Saturday, September 25, 2021

Mexican sea turtles find new home in California river

Los Angeles, Aug 25 (EFE).- Green sea turtles from Mexico’s Pacific coast are now living in California’s San Gabriel River, where experts in marine life are studying the reasons for their migration and adaptation to this urban waterway.

“They’re probably looking for food, a safe place to grow and this is like the limit of where they can live, because they need warm water and they need seaweed, invertebrates and other small creatures they can feed on,” Cassandra Davis, education volunteer coordinator at the Aquarium of the Pacific in Long Beach, California, told EFE.

The specialist said that these young specimens are “genetically linked to Mexican green sea turtles that are found in Michoacan.”

The green sea turtle (Chelonia mydas) is on the National Oceanic and Atmospheric Administration (NOAA) Red List of Threatened Species.

Together with the Aquarium of the Pacific and the Los Cerritos Wetlands Authority, the federal agency has been studying the sea turtles since the first reports of their 2009 appearance in the San Gabriel River that runs between California’s Los Angeles and Orange Counties.

“It could be that with global warming, the ocean is warmer and for that reason the green sea turtles swim farther north. We have detected around 100 in the estuary of the San Gabriel River, with its mix of fresh water and salt water,” Davis said.

“When the sea is cold they’re paralyzed. We believe that with the cooling method with water from the Department of Water and Power (DWP) plant, the river is lukewarm and they feel fine,” she said.

Something that helps keep the river warm, the educator said, is that since 1930 the riverbeds in Los Angeles urban areas have been coated with cement “to avoid flooding.”

Davia said it could be that for centuries the green sea turtles have swum from their birthplace in central Mexico to the California beaches.

“But we humans have done away with as much as 96 percent of the California wetlands” where they could to grow and then “return to Mexico as adults and lay eggs on the Mexican beaches,” repeating the cycle time and again, she said.

Dan Lawson, a biologist with the NOAA Fisheries Service, told EFE that “the studies began with a simple observation in 2009. We took some turtles and put them in an acoustic telemetry tracker to observe their displacement.”

Later, they collected genetic samples in order to “understand the origin” of these amphibians, which also helped them carry out contaminant studies.

As a result they found samples in the turtles derived from “abundant pollution in urban areas” from such contaminants as the industrial chemical polychlorinated biphenyl and the agricultural pesticide dichlorodiphenyltrichloroethane, both banned in the United States for decades.