Dragonflies Make Epic Migrations, But Climate Change Could Foil Their Itineraries
By Jason Bittel
It's that time of year again: Right now, monarch butterflies are taking wing in the mountains of northwestern Mexico and starting to flap their way across the United States.
The great monarch migration always makes headlines, in part because climate change, along with our pesticides and agricultural monocultures, threatens to erase the natural spectacle, but also because this natural phenomenon is simply amazing. The trip of nearly 5,000 miles is an unlikely one for an insect, but these butterflies don't have a monopoly on the massive, multigenerational migration game.
It's time to give some love to the epic feats of dragonflies.
According to a study published by the Royal Society last fall, common green darners, which are found from Cuba to Canada, make a long, complex journey that takes three generations and spans a distance of more than 1,500 miles. Scientists are still trying to figure out exactly how they do it, but temperature seems to play a key role in telling the animals when to move. Unfortunately, this means climate change could well wreck the whole event even before we fully understand it. Worse, it would leave much of eastern North America without an important member of its food web.
The news that dragonflies migrate probably won't shock people who study insects, says the study's senior author, Colin Studds, a wildlife ecologist at the University of Maryland. "We've had an inkling of how many insects migrate," he said. "There are moths, there are beetles, and there are probably about 20 species of dragonflies that we have expected of migration. But we don't know much about it other than that it's a phenomenon."
One of the reasons why insect migration remains so much of a mystery is that bugs are tough to track. They're tiny, they die all the time, and they're quick as heck — especially dragonflies. "Unlike monarchs, common green darners are fast fliers," said MaLisa Spring, state coordinator for the Ohio Dragonfly Survey at the Museum of Biological Diversity just north of Columbus. "This makes them hard to catch and potentially add identification tags or stickers, and even harder to photograph. Most photo observations are a blur of blue and green, so a tiny sticker doesn't work so well."
This is why Studds and his coauthors decided to study where the dragonflies had been, rather than where the critters were heading. To do this, they took tissue samples from the wings of more than 850 green darners, some collected from the wild and others from museum specimens going back 140 years. A molecular analysis of the wings allowed the scientists to identify hydrogen isotopes that revealed the latitudes at which the dragonflies were born. (These isotopes vary at reliable rates as one moves north or south, so determining which ones are present and in what quantities can drop a pin of origin within about 100 to 200 miles.)
The team also made use of 21 years' worth of citizen science data to understand when and under what conditions dragonflies appear across their vast range. With all of these pieces put together, common green darner migration patterns are no longer so much of a blue-green blur.
Tina Vance / Flickr
In February the dragonflies appear only in warm latitudes, which is reflected in data showing dragonfly emergences at this time in Florida, Louisiana and Texas, as well as Puerto Rico, Cuba and southern Mexico. But come March, this first generation has already winged it up to the American Northeast, the Great Lakes region and southern Canada. And then those well-traveled dragonflies mate, lay eggs and die.
In May and June, the second generation hatches onto the scene. Some live their whole lives locally, but others — driven by what, we do not know — point their beautiful compound eyes south. Between September and November, these snowbirds don floral shirts and sunglasses and can be found flitting around the southern U.S. and Caribbean. Like the first generation, these dragonflies mate, lay eggs and die.
This leaves us with the third generation in the cycle, which are the population's homebodies. Because winter hits the south soon after they hatch, and they definitely don't want to head north to even colder climes, these lucky darners live out their life span locally. And then they ... mate, lay eggs and die like the rest. Their offspring then hatch around February, transform from larvae to adults, and head up north, starting the cycle anew.
The great dragonfly migration has likely been taking place for many millennia. Each generation has a job to do and an itinerary to follow, and every step is tied to a specific temperature range.
"So one of the things that we figured out from the citizen science data of over 20 years across the whole eastern United States is that the dragonflies don't begin migrating until it gets to about 9.5 degrees Celsius, or just shy of 50 degrees Fahrenheit," said Studds. "They kind of wait for it to go up to that point and they follow that temperature north."
Enter climate change. Temperature patterns are shifting all over the U.S. (indeed, the whole planet), and research on monarchs is already showing that such fluctuations may affect how the butterflies inoculate themselves against parasites. Could there be similar consequences for other migratory insects?
"If we are moving into a period where winter temperatures are warming and spring temperatures are getting warmer through time, then that will probably affect the entire timing and pace of dragonfly migration," said Studds. "It will affect how far north they go and how quickly they develop."
In some areas, warmer temperatures year-round may mean dragonflies won't even need to migrate at all. This isn't necessarily bad for the darners, mind you. But because dragonflies are important predators of mosquitoes, aphids, and other insects, as well as nutritious food for ducks, toads, newts, fish and even carnivorous plants like sundew, losing a seasonal influx of these creatures could ripple out through North America's ecosystems. (Plus, dragonflies are beautiful, and people up north will miss them.)
The truth is, scientists still know very little about how these seasonal shake-ups will affect wildlife, and common green darners and monarch butterflies are just two species among many that are facing big changes. But given that insects are experiencing dramatic declines worldwide, we need to unpack as many of these little mysteries as we can now — instead of trying to piece the puzzle back together after it's too late.
Reposted with permission from our media associate onEarth.
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Wisdom the mōlī, or Laysan albatross, is the oldest wild bird known to science at the age of at least 70. She is also, as of February 1, a new mother.
<div id="dadb2" class="rm-shortcode" data-rm-shortcode-id="aa2ad8cb566c9b4b6d2df2693669f6f9"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1357796504740761602" data-partner="rebelmouse"><div style="margin:1em 0">🚨Cute baby alert! Wisdom's chick has hatched!!! 🐣😍 Wisdom, a mōlī (Laysan albatross) and world’s oldest known, ban… https://t.co/Nco050ztBA</div> — USFWS Pacific Region (@USFWS Pacific Region)<a href="https://twitter.com/USFWSPacific/statuses/1357796504740761602">1612558888.0</a></blockquote></div>
By Hui Hu
Winter is supposed to be the best season for wind power – the winds are stronger, and since air density increases as the temperature drops, more force is pushing on the blades. But winter also comes with a problem: freezing weather.
Comparing rime ice and glaze ice shows how each changes the texture of the blade. Gao, Liu and Hu, 2021, CC BY-ND
Ice buildup changes air flow around the turbine blade, which can slow it down. The top photos show ice forming after 10 minutes at different temperatures in the Wind Research Tunnel. The lower measurements show airflow separation as ice accumulates. Icing Research Tunnel of Iowa State University, CC BY-ND
While traditional investment in the ocean technology sector has been tentative, growth in Israeli maritime innovations has been exponential in the last few years, and environmental concern has come to the forefront.
theDOCK aims to innovate the Israeli maritime sector. Pexels<p>The UN hopes that new investments in ocean science and technology will help turn the tide for the oceans. As such, this year kicked off the <a href="https://www.oceandecade.org/" target="_blank" rel="noopener noreferrer">United Nations Decade of Ocean Science for Sustainable Development (2021-2030)</a> to galvanize massive support for the blue economy.</p><p>According to the World Bank, the blue economy is the "sustainable use of ocean resources for economic growth, improved livelihoods, and jobs while preserving the health of ocean ecosystem," <a href="https://www.sciencedirect.com/science/article/pii/S0160412019338255#b0245" target="_blank" rel="noopener noreferrer">Science Direct</a> reported. It represents this new sector for investments and innovations that work in tandem with the oceans rather than in exploitation of them.</p><p>As recently as Aug. 2020, <a href="https://www.reutersevents.com/sustainability/esg-investors-slow-make-waves-25tn-ocean-economy" target="_blank" rel="noopener noreferrer">Reuters</a> noted that ESG Investors, those looking to invest in opportunities that have a positive impact in environmental, social and governance (ESG) issues, have been interested in "blue finance" but slow to invest.</p><p>"It is a hugely under-invested economic opportunity that is crucial to the way we have to address living on one planet," Simon Dent, director of blue investments at Mirova Natural Capital, told Reuters.</p><p>Even with slow investment, the blue economy is still expected to expand at twice the rate of the mainstream economy by 2030, Reuters reported. It already contributes $2.5tn a year in economic output, the report noted.</p><p>Current, upward <a href="https://www.ecowatch.com/-innovation-blue-economy-2646147405.html" target="_self">shifts in blue economy investments are being driven by innovation</a>, a trend the UN hopes will continue globally for the benefit of all oceans and people.</p><p>In Israel, this push has successfully translated into investment in and innovation of global ports, shipping, logistics and offshore sectors. The "Startup Nation," as Israel is often called, has seen its maritime tech ecosystem grow "significantly" in recent years and expects that growth to "accelerate dramatically," <a href="https://itrade.gov.il/belgium-english/how-israel-is-becoming-a-port-of-call-for-maritime-innovation/" target="_blank" rel="noopener noreferrer">iTrade</a> reported.</p><p>Driving this wave of momentum has been rising Israeli venture capital hub <a href="https://www.thedockinnovation.com/" target="_blank" rel="noopener noreferrer">theDOCK</a>. Founded by Israeli Navy veterans in 2017, theDOCK works with early-stage companies in the maritime space to bring their solutions to market. The hub's pioneering efforts ignited Israel's maritime technology sector, and now, with their new fund, theDOCK is motivating these high-tech solutions to also address ESG criteria.</p><p>"While ESG has always been on theDOCK's agenda, this theme has become even more of a priority," Nir Gartzman, theDOCK's managing partner, told EcoWatch. "80 percent of the startups in our portfolio (for theDOCK's Navigator II fund) will have a primary or secondary contribution to environmental, social and governance (ESG) criteria."</p><p>In a company presentation, theDOCK called contribution to the ESG agenda a "hot discussion topic" for traditional players in the space and their boards, many of whom are looking to adopt new technologies with a positive impact on the planet. The focus is on reducing carbon emissions and protecting the environment, the presentation outlines. As such, theDOCK also explicitly screens candidate investments by ESG criteria as well.</p><p>Within the maritime space, environmental innovations could include measures like increased fuel and energy efficiency, better monitoring of potential pollution sources, improved waste and air emissions management and processing of marine debris/trash into reusable materials, theDOCK's presentation noted.</p>
theDOCK team includes (left to right) Michal Hendel-Sufa, Head of Alliances, Noa Schuman, CMO, Nir Gartzman, Co-Founder & Managing Partner, and Hannan Carmeli, Co-Founder & Managing Partner. Dudu Koren<p>theDOCK's own portfolio includes companies like Orca AI, which uses an intelligent collision avoidance system to reduce the probability of oil or fuel spills, AiDock, which eliminates the use of paper by automating the customs clearance process, and DockTech, which uses depth "crowdsourcing" data to map riverbeds in real-time and optimize cargo loading, thereby reducing trips and fuel usage while also avoiding groundings.</p><p>"Oceans are a big opportunity primarily because they are just that – big!" theDOCK's Chief Marketing Officer Noa Schuman summarized. "As such, the magnitude of their criticality to the global ecosystem, the magnitude of pollution risk and the steps needed to overcome those challenges – are all huge."</p><p>There is hope that this wave of interest and investment in environmentally-positive maritime technologies will accelerate the blue economy and ESG investing even further, in Israel and beyond.</p>
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