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Climate Change Affecting Sea Turtle Nesting Habits

Stabroek News  June 25, 2007

The changing nesting patterns of endangered sea turtles in Guyana, is alerting environmentalists to the impact of climate change on these marine animals.

The shell beaches in Region One have hosted thousands of nesting turtles over the years, and conservationists have been endeavouring to protect the turtles from heavy domestic use and from being traded.

Project Coordinator of the Guyana Marine Turtle Conservation Society (GMTCS) Michelle Kalamandeen told Stabroek News recently that climate change is affecting the sea turtle population.

According to Kalamandeen, in the 1960s the Hawksbill (critically endangered) and the Olive-Ridley (endangered) were our main nesting turtles, now the green turtles (endangered) and the leatherbacks (critically endangered) are mostly coming to nest on Guyana's shores. The Pacific Leatherback is said to be now extinct and the Atlantic Leatherback is facing extinction.

The change in the time period for nesting in Guyana, she said, may also be a significant sign.

Usually sea turtles nest in Guyana from March to August every year. However, for the last three to four years, says Kalamandeen, the nesting pattern has shifted from mid-January to mid-July. This may have a significant impact on the hatchlings as food availability may be an issue for them.

The project coordinator noted that in late January, a fisherman from the Waramuri community reported an encounter with six Olive Ridleys nesting at Tiger Beach. She said, "This is a very unusual event for Guyana," since Olive Ridleys are known to nest mostly in June-August, and for the past three years they have only documented four Olive Ridley nesting in Guyana.

It was noted as well that at the World Wildlife Fund (WWF) Sea Turtle Symposium in Suriname last year, GMTCS learned that the nesting of Olive Ridleys has increased in French Guiana and Brazil. This, Kalamandeen believes, "may explain why Guyana is not seeing many nestings of this species on her shores."

In French Guiana, 'little arribadas' (arrivals) of Olive Ridleys are now occurring, and this signifies the mass nesting (in the thousands) of sea turtles, she said. Costa Rica and India are the main areas for arribadas.

In relation to the Hawksbill, which nested in Guyana in fair numbers in the 1960s, Kalamandeen reported that human harvesting may be affecting the nesting of this species here.

Throughout the Caribbean, Hawksbills nest in generally low densities with the largest known nesting populations in Barbados, Cuba, Guyana, Panama, Antigua, Venezuela, Puerto Rico, Colombia, Jamaica, St Vincent and the Grenadines and the Dominican Republic. A report recently completed by GMTCS in collaboration with the University of Guyana noted that far more Hawksbills nested in 1964-65 than now, and it was noted that human harvesting of the sea turtle was the main cause for the decline. Recovery, she said, "may now be occurring but it is slow."

Hawksbills are being reported in the fresh water creeks in the Waini River, where salt water has inundated, she said. Guyana is also seeing Hawksbills drifting ashore in Georgetown, and recently GMTCS Co-Founder Annette Arjoon released a juvenile Hawksbill into the ocean after it was rescued from a vagrant by a man.

The GMTCS has around eight wardens and five interns from the Waini and Waramuri who have completed a ranger course at Iwokrama through the GMTCS.

With this manpower and funding from the WWF, GMTCS is only able to monitor 15 to 20 miles of the 90-mile stretch of beach that turtles use to nest. In 2005, when a lack of manpower prevented the GMTCS from monitoring Tiger Beach (a main nesting site), a significant number of turtles were slaughtered. No formal count was given but GMTCS suspects it was in the hundreds.

The project coordinator explained that on occasions such as weddings and the christening of babies the 'turtle take,' is higher. And she confirms that "there is still a constant level of take."

The buoyancy of the black market turtle trade plays a role - for example if there is a heavy demand for turtle meat on the black market this also increases the turtle take.

Kalamandeen indicated that the society would ensure the main nesting sites like Tiger Beach were closely monitored, but the erosion of Tiger Beach has posed some challenge to its monitoring this year. The erosion of beaches, according to the project coordinator, is part of a natural cycle that occurs every 30-35 years, but the erosion is occurring before this cycle is up. And with climate change, she said, beach erosion "could happen within a couple of weeks."

Kalamandeen said that GMTCS needs to further monitor these changes and will try to conduct a study in collaboration with the University of Guyana to ascertain how sea turtles will react to climate change, for example the impacts specific to Guyana.

Education and awareness continue to be a big focus of the society.

According to research, the impact of climate change on sea turtles includes a more limited food supply; for example, a Hawksbill nesting in Guyana may feed in the coral reefs of the Caribbean. And if the rising sea temperature damages the reefs (through coral bleaching), this can significantly impact on food supplies for the Hawksbill.

The main effects of climate change on sea turtles are thought to be:

1) Loss of nesting and feeding habitats due to sea-level rise;

2) Increased sand temperatures, which can lead to changes in sex ratios or potentially result in mortality;

3) Increased ocean temperatures, which can lead to changing nesting times, and coral bleaching and other damage to turtle feeding habitats;

4) Changes in ocean currents, which can modify migration paths and feeding patterns.

The Shell Beach is a potential tourism destination in Guyana specifically for the sea turtles, and if the populations are adversely affected or they have to relocate their nesting sites, this would significantly impact on the prospects for developing a viable tourist industry in an area where poverty is widespread.

Unless climate change is slowed down these adverse impacts are expected to continue.

Source: Stabroek News

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