carried by rivers draining deforested areas in Madagascar is smothering
local coral reefs, increasing the incidence of disease and suppressing
growth, report new studies published in the journals Biogeosciences and Marine Pollution Bulletin.
The first study looked specifically at coral communities in Antongil
Bay, located in northeastern Madagascar, while the second included data
from Western Madagascar. Antongil Bay is Madagascar's largest bay and
world-famous as nursing grounds for humpback whales.
The authors analyzed coral's luminescent bands, which reveal the growth
history of coral much like growth rings of a tree. They found that
corals near rivers "showed clear signs of disease and distorted growth
patterns", according to study co-author Jens Zinke of the University of
Western Australia's Oceans Institute.
"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," Zinke added in a
statement. "This is the first direct evidence that catchment activity
in Madagascar through deforestation and land use practices affects
near-shore reef ecosystems."
Madagascar has suffered from widespread deforestation. Around Antongil
Bay forests have been cleared for rice cultivation and cattle grazing.
Remaining forests have been heavily impacted by illegal rosewood and
Zinke says the results underline the importance of holistic approaches to conservation.
"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," he said. "There is a dire need to combine
efforts on terrestrial and marine conservation in unison to sustain
C.A. Grove at al (2012). Spatial linkages between coral proxies of
terrestrial runoff across a large embayment in Madagascar,
Biogeosciences, 9, 3063-3081, doi:10.5194/bg-9-3063-2012.
Joseph Maina et al (2012). Linking coral river runoff proxies with
climate variability, hydrology and land-use in Madagascar catchments.
Marine Pollution Bulletin, Available online 31 July 2012