females

Rainfall and sea turtles

October 4, 2024 By EarthWise Leave a Comment

There are seven species of sea turtles that inhabit the world’s oceans. Six of the seven sea turtle species – all of them except the flatback – are present in U.S. waters, and are listed as threatened or endangered under the Endangered Species Act.

Sea turtles, which have been around for more than 100 million years, spend the majority of their lives in the ocean, but they do periodically come ashore to nest. Female sea turtles lay their eggs in the sand and then return to the ocean. Survival odds for sea turtle hatchlings are quite bleak. In fact, only one out of every 1,000 makes it to adulthood.

Research shows that both air and sand temperatures are critical for sea turtle hatchling development. Cooler temperatures produce larger, heavier hatchlings with more males. Hatchling size matters because larger hatchlings, which can move faster, are more likely to survive because they spend less time on risky beaches. But rising temperatures might shorten incubation periods, and erratic rainfall can disrupt growth, potentially affecting survival.

A new international study by researchers from Florida Atlantic University and the University of Tübingen in Germany found that fluctuating rainfall patterns have a greater impact than changes in air temperature on sea turtle hatchling development.

The results, which were recently published in the journal BMC Ecology and Evolution, reveal that the impact of rainfall varies between species. As climate change shifts rainfall patterns, the impact on sea turtle nesting sites suggests that global conservation strategies for some species – like loggerhead and green sea turtles – likely need to be updated.

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Rain or Shine? How Rainfall Impacts Size of Sea Turtle Hatchlings

Sea Turtle

Photo, posted August 27, 2015, courtesy of USFWS/Orsulak via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Satellites discovering penguins

February 20, 2024 By EarthWise Leave a Comment

The loss of sea ice in Antarctica has forced emperor penguins to seek out new breeding grounds. Some colonies have traveled more than 20 miles in search of stable ice. Emperor females lay a single egg on a stretch of sea ice at the start of winter and males keep the eggs warm while the females go hunting for up to two months to bring back food for their hatchlings.

Emperor penguins are the tallest and heaviest of all living penguin species. The loss of sea ice has led to unprecedented breeding failure in some emperor penguin colonies. Emperor penguins are not threatened by hunting, habitat loss, or other human-caused problems, but the changing climate could be their undoing.

Emperor colonies are easy to spot from above. The penguins are up to four feet tall and the droppings from large colonies stand out vividly against white snow. A careful study of satellite imagery has revealed four previously unknown colonies of emperor penguins along the edges of Antarctica. This is the first bit of good news about the penguins in quite a while. The new discoveries, reported in the journal Antarctic Science, brings the total number of known colonies to 66.

The new discoveries are encouraging, but emperor penguins remain at risk from the warming climate. Three of the four new colonies are small, with fewer than 1,000 birds. So, the discovery does not have a big impact on the overall emperor penguin population. The addition of the new colonies is overshadowed by the recently reported colony breeding failures resulting from early and rapid ice losses.

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Thousands of Emperor Penguins Discovered by Satellite

Photo, posted January 19, 2014, courtesy of Christopher Michel via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Finding Homes For Rhinos | Earth Wise

October 6, 2023 By EarthWise Leave a Comment

Northern White Rhinos are virtually extinct; only two female individuals survive in Kenya. Southern White Rhinos also nearly vanished early in the 20th century, mostly because of excessive hunting. A surviving group of fewer than 100 animals was identified in South Africa, and ongoing conservation efforts led to the existing population of southern white rhinos, which now numbers more than 16,000.

Among the most successful conservation efforts took place at a 30-square-mile farm, Platinum Rhino, that was set up in 2009 about 100 miles southwest of Johannesburg. The owner of the farm did a great job of maintaining genetic diversity of the herd and protecting it from poachers. Eventually, it was costing $175,000 a month just for security against illegal hunters seeking rhino horns.

Faced with unsustainable expenses, the farm put the herd of 2,000 rhinos up for auction in April with a starting price of $10 million. No bidders came forward.

Fortunately, in September, the conservation group African Parks announced that it had reached a deal to take over the herd. African Parks partners with 12 countries in Africa to manage 77,000 square miles of protected areas.

The plan is to start moving the rhinos into a series of new sites in the wild starting next year. Moving the 5,000-pound animals to new locations will be complicated and expensive, costing anywhere from $1,500 to move a single rhino by land within South Africa to $50,000 for far afield air transport. African Parks is now raising funds to relocate the animals.

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Now Available: 2,000 Rhinos, Free to Good Homes With Plenty of Space

Photo, posted September 4, 2023, courtesy of Eric Huybrechts via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Saving The Sumatran Rhino | Earth Wise

January 2, 2023 By EarthWise Leave a Comment

The Sumatran rhinoceros is the smallest and most ancient rhino species and is the only surviving species with hair. It is critically endangered. Because of poaching and habitat destruction, there are fewer than 50 of them left in the wild and those are scattered in the rainforests of Sumatra and the Indonesian part of Borneo. Mating encounters between surviving males and females are increasingly rare.

The last male Sumatran rhino in Malaysia died in 2019 but cell samples from that individual are the basis of an ambitious effort in bioengineering.

Researchers from the Max Delbruck Center in Germany are taking skin cells from the deceased rhino and turning them into stem cells. The hope is to use these stem cells to derive egg and sperm cells to be the basis of assisted reproduction. Fertilization would take place in a petri dish. The resultant embryos would then be carried to term by surrogate rhino mothers.

The researchers have reported success generating induced pluripotent stem cells or IPS cells from the rhino skin samples. IPS cells are able to divide indefinitely and can transform into any cell type in the body.

The next step is to try to cultivate primordial germ cells – the precursors of eggs and sperm.

This work is going on because it is increasingly difficult to preserve the Sumatran rhino population by gathering together remaining individuals in wildlife Reserves. Females that have not been pregnant for a long time often become infertile because of cyst growth on their reproductive organs, and some are just too old to bear young.

It may take extraordinary efforts like these to save these animals from extinction.

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A second chance for the Sumatran rhino

Photo, posted April 30, 2008, courtesy of Willem V. Strien via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Global Warming And Sea Turtle Births | Earth Wise

January 11, 2021 By EarthWise Leave a Comment

Climate change is a serious threat to species whose sex is determined by temperature. Among these are sea turtles. Whether marine turtles are born male or female turns out to depend on the temperature of their nest during incubation.

Sea turtle nests need to be around 84.6 degrees Fahrenheit on average to produce a 50:50 sex ratio for embryos developing in eggs. If temperatures are higher, embryos predominantly become female. There is a transitional range of temperatures over which both males and females are produced. Below that range, only males are produced; above that range, only females are produced.

According to recent research published in the journal Conservation Science and Practice, sand temperatures along the Red Sea exceeded the 84.6-degree threshold in all but one of the sites studied. Some sites measured nearly 96 degrees. The Red Sea region is home to five of the world’s seven species of sea turtles, including endangered green turtles and critically endangered hawksbill turtles.

Skewing the sex distribution of a species is a serious threat to the future survival of the population.

The Red Sea findings are similar to observations around the world. In Florida, sea turtle hatchlings were born 100% female in seven out the past 10 years, and in the other three years, males only made up 10-20% of the brood. In Australia’s Raine Island, the largest green turtle nesting ground in the Pacific Ocean, the ratio of female to male turtle hatchlings in 2018 was 116:1.

Marine turtles have been around since the late Triassic period and have adapted to previous climate shifts. But the rapid pace of human-driven climate change is threatening the future survival of these creatures.

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Rising Temperatures Driving a Shift to All-Female Sea Turtle Populations

Photo, posted in October, 2005, courtesy of Frank_am_Main via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Engineering Mosquitoes | Earth Wise

February 21, 2020 By EarthWise Leave a Comment

Tropical regions grapple with the spread of diseases – such as dengue, yellow fever, zika, chikungunya, and malaria – by mosquitoes. A fairly successful strategy has been the Sterile Insect Technique, which is essentially insect birth control. The process involves rearing large quantities of sterilized male mosquitoes in dedicated facilities, and then releasing them to mate with females in the wild. As they do not produce any offspring, the insect population declines over time.

A problem with this approach is that while mosquitoes create health problems for people, they also play important roles in various ecosystems, such as providing food for bats and other animals. Eliminating mosquito populations on a large scale can trigger major changes in ecosystems.

Recently, an international team of scientists has synthetically engineered mosquitoes that halt the transmission of the dengue virus. They genetically engineered mosquitoes with an antibody “cargo” that gets expressed in the female mosquitoes that spread the dengue virus. Once the female mosquito takes in blood, the antibody is activated which hinders the replication of the virus and prevents its dissemination throughout the mosquito, thereby preventing its transmission to humans. Essentially, what the researchers have done is transfer genes from the human immune system to confer immunity to mosquitoes. The researchers are testing methods to neutralize mosquitoes against other viruses they spread.

This opens up a whole new approach to interrupt mosquito-borne human diseases. Mosquitoes are among the deadliest killers on the planet because they are the messengers that transmit deadly diseases. Until now, the only real solution has been to kill the messenger. The new approach may be a better way to deal with a serious problem.

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Mosquitoes engineered to repel dengue virus

Photo, posted June 20, 2014, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Fewer Snowbird Sharks

April 23, 2018 By EarthWise Leave a Comment

Blacktip sharks are snowbirds, to use a cross-species metaphor. At least, they usually are. The males of the species swim south to southern Florida during the coldest months of the year and head back north to North Carolina in the spring to mate with females.