Ancient coral reefs at risk from deforestation and land use practices

Aug 03, 2012
Ancient coral reefs at risk from deforestation and land use practices

(Phys.org) -- A team of international scientists, including a researcher from The University of Western Australia, has found that soil erosion, land degradation and climate change pose a mounting threat to coastal reefs and their ecosystems in the western Indian Ocean.The study examined sediment and freshwater discharge over recent decades in two catchments in Madagascar's Antongil Bay and the island nation's Great Barrier Reef of Tulear, and the climatic processes that drive them.

The unique study incorporated hydrological catchment modeling as well as coral data over the past 60 years.

This was possible because Madagascar's giant Porites corals have grown continuously over several centuries at 1-2cm annually and record the changes in their environment by absorbing trace elements into their skeleton.

Deforestation is often linked with degradation of but until now no study has revealed its impact on adjacent .

"Results from the study suggest that changes in land use - primarily the removal of forests - and Madagascar's increased population density are the key drivers of long-term reef sedimentation trends but that these are slow processes," said study co-leader Dr Jens Zinke, of UWA's Oceans Institute.

Dr Zinke said those factors combined with climate changes - including hinterland rainfall, temperature and El Niño-Southern Oscillation - to influence the amount of sediment transported through river run-off, which is subsequently deposited in coastal waters and reflected in elevated geochemical indicators in corals.

"This is the first direct evidence that catchment activity in Madagascar through deforestation and land use practices affects near-shore reef ecosystems," Dr Zinke said.

"Just as importantly, these results reinforce the need to incorporate terrestrial land-use management in the design of coral reef protection networks in the region."

Dr Zinke, who is also with UWA's School of Earth and Environment and the Australian Institute of Marine Science (AIMS), said Madagascar was a biodiversity hotspot affected by massive 20th Century deforestation.

"There is a dire need to combine efforts on terrestrial and marine conservation in unison to sustain Madagascar's biodiversity," he said.

"The study proposes that the reduction of sediment and nutrients loads during floods and cyclones - for example through better control of hinterland - should be a priority in marine conservation planning.

"Water quality in near-shore coral reefs is critically important for a healthy ecosystem and sustaining livelihoods in small-scale fisheries communities across the globe.

"When water quality deteriorates, we see deterioration of important habitats, including coral reefs that are home to many species of reef fish, crustaceans and marine mammals."

Dr Zinke was the leader of the research, along with Professors Jan Vermaat and Hans de Moel from the Institute for Environmental Studies at VU University Amsterdam, and Dr Craig Grove of the Royal Netherlands Institute for Sea Research. The lead author was PhD student Joseph Maina from Macquarie University.

The study, Linking coral river runoff proxies with climate variability, hydrology and land-use in Madagascar catchments, is published in the Marine Pollution Bulletin.

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mememine69
1.7 / 5 (6) Aug 03, 2012
Safe to say there isnt any crisis and the theory was 100% wrong.
Look for yourself; not one single IPCC report mentions any crisis without a possible or likely. The end is near............maybe? Help my house is on fire.........maybe after 26 years and millions of studies. Can you say consultants wet dream.
I need proof before I condemn my own children to the greenhouse gas ovens of climate change crisis hell. REAL planet lovers are glad any crisis was exaggerated.
Do you WANT Romney in power? The just keep cursing the voters kids with CO2 threats of death.
tadchem
1 / 5 (1) Aug 03, 2012
Does anybody really need to be reminded of the inadvisability of *extrapolating* from local conditions at one site to a globe-girdling generality? Evidently so...
As I scientist, I have had to train many engineers in the traps hidden in extrapolations, but mathematicians and empirical scientists seem to understand almost innately.
rwinners
1.5 / 5 (4) Aug 03, 2012
Ancient forms of life die and new forms develop. So it was and so it will be.
Of course, we might not be among the new forms... but what the hell.

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