biology

The end of a supergiant iceberg

November 16, 2023 By EarthWise Leave a Comment

In 2017, a supergiant iceberg known as A-68 calved from the Larsen C ice shelf in Antarctica. In 2020, it drifted close to South Georgia, a British island in the South Atlantic Ocean, and then began to break up. This iceberg was enormous – nearly the size of Delaware. When it started to break up, it released huge quantities of fresh, cold meltwater in a relatively small region.

Scientists from the British Antarctic Survey and the University of Sheffield have studied how the melting iceberg has affected the temperature and the salinity of the ocean surface in the area. They found that the water near the surface was 8 degrees Fahrenheit colder than normal and the water only had about two-thirds of its normal saltiness.

The effects from the melted iceberg eventually extended well beyond South Georgia as the colder, less-salty water was carried by ocean currents to form a long plume that stretched more than 600 miles across the South Atlantic. It also took several months to disappear.

The calving of this massive iceberg provided a unique opportunity for scientists to study the impact of iceberg melting on surface ocean conditions. A-68 was one of the largest and most studied of all icebergs. The study has shown that each individual melting giant iceberg can have widespread and long-lasting impacts on ocean conditions, which has consequences for the plant and animal life that lives there.

Climate change is likely to lead to more giant iceberg calving in the future. It is important to monitor these events to assess their future impacts on ocean circulation, biology, and even seafloor geology.

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Supergiant iceberg makes surrounding ocean surface colder and less salty

Photo, posted October 24, 2018, courtesy of Jefferson Beck / NASA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Healthy Soil Is Healthy For People | Earth Wise

March 30, 2022 By EarthWise Leave a Comment

A new study by researchers at the University of Washington looked at the impact of regenerative farming practices on the nutritional content of the food that is grown.

Regenerative agriculture involves farming practices that not only “do not harm” to the land but actually improve it by regenerating and revitalizing the soil. The practices focus on topsoil regeneration, increasing biodiversity, improving the water cycle, and enhancing ecosystem services. Examples are soil-building techniques that minimize plowing, the use of cover crops, and the planting of diverse crops rather than monocultures.

The study included 10 farms across the U.S. that followed soil-friendly practices for at least five years. The results were that the crops from those farms had a healthier nutritional profile than the same crops grown on neighboring, conventional farms. In particular, there was a boost in certain minerals, vitamins and phytochemicals that are beneficial to human health. Across the board, regenerative practices resulted in crops with more anti-inflammatory compounds and antioxidants.

The participating farms grew one acre of a test crop – peas, sorghum, corn, or soybeans – for comparison with the same crop grown on a neighboring farm using conventional agriculture. Analysis showed that the farms practicing regenerative agriculture had healthier soils, as measured by their organic matter – or carbon – content and by other tests.

Organic farms avoid chemical pesticides, but they operate with a variety of farming processes. Nonetheless, they have also been found to produce crops with higher levels of beneficial nutrients. The biology of the soil in which crops are grown is an important factor for human health. It isn’t just what we eat that matters; it is how we grow it.

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Farms following soil-friendly practices grow healthier food, study suggests

Photo, posted January 10, 2020, courtesy of Les via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Transmission Lines And Wildlife Habitat Connectivity | Earth Wise

April 14, 2021 By EarthWise Leave a Comment

Electrical transmission lines and their support towers tend to be a blight on the landscape but are something modern society cannot avoid. Power transmission networks – with towers every 200 meters or so of line – are in place throughout the world’s developed nations. Another common feature of developed nations is the fragmentation of animal species caused by human activity breaking up their natural habitats.

It is important for biodiversity conservation for animals to get their environments connected. It turns out that transmission line infrastructure can provide an important tool for reconnecting wildlife habitats.

In a study conducted in Spain’s Andalusia region, scientists planted native shrubs and seedlings under six towers along power lines running through cereal cropland. The area of each tower base was 100 square meters.

Compared to four control sites, the researchers measured increased population density and diversity among arthropods and small mammals observed in the four-year study.

Enhancing connectivity through networks of habitat corridors or stepping-stone patches has become a key concept in conservation biology and landscape ecology. Renting or buying large parcels of land to connect protected natural areas to one another would be cost prohibitive but planting suitable native shrubs and other flora under existing transmission line networks can provide many of the same benefits.

In general, power companies pay rent to landowners – often farmers or agribusinesses – for the rights to place towers on their land. Because it is difficult to work the areas under towers with farm equipment, that space is typically unused, which opens the door to low-cost efforts by environmentalists.

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Electrical transmission lines have power to enhance habitat connectivity for wildlife

Photo, posted April 29, 2018, courtesy of Georgi Todorov/digitalnovas.com via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Native Species Or Invasive Species? | Earth Wise

February 27, 2020 By EarthWise Leave a Comment

For decades, conservation biology has characterized the movement of species into new habitats as potential invasions of alien species that pose serious dangers to local ecosystems and resident species. Wild species are classified as either native or alien. But this way of looking at the natural world is becoming increasingly controversial.

As the world warms, a mass exodus of tens of thousands of species is transforming the distribution of biodiversity. Scientists have documented countless species shifting their ranges towards the poles, higher up into the mountains, and deeper into the oceans in response to the changing climate.

Deciduous shrubs have spread into the Arctic tundra. Tropical fish have arrived in the kelp forests of the eastern Mediterranean.

A growing number of scientists now say that continuing to base conservation policy on the native-alien dichotomy may actually endanger biodiversity. The climate-driven range shifts may be the only way for many species to survive. Furthermore, only a small fraction of new arrivals may actually endanger resident species and ecosystems.

There are real distinctions between climate-displaced species and disruptive alien species introduced through global trade and travel. Among other things, climate-displaced species tend to shift their ranges alongside other species they have co-evolved with.

There is talk of establishing a Climate Change Redistribution Treaty that would create a transnational system to manage species shifting across geopolitical and biogeographical borders. The assumptions traditionally made as to which species to protect, which to leave to their own devices, and which to eradicate are no longer valid and the time has come to base conservation policies on the new reality.

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