Climate change is affecting sea turtles in an unusual way: sex. The sex of hatchlings, that is.
According to a study by Florida State University, rising global temperatures are causing a gender imbalance. Scientists researched Brazilian loggerhead turtles and found that the warmer temperatures cause higher incubating temperatures, which leads to more female hatchlings.
Optimal hatching temperatures are between 75.2 to 93.2 degrees Fahrenheit, but temperatures below 85.1 degrees results in more male turtles and temperatures above yield more females.
Assistant Professor of Oceanography at Florida State University Mariana Fuentes said:
“We’re concerned we’re going to have a feminization of marine turtles. This study came from the need to understand the current sex ratio being produced at loggerhead nesting grounds to establish baseline parameters as climate change progresses and to identify beaches that produce a higher proportion of males.”
Researchers believe projected increases in temperature will cause gender imbalance in marine turtle populations to worsen. Fuente and her team will move forward trying to identify the best practices to protect the turtles. They will coordinate with government officials and conservationists in Brazil to create conservation plans, working to make sure this imbalance does not negatively impact the species.
Nearly half of all life under the sea has disappeared in the past 50 years.
A new study by the World Wildlife Fund and researchers at the Zoological Society of London found that global populations of marine species have declined by 49% since 1970 due to pollution, habitat loss, overfishing and climate change.
Researchers were able to approximate this drastic decline using data that was collected from 2,337 individual sources, including population estimates from scientific studies and databases.
The study also found that some fish species people rely on for food – like tuna, bonito and mackerel – has declined by as much as 74%. Shark finning and industrial fishing have wiped out shark and ray populations to the point where one in four species are now threatened by extinction. And the number of sea cucumbers, a luxury food in Asia, have dropped by 98% in the Galápagos and by 94% in the Egyptian Red Sea.
Furthermore, industrial pollution and plastic contamination have destroyed marine habitats and caused the death of endangered sea turtles and other wildlife. Fossil fuels that accelerate the acidifcation of the oceans has led to the degradation of coral reefs, which support 25% of marine species on top of 400 million people. The world’s coral reefs will disappear if ocean temperatures continue rising at the current rate.
The report’s findings include a lot of bad news, but there is a silver lining. The world’s leaders and nations can use this information to turn things around by halting illegal fishing, cutting greenhouse gas emissions and protecting critical marine habitats like the remaining coral reefs. Director general of WWF International Marco Lambertini said in a statement:
“The ocean is a renewable resource that can provide for all future generations if the pressures are dealt with effectively. If we live within sustainable limits, the ocean will contribute to food security, livelihoods, economies and our natural systems.”
As the planet warms, cold-blooded animals will have trouble adjusting. According to a study by two biologists, cold-blooded animals, which cannot regulate their internal temperatures, will struggle with climate change.
The biologists, Alex R. Gunderson and Jonathon H. Stillman from the University of California, Berkeley and San Francisco State University, analyzed 230 cold-blooded species from 112 published studies on plasticity – or the ability of animals to modify their thermal tolerance when they experience new environmental temperatures. They found that cold-blooded animals have an particularly tough time adjusting and that on average most aren’t flexible to warming climate changes.
“Overall, we found that even though all of the animals have some plasticity, they all have relatively low levels of plasticity. As environmental temperatures rise due to global warming, the animals will get closer and closer to their thermal limits, and plasticity won’t do much to help them.”
Gunderson and Stillman discovered that the plasticity of animals differs based on their habitat. So cold-blooded species like lizards and insects have less plasticity than fish and crustaceans, and thus will have a more difficult time surviving in the changing climate. Gunderson explains:
“The difference between terrestrial and aquatic animals is that the aquatic ones have a higher capacity to adjust, but it is still relatively low. Ideally, if temperatures went up three degrees, the animals’ tolerance would go up three degrees as well. But that’s not what we see.”
The study’s analysis suggests that certain animals – such as lizards, insects and snakes – can’t depend on plasticity. Rather, they will have to rely on behavior modifications, like moving to greater altitudes or more shaded habitats. But unfortunately, not all animals live in regions where such behavioral adaptations are feasible and in those cases, the species will have to evolve higher tolerance for the heat in order to survive.
All seven species of sea turtles are at risk of extinction. But there is hope for one sub-population in Florida.
In 2015, researchers counted 14,152 turtle nests in the Archie Carr National Wildlife Refuge, the principal green sea turtle nesting habitat in North America. This number broke the previous record of just under 13,000 in 2013 and completely shattered past yearly totals, ranging from slightly below 200 in 2001 to slightly over 6,000 in 2011.
Executive director of the Sea Turtle Conservancy David Godfrey says:
“From any spot on the beach during the peak of nesting, we might just within eyesight see see maybe 10 turtles. And imagine, all these turtles are approaching 300 pounds each…That’s a phenomenon we have not seen before in Florida.”
Green sea turtles lay between 75 and 200 eggs per nest, so this past season may have produced as many as 3 million babies. However, because of all the threats they face, such as hungry gulls and fishing nets, only a fraction of these nestlings will likely survive to maturity.
Fortunately, this should still be enough for future viable nesting seasons. In fact, the 2015 turnout was so significant that the United States Fish and Wildlife Service (USFWS) is preparing to downgrade the turtle’s conservation status on the federal list from “endangered” to “threatened.”
The Archie Carr refuge was established in 1990 and since then, the green sea turtle nesting numbers have steadily risen. Lending to this increase are the efforts of conservationists, government officials and residents to reduce pollution and other human effects.
“We’re really seeing the fruits of all that work now with the exponential growth in green turtle nesting. That is what it takes with sea turtles in particular, because they grow so slowly. Those hatchlings from 30 years ago are reaching adulthood and coming back.”
Featured image by Keenan Adams, U.S. Fish and Wildlife Service Southeast Region / CC BY 2.0
What is the most common type of trash in our oceans? And which ones are the most deadly?
More than 560,000 volunteers in 91 countries spanned over 13,000 miles in the 2014 International Coastal Cleanup. And over 16 million pounds of trash were collected in last year’s Ocean Conservancy’s International Coastal Cleanup program.
The data from the program, dating back 30 years, in addition to a survey of 274 experts, was put into a study that ranked their findings.
The most common types of trash found were cigarette butts, food wrappers, bottles and bottle caps. And some of the deadliest types for marine mammals, turtles and seabirds included fishing gear, plastic bags and utensils, balloons, cigarette butts and bottle caps.
See the report by the numbers with Ocean Conservancy’s infographics:
Ever wonder what it would be like to be an animal swimming in the Great Barrier Reef? Now you can find out, thanks to a helpful turtle and a GoPro. See what the reef looks like through the eyes of one of its very own inhabitants.
A step forward for the Great Barrier Reef is a step forward for conservation.
Earlier this year, the Australian government banned dumping in the Great Barrier Reef Marine Park. In November, the government extended the ban outside the park, to include the entire World Heritage Area, where 80% of the dumping had occurred closer to the shore.
This closed a legal loophole that would have allowed 46 million cubic meters of seabed to be dug up and dumped in the fragile and biodiverse ecosystem. The Great Barrier Reef is home to more than 1,500 species of fish, 134 species of sharks and rays, over 30 species of marine mammals, six of the world’s seven species of threatened marine turtles, as well as 411 kinds of hard coral and one-third of the world’s soft corals.
“For everyone around the world who cares about the Reef, this is a moment to savor.”