Anthropogenic Anoxic Black Bands in Tuvalu Coral

Tuvalu coral records domestic waste-induced eutrophication since 1990s, which has promoted the seasonal anoxic (strong reduced) condition and formed iron sulfide- black bands like ocean sediment inside coral skeleton!

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Tuvalu atoll, located in the tropical South Pacific, is a symbolic atoll country that is being submerged due to Sea Level Rise. On the other hand, the local human waste and sewage are serious and affect the coral reef ecosystem. We found the annual black bands in a coral boring core (Porites lutea) from Fongafale Island, the capital of Tuvalu. Coral records anthropogenic domestic waste-induced eutrophication since 1990s, which has promoted the seasonal anoxic (strong reduced) condition and formed iron sulfide- black bands like ocean sediment inside coral skeleton! This massive Porites coral was a rare survivor and appealed strongly the environmental deterioration. In this coral annual band study we applied firstly the complex isotopic- trace element- organics- DNA segments- multi analyses. Especially iron redox indicator and DNA segments inside coral annual bands have the potential to reconstruct the anthropogenic ecosystem deterioration!

https://www.nature.com/article...

   In January of this year we visited Tuvalu, Fongafale Island and watched the ecosystem shift from coral reefs to macroalgae (Sargassum polycystum). The new government plan of dredging and reclamation in the lagoon to protect the coast progress. Ecosystem restoration should also be considered for the island resilience against sea level rise. 

Fongafale coast

Macroalgae kelp    photo by A.Watanabe

King Tide around runway


Nobuko Nakamura

Research Fellow, The Ocean Policy Research Institute, THE SASAKAWA PEACE FOUNDATION

1 Comments

Go to the profile of Antoine De Ramon N'Yeurt

Thank you for this most interesting research. The main driver of coastal polution in Tuvalu's main island appears to be population-driven, and the excess nutrients in the lagoon lead to regular macroalgal blooms (Sargassum sp., Padina sp. and Lyngbya sp.). Better waste management policies could be the key to healthier coastal waters in this vulnerable atoll island nation.