project news

Turtles in Trouble

News item submitted by Flora O'Brien
News item dated 15 Nov 2010

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Polluted waters are causing many turtles to die from tumours, according to a recent study by a team of ecologists from the National Oceanic and Atmospheric Administration's Pacific Islands Fisheries Science Center in Honolulu.  Hawaiian Green turtles (Chelonia mydas) are recognised as an endangered species according to the IUCN Red List, and suffer from many anthropogenic threats such as fishing, habitat loss and poaching. However, new evidence has come to light indicating that nitrogenous waste, which usually originates from agriculture run-off, sewage effluents, and fossil fuel combustion, is indirectly causing an increase in the incidence of the tumour-forming disease fibropapillomatosis (FP). 

Nitrogenous effluents were first suspected to be linked to the disease when researchers observed that turtles only developed FP after they visited nearshore waters. Records of turtles found stranded on the beaches of Hawaiian Islands over 28 years show that in addition to turtle size, land-use was closely correlated to disease rate. The results strongly suggest that FP was more prevalent in areas where anthropogenic land-use was greatest. Eutrophication from agricultural and sewage run-off has led to blooms of non-native macroalgae, such as Hypnea musciformis, which sequester the nitrogen and store it. Thus, when turtles consume the algae, they also ingest the nitrogenous compound which stimulates herpes viruses which normally lie dormant inside a turtle’s body. It is this virus which has been identified as triggering the potentially fatal tumours forming on the eyes, mouth, joints, and organs of green turtles.

Currently, the Frontier team in Costa Rica are busy monitoring the sea turtles nesting on the shores of the Osa Peninsula. Two turtle species are known to nest there every year, one of which is Chelonia mydas, and our volunteers have been conducting morning and night patrols with an aim to ensure the successful hatching of the turtles. By deterring both poachers and predators, it is hoped that our team will help protect this endangered species from further declines.

Find out more about the Costa Rica Forest project.