Today's Image of the Day from <a href="https://earthobservatory.nasa.gov/" target="_blank" rel="noreferrer noopener">NASA Earth Observatory</a> features a striking phytoplankton bloom off the coast of southeast Greenland. 



While satellite imagery suggested that the bloom emerged in May, persistent cloud cover had obstructed optical sensors from capturing a clear view.



<h2 class="wp-block-heading" id="h-a-break-in-the-clouds">A break in the clouds</h2>



The situation changed in mid-June when a brief gap in the clouds over the North Atlantic Ocean revealed the bloom's vibrant swirls.



The captivating phenomenon was captured on June 16, 2024, by the MODIS (Moderate Resolution Imaging Spectroradiometer) on NASA’s Aqua satellite.&nbsp;



The image depicts an 800-kilometer-wide expanse of the North Atlantic Ocean, positioned east of Greenland and south of Iceland, with the bloom extending far beyond the image’s boundaries.



<h2 class="wp-block-heading" id="h-ecological-role-of-phytoplankton-nbsp">Ecological role of phytoplankton&nbsp;</h2>



<a href="https://www.earth.com/news/arctic-heatwaves-have-complex-effects-on-phytoplankton-food-web/" target="_blank" rel="noreferrer noopener">Phytoplankton</a> blooms are large concentrations of microscopic, plant-like organisms that usually float near the surface of the ocean. 



These tiny organisms play a fundamental role in marine ecosystems by serving as the primary <a href="https://www.earth.com/news/marine-food-chains-threatened-by-ocean-acidification/" target="_blank" rel="noreferrer noopener">food source</a> for a wide range of marine life, from other small plankton to larger fish and mammals.&nbsp;



Phytoplankton are also essential for the global carbon cycle and oxygen production, as they absorb carbon dioxide during photosynthesis and release oxygen.



<h2 class="wp-block-heading" id="h-unknown-source-of-the-phytoplankton-bloom">Unknown source of the phytoplankton bloom</h2>



The exact type of phytoplankton in this bloom cannot be determined from this natural-color image alone. It might include coccolithophores, which are characterized by their white calcium carbonate plates that can lend the ocean a milky appearance.&nbsp;



Alternatively, the bloom could consist of diatoms, a form of microscopic algae with silica shells and abundant chlorophyll, giving them a green hue.



Regardless of the species, the timing of this bloom is notable. Phytoplankton blooms typically emerge at lower latitudes first, subsequently appearing in the high latitudes of the North Atlantic by spring and mid-summer.



<h2 class="wp-block-heading" id="h-more-about-phytoplankton-blooms">More about phytoplankton blooms</h2>



Phytoplankton blooms occur when conditions such as sunlight, temperature, and nutrient availability are optimal for rapid phytoplankton growth. 



These conditions are often found in nutrient-rich waters, particularly where upwelling currents bring nutrients from the ocean depths to the surface. 



When the ideal conditions align, <a href="https://www.earth.com/news/rising-temperatures-may-flip-plankton-into-carbon-emitters/" target="_blank" rel="noreferrer noopener">phytoplankton</a> reproduce rapidly, leading to visible blooms that can cover large areas of the ocean.



<h2 class="wp-block-heading" id="h-how-do-phytoplankton-blooms-affect-marine-life">How do phytoplankton blooms affect marine life?</h2>



Phytoplankton blooms have a profound impact on marine life. As primary producers, phytoplankton form the base of the oceanic <a href="https://www.earth.com/news/climate-change-restructures-marine-food-webs-in-unexpected-ways/" target="_blank" rel="noreferrer noopener">food web</a>, supporting a wide array of marine organisms.&nbsp;



<h3 class="wp-block-heading" id="h-food-availability-nbsp">Food availability&nbsp;</h3>



When a bloom occurs, the abundance of phytoplankton provides a substantial food source for zooplankton, which in turn feed fish, crustaceans, and other larger marine animals.&nbsp;



This increase in food availability can lead to a temporary surge in populations of these species, promoting the overall health and diversity of the <a href="https://www.earth.com/news/overfishing-and-habitat-degradation-have-devastated-marine-ecosystems/" target="_blank" rel="noreferrer noopener">marine ecosystem</a>.



<h3 class="wp-block-heading" id="h-harmful-blooms">Harmful blooms</h3>



However, not all effects of phytoplankton blooms are beneficial. When blooms become excessively large, they can lead to harmful algal blooms (HABs).&nbsp;



These blooms can produce toxins that are harmful to marine life, causing mass die-offs of fish, shellfish, and other marine animals.&nbsp;



Moreover, as the bloom decays, the decomposition process consumes large amounts of oxygen from the water, leading to hypoxic conditions or "dead zones" where oxygen levels are too low to support most marine life. This can result in significant disruptions to marine ecosystems and loss of biodiversity.



Image Credit: NASA Earth Observatory&nbsp;



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Vibrant phytoplankton bloom in the North Atlantic

Today's Image of the Day from NASA Earth Observatory features...

Today's Image of the Day from <a href="https://earthobservatory.nasa.gov/" target="_blank" rel="noreferrer noopener">NASA Earth Observatory</a> features Clear Lake in northern California, which is one of the oldest <a href="https://www.earth.com/news/alarming-study-most-of-the-worlds-largest-lakes-are-quickly-losing-water/" target="_blank" rel="noreferrer noopener">freshwater lakes</a> in the United States. 



In mid-May 2024, the waters of Clear Lake were transformed into a vivid tapestry of bright green swirls, as seen in this image captured on May 15, 2024 by the Operational Land Imager-2 (OLI-2) on the Landsat 9 satellite.&nbsp;



<h2 class="wp-block-heading" id="h-clear-lake-algal-bloom-is-visible-from-space-nbsp">Clear Lake algal bloom is visible from space&nbsp;</h2>



The algal bloom, potentially comprised of blue-green algae (cyanobacteria) and other phytoplankton, was documented from space. Direct sampling is needed to precisely identify the algal organisms present in the lake.



Cyanobacteria, single-celled photosynthetic organisms, are notorious for some species' ability to produce microcystin, a toxin harmful to the skin, liver, and kidneys.&nbsp;



<h2 class="wp-block-heading" id="h-large-algal-blooms-in-clear-lake-nbsp">Large algal blooms in Clear Lake&nbsp;</h2>



Clear Lake, about 60 miles north of San Francisco Bay, is a naturally nutrient-rich body of water that has historically supported large algal populations dating back to the end of the last ice age, around 10,000 years ago, based on sediment core studies.



Recent human activities have exacerbated nutrient levels in the lake, leading to a rise in harmful algal blooms.&nbsp;



Out of over 130 algal species that have been identified in the lake, three types of blue-green algae pose health risks under certain conditions. These blooms typically appear in the spring and late summer, as reported by Lake County officials.



Nutrient influx from agriculture, vineyards, inadequate septic systems, gravel mining, and an abandoned mercury mine, along with natural factors such as lakebed sediment disturbances caused by waves and fish, have contributed to the lake's <a href="https://www.earth.com/news/rivers-at-risk-climate-change-is-diminishing-global-water-quality/" target="_blank" rel="noreferrer noopener">water quality</a> decline.&nbsp;



<h2 class="wp-block-heading" id="h-chlorophyll-a-and-cyanobacteria-nbsp">Chlorophyll-a and cyanobacteria&nbsp;</h2>



This year, data from a satellite-based ocean color instrument on Sentinel-3, processed further by the NOAA National Ocean Service, showed increased concentrations of chlorophyll-a and cyanobacteria leading up to May 15.



As of May 25, local monitors have not reported microcystin levels for the current bloom. Nonetheless, the high algal density poses risks to aquatic ecosystems, as decomposing phytoplankton deplete oxygen, potentially leading to <a href="https://www.earth.com/news/hypoxia-is-a-serious-problem-in-rivers-worldwide/" target="_blank" rel="noreferrer noopener">hypoxic conditions</a> and aquatic dead zones.



<h2 class="wp-block-heading" id="h-more-about-clear-lake-nbsp">More about Clear Lake&nbsp;</h2>



Clear Lake is the largest natural freshwater lake wholly within the state of California. Geological estimates suggest that it formed about 2.5 million years ago.&nbsp;



The lake is a popular destination for fishing, particularly for largemouth bass, and its scenic beauty attracts many visitors for boating, bird watching, and other recreational activities.&nbsp;



Clear Lake's ecosystem supports a diverse range of wildlife, but it also faces environmental challenges such as water quality issues, partly due to <a href="https://www.earth.com/news/water-quality-threatened-by-nutrient-pollution-in-40-u-s-states/" target="_blank" rel="noreferrer noopener">agricultural runoff</a> and other human activities.



<h2 class="wp-block-heading" id="h-freshwater-lakes-and-climate-change-nbsp">Freshwater lakes and climate change&nbsp;</h2>



Freshwater lakes are significantly impacted by climate change, which manifests in various ways, affecting both their ecological balance and their roles in local environments.&nbsp;



<h3 class="wp-block-heading" id="h-warming-lake-water">Warming lake water</h3>



As global temperatures rise, lakes experience changes in water temperature and ice cover. Warmer water tends to hold less oxygen, which can harm fish and other aquatic life; it can also encourage the growth of harmful algal blooms that further deplete oxygen and release toxins into the water.&nbsp;



<h3 class="wp-block-heading" id="h-ice-cover">Ice cover</h3>



Reduced ice cover during winter changes the seasonal rhythms of lakes, affecting species that rely on ice cover for part of their life cycle, like some cold-water fish and plants.



<h3 class="wp-block-heading" id="h-water-level-fluctuations-nbsp">Water level fluctuations&nbsp;</h3>



Additionally, changes in precipitation patterns and increased evaporation due to higher temperatures can alter water levels. These fluctuations not only impact the aquatic habitats but also affect water availability for human use, agriculture, and hydroelectric power generation.&nbsp;



The increasing frequency of extreme weather events, like storms and droughts, leads to more pronounced cycles of flooding and low water levels, creating challenges for managing water resources and preserving lake ecosystems.&nbsp;



As <a href="https://www.earth.com/news/how-some-lakes-resist-the-heat-of-atmospheric-warming/" target="_blank" rel="noreferrer noopener">lakes</a> are integral to their local climates, biodiversity, and economies, these changes can have widespread implications for the communities and ecosystems that depend on them.



Image Credit: NASA Earth Observatory&nbsp;



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Clear Lake turns green with algal growth

Today's Image of the Day from <a href="https://earthobservatory.nasa.gov/" target="_blank" rel="noreferrer noopener">NASA Earth Observatory</a> features the Aral Sea, captured by an astronaut aboard the International Space Station while orbiting over Kazakhstan.&nbsp;



Although it is referred to as a sea, the Aral Sea is technically an endorheic lake that straddles the border between Kazakhstan and Uzbekistan, receiving water from the Amu Darya and Syr Darya rivers.&nbsp;



<h2 class="wp-block-heading" id="h-severe-desertification-nbsp-of-the-aral-sea">Severe desertification&nbsp;of the Aral Sea</h2>



Over the last six decades, extensive diversion of these rivers for agricultural <a href="https://www.earth.com/news/satellites-can-now-show-us-how-much-water-we-use-for-irrigation/" target="_blank" rel="noreferrer noopener">irrigation</a> has dramatically reduced the lake's surface area, which once might have covered most of this image.



Formerly the fourth largest lake in the world by surface area, the Aral Sea has shrunk to about 10% of its original size since the 1960s.&nbsp;



<h2 class="wp-block-heading" id="h-the-aralkum-desert">The Aralkum Desert</h2>



The southeast region of the lake has undergone severe <a href="https://www.earth.com/news/oases-grow-by-human-effort-but-face-threats-from-desertification/" target="_blank" rel="noreferrer noopener">desertification</a>, giving rise to the Aralkum Desert - one of the world's newest deserts, covering 62,000 square kilometers (24,000 square miles).&nbsp;



The image shows sand dunes in the bottom-center, formed by winds sweeping across the barren landscape. The shrinking of the Aral Sea has also led to frequent sand and <a href="https://www.earth.com/news/sand-and-dust-storms-have-become-unpredictable-and-dangerous/" target="_blank" rel="noreferrer noopener">dust storms</a>, worsening local air quality.



<h2 class="wp-block-heading" id="h-the-barsa-kelmes-nature-reserve">The Barsa-Kelmes Nature Reserve</h2>



In the local Turkic language, "aral" means "island," reflecting the lake's history of containing over 1,100 islands. One such island hosts the Barsa-Kelmes Nature Reserve, located between what remains of the North and South Aral Seas.&nbsp;



The reserve is home to hundreds of plant and animal species. Efforts to revive the local ecosystem and curb further aridification are underway, including a project supported by the U.S. Agency for International Development which involves planting black saxaul shrubs (Haloxylon aphyllum).&nbsp;



These shrubs help stabilize the soil and reduce dust storm impacts, aiding in the recovery of native flora and fauna.



<h2 class="wp-block-heading" id="h-destruction-of-the-aral-sea">Destruction of the Aral Sea</h2>



The Aral Sea was once known for its vibrant fishing industry, which was a cornerstone of the local economy - particularly in Kazakhstan and Uzbekistan - for centuries.&nbsp;



In the 1950s, the sea supported a thriving fishery, with annual catches of around 40,000 to 50,000 tons of fish. Several species of <a href="https://www.earth.com/news/one-quarter-of-freshwater-fish-species-face-extinction/" target="_blank" rel="noreferrer noopener">fish</a> thrived in its waters, including carp, roach, bream, and the Aral barbel.



<h3 class="wp-block-heading" id="h-collapse-of-the-fishing-industry-nbsp">Collapse of the fishing industry&nbsp;</h3>



However, the industry began to collapse in the 1960s when the Soviet government initiated massive irrigation projects that diverted the Amu Darya and Syr Darya rivers away from the <a href="https://www.earth.com/news/alarming-study-most-of-the-worlds-largest-lakes-are-quickly-losing-water/" target="_blank" rel="noreferrer noopener">lake</a> to irrigate cotton fields.&nbsp;



As water levels dropped, salinity increased, making the environment uninhabitable for most fish species. 



By the 1980s, commercial fishing became untenable; the industry virtually disappeared, resulting in economic and social hardship for the communities that depended on it.



<h3 class="wp-block-heading" id="h-ecological-disaster">Ecological disaster</h3>



The shrinkage of the Aral Sea is one of the most severe anthropogenic ecological disasters of the 20th century. The loss of the fishing industry was just one of many devastating consequences.



The region experienced a sharp decline in biodiversity, with many native fish species becoming extinct, severely affecting the local fishing industry. The exposed sea bed also created health problems for local populations as winds spread toxic dust and salt from the dry seabed.



<h3 class="wp-block-heading" id="h-ongoing-efforts-to-restore-the-aral-sea">Ongoing efforts to restore the Aral Sea</h3>



Today, the area struggles with these legacies, even as there are ongoing efforts to revive some parts of the sea and mitigate the environmental damage.



Efforts have been made to partially restore the Northern Aral Sea, which has seen some improvement in water levels and fish populations due to the construction of a dam.&nbsp;



However, the larger Southern Aral Sea remains largely desiccated and the overall environmental restoration of the area is a complex and ongoing challenge.



Image Credit: NASA Earth Observatory&nbsp;



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The shrinking Aral Sea: An environmental disaster

Today's Image of the Day from <a href="https://earthobservatory.nasa.gov/" target="_blank" rel="noreferrer noopener">NASA Earth Observatory</a> features a large fire burning in the Abyysky District, located in the Sakha region of northeastern <a href="https://www.earth.com/news/wildfires-in-siberia-are-a-growing-global-threat/" target="_blank" rel="noreferrer noopener">Siberia</a>. The image was captured on July 10, 2024 by the OLI (Operational Land Imager) on Landsat 8.



“The fire burned along the Khatyngnakh River in a remote area south of National Park Kytalyk, a UNESCO world heritage site,” said NASA.



“Burned areas appear brown. Darker green areas are forested and likely include dwarf larch and birch. Tundra grasses, mosses, and lichen are dominant in the lighter green areas.”



<h2 class="wp-block-heading" id="h-dozens-of-fires-in-siberia-nbsp">Dozens of fires in Siberia&nbsp;</h2>



In a separate satellite image captured on July 15, several large <a href="https://www.earth.com/news/discovery-massive-amounts-of-methane-gas-spews-from-wildfires/" target="_blank" rel="noreferrer noopener">fires</a> were visible burning in the same region.



By July 18, there were 69 fires burning across 276,983 hectares in Sakha, according to Russia’s Federal Forestry Agency.&nbsp;



“More than 2,000 people were in the region, including hundreds of paratroopers providing firefighting assistance. Sakha is one of nine areas in Russia that have declared a state of emergency due to fires,” said NASA.



<h2 class="wp-block-heading" id="h-fires-cut-off-communities-in-sakha">Fires cut off communities in Sakha</h2>



The region is mostly populated by the <a href="https://www.earth.com/news/fear-and-anxiety-the-mental-health-impacts-of-wildfires/" target="_blank" rel="noreferrer noopener">communities</a> of Eveny, Evenki, and Sakha, Indigenous peoples who have lived in the region for hundreds of years, noted NASA.&nbsp;



Stanislav Saas Ksenofontov is a postdoctoral scholar at the University of Northern Iowa who studies how climate change is affecting Indigenous communities in the Siberian Arctic.&nbsp;



Ksenofontov described the Sakha communities as small, dispersed, sometimes semi-nomadic groups with traditional activities such as fishing, hunting, foraging, and reindeer herding.



“Devasting fires like this can cut off communities, damage hunting grounds and berry-picking areas, and disrupt reindeer migration routes.”



<h2 class="wp-block-heading" id="h-increasing-fire-activity-in-siberia">Increasing fire activity in Siberia</h2>



The Arctic lowlands of the Russian Far East are typically a frigid landscape of permafrost and peat, said NASA, but it's also increasingly becoming a region that is prone to <a href="https://www.earth.com/news/wildfire-smoke-is-an-underestimated-threat-to-public-health/" target="_blank" rel="noreferrer noopener">wildfires</a>.&nbsp;



Kevin Smith is a U.S. Forest Service plant physiologist who co-authored a 2022 analysis of wildland fire activity in the Siberian Arctic.&nbsp;



Smith pointed out that most fires in this region are ignited by dry lightning. “Fires are a natural part of boreal and high Arctic landscapes in Sakha and the broader Siberian Arctic.”



“However, the frequency, severity, and area encompassed by current wildfire conditions are truly striking.”



Smith and his colleagues focused a study on two decades of fire detections captured by MODIS sensors.



The team found a three-fold increase in the number of fires and more than a doubling in the total area burned between 2000-2010 and 2010-2020. The biggest changes had occurred in the western and central regions of Siberia.



<h2 class="wp-block-heading" id="h-carbon-emissions-from-arctic-fires">Carbon emissions from Arctic fires</h2>



Mark Parrington is an atmospheric scientist with the European Centre for Medium-Range Weather Forecasts (ECMWF). According to his data,&nbsp; carbon emissions from fires within the Arctic Circle have been much higher so far in June and July 2024 than during this period over the past few decades.



While Arctic fires result in an immediate release of carbon into the <a href="https://www.earth.com/news/twenty-years-of-air-quality-improvement-erased-by-wildfires/" target="_blank" rel="noreferrer noopener">atmosphere</a>, determining the long-term effects of Arctic fires on the carbon cycle can be challenging due to the complexities of the ecosystem’s response. 



Smith noted that tundra fires can disturb soils in ways that make it easier for trees to colonize areas that had previously been dominated by grasses and mosses - a process that draws boreal forests northward and can result in increased carbon storage.



“On the other hand, climate and associated vegetation shifts can result in whole new regimes that reduce the natural storage of carbon by peat bogs and lead to increases in the release of methane, a strong greenhouse gas,” said Smith.&nbsp;



“To truly understand the ecological consequences of Arctic fires like these, it’s essential that we track fire activity and ecosystem responses with satellites but also that we follow up with on-the-ground research to better understand the implications.”



Image Credit: NASA Earth Observatory&nbsp;



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Dozens of fires are raging in Siberia

Today's Image of the Day from <a href="https://earthobservatory.nasa.gov/" target="_blank" rel="noreferrer noopener">NASA Earth Observatory</a> features Culebra Island, located about 17 miles east of Puerto Rico.&nbsp;



The unique marine ecosystems of Culebra include extensive <a href="https://www.earth.com/news/satellites-discover-huge-expanse-of-earths-coral-reefs-that-were-previously-unknown/" target="_blank" rel="noreferrer noopener">coral reefs</a> safeguarded by the Culebra National Wildlife Refuge and the Luis Peña Channel Natural Reserve.&nbsp;



Known as the "rainforests of the sea," coral reefs host a diverse array of <a href="https://www.earth.com/news/climate-change-is-impacting-marine-life-more-than-we-realized/" target="_blank" rel="noreferrer noopener">marine life</a>. They are formed from the calcium carbonate excreted by tiny organisms called polyps. 



Although coral reefs occupy less than 1% of the ocean floor, they are crucial habitats for nearly 25% of ocean species at some stage of their lives.



<h2 class="wp-block-heading" id="h-landsat-image-of-culebra-nbsp">Landsat image of Culebra&nbsp;</h2>



This Landsat 8 image - captured on February 10, 2024 - illustrates Culebra’s varied landscapes, ranging from the dry forests covering its hills to the stunning sandy beaches along its northern shore. 



“Deeper (dark blue) waters surround the island and nearby cays, while shallower (light blue) waters line the shores and lagoons. The green areas in shallow water are likely coral reefs, though seagrass meadows and seaweed patches can look similar,” noted NASA.



“You can absolutely see patch reefs east of Culebra in this image. But know that many of its reefs are located near the shore and are not easy to distinguish in Landsat imagery, depending on the depth of the water and the type of coral,” said Juan Torres-Pérez, a research scientist at NASA’s Ames Research Center.



<h2 class="wp-block-heading" id="h-fringing-and-patch-reefs-nbsp">Fringing and patch reefs&nbsp;</h2>



NOAA's detailed benthic habitat maps reveal that fringing and patch reefs are prevalent around Culebra, particularly to the north and east, with seagrass and seaweed meadows more common in the southern shallows.&nbsp;



Fringing reefs are the most common type of coral reef. They are directly attached to a shore or border a landmass with little to no lagoon between the shore and the main reef body. Fringing reefs grow seaward directly from the coastline.



Patch reefs are small, isolated platforms of coral that can occur independently or within a larger system of reefs, such as a barrier reef. They often appear as "patches" dispersed throughout a lagoon, separated by areas of sand or sea grass.&nbsp;



The reefs of Culebra feature key species such as branching staghorn and <a href="https://www.earth.com/news/favorable-conditions-offer-hope-for-endangered-elkhorn-coral/" target="_blank" rel="noreferrer noopener">elkhorn corals</a>, as well as mound-shaped and brain corals.



<h2 class="wp-block-heading" id="h-environmental-threats">Environmental threats</h2>



Environmental threats such as coastal development, overfishing, and warming, acidic waters challenge reefs worldwide, including those around Culebra.&nbsp;



Local issues, like increased runoff from development, also threaten these delicate ecosystems by introducing harmful pollutants.&nbsp;



Furthermore, record-high global <a href="https://www.earth.com/news/extreme-ocean-heating-signals-alarm-for-a-3c-warmer-world/" target="_blank" rel="noreferrer noopener">ocean temperatures</a> in 2023 have led to a significant coral bleaching event, affecting reefs across 62 countries and territories.



The ongoing marine heat wave poses an added risk, especially with higher starting sea surface temperatures this summer compared to last.&nbsp;



<h2 class="wp-block-heading" id="h-oceanos-program-nbsp">OCEANOS program&nbsp;</h2>



NASA’s OCEANOS program is actively involved in studying and conserving these reefs. This program, designed for Hispanic/Latino high school graduates and first-generation college students in Puerto Rico, offers training in remote sensing, coral reef ecology, and other marine sciences.



In partnership with Sociedad Ambiente Marino, NASA’s efforts include planting over 160,000 coral pieces around Culebra to strengthen the reefs.&nbsp;



This summer, OCEANOS students will also learn about coral farming, beach profiling, reef ecology, 3D printing of coral colonies, and <a href="https://www.earth.com/news/seagrass-is-of-fundamental-importance-to-earths-future/" target="_blank" rel="noreferrer noopener">seagrass conservation</a>, further contributing to the health and resilience of Culebra's marine environments.



<h2 class="wp-block-heading" id="h-culebra-island-nbsp">Culebra Island&nbsp;</h2>



Culebra Island is renowned for its stunning natural beauty and laid-back atmosphere. This small island is part of the Spanish Virgin Islands and is less commercialized than its neighbor, Vieques, or the main island of Puerto Rico.&nbsp;



It's especially famous for Flamenco Beach, often ranked among the most beautiful beaches in the world with its white sands and clear, turquoise waters.



Culebra has a protected wildlife refuge that covers approximately one-third of the island, providing shelter to a variety of wildlife, including sea turtles and seabirds. 



The surrounding coral reefs are vibrant and full of marine life, making it a popular spot for snorkeling and diving. Despite its small size, the island has a rich history, having been used as a naval gunnery and bombing practice site until 1975.



Today, Culebra is a favorite destination for those seeking a peaceful retreat in nature. The island's emphasis on conservation and its community's commitment to preserving its natural environment make it a unique place for eco-tourism.&nbsp;



Visitors can also enjoy hiking, kayaking, and fishing alongside the local population, which is known for its warmth and hospitality.



Image Credit: NASA Earth Observatory&nbsp;



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Protecting the coral reefs of Culebra

Traditionally, we have always believed that&nbsp;photosynthesis&nbsp;by plants and algae fuel our planet's oxygen supply, even in the deep ocean, providing the essential gas for life on Earth.&nbsp;However, an international team of scientists has made a startling discovery, finding "dark oxygen" in the deep ocean that challenges this long-held premise.



Their critical finding proves that the Earth's oxygen could also be generated by metallic minerals on the deep-ocean floor, some 13,000 feet below the surface, where no sunlight penetrates.&nbsp;



This revelation opens up exciting new possibilities. We can now better understand the origins of oxygen on our planet. It also sheds light on its distribution.



<h2 class="wp-block-heading" id="h-oxygen-with-photosynthesis-the-norm">Oxygen with photosynthesis -- the norm</h2>



Have you ever wondered why we call plants the "lungs" of the Earth? It's simple: they breathe out what we breathe in. This happens through a fantastic process called <a href="https://www.earth.com/news/scientists-have-finally-decoded-the-process-of-photosynthesis/" target="_blank" rel="noreferrer noopener">photosynthesis</a>.



Imagine a world without trees, plants, or algae. It's not just a barren, lifeless landscape. It’s a world without oxygen. 



Thanks to photosynthesis, plants, algae, and some bacteria are like busy little factories, turning sunlight into the very air we breathe. They're the unsung heroes of life on Earth.



Here's an interesting twist. The waste product of our respiration, carbon dioxide, is like gold for plants. They transform it back into oxygen and nutrients in what's known as the Calvin cycle.



The oxygen we enjoy today didn't always exist. Thanks to a unique group of photosynthesizing bacteria, our planet's atmosphere underwent a dramatic makeover 2.4 billion years ago, known as the <a href="https://www.earth.com/news/it-took-200-million-years-for-earth-to-get-its-oxygen/" target="_blank" rel="noreferrer noopener">Great Oxygenation Event</a>. This poured oxygen into our atmosphere, paving the path for more complex forms of life to evolve.



<h2 class="wp-block-heading" id="h-oxygen-without-photosynthesis-not-normal">Oxygen withOUT photosynthesis -- not normal</h2>



Discovering that oxygen is produced at the bottom of the deepest parts of Earth's ocean, without sunlight or photosynthesis, is stunning as it singles out an unlikely <a href="https://www.earth.com/news/oxygen-may-have-come-from-ancient-rocks-of-early-earth/" target="_blank" rel="noreferrer noopener">source of oxygen</a> -- the seafloor, an area completely devoid of light. 



Previously, it was unthinkable that oxygen-breathing (aerobic) marine life could exist in such darkness. Yet, this discovery is astonishing. It could reshape our understanding of aerobic life's origin on Earth.



Researcher Andrew Sweetman, who spearheads the Seafloor Ecology and Biogeochemistry research team at the Scottish Association for Marine Science (<a href="https://www.sams.ac.uk/" target="_blank" rel="noreferrer noopener">SAMS</a>), was instrumental in this discovery.&nbsp;



"For aerobic life to begin on the planet, there had to be oxygen, and our understanding has been that&nbsp;<a href="https://www.earth.com/news/it-took-200-million-years-for-earth-to-get-its-oxygen/" target="_blank" rel="noreferrer noopener">Earth’s oxygen</a>&nbsp;supply began with <a href="https://www.earth.com/news/key-to-life-on-earth-photosynthesis-begins-on-the-quantum-level-with-a-single-photon/" target="_blank" rel="noreferrer noopener">photosynthetic</a> organisms," Sweetman explains.



"But we now know that there is oxygen produced in the deep sea, where there is no light. I think we, therefore, need to revisit questions like: Where could aerobic life have begun?”



<h2 class="wp-block-heading" id="h-polymetallic-nodules-in-ocean">Polymetallic nodules in ocean</h2>



Polymetallic nodules - natural mineral accumulations on the ocean floor, possessing a mix of various minerals, are central to this discovery.&nbsp;



These nodules, varying in size, contain critical metals like cobalt, nickel, copper, lithium, and manganese -- elements used in batteries.



“The polymetallic nodules that produce this oxygen contain metals such as cobalt, nickel, copper, lithium, and manganese -- which are all critical elements used in batteries," asserts Franz Geiger, professor of Chemistry at the <a href="https://www.northwestern.edu/" target="_blank" rel="noreferrer noopener">Northwestern University</a> and lead experimenter in the electrochemistry tests. 



"Several large-scale mining companies now aim to extract these precious elements from the seafloor at depths of 10,000 to 20,000 feet below the surface. We need to rethink how to mine these materials, so that we do not deplete the oxygen source for deep-sea life.” 



<h2 class="wp-block-heading" id="h-unearthing-oxygen-in-deep-ocean">Unearthing oxygen in deep ocean</h2>



Sweetman recounts the tale of his initial incredulity upon <a href="https://www.earth.com/news/summer-storms-stir-oxygen-into-the-deep-ocean/" target="_blank" rel="noreferrer noopener">detecting oxygen</a> during his seabed sampling in the Pacific Ocean's Clarion-Clipperton Zone.&nbsp;



He initially suspected faulty equipment, given that conventional wisdom dictates oxygen consumption rather than production in deep-sea environments.



“When we first got this data, we thought the sensors were faulty because every study ever done in the deep sea has only seen oxygen being consumed rather than produced,” Sweetman said. 



“We would come home and recalibrate the sensors, but, over the course of 10 years, these strange oxygen readings kept showing up."



The scientists decided to take a back-up method that worked differently to the optode sensors they were originally using. When both methods came back with the same result, they realized they were onto something big.



<h2 class="wp-block-heading" id="h-geobatteries-from-deep-ocean-oxygen">Geobatteries from deep ocean oxygen</h2>



To better comprehend the oxygen production, the researchers explored a hypothesis that relates to the concept of Geobatteries.&nbsp;



Through a chemical process known as seawater electrolysis, they wondered if the deep-ocean’s polymetallic nodules generated enough electricity to produce oxygen.&nbsp;



The results were conclusive. “It appears that we discovered a natural ‘geobattery.’ These geobatteries are the basis for a possible explanation of the ocean’s dark oxygen production,” stated Geiger.



<h2 class="wp-block-heading" id="h-deep-ocean-oxygen-and-mining-implications">Deep ocean oxygen and mining implications</h2>



This revelation could have significant implications for the mining industry.&nbsp;



The researchers emphasize the importance of considering the potential impact on the ocean's dark oxygen production before planning&nbsp;<a href="https://www.earth.com/news/deep-sea-mining-has-deadly-consequences-for-marine-life/" target="_blank" rel="noreferrer noopener">deep-sea mining</a>&nbsp;activities.&nbsp;



“In 2016 and 2017, marine biologists visited sites that were mined in the 1980s and found not even bacteria had recovered in mined areas. In unmined regions, however, marine life flourished. Why such ‘dead zones’ persist for decades is still unknown," Geiger concludes.



"However, this puts a major asterisk onto strategies for sea-floor mining as ocean-floor faunal diversity in nodule-rich areas is higher than in the most diverse tropical rainforests."



In summary, discovering dark oxygen production in the&nbsp;<a href="https://www.earth.com/news/how-can-deep-ocean-microbes-survive-without-sunlight/" target="_blank" rel="noreferrer noopener">deep-ocean</a>&nbsp;sets a new direction for our understanding of Earth's oxygen supply. The implications of this discovery, for both science and industry, are profound.



The full study was published in the journal&nbsp;<a href="https://www.nature.com/articles/s41561-024-01480-8" target="_blank" rel="noreferrer noopener">Nature Geoscience</a>.



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Discovery: "Dark oxygen" is produced on the ocean floor without sunlight

Traditionally, we have always believed that&nbsp;photosynthesis&nbsp;by plants and algae fuel...

Grassland ecosystems, contributing to over a quarter of the world's land surface and containing a third of terrestrial carbon, are a lifeline for food production, wildlife habitat, and overall <a href="https://www.earth.com/news/grassland-ecosystem-stability-is-driven-by-biodiversity/" target="_blank" rel="noreferrer noopener">biodiversity</a> in the face of climate change.&nbsp;



These vast landscapes provide essential ecosystem services, such as&nbsp;<a href="https://www.earth.com/news/grasslands-can-be-managed-to-benefit-biodiversity-and-soil-health/" target="_blank" rel="noreferrer noopener">soil</a>&nbsp;stabilization, water filtration, and carbon sequestration.&nbsp;



The future of these vital ecosystems is uncertain. Two major environmental shifts are contributing to this crisis. First, land use is intensifying. And the second, the impacts of climate change are escalating.



<h2 class="wp-block-heading" id="h-grassland-use-and-climate-change">Grassland use and climate change</h2>



Grasslands, particularly in Europe, are experiencing intensified use, including higher levels of fertilization, more frequent mowing, and concentrated grazing.&nbsp;



This intensified agricultural activity is driven by the demand for increased productivity and efficiency in&nbsp;<a href="https://www.earth.com/news/food-production-more-difficult-climate-change-plant-pollinators/" target="_blank" rel="noreferrer noopener">food production</a>.&nbsp;



Furthermore, farmers often limit their sowing to a few grass varieties that promise high yields. This shift in agricultural practices dramatically alters the species composition and functionality of meadows and pastures, <a href="https://www.earth.com/news/grassland-ecosystem-stability-is-driven-by-biodiversity/" target="_blank" rel="noreferrer noopener">reducing biodiversity</a> and impacting ecosystem health.



Climate change adds another considerable layer of threat, with precipitation patterns changing and climatic extremities, like heavy rainfall and droughts, predicted to escalate.&nbsp;



These changes in climate not only affect the growth and survival of plant species but also disrupt the delicate balance of grassland ecosystems.&nbsp;



When these two changes intersect, they can intensify each other. This creates a synergistic effect that worsens the challenges faced by grassland ecosystems. As a result, the future of these vital landscapes becomes uncertain.



<h2 class="wp-block-heading" id="h-land-use-and-climate-change-interaction">Land-use and climate change interaction</h2>



A unique large-scale, long-term experiment conducted at the <a href="https://www.ufz.de/" target="_blank" rel="noreferrer noopener">UFZ</a> in Bad Lauchstädt near Halle, known as the Global Change Experimental Facility (<a href="https://www.ufz.de/index.php?en=42385" target="_blank" rel="noreferrer noopener">GCEF</a>), has assisted in understanding the combined effects of these changes. 



The experiment manipulated varying degrees of land use intensity, temperatures, and precipitation levels on 50 plots, each sized 16 x 24 m.&nbsp;



Specific plots were given 10% more rainfall during spring and autumn and 20% lesser in summer, mirroring the climatic conditions expected for Central Germany.



This experiment yielded an eight-year data collection, used to conduct an in-depth study between 2015 and 2022, included in the research publication.&nbsp;



The period constituted three of the driest years in recorded regional history. The droughts seemingly had greater impact on the plants than the simulated climate change during the study period.



<h2 class="wp-block-heading" id="h-diverse-grassland-for-intense-climates">Diverse grassland for intense climates</h2>



The study revealed that species-rich grassland, which is less frequently mown or sparsely grazed, coped better with heat and drought than the high-yielding meadows under heavy use.&nbsp;



The difference lies in biodiversity, which varied greatly depending on the land use of the grasslands.



The less intensively used meadows and pastures had a diverse mix of over 50 native grasses and herbs, while the high-intensity grassland had only five types of grass recommended for drier sites.&nbsp;



These high-yield varieties are bred for maximum productivity. They are heavily fertilized and perform exceptionally well under favorable climatic conditions. However, they struggle during drought.



In such situations, the high-intensity meadows saw a marked decrease in these grasses and an increase in short-lived species that survive as seeds.&nbsp;



These new species are usually of lower fodder quality, reducing the productivity of the land.



<h2 class="wp-block-heading" id="h-migration-in-high-performance-grassland">Migration in high-performance grassland</h2>



Farmers are familiar with this degradation of high-performance grasslands due to migrating species and regularly plough up and re-seed their land.



However, climate change might accelerate this process, adding extra costs and unpredictable conditions. Farmers relying solely on intensive grassland stand to bear higher economic risks.



On the contrary, low-intensity meadows and pastures not only help preserve biodiversity but also stabilise grassland productivity during&nbsp;<a href="https://www.earth.com/news/understanding-the-impact-of-climate-change-at-the-national-level/" target="_blank" rel="noreferrer noopener">climate change</a>.&nbsp;



Understanding these findings is crucial. Implementing solutions accordingly is essential. This helps preserve our invaluable grassland ecosystems. Responsible management is key.



<h2 class="wp-block-heading" id="h-native-species-and-genetic-diversity">Native species and genetic diversity</h2>



Planting a variety of native species that are well-adapted to local conditions can improve the resilience of grasslands.&nbsp;



These species are more likely to withstand climatic variations and pest outbreaks, reducing the need for chemical interventions.&nbsp;



Maintaining genetic diversity in livestock herds is crucial. It helps animals cope with environmental stressors. This support leads to a more robust agricultural system.



<h2 class="wp-block-heading" id="h-policy-and-community-engagement">Policy and community engagement</h2>



Effective grassland management requires supportive policies and community involvement.&nbsp;



Governments and organizations need to offer incentives for sustainable practices. They should also educate farmers about the benefits of biodiversity. Additionally, understanding ecosystem services is crucial for long-term success.



Community engagement programs can foster a sense of stewardship and collective action towards preserving these vital landscapes.



By incorporating these sustainable practices, we can ensure that grassland&nbsp;<a href="https://www.earth.com/news/grasslands-crucial-role-global-agriculture-environment-ecosystems/" target="_blank" rel="noreferrer noopener">ecosystems</a>&nbsp;remain productive, resilient, and rich in biodiversity, securing their role in food production and environmental health for future generations.



The full study was published in the journal&nbsp;<a href="https://onlinelibrary.wiley.com/doi/10.1111/gcb.17418" target="_blank" rel="noreferrer noopener">Global Change Biology</a>.



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Some grassland ecosystems handle climate change better than others

Grassland ecosystems, contributing to over a quarter of the world's...

For centuries, the seemingly stable world of zooplankton, specifically the water flea, Daphnia pulex, has captivated biologists interested in natural selection. 



These minute yet fascinating crustaceans, often invisible to the naked eye, play a critical and multifaceted role in aquatic ecosystems. 



They are a primary food source for many fish species. They also help regulate the populations of algae and other microorganisms. This regulation maintains the delicate balance of their habitats.



A recent study has reaffirmed the <a href="https://www.earth.com/news/new-deep-sea-crustacean-species-discovered-in-the-bahamas/" target="_blank" rel="noreferrer noopener">ecological significance</a> of our environment. It offers a unique perspective on the mystery of evolution.



This research provides new insights into the intricate mechanisms behind genetic adaptation and also sheds light on the importance of biodiversity.



<h2 class="wp-block-heading" id="h-daphnia-s-genetic-secrets">Daphnia's genetic secrets</h2>



This groundbreaking research, conducted over a decade, involved scientists from&nbsp;<a href="https://www.asu.edu/" target="_blank" rel="noreferrer noopener">Arizona State University</a>&nbsp;(ASU),&nbsp;<a href="https://english.ccnu.edu.cn/" target="_blank" rel="noreferrer noopener">Central China Normal University</a>, and the&nbsp;<a href="https://www.nd.edu/" target="_blank" rel="noreferrer noopener">University of Notre Dame</a>.&nbsp;



The team analyzed DNA samples from nearly 1,000 Daphnia, aiming to understand the dynamics of natural selection in this species.



<h2 class="wp-block-heading" id="h-fluctuating-force-of-natural-selection">Fluctuating force of natural selection</h2>



The researchers made a very significant discovery. The strength of <a href="https://www.earth.com/news/coexisting-lizards-challenge-what-we-know-about-natural-selection/" target="_blank" rel="noreferrer noopener">natural</a> selection on individual genes fluctuates drastically from year to year, even in seemingly constant environments. 



This surprising and dynamic oscillation could be key for better adaptation to changing environments. It allows populations to stay flexible and responsive. Over time, this helps them cope with varying selective pressures.



Such insights deepen our understanding of evolutionary processes. They highlight the complex interplay between genetics and environmental factors.



"Even in seemingly constant environments, we detected profound fluctuations in the frequency of gene variants at specific chromosomal regions over time," explains Michael Lynch, the lead author of the study and director of the Biodesign Center for Mechanisms of Evolution at ASU.



<h2 class="wp-block-heading" id="h-rethinking-natural-selection">Rethinking natural selection</h2>



These findings challenge the conventional belief. Analyzing genetic diversity and divergence does not easily reveal how natural selection operates. The evidence suggests a more complex relationship than previously understood.



Instead, natural selection appears to function with a higher level of subtlety and complexity than previously acknowledged.



The study revealed that most genetic sites experience varying selection, with an average effect close to zero, indicating little consistent selection pressure over different times.&nbsp;



This fluctuation in <a href="https://www.earth.com/news/sea-ice-decline-changes-the-behavior-of-zooplankton/" target="_blank" rel="noreferrer noopener">genetic variation</a> allows populations to remain highly adaptable to environmental changes. 



Gene variants, also known as alleles, are different versions of the same gene that can result in different traits.



Furthermore, the research showed that genes located near each other on chromosomes tend to evolve in a coordinated manner.&nbsp;



This linkage allows for beneficial combinations of gene variants to be inherited together, potentially accelerating the&nbsp;<a href="https://www.earth.com/news/tiny-songbirds-are-masters-of-memory-and-adaptation/" target="_blank" rel="noreferrer noopener">adaptation</a>&nbsp;process.



<h2 class="wp-block-heading" id="h-from-water-fleas-to-ecosystem-resilience">From water fleas to ecosystem resilience</h2>



Understanding how Daphnia evolve through natural selection offers valuable insights. It reveals the resilience of entire ecosystems. 



This knowledge could help us predict the impacts of environmental changes. It can also aid in mitigating effects on biodiversity and food webs.



By examining the genetic variations and adaptations of these&nbsp;<a href="https://www.earth.com/news/tiny-crustaceans-have-what-it-takes-to-survive-climate-change/" target="_blank" rel="noreferrer noopener">tiny crustaceans</a>, scientists can better grasp the underlying mechanisms that enable ecosystems to endure and thrive amidst shifting environmental conditions.&nbsp;



"This study has, for the first time, given us a glimpse into the kinds of temporal changes in gene frequencies that occur even in seemingly constant environments, a sort of ongoing churn of genetic variation distributed across the genome," Lynch states.



This research is crucial for predicting how species might adapt to changing environments, including those caused by climate change.&nbsp;



<h2 class="wp-block-heading" id="h-harnessing-daphnia-insights-for-modern-environmental-challenges">Harnessing Daphnia insights for modern environmental challenges</h2>



This groundbreaking research on Daphnia pulex not only enhances our understanding of <a href="https://www.earth.com/news/ecosystem-behavior-earth-first-sea-creatures-stirring-water-drove-evolution/" target="_blank" rel="noreferrer noopener">evolution</a> but also has far-reaching potential applications in various fields, ranging from conservation biology to climate change adaptation strategies. 



We are facing unprecedented environmental challenges. Habitat loss, pollution, and global warming are major issues. Understanding nature's remarkable ability to adapt and be resilient is more important than ever.



This study reveals important insights about genetic variability and natural selection. These findings provide a strong foundation for new methods in biodiversity conservation. They also pave the way for improved ecosystem management.



By deepening our understanding of evolutionary dynamics, we can anticipate environmental stressors more effectively. 



This knowledge helps us mitigate their impacts. Ultimately, it contributes to the health and stability of our planet's ecosystems.



The full study was published in the journal&nbsp;<a href="https://www.pnas.org/doi/10.1073/pnas.2307107121" target="_blank" rel="noreferrer noopener">Proceedings of the National Academy of Sciences</a>.



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Life's rules of natural selection change significantly and very often

For centuries, the seemingly stable world of zooplankton, specifically the water...

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Today&#8217;s Video of the Day from the University of Miami (UM) <a href="https://www.rsmas.miami.edu/">Rosenstiel School of Marine and Atmospheric Science</a> explains why fish often take the risk of rubbing up against sharks. The researchers have discovered that this surprising <a href="https://www.earth.com/news/repetitive-behaviors-in-dogs-are-influenced-by-many-factors/">behavior</a>, which is referred to as chafing, is much more widespread than what was expected. 



“While we don’t exactly know why it’s happening, we have a few theories. Shark skin is covered in small tooth-like scales called dermal denticles, which provide a rough sandpaper surface for the chafing fish,” said study co-author Professor Neil Hammerschlag.&nbsp;



“We suspect that chafing against shark skin might play a vital role in the removal of parasites or other skin irritants, thus improving fish health and fitness.”



Based on the analysis of underwater images, drone videos, and witness reports, the team documented 47 instances of fish rubbing themselves against the skin of a shark.&nbsp;



Taking place in 13 locations around the world, the chafing events varied in duration from eight seconds to over five minutes. The experts believe that chafing could play an important and underappreciated ecological role for aquatic animals.



“While chafing has been well documented between fish and inanimate objects, such as sand or rocky substrate, this shark-chaffing phenomenon appears to be the only scenario in nature where prey actively seek out and rubs up against a predator,” said study co-lead author Lacey Williams.



Video Credit: Great white and Leerie by Lacey Williams and Alex Anstett Great white and Pacific jack mackerel by Jesus Erick Higuera Rivas Silky shark and rainbow runner by Victor Bach Munoz Whale shark and silky sharks by Jonathan Green



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By <a href="http://csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Why do fish rub up against sharks?