A moribund tropical green sea turtle rescued by members of the Wider Caribbean Sea Turtle Conservation Network (WIDECAST) in Costa Rica is improving and might be returned to its habitat. Fishermen and maritime tour operators in the Guanacaste province found more than 40 dead sea turtles on Tuesday, November 5th, and immediately alerted nature conservation officials. Marine biologists are still looking into the possible causes for these massive deaths, which extend throughout the Pacific coast of Central America.
Two fading green sea turtles were found among the carcasses and were immediately given emergency treatment to evacuate water from their lungs. Antibiotics were administered as well, but one of the turtles perished on Thursday morning and was transported to a research center of the National University (Spanish initials: UNA) in the Central Valley. According to WIDECAST marine biologist David Herrera, the other turtle is being considered for a possible return to the ocean.
The dead sea turtles were spotted in the vicinity of Murcielago (Bat) Islands , which are part of a small archipelago located in the Santa Rosa National Park of Guanacaste. This archipelago is a scuba divers’ paradise that is routinely visited by dive tour operators based in Playas del Coco. Early field necropsies indicate that these turtles, which were tagged near the Galapagos Archipelago, have run into nets and fishing hooks. They also present signs of concussions near their skulls. Still, researchers are conducting pathological analyses to rule out toxicity.
The Costa Rica Star recently reported on the findings of more than 20 dead green sea turtles just across the border in Nicaragua, where conservation activists believe that trammel nets or the use of explosives for fishing purposes may be to blame for this Cheloniidae massacre. Researchers in Costa Rica, however, are leaning towards a neurological syndrome caused possibly related to brevetoxicosis, which was explained earlier this year by marine biologists at the Sea Turtle Rehabilitation Hospital of the Mote Marine Laboratory and Aquarium in Sarasota, Florida:
Harmful algal blooms are known to cause morbidity and mortality to a large number of marine and estuarine organisms worldwide, including fish and marine mammals, birds, and turtles. The effects of these algal blooms on marine organisms are due to the various toxins produced by the different algal species.
In green sea turtles, Chelonia mydas, and Kemp’s ridley sea turtles, Lepidochelys kempii, symptoms associated with brevetoxicosis were limited to neurologic signs, such as the inability to control the head (head bobbing) and nervous twitching. For these turtles, treatment involved removing the turtles from the environment containing the toxins and providing short-term supportive care.
Mr. Herrera further explained that he surveyed hawksbill sea turtles in the area, which did not exhibit any of the symptoms of the dead green sea turtles. Chelonia mydas feeds almost exclusively on algae and other marine plant life, whereas Eretmochelys imbricate (hawksbill) is carnivorous and less likely to be affected by brevetoxicosis. It is important to note that hawksbill sea turtles are a welcome sight in Costa Rica, since they were thought to be nearly extinct not long ago.
Source: La Nacion