Marine Heat Waves Could Threaten Dolphin Survival, Study Suggests
That's the saddening implication of a study published in Current Biology Monday. Researchers looked at what happened when a marine heat wave scorched waters off the coast of Western Australia in 2011. What they found was that the survival rate of dolphins in the area declined by 12 percent and that female dolphins gave birth to a smaller number of calves. The effects lasted up until 2017.
"The extent of the negative influence of the heat wave surprised us," lead study author and University of Leeds PhD student Sonja Wild in a statement reported by USA Today. "It is particularly unusual that the reproductive success of females appears to have not returned to normal levels, even after six years."
The researchers had been studying dolphins in an area known as Shark Bay, a World Heritage Site home to Indo-Pacific bottlenose dolphins. The 2011 heat wave, which raised ocean temperatures in the area as much as four degrees Celsius above average, killed off seagrass and fish in the iconic bay, a University of Bristol press release explained.
The researchers wanted to know if the seagrass die-off had impacted larger animals.
Marine heatwave proves devastating to Shark Bay, Western #Australia. #Dolphin survival and reproductive rates suf… https://t.co/01cZ4wZPpW— Bristol University 🎓 (@Bristol University 🎓)1554135543.0
"It was serendipity really. We have been working in that part of Shark Bay since 2007, now as part of a large study," study author and Department of Anthropology at the University of Zurich Director Michael Krützen told CNN in an email.
The researchers reviewed more than 5,000 dolphin encounters between 2007 and 2017 and found that the heat wave had indeed had a lasting impact, according to the press release. Researchers thought that the loss of food and habitat meant that fish in the area could not recover quickly. This forced dolphins to spend more time hunting, making them less aware. This in turn increased the chances that sharks would prey on calves. In addition, the researchers thought that the lack of nutrition might have made it harder for both mothers and young dolphins to get enough to eat, leading to more calf deaths.
For the researchers, the findings were yet another example of the threat climate change poses to the oceans. A study published in March for example, found that the number of ocean heat wave days per year had increased by 50 percent between 1987 and 2016 and that they had the same destructive impact on marine ecosystems as wildfires on land.
"Given that marine heatwaves are occurring more often in association with climate change this raises serious concerns over the long-term prospects for the dolphin population, commercial fisheries and the ecosystem as a whole," senior study author and senior research associate at Bristol's School of Biological Sciences Dr. Simon Allen said in the press release.
The one silver lining from the study was that dolphins that used sponges to hunt were not as impacted as those who did not, but the researchers did not know if that advantage would hold for an extended period of time, CNN reported.
"It seems that extreme weather events appear to threaten marine mammal populations in their existence. If we want to conserve these populations, we have to think how the frequency of such events can be kept at a minimum," Krützen told CNN.
Sweden's reindeer have a problem. In winter, they feed on lichens buried beneath the snow. But the climate crisis is making this difficult. Warmer temperatures mean moisture sometimes falls as rain instead of snow. When the air refreezes, a layer of ice forms between the reindeer and their meal, forcing them to wander further in search of ideal conditions. And sometimes, this means crossing busy roads.
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By Aaron W Hunter
A chance discovery of a beautifully preserved fossil in the desert landscape of Morocco has solved one of the great mysteries of biology and paleontology: how starfish evolved their arms.
The Pompeii of palaeontology. Aaron Hunter, Author provided<h2></h2><p>Although starfish might appear very robust animals, they are typically made up of lots of hard parts attached by ligaments and soft tissue which, upon death, quickly degrade. This means we rely on places like the Fezouata formations to provide snapshots of their evolution.</p><p>The starfish fossil record is patchy, especially at the critical time when many of these animal groups first appeared. Sorting out how each of the various types of ancient starfish relate to each other is like putting a puzzle together when many of the parts are missing.</p><h2>The Oldest Starfish</h2><p><em><a href="https://www.biorxiv.org/content/10.1101/216101v1.full.pdf" target="_blank" rel="noopener noreferrer">Cantabrigiaster</a></em> is the most primitive starfish-like animal to be discovered in the fossil record. It was discovered in 2003, but it has taken over 17 years to work out its true significance.</p><p>What makes <em>Cantabrigiaster</em> unique is that it lacks almost all the characteristics we find in brittle stars and starfish.</p><p>Starfish and brittle stars belong to the family Asterozoa. Their ancestors, the Somasteroids were especially fragile - before <em>Cantabrigiaster</em> we only had a handful of specimens. The celebrated Moroccan paleontologist Mohamed <a href="https://doi.org/10.1016/j.palaeo.2016.06.041" target="_blank" rel="noopener noreferrer">Ben Moula</a> and his local team was instrumental in discovering <a href="https://www.sciencedirect.com/science/article/abs/pii/S0031018216302334?via%3Dihub" target="_blank" rel="noopener noreferrer">these amazing fossils</a> near the town of Zagora, in Morocco.</p><h2>The Breakthrough</h2><p>Our breakthrough moment came when I compared the arms of <em>Cantabrigiaster</em> with those of modern sea lilles, filter feeders with long feathery arms that tend to be attached to the sea floor by a stem or stalk.</p><p>The striking similarity between these modern filter feeders and the ancient starfish led our team from the University of Cambridge and Harvard University to create a new analysis. We applied a biological model to the features of all the current early Asterozoa fossils in existence, along with a sample of their closest relatives.</p>
Cantabrigiaster is the most primitive starfish-like animal to be discovered in the fossil record. Aaron Hunter, Author provided<p>Our results demonstrate <em>Cantabrigiaster</em> is the most primitive of all the Asterozoa, and most likely evolved from ancient animals called crinoids that lived 250 million years before dinosaurs. The five arms of starfish are a relic left over from these ancestors. In the case of <em>Cantabrigiaster</em>, and its starfish descendants, it evolved by flipping upside-down so its arms are face down on the sediment to feed.</p><p>Although we sampled a relatively small numbers of those ancestors, one of the unexpected outcomes was it provided an idea of how they could be related to each other. Paleontologists studying echinoderms are often lost in detail as all the different groups are so radically different from each other, so it is hard to tell which evolved first.</p>
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