil contents and soil erosion patterns, which then discharge sediments into freshwater systems and nearby marine environments, ultimately altering the water quality on coral reefs," Browne said.

The study provides the first long-term data on the synchrony - driven by the El Nino Southern Oscillation (ENSO) climate pattern - of climate impacts on both terrestrial and marine ecosystems in northern Borneo, according to the researchers. They analyzed coral reef samples to learn about regional environmental changes, including changes that have occurred during the last few decades.

"Weather patterns that bring heavy rainfalls, such as those seen with the ENSO climate pattern, can exacerbate these erosion patterns even more, bringing more sediments into the local marine environments, which then ultimately end up affecting the coral reef ecosystems," Browne said.

Through the analysis of coral core samples from the Miri-Sibuti Coral Reefs National Park in Sarawak, Malaysia, the researchers said they found "decade-long, synchronous climatic impacts on the reef systems in northern Borneo, linking the El Nino Southern Oscillation climate pattern to effects shown on the area's coral reefs". The findings were published in the Scientific Reports journal.

The coral cores analyzed act as a type of "record keeper" of the local marine environments, creating fossils which can be read, interpreted and used to predict future ecosystem impacts, researcher Hedwig Krawczyk said.

"Corals incorporate geochemical tracers from the surrounding water into their skeleton, leaving behind a type of record of the marine environment at specific instances in time," Krawczyk said.

"In coastal regions where there is limited, long-term environmental data, such as in Borneo, coral cores provide a critical record of local changes in river runoff and rainfall. These records help us to understand the types of pressures these reefs have been exposed to over the last 30 years, and their level of resilience to future environmental changes," Krawczyk said.

"Our study testified that both marine and terrestrial environments in Borneo are massively affected by changes in the hydroclimate associated with ENSO, and longer term cycles in regional rainfall and temperature." Enditem

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