Tuesday, February 14, 2023

The world of corals

The Great Barrier Reef is the largest coral reef system in the world visible from space.

Corals, the beautiful plantlike structures in the sea floor, are actually hundreds to thousands of tiny creatures called polyps. Soft polyp secretes a hard skeleton of limestone that attaches itself to other sea structures like rock or dead skeletons of other polyps. Polyps live in colonies and grow connected to each other. They are dependent on one another for survival.
 

Most coral reefs are found in the warm shallow waters of tropics and subtropics. About 90 percent of the world’s coral reefs occur in the Indo-West Pacific region. Some Reef systems also exist in the West and East Atlantic, and East Pacific oceans between 30° N and 30° S. Major Reef systems are recognised on the basis of their location like Caribbean reefs; the Great Barrier Reef; the Red Sea; Arabian Sea; and Persian Gulf reefs.

                                                     Distribution of the world's coral reefs                                    Cartographer: Hugo Ahlenius

 

Out of them, The Great Barrier Reef is the most well-known. It’s the largest coral reef system in the world, extending 2,300 kilometers from the Torres Strait, just south of Papua New Guinea down the eastern coast of Australia. It is the world’s largest structure built from living organisms visible from space.

Coral reefs are among the most complex and fascinating marine ecosystems in the seas and are home to the planet’s most diverse habitats. That's why they are sometimes known as the “rainforests of the sea.” Nearly a quarter of all the fish in the sea and many other organisms rely on healthy coral reefs. 

Coral reefs are known as the “rainforests of the sea.” as they are habitat for fishes and  many other organisms.
 

The Northwest Hawaiian Island coral reefs are home to about seven thousand species of plants and animals. They are not only home to many marine species, but they are a source of livelihood for many local communities. Millions of people around the world rely on fish caught in and around coral reefs. 

 

Corals are a source of livelihood for many local communities.

The reefs also draw in tourists, which helps the local economies. Coral reefs protect people and land from storms as well, serving as a barrier that reduces the impact of large waves on shore. 

However, they’re increasingly threatened from pollution, increasing ocean temperatures, overfishing, water pollution, coral bleaching and ocean acidification. Coral reef systems are most sensitive to pollution and increasing ocean temperatures and this can adversely affect humans and marine species alike. It results in coral bleaching where stressed corals expel their symbiotic algae causing them to turn white. The absence of the zooxanthellae in ocean waters causes the coral to have limited food supply and they become more susceptible to diseases.

Corals are under severe threat from pollution, increasing ocean temperatures, overfishing, water pollution, coral bleaching and ocean acidification.
 


Recent research shows that the world has already lost nearly 20 percent of its coral reefs and many more reefs are under severe threat. It is now needed that preventive and mitigating steps are taken to prevent further deterioration of coral reefs and their extinction.



Reference -

Distribution of the world's coral reefs, 2010, Cartographer: Hugo Ahlenius, Available at -https://www.grida.no/resources/7765

Images form Pixabay


Wednesday, July 6, 2022

Mars from the eyes of NASA’s Curiosity Rover – Recently released Mars surface images and new findings


Image credit - NASA/JPL-Caltech

NASA’s Curiosity rover is part of Mars Exploration Program. Packed with the biggest, most advanced suite of instruments for scientific exploration of mars, its mission was to assess the planet’s environment for “habitability”. Reaching the red planet on August 5, 2012, NASA’s curiosity rover will shortly complete its 10 year on Martian soil.

Curiosity rover was designed to collect soil samples from surface and rock drills on Martian land. Additionally, Its purpose was to analyze the formation, structure, and chemical composition of the rocks as well as to examine the local geologic setting to detect chemical building blocks of life on Mars and reconstruct the Martian environment in past.

Recently, NASA has released some images of Mars surface clicked by the Mast camera or the Mastcam on-board the curiosity rover. The images have revealed some interesting findings about our neighboring red planet.

Here, we share some interesting images released by NASA from Curiosity rover, Mars.



Image credit - NASA/JPL-Caltech/MSSS

Flaky, Streambed Rocks formed in an ancient stream-bed or small pond.



Image credit - NASA/JPL-Caltech/MSSS

Finger-Like Rocks likely formed as groundwater trickled through rock in the ancient past, depositing mineral cements over time. Later, the softer rock was eroded by wind around the cemented portions. The rocks were found on Mount Sharp.



Image credit - NASA/JPL-Caltech/MSSS

Sulfate-Bearing Region in the middle of the image. Layers or stripes can be seen across the mountainside. These layers represent an excellent record of how Mars’ water and climate changed over time. 



Image credit -NASA/JPL-Caltech/York University

Drifting high Clouds on the Martian sky. NASA scientists believe that these clouds are very high and cold suggesting presence of carbon dioxide ice. Martian clouds are also faintly visible in the atmosphere and special imaging techniques has been used to detect them.




Image credit - NASA/JPL-Caltech

Spectacular Picture Postcard from Curiosity's Navcam. This panoramic view of Mars, artistically recreated by color addition is both gorgeous and informative. Rounded hills at center –right; a field of sand ripples “Sands of Forvie”; craggy “Rafael Navarro Mountain”, all these features show intriguing changes in the martian landscape over time.



Image credit - NASA/JPL-Caltech

Sedimentary structure of a Martian Lake-bed shows typical pattern of a lake-floor sedimentary deposit in ancient past.



Image credit - NASA/JPL-Caltech

Martian rock slab known as "Old Soaker" shows a network of cracks. Scientists presume that it may have formed from the drying of a mud layer more than 3 billion years ago.

These stunning images together with the data samples analyzed by NASA scientist also reveal presence of organic carbon in the Martian soil. Organic carbon is the same type of carbon associated with biological processes on Earth. Scientists believe that though our neighboring planet is inhospitable now but billion years ago it has a thicker atmosphere and liquid water in streams and seas. Scientists are trying to understand and reconstruct the past climate and life on planet Mars with the vast amount of data available from the Curiosity rover and other such missions.

For more about Curiosity rover, visit http://mars.nasa.gov/msl or https://www.nasa.gov/mission_pages/msl/index.html.

Reference - 

NASA's Curiosity Takes Inventory of Key Life Ingredient on Mars, Available at - https://mars.nasa.gov/news/9113/nasas-curiosity-rover-measures-intriguing-carbon-signature-on-mars/ 

NASA's Curiosity Rover Measures Intriguing Carbon Signature on Mars. Available at - https://mars.nasa.gov/news/9113/nasas-curiosity-rover-measures-intriguing-carbon-signature-on-mars/

NASA's Curiosity Captures Stunning Views of a Changing Mars Landscape. Available at - https://mars.nasa.gov/news/9209/nasas-curiosity-captures-stunning-views-of-a-changing-mars-landscape/