Climate Change and Overfishing Could Lead to More Toxic Seafood
Scientists continue to uncover more ways climate change poses a threat to our health, such as the spread of tropical diseases northward and the loss of crucial nutrients in crops. Now, researchers at Harvard have added another risk to that list: increased neurotoxins in seafood.
According to a new study, published in the journal Nature, overfishing and the rising temperature of the oceans are increasing the amount of methylmercury in commonly eaten fish such as tuna, cod and dogfish, despite decades of government regulations reducing mercury emissions from industry seeping into the water.
"You would expect that as mercury was reduced in seawater, then it would go down in all the fish," lead author Amina Schartup, who was a research associate at the Harvard School of Engineering and Applied Sciences, told NBC News. "But there was variability. We were trying to tease out the different factors contributing to those differences."
Methylmercury is a harmful toxin that can damage the heart and blood vessel system, reduce immune function, and could be particularly harmful to the nervous systems of pregnant women and their babies, the Centers for Disease Control and Prevention warns.
For the study, the researchers used 30 years of data from the Gulf of Maine to develop a food web model that shows how mercury levels in certain fish are affected by overfishing, warming waters and other environmental factors.
By the 1970s the Gulf of Maine had been overfished, particularly of herring, meaning that herring predators cod and dogfish were forced to find new prey. While cod switched to eating smaller fish, the dogfish started to eat squid and other high-mercury cephalopods.
The dogfish ended up with higher mercury levels, while mercury levels in cod dipped. After the fishery stocks rebounded, both fish returned to eating mostly herring. Cod saw a 23 percent mercury increase and the dogfish lowered their mercury levels after switching back. The model predicts that if the oceans were to warm by 1 degree Celsius over the 2000 temperature, mercury levels would jump by 32 percent in cod and 70 percent in dogfish, The Harvard Gazette reported.
The researchers then examined why mercury levels of Atlantic bluefin tuna have increased without any change in prey and amid decreasing mercury emissions from humans.
The model showed that in the 1990s, water temperatures in the Gulf of Maine temporary cooled, which corresponded with a decrease in mercury levels in the tuna. But climate change has steadily been warming the oceans and it's happening faster in the Gulf of Maine than most places, according to The Harvard Gazette. Following rising temperatures between 2012 and 2017, mercury levels in the tuna rose 3.5 percent per year, and could rise by 30 percent over 2015 levels by 2030.
The team identified two reasons for this.
One, tuna are higher on the food chain and use more energy than other fish, so they eat more prey that already contains mercury, Schartup said. Two, warmer waters mean that fish need to use more energy to swim and increase their calorie intake to do so. In total, mercury levels in tuna increased by 27 percent, the model suggested, due to the warming of their habitat.
But the researchers say they're not trying to scare people away from seafood.
"It's not that everyone should be terrified after reading our paper and stop eating seafood, which is very healthy, nutritious food," researcher Elsie Sunderland, a professor of environmental chemistry at Harvard University, told Al Jazeera. "We wanted to show people that [climate change] can have a direct impact on what you're eating today, that these things can affect your health ... not just things like severe weather and flooding and sea-level rise."
"If we do not act to lower greenhouse gas emissions, new fish species will enter the waters of at least 70 countries by 2100, challenging the regulatory framework for managing fishing rights" Read more: https://t.co/Ar7XBPik8Z— Our Children's Trust (@youthvgov) June 18, 2018
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By Jason Bruck
Human actions have taken a steep toll on whales and dolphins. Some studies estimate that small whale abundance, which includes dolphins, has fallen 87% since 1980 and thousands of whales die from rope entanglement annually. But humans also cause less obvious harm. Researchers have found changes in the stress levels, reproductive health and respiratory health of these animals, but this valuable data is extremely hard to collect.
Researchers work with trained dolphins to learn more about their sensory abilities, seen here testing a dolphin's hearing. Jason Bruck / CC BY-ND
A Lot to Learn From Hormones<p>When sampling the blow, we are looking for hormones in mucus as these can be used to gauge psychological and physiological health. We are specifically interested in <a href="https://dx.doi.org/10.1371%2Fjournal.pone.0114062" target="_blank">hormones like cortisol</a> and <a href="https://doi.org/10.1016/j.ygcen.2018.04.003" target="_blank">progesterone</a>, which indicate stress levels and reproductive ability respectively, but can also help determine overall health.</p><p>Additionally, blow samples can detect <a href="https://dx.doi.org/10.1128%2FmSystems.00119-17" target="_blank">respiratory pathogens</a> in the lungs or nasal passages - blowholes evolved from noses after all.</p><p>This health analysis is especially important in areas with oil spills as the chemicals can cause hormonal problems that harm <a href="https://www.carmmha.org/investigating-how-oil-spills-affect-dolphins-and-whales/" target="_blank">development, metabolism and reproduction</a> in dolphins.</p><p>Hormone samples can provide scientists with valuable data, but collecting them from intelligent and unpredictable animals is challenging.</p>
Cetacean Collaborators<p>To build a drone that can stealthily collect spray from moving dolphins, we needed more data on their eyesight and hearing, and this is data that couldn't be collected in the wild nor simulated in a lab.</p><p>We worked with dolphins at facilities like Dolphin Quest in Bermuda, which provides guests opportunities to learn about dolphins while allowing <a href="https://dolphinquest.com/about-us/our-story/" target="_blank">scientists access to animals for noninvasive research</a>. Here the dolphins can swim away if they choose not to work with us, so we had to design the study like a game; the way a kindergarten teacher entertains a class. If the dolphins aren't interested, we don't get to do the science.</p><p>Over the course of hundreds of sessions, we sought to answer two questions: What can dolphins hear and what can they see around their heads?</p><p>To test dolphin hearing, we set up microphones and cameras to record dolphin behavior as we played drone noise in the air. We analyzed the responses to each noise – such as how many dolphins looked at the speaker – and used these as a proxy for their ability to hear the sounds.</p>
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Robodolphin doesn't look like a real dolphin, but it doesn't need to in order to train our drone pilots. C.J. Barton / Oklahoma State University / CC BY-ND<p>To build robodolphin, we worked with dolphins trained to "chuff" or sneeze on command to measure spray characteristics. We used high-speed photography to see the dolphins' breath as it moved through the air. Then we conducted high resolution CT scans of a dolphin head and 3D-printed a replica of a nasal passage.</p><p>Now, we have a complete robodolphin and are tweaking its sprays to be nearly identical to the real thing. This will allow us to determine how close we need to get to collect the samples, and therefore, how quiet our drone needs to be.</p>
The replica dolphin blowhole was designed from a scan of a real blowhole passage, and the spray it produces closely matches the real thing. Alvin Ngo, Mitch Ford and CJ Barton / Oklahoma State University / CC BY-ND
A Bit of Practice, Then Into the Wild<p>In the next few months, we will test flights over robodolphin with existing drones to determine the timing and strategy for collection. From there, we will fabricate a low-noise drone that can fly fast enough and with sufficient maneuverability to capture samples from wild dolphins. Like a video game, we will use the visual field data to develop approach trajectories to stay in the visual blindspots.</p><p>We plan to test our drones on a truck-mounted robodolphin moving down a runway, then using a boat to simulate realistic conditions. The next steps will involve ocean testing with dolphins trained for open ocean swimming. These tests will determine if our devices can catch and hold the hormones as the drone flies back to a researcher's boat.</p><p>Finally, we will deploy the system to collect data on wild dolphins. Our first goal is to test resident dolphins – animals that live on the coasts and deal directly with boat and oil industry noise – which will allow us to learn more about stress resulting from human impacts.</p><p>Those samples are a way off, but if all goes well we will have a specially built drone capable of flying long distances and capturing samples undetected in a few years. The samples collected will allow researchers to do better science with impact on the animals they study.</p>
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Sunscreen pollution is accelerating the demise of coral reefs globally by causing permanent DNA damage to coral. gonzalo martinez / iStock / Getty Images Plus
On July 29, Florida Governor Ron DeSantis signed into law a controversial bill prohibiting local governments from banning certain types of sunscreens.
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By Kelli McGrane
Oat milk is popping up at coffee shops and grocery stores alike, quickly becoming one of the trendiest plant-based milks.
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"Emissions from pyrotechnic displays are composed of numerous organic compounds as well as metals," a new study reports. Nodar Chernishev / EyeEm / Getty Images
Fireworks have taken a lot of heat recently. In South Dakota, fire experts have said President Trump's plan to hold a fireworks show is dangerous and public health experts have criticized the lack of plans to enforce mask wearing or social distancing. Now, a new study shows that shooting off fireworks at home may expose you and your family to dangerous levels of lead, copper and other toxins.
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By Ashutosh Pandey
Billions worth of valuable metals such as gold, silver and copper were dumped or burned last year as electronic waste produced globally jumped to a record 53.6 million tons (Mt), or 7.3 kilogram per person, a UN report showed on Thursday.
Environmental and Health Hazard<p>Experts say e-waste, which is now the world's fastest-growing domestic waste stream, poses serious environmental and health risks.</p><p>Simply throwing away electronic items without ensuring they get properly recycled leads to the loss of key materials such as iron, copper and gold, which can otherwise be recovered and used as primary raw materials to make new equipment, thereby reducing greenhouse gas emissions from extraction and refinement of raw materials.</p><p>Refrigerants found in electronic equipment such as fridge and air conditioners also contribute to global warming. A total of 98 Mt of CO2-equivalents, or about 0.3% of global energy-related emissions, were released into the atmosphere in 2019 from discarded refrigerators and ACs that were not recycled properly, the report said.</p><p>E-waste contains several toxic additives or hazardous substances, such as mercury and brominated flame retardants (BFR), and simply burning it or throwing it away could lead to serious health issues. Several studies have linked unregulated recycling of e-waste to adverse birth outcomes like stillbirth and premature birth, damages to the human brain or nervous system and in some cases hearing loss and heart troubles.</p><p>"Informal and improper e-waste recycling is a major emerging hazard silently affecting our health and that of future generations. One in four children are dying from avoidable environmental exposures," said Maria Neira, director of the Environment, Climate Change and Health Department at the World Health Organization. "One in four children could be saved, if we take action to protect their health and ensure a safe environment."</p>
Europe Leads the Way<p>While most of the e-waste was generated in Asia (24.9 Mt) in 2019, Europe led the charts on a per person basis with 16.2 kg per capita, the report said.</p><p>But the continent also recorded the <a href="https://www.dw.com/en/the-eu-declares-war-on-e-waste/a-51108790" target="_blank">highest documented formal e-waste collection and recycling</a> rate at 42.5%, still below its target of 65%. Europe was well ahead of the others on this front. Asia ranked second with 11.7%.</p><p>The authors said while more that 70% of the world's population was covered by some form of e-waste policy or laws, not much was being done toward implementation and enforcement of the regulations to encourage the take-up of a collection and recycling infrastructure due to lack of investment and political motivation.</p><p>"You have to think about new economic systems," said Kühr.</p><p>One approach could be that consumers no longer buy the products, but only the service they offer. The device would remain the property of the maker, who would then have an interest in offering his customers the best service and the necessary equipment. The maker would also be interested in designing his products in such a way that they are easier to repair and easier to recycle, Kühr said.</p>
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Did you know that some snakes can fly?
The south Asian paradise tree snake (Chrysopelea paradisi) can launch itself into the air and glide from one tree branch to another. And when it does, it moves its body in waves in something known as aerial undulation. Scientists have long known how the snakes moved. But they didn't know why. Until now.
The Cube is home to a 23-camera motion capture system. Jake Socha
The snakes wore 11 to 17 infrared-reflective markers, which gave the team high-resolution data while still allowing the animals to move freely. Jake Socha
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