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To Stop an Insect Die-Out, the World Needs Pollinator-Friendly Policies, Scientist Warns
By Kerstin Palme
Creepy-crawlies are among the oldest life forms on this planet. Before dinosaurs ever walked the earth, insects were certainly already there. Some estimates date their origins to 400 million years ago. They're also extremely successful. Of the 7 to 8 million species documented on Earth, around three quarters are likely bugs.
But several insect species could disappear for good in the next few decades and that would have serious consequences for humans.
Insects like bees, butterflies and even certain species of beetle and ant incidentally pollinate our crops when they collect protein-rich pollen and sugary nectar, ensuring we have enough to eat.
DW spoke to Josef Settele, a professor and entomologist at the Helmholtz Centre for Environmental Research (UFZ) in the eastern German city of Halle, about whether we need to worry about our food and how politics and business could intervene to halt the insect decline.
Settele was in the global spotlight in May 2019 when the United Nations IPBES Global Assessment Report on Biodiversity and Ecosystem Services was published. In the report, the entomologist and his colleagues determined that around 1 million plant and animal species are threatened with extinction.
Insects are being hit particularly hard. The scientists estimate that around 10% of all insect species are threatened with dying out over the next few decades — and that's a conservative calculation.
Entomologist Josef Settele says we need insect-friendly agriculture to help counteract the decline in pollinators.
DW: In the report, you conclude that in some world regions 40% of wild, pollinating insects, particularly wild bee species, are already facing extinction. Why don't we just put up bee boxes and hives everywhere?
Josef Settele: That will only help so much. The wild cousins of the honeybee don't necessarily live under the guardianship of humans. And the honeybee is responsible for pollinating only a certain percentage of our crops. For instance, they pollinate just a small portion of our apples. Wild pollinators whether they be hoverflies, bumblebees or other insects like butterflies are more important in this regard.
Solitary pollinators like the leafcutter bee like to nest in tunnels, like the ones provided in this insect hotel.
So my apple harvest could be less bountiful if the honeybee is the only species available to pollinate it?
Correct but even more importantly, certain plants can't be pollinated by honeybees in the first place. Bumblebees, for instance, typically pollinate broad beans. Honeybees can't do much here really.
Broad-bean blossoms are closed and the bumblebee can easily force its way in with its wide body. Another example is alfalfa, an important forage crop that is dependent on the bumblebee. Honeybees just can't get into the blossom.
What would the global community have to fork out if all pollinating insects suddenly disappeared and our food crops had to be pollinated by hand?
Global pollination [by insects and other animals] is worth at least $235 billion a year, according to our conservative estimates. And you'd really have to expend considerable resources to imitate the animals' pollination performance. Humans just haven't mastered the technique. Look at the use of brushes. The yields are always paltry in comparison to natural pollination.
The other question is: where in the world am I doing it? If I'm in a country where the labor costs are low, then it could provide some kind of alternative. But there would be no point in trying that in Germany, for instance. Your apples would suddenly be 10 times more expensive when you take our labor costs into account.
Considering those prospects, you would think that politicians and businesses would have a big interest in stopping species loss. What courses of action are there for policy makers? What shape would pollinator-friendly politics take?
Many different factors contribute to the disappearance of insects but a lot of it is very much connected to our land use. A more sustainable use of our land needs to be encouraged. That could be achieved by, for instance, having a higher diversity of habitats and by reducing pesticides, particularly insecticides.
We really need policy that would heavily promote the production of sustainable products. So, groceries that require fewer pesticides and make more sense from an energy perspective. That means eating more plants in our diet and fewer animal-based products.
I'm not a vegetarian but the strong preference in Europe and North America for consuming meat has to change. Our high meat consumption fuels the demand for soy, which is used as a feed for cattle. By importing soy from South America, we're contributing to species extinction. That's because forests and areas that were full of species-rich ecosystems are often turned into plantations. These are grave changes that are causing habitats to disappear.
But are large, blooming monoculture plantations not good for wild pollinators?
Settele advises people to plant blooming flowers in their gardens and balconies to give bees, butterflies and other pollinators a helping hand.
Pollinators need more than just food. They need nesting habitats. Solitary wild bees lay their eggs in holes in the ground or hollow stems, the likes of which are mimicked in insect hotels. Those are basically reproductions of the shelters found in nature and where they lay their eggs.
What can I do as an individual?
Being aware of the impact of how you consume is a good start, although, that is often difficult to navigate. It's always a good idea to make sure you've got a diversity of flowering plants around your home. Even just getting in touch with nature is good.
So, just get outside into nature?
Yes! Out into nature. And bringing nature to your own front door.
Kerstin Palme conducted the interview, which has been condensed and edited for clarity.
Reposted with permission from our media associate DW.
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By Melissa Gaskill
Two decades ago scientists and volunteers along the Virginia coast started tossing seagrass seeds into barren seaside lagoons. Disease and an intense hurricane had wiped out the plants in the 1930s, and no nearby meadows could serve as a naturally dispersing source of seeds to bring them back.
Restored seagrass beds in Virginia now provide habitat for hundreds of thousands of scallops. Bob Orth, Virginia Institute of Marine Science / CC BY 2.0<p>The paper is part of a growing trend of evidence suggesting seagrass meadows can be easier to restore than other coastal habitats.</p><p>Successful seagrass-restoration methods include <a href="https://www.sciencedirect.com/science/article/abs/pii/S0304377099000078?via%3Dihub" target="_blank">transplanting shoots</a>, <a href="https://onlinelibrary.wiley.com/doi/10.1111/j.1061-2971.2004.00314.x" target="_blank" rel="noopener noreferrer">mechanized planting</a> and, more recently, <a href="https://www.nature.com/articles/s41467-020-17438-4" target="_blank" rel="noopener noreferrer">biodegradable mats</a>. Removing threats, proximity to donor seagrass beds, planting techniques, project size and site selection all play roles in a restoration effort's success.</p><p>Human assistance isn't always necessary, though. In areas where some beds remain, seagrass can even recover on its own when stressors are reduced or removed. For example, seagrass began to recover when Tampa Bay improved its water quality by reducing nitrogen loads from runoff by roughly 90%.</p><p>But more and more, seagrass meadows struggle to hang on.</p><p>The marine flowering plants have declined globally since the 1930s and currently disappear at a rate equivalent to a football field every 30 minutes, according to the <a href="https://www.unep.org/resources/report/out-blue-value-seagrasses-environment-and-people" target="_blank" rel="noopener noreferrer">United Nations Environment Programme</a>. And research published in 2018 found the rate of decline is <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GB005941" target="_blank" rel="noopener noreferrer">accelerating</a> in many regions.</p><p>The causes of decline vary and overlap, depending on the region. They include thermal stress from climate change; human activities such as dredging, anchoring and coastal infrastructure; and intentional removal in tourist areas. In addition, increased runoff from land carries sediment that clouds the water, blocking sunlight the plants need for photosynthesis. Runoff can also carry contaminants and nutrients from fertilizer that disrupt habitats and cause algal blooms.</p><p>All that damage comes with a cost.</p>
The Value of Seagrass<p>As with ecosystems like rainforests and <a href="https://therevelator.org/mangroves-climate-change/" target="_blank">mangroves</a>, loss of seagrass increases carbon dioxide emissions. And that spells trouble not just for certain habitats but for the whole planet.</p><p>Although seagrass covers at most 0.2% of the seabed, it <a href="https://www.unenvironment.org/news-and-stories/story/seagrass-secret-weapon-fight-against-global-heating" target="_blank">accounts for 10%</a> of the ocean's capacity to store carbon and soils, and these meadows store carbon dioxide an estimated 30 times faster than most terrestrial forests. Slow decomposition rates in seagrass sediments contribute to their <a href="https://www.researchgate.net/publication/238506081_Assessing_the_capacity_of_seagrass_meadows_for_carbon_burial_Current_limitations_and_future_strategies" target="_blank" rel="noopener noreferrer">high carbon burial rates</a>. In Australia, according to <a href="https://onlinelibrary.wiley.com/doi/10.1111/gcb.15204" target="_blank" rel="noopener noreferrer">research</a> by scientists at Edith Cowan University, loss of seagrass meadows since the 1950s has increased carbon dioxide emissions by an amount equivalent to 5 million cars a year. The United Nations Environment Programme reports that a 29% decline in seagrass in Chesapeake Bay between 1991 and 2006 resulted in an estimated loss of up to 1.8 million tons of carbon.</p>
Eelgrass in the river delta at Prince William Sound, Alaska. Alaska ShoreZone Program NOAA / NMFS / AKFSC; Courtesy of Mandy Lindeberg / NOAA / NMFS / AKFSC<p>Seagrasses also protect costal habitats. A healthy meadow slows wave energy, reduces erosion and lowers the risk of flooding. In Morro Bay, California, a 90% decline in the seagrass species known as eelgrass caused extensive erosion, according to a <a href="https://www.sciencedirect.com/science/article/abs/pii/S0272771420303528?via%3Dihub" target="_blank" rel="noopener noreferrer">paper</a> from researchers at California Polytechnic State University.</p><p>"Right away, we noticed big patterns in sediment loss or erosion," said lead author Ryan Walter. "Many studies have shown this on individual eelgrass beds, but very few studies looked at it on a systemwide scale."</p><p>In the tropics, seagrass's natural protection can reduce the need for expensive and often-environmentally unfriendly <a href="https://www.nioz.nl/en/news/zeegras-spaart-stranden-en-geld" target="_blank" rel="noopener noreferrer">beach nourishments</a> regularly conducted in tourism areas.</p><p>Seagrass ecosystems improve water quality and clarity, filtering particles out of the water column and preventing resuspension of sediment. This role could be even more important in the future. By producing oxygen through photosynthesis, meadows could help offset decreased oxygen levels caused by warmer water temperatures (oxygen is less soluble in warm than in cold water).</p><p>The meadows also provide vital habitat for a wide variety of marine life, including fish, sea turtles, birds, marine mammals such as manatees, invertebrates and algae. They provide nursery habitat for <a href="https://wedocs.unep.org/bitstream/handle/20.500.11822/32636/seagrass.pdf?sequence=1&isAllowed=y" target="_blank" rel="noopener noreferrer">roughly 20%</a> of the world's largest fisheries — an <a href="https://www.floridamuseum.ufl.edu/science/seagrass-meadows-harbor-wildlife-for-centuries/" target="_blank" rel="noopener noreferrer">estimated 70%</a> of fish habitats in Florida alone.</p><p>Conversely, their disappearance can contribute to die-offs of marine life. The loss of more than 20 square miles of seagrass in Florida's Biscayne Bay may have helped set the stage for a widespread <a href="https://www.wlrn.org/2020-08-14/the-seagrass-died-that-may-have-triggered-a-widespread-fish-kill-in-biscayne-bay" target="_blank">fish kill</a> in summer 2020. Lack of grasses to produce oxygen left the basin more vulnerable when temperatures rose and oxygen levels dropped as a result, says Florida International University professor Piero Gardinali.</p>
Damaged Systems, a Changing Climate<p>Governments and conservationists around the world have already put a lot of effort into coastal restoration efforts. And that's helped some seagrass populations.</p><p>Where stressors remain, though, restoration grows more complicated. <a href="https://www.rug.nl/research/portal/en/publications/the-future-of-seagrass-ecosystem-services-in-a-changing-world(3a8c56db-7bed-4c9e-ac7f-c72453e2a102).html" target="_blank">Research</a> published this September found that only 37% of seagrass restorations have survived. Newly restored meadows remain vulnerable to the original stressors that depleted them, as well as to storms — and <a href="https://www.ecowatch.com/tag/climate-crisis">climate change</a>.</p>
Seagrass in Dry Tortugas National Park, Florida. Alicia Wellman / Florida Fish and Wildlife / CC BY-NC-ND 2.0<p>In Chesapeake Bay a cold-water species of seagrass is currently hitting its heat limit, especially in summer, according to Alexander Challen Hyman of University of Florida's School of Natural Resources and Environment. As waters continue to warm due to climate change, the species likely will disappear there.</p><p>Climate-driven sea-level rise complicates the problem as well. Seagrasses thrive at specific depths — too shallow and they dry out or are eaten, too deep and there isn't enough light for photosynthesis.</p>
But There’s Good News, Too<p>Luckily, left to its own devices, a seagrass meadow can flourish for hundreds of years, according to a <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2019.1861" target="_blank" rel="noopener noreferrer">paper</a> published last year by Hyman and other researchers from the University of Florida. The researchers arrived at their conclusion by looking at shells of living mollusks and fossil shells to estimate the ages of meadows in Florida's Big Bend region on the Gulf Coast.</p><p>That area has extensive, relatively pristine seagrass meadows. "Our motivation was to understand the past history of these systems, and shells store a lot of history," said co-author Michal Kowalewski.</p><p>A high degree of similarity between living and dead shells indicates a stable area, while a mismatch suggests an area shifted from seagrass to barren sand. The researchers found that long-term accumulations of shells resembled living ones, suggesting that the seagrass habitats have been stable over time.</p><p>That stability allows biodiversity to thrive, creating conditions where specialist species can survive and flourish, according to Hyman.</p><p>Discovering the long-term stability of seagrass meadows has implications for choosing restoration sites, Kowalewski notes.</p><p>"There must be reasons they thrive in one place, while a mile away they don't and fossil data says they probably never did," he said. "If we remove a seagrass patch, we cannot hope to plant it somewhere else. It's not just the seagrass that is special. The location at which it's found is special, too."</p><p>A better approach is conserving these habitats in the first place, but we're not doing enough of that right now. The UN reports that marine protected areas safeguard just 26% of recorded seagrass meadows, compared with 40% of coral reefs and 43% of mangroves.</p>
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