Loggerhead turtle in the North Pacific Sea turtle (((Caretta Caretta) It hatches on the coast of Japan and spends most of its time in the open Pacific Ocean, but it can also be mysteriously harvested in Mexico, 9,000 miles (14,500 km) from its original nesting site.
Its incredible journey depends on the warmth from the surroundings to maintain their core body temperature, so they are potentially deadly cold, which should be hard for them to live in. Require them to pass through the water. Scientists now have clues as to how turtles survive this epic movement.
Larry Clouder, a senior author and professor of marine ecosystems and conservation at Stanford University’s Hopkins Coastal Laboratory and a senior researcher at the Stanford Woods Institute, said: environment.
Along the Pacific coast of North America, monsoons from the north regularly blow down the coastline, pushing warm surface waters offshore. After that, the cold water from the deep sea rises and replaces the hot water, dragging up abundant nutrients. Tropical animals, including Loggerhead, rarely set foot in these cold waters from the Pacific, according to Clauder. Charles Darwin even described the area as “impossible” for hot-water-loving creatures, he added.
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However, according to a new study, it was published in the journal on April 8th. Frontier of oceanology, Loggerhead may have a fleeting opportunity to reach the Mexican coast El NinoA climate cycle that moves warm water from the western tropical Pacific to the east along the equator.
“For these turtles to arrive in Mexico, they need to open a warm’door’,” Crowder told Live Science. The authors of the study call this temporary door a “heat corridor,” or essentially a hot water passage. “During El Nino, the turtle shoots across.”
Not only does this study shed light on a long-standing mystery, it may also provide important information to protect Loggerhead, which is considered “vulnerable.” By the International Union for Conservation of Nature (IUCN). Conservation efforts may need to be adapted as turtles react to warm water. Climate changeSaid Clouder.
“Climate change will make the Pacific Ocean surface warmer and longer, and the duration of the hot water event will be longer,” said Carolyn Calle, an associate professor of biological sciences at the University of California, San Diego.
If the thermal corridor hypothesis is true, more loggerhead turtle larvae could move to the North American coast over time, Kurle told Live Science in an email. She said this may be beneficial for young turtles, as the abundant nutrients in these coastal waters boost the turtle’s food supply. “But that’s terrible,” Kurle told Live Science if more young turtles were accidentally caught in coastal fishing nets, especially because they didn’t have the opportunity to return to Japan to mate. ..
Decades of mystery
Loggerhead is found worldwide, primarily in subtropical and temperate waters, and is divided into nine subpopulations, including the North Pacific subpopulation. According to the US National Oceanic and Atmospheric Administration (NOAA). Scientists said the North Pacific Loggerhead was between Mexico and Japan when the female turtle Aderita was released from captivity in Baja California in 1996 and soon made a beeline for East Asia. Mr. Clouder said he had a clue to move.
Marine biologist Wallace Nichols had attached a satellite tag to Aderita, which allowed him to track her entire journey to Japan. According to PBS.. Clauder and his co-authors used similar follow-up data in a new study, but they obtained from a vast dataset of 231 juveniles whose migration patterns had been monitored for 15 years.
About 97% of these Loggerheads stayed in the open sea and did not adventure towards the North American coast. In fact, when these turtles went near the edge of the coastal ecosystem, they quickly turned around.Dana Brisco, a postdoctoral fellow in Crowder’s lab at the time, had a turnaround timing. Driven by the earth’s magnetic field, What turtles can sense and use to navigate the ocean. Perhaps this ability will help them avoid cold water, Clouder said.
However, Briscoe noticed that not all turtles turned around at typical points — six of 231. tortoise Just followed their cheerful path, and soon swam into coastal waters into an area known as the California Current Large Marine Ecosystem (CCLME). The team scrutinized these six outliers and found that each had traveled in the spring. Based on data collected from remote sensors, these wandering turtles “experienced an unusually warm condition” compared to their corresponding turtles.
“And the two who brought it closest to Baja experienced the warmest water conditions,” said Clouder. Looking at this relationship with hot water, the team made a thermal corridor hypothesis.
However, only 6 out of 231 (about 3%) participated in CCLME, so the team needed more data to support the idea. There, they collaborated with Calandra Turner Tomaszewicz, a scientist at the NOAA Southwestern Fisheries Science Center, who was studying the bones of turtles stuck on the beach in Mexico.
Sea turtle bones have annual rings, similar to trees. New rings grow around the outside of the bone each year, but one ring erodes from the center of the bone. The humerus of a turtle, a type of leg bone, always has about 6-8 growth rings.
These growth rings contain clues as to what the turtle ate in a particular year, in the form of stable isotopes, which are chemical elements with different numbers of neutrons. If scientists know when a turtle died, these chemical cues can be used to determine what the turtle ate throughout its life and therefore where it was.
“And the stable isotope ratios of pelagic foods like jellyfish are dramatically different from those of crabs,” said Loggerhead, who eats in coastal waters. In this way, the team determined when a particular turtle jumped from open water to coastal water. After that, they checked the water quality for the year.
Turner Tomaszewicz and her colleagues analyzed the annual rings of 33 loggerhead turtles in Mexico and found that more than 60% of turtles entered areas near the coast each year in warm sea conditions. Grouping turtles by year revealed that much more turtles arrived in Mexico in warmer years than in cooler ones.
“Analysis of the bone growth layer completely strengthened their thermal corridor hypothesis,” supporting the idea that the passage of these temporary hot waters would help more turtles reach the North American coast. Kurle said.
This hypothesis may also explain why loggerhead turtles from Japan were harvested in San Diego Bay in 2016, the year of El Nino, Crowder said. Turtles rarely appear in Southern California, yet they usually do not appear in large groups, as they did that year. According to the San Diego Union-Tribune.. Due to a strange event, some scientists wondered if Loggerhead would come to San Diego more often due to climate change.
Of course, that’s the only hypothesis of the thermal corridor — the hypothesis. Ideally, the team would be able to tag more Loggerheads with satellites, track their movements, and see how many people migrated to Mexico in El Nino compared to Cool. La Nina For years, Kurle said. However, this effort is likely to be costly and impractical, as very few turtles appear to enter CCLME, Crowder said. Instead, he said he would like to do experimental research with dozens of turtles. There, two groups of loggerhead turtles are released into the open sea near the CCLME boundary.
But for now, even with limited data, current research “will help those who try to understand and manage this vulnerable species in one of the longest migrations in the animal kingdom,” Kurle told Live Science. Told.
Originally published in Live Science.
Turtles complete a seemingly impossible journey thanks to a hidden “corridor” through the Pacific Ocean
Source link Turtles complete a seemingly impossible journey thanks to a hidden “corridor” through the Pacific Ocean