As nesting beaches warm, sea turtle populations are turning female–how scientists found out

first_imgClimate Change And Biodiversity, DNA, Genetics, Global Warming, Marine, Marine Ecosystems, Research, Sea Turtles, Technology, Wildtech Article published by Sue Palminteri Popular in the CommunitySponsoredSponsoredOrangutan found tortured and decapitated prompts Indonesia probeEMGIES17 Jan, 2018We will never know the full extent of what this poor Orangutan went through before he died, the same must be done to this evil perpetrator(s) they don’t deserve the air that they breathe this has truly upset me and I wonder for the future for these wonderful creatures. So called ‘Mankind’ has a lot to answer for we are the only ones ruining this world I prefer animals to humans any day of the week.What makes community ecotourism succeed? In Madagascar, location, location, locationScissors1dOther countries should also learn and try to incorporateWhy you should care about the current wave of mass extinctions (commentary)Processor1 DecAfter all, there is no infinite anything in the whole galaxy!Infinite stupidity, right here on earth.The wildlife trade threatens people and animals alike (commentary)Anchor3dUnfortunately I feel The Chinese have no compassion for any living animal. They are a cruel country that as we knowneatbeverything that moves and do not humanily kill these poor animals and insects. They have no health and safety on their markets and they then contract these diseases. Maybe its karma maybe they should look at the way they live and stop using animals for all there so called remedies. DisgustingConservationists welcome China’s wildlife trade banThobolo27 JanChina has consistently been the worlds worst, “ Face of Evil “ in regards our planets flora and fauna survival. In some ways, this is nature trying to fight back. This ban is great, but the rest of the world just cannot allow it to be temporary, because history has demonstrated that once this coronavirus passes, they will in all likelihood, simply revert to been the planets worst Ecco Terrorists. Let’s simply not allow this to happen! How and why they have been able to degrade this planets iconic species, rape the planets rivers, oceans and forests, with apparent impunity, is just mind boggling! Please no more.Probing rural poachers in Africa: Why do they poach?Carrot3dOne day I feel like animals will be more scarce, and I agree with one of my friends, they said that poaching will take over the world, but I also hope notUpset about Amazon fires last year? Focus on deforestation this year (commentary)Bullhorn4dLies and more leisSponsoredSponsoredCoke is again the biggest culprit behind plastic waste in the PhilippinesGrapes7 NovOnce again the article blames companies for the actions of individuals. It is individuals that buy these products, it is individuals that dispose of them improperly. If we want to change it, we have to change, not just create bad guys to blame.Brazilian response to Bolsonaro policies and Amazon fires growsCar4 SepThank you for this excellent report. I feel overwhelmed by the ecocidal intent of the Bolsonaro government in the name of ‘developing’ their ‘God-given’ resources.U.S. allocates first of $30M in grants for forest conservation in SumatraPlanet4dcarrot hella thick ;)Melting Arctic sea ice may be altering winds, weather at equator: studyleftylarry30 JanThe Arctic sea ice seems to be recovering this winter as per the last 10-12 years, good news.Malaysia has the world’s highest deforestation rate, reveals Google forest mapBone27 Sep, 2018Who you’re trying to fool with selective data revelation?You can’t hide the truth if you show historical deforestation for all countries, especially in Europe from 1800s to this day. WorldBank has a good wholesome data on this.Mass tree planting along India’s Cauvery River has scientists worriedSurendra Nekkanti23 JanHi Mongabay. Good effort trying to be objective in this article. I would like to give a constructive feedback which could help in clearing things up.1. It is mentioned that planting trees in village common lands will have negative affects socially and ecologically. There is no need to even have to agree or disagree with it, because, you also mentioned the fact that Cauvery Calling aims to plant trees only in the private lands of the farmers. So, plantation in the common lands doesn’t come into the picture.2.I don’t see that the ecologists are totally against this project, but just they they have some concerns, mainly in terms of what species of trees will be planted. And because there was no direct communication between the ecologists and Isha Foundation, it was not possible for them to address the concerns. As you seem to have spoken with an Isha spokesperson, if you could connect the concerned parties, it would be great, because I see that the ecologists are genuinely interested in making sure things are done the right way.May we all come together and make things happen.Rare Amazon bush dogs caught on camera in BoliviaCarrot1 Feba very good iniciative to be fallowed by the ranchers all overSponsored Male sea turtles are becoming increasingly scarce, due most likely to warming global temperatures.Scientists combined hands-on field measurements with genetic and hormonal analyses to link free-swimming sea turtles of known sex back to their natal rookeries along Australia’s Great Barrier Reef (GBR) and determine the sex ratios over time at these locations.They found that females comprised over 2/3 of the turtles originating from beaches in the cooler southern portion of the GBR and nearly all the turtles (up to 99%) that originated from the warmer northern beaches.While a somewhat higher ratio of females may help maintain reproduction, scientists fear the loss of male turtles could jeopardize a population’s ability to sustain itself in the future. Is Australia’s Great Barrier Reef losing its male sea turtles?A new study has found that green sea turtle hatchlings in one of the world’s largest colonies are increasingly female, and this trend has been ongoing for decades, with warming global temperatures the suspected culprit.Sea turtles, as well as some other reptiles, lack sex chromosomes. Their gender is determined by the environment of the nest while the embryos are incubating, and by nest temperature in particular. Warmer sand tends to produce higher numbers of female hatchlings, making sea turtles and other reptiles particularly vulnerable to a warming Earth. Moreover, the range of temperatures that produce 100% males or 100% females spans only a few degrees Celsius.Sea turtle hatchling begins the perilous trip to the ocean’s edge. Baby sea turtles face extreme predation pressure from birds, mammals, and people. Photo credit: Wildlifeppl CC 3.0The study’s authors developed a novel method to determine sex ratios of free-ranging turtles from specific regions of the Great Barrier Reef (GBR). The researchers matched the sex and age class of green sea turtles to the nesting beaches from which they hatched by combining basic field methods with genetic and hormone analyses.Lead author Michael Jensen, of the National Oceanic and Atmospheric Administration (NOAA)’s Southwest Fisheries Science Center, said in an email to Mongabay-Wildtech that where turtle populations from genetically distinct rookeries feed together, scientists have been able to estimate the rookery origin of these turtles through their DNA.“The novelty of this work was the multidisciplinary approach that combined genetic and endocrine data from the same turtle,” Jensen said. “We assessed the secondary sex ratios of turtles at foraging grounds – as opposed to looking at primary sex ratios of hatchlings produced on a specific nesting beach. We believe our approach offers a better way of tracing trends in a population’s sex ratio. Foraging grounds encompass turtles of different life stages (juveniles, subadults and adults), which represents different generations of turtles and therefore many years of hatchlings produced from regional nesting beaches. That gave us a window into sex ratios produced over time from different rookeries.”Wrangling turtles for their DNA Virtually no turtles nest in the middle stretch of Australia’s 2,300 kilometer (1,400 mile) long Great Barrier Reef (GBR), so the northern and southern breeding populations are genetically distinct.The researchers sampled 411 turtles at foraging sites (74 of them during a 2008 study) in the middle section. Turtles of many ages from distinct nesting areas congregate in these shallow waters to feed, so sampling there allowed the researchers to estimate sex ratios of turtle cohorts from various beaches over the past 50+ years.Green sea turtles are vegetarians and forage on sea grasses and algae in shallow waters for years before returning to their natal nesting beach to breed. Photo credit: Brocken Inaglory CC 4.0They first had to catch the turtles—“rodeo-style”—which consisted of finding, following, and hand-catching the animals from a small boat, then bringing them to shore to process them. Assigning age class was easy and based on the length of each animal’s curved carapace.The researchers distinguished adult males turtles from females by noting their longer tails and measuring testosterone in blood samples. Sea turtles lack external sex-based traits until they reach maturity, however, so the scientists also physically examined most of the immature turtles to ensure they’d assigned gender correctly.Laparoscopy, the surgical technique used to definitively determine a turtle’s sex, runs a thin tube into the turtle to briefly examine its reproductive organs. The turtle recovers from the procedure in a couple of days, so researchers have been testing less-invasive and labor-intensive techniques to assess sex ratios of immature turtles.Measuring a turtle’s testosterone level required a far simpler blood sample, allowing the researchers to process hundreds of turtles with high accuracy.The researchers linked each turtle back to the beach from which it hatched by analyzing DNA from skin tissue samples and ran models to group the foraging turtles based on their genetic similarity. Female and male green turtles along Australia’s east coast will feed in various preferred foraging grounds but return to the area around their nesting beach to mate.A lone green sea turtle returns to the sea after nesting on the beach. Photo credit: Brocken Inaglory CC 3.0Where the boys are (not)The scientists showed that the northern part of the GBR, in particular, has been producing mainly females for more than 20 years by determining the genetic origin of turtles from each sex relative to their life stage. They found that turtles that had hatched on the cooler southern nesting beaches showed a “moderate” sex bias (65–69% female), similar to reports from feeding grounds located in the southern region. However, nearly all the turtles (87% of adults and over 99% of both juveniles and subadults) that originated from beaches in the warmer northern portion of the GBR were female.The scientists estimated monthly temperatures of the sand on the key nesting beaches using air and sea surface temperatures from 1960 to 2016. They found sand temperatures consistently remained above the “pivotal” temperature of 29.3o C (84.7o F)—the value corresponding to a roughly equal number of male and female hatchlings—starting around 1980.Some imbalance in the female-male ratio may be expected and potentially beneficial. Male sea turtles tend to breed more frequently and with more individuals than females do, which may mitigate some of the imbalance.Nevertheless, scientists have seen turtle sex ratios become increasingly female-dominated over the past few decades, and they fear that warming air and sea temperatures may begin causing single-sex populations that cannot sustain themselves.Moreover, the authors state in their paper, “extreme incubation temperatures not only produce female-only hatchlings but also cause high mortality of developing clutches.”“While some of the decreased hatching success [that researchers in Australia have observed] might be explained by high temperatures, many other factors influence hatching success (e.g. flooding of the nest from increased water table),” said Jensen. “We are just now beginning to understand the problem, so we have more work to do before we can begin to suggest ways to address it. The good news is that a lot of research is now focusing on understanding the influence of environmental factors on sea turtle hatchlings’ success.”Researchers have seen over decades that warming temperatures alter the sex of sea turtle hatchlings; this study is the first to document the trend in a major wild population.The findings suggest that wildlife managers consider strategies to lower incubation temperatures at key nesting sites of sea turtles and other temperature-dependent species around the world. Moisture and shade from coastal vegetation, for example, also affect sea turtles’ incubation and, thus, the sex of hatchlings, by keeping sand temperatures cooler.Avoiding extreme incubation temperatures, the authors state in their paper, would help “boost the ability of local turtle populations to adapt to the changing environment and avoid a population collapse or even extinction.”Sea turtles like this one in the Philippines, are graceful swimmers. Photo credit: Almudena BartayresJensen and colleagues hope their work will encourage others to do similar studies, as it offers a rapid way to monitor trends in turtle population sex ratios.“However,” said Jensen, “the success of this method depends on many factors, such as accessibility to large sample sizes of turtles at foraging grounds, understanding the genetic characterization of rookeries that might be contributing to the foraging grounds, and the degree of genetic structure among those rookeries. So whether this method will work in other regions and other species should be assessed on a case-by-case basis.”center_img FEEDBACK: Use this form to send a message to the editor of this post. If you want to post a public comment, you can do that at the bottom of the page. ReferenceJensen, M. P., Allen, C. D., Eguchi, T., Bell, I. P., LaCasella, E. L., Hilton, W. A., … & Dutton, P. H. (2018). Environmental Warming and Feminization of One of the Largest Sea Turtle Populations in the World. Current Biology, 28(1), 154-159.  DOI: http://dx.doi.org/10.1016/j.cub.2017.11.057last_img

Leave a Reply

Your email address will not be published. Required fields are marked *