Sundarbans’ Tigers Further Pushed Towards Extinction by Rising Sea Levels

bengal-tiger-sundarbans
Photo Source: 44-D, Flick’r

Excerpt from the WWF

One of the world’s largest tiger populations could disappear by the end of this century as rising sea levels caused by climate change destroy their habitat along the coast of Bangladesh in an area known as the Sundarbans, according to a 2010 WWF-led study, published in the journal Climatic Change.

Tigers are among the world’s most threatened species, with only an estimated 3,200 remaining in the wild. WWF officials said the threats facing these Royal Bengal tigers and other iconic species around the world highlight the need for urgent international action to reduce greenhouse gas emissions.

“If we don’t take steps to address the impacts of climate change on the Sundarbans, the only way its tigers will survive this century is with scuba gear,” said Colby Loucks, WWF-US deputy director of conservation science and the lead author of the study Sea Level Rise and Tigers: Predicted Impacts to Bangladesh’s Sundarbans Mangroves. “Tigers are a highly adaptable species, thriving from the snowy forests of Russia to the tropical forests of Indonesia.

“The projected sea level rise in the Sundarbans will likely outpace the tiger’s ability to adapt.”

An expected sea level rise of 28 cm above 2000 levels may cause the remaining tiger habitat in the Sundarbans to decline by 96 percent, pushing the total population to fewer than 20 breeding tigers, according to the study.

Unless immediate action is taken, the Sundarbans, its wildlife and the natural resources that sustain millions of people may disappear within 50 to 90 years, the study states.

“The mangrove forest of the Bengal tiger now joins the sea-ice of the polar bear as one of the habitats most immediately threatened as global temperatures rise during the course of this century,” said Keya Chatterjee, acting director of the WWF-US climate change program. “To avert an ecological catastrophe on a much larger scale, we must sharply reduce greenhouse gas emissions and prepare for the impacts of climate change we failed to avoid.”

The Sundarbans, a UNESCO World Heritage Site shared by India and Bangladesh at the mouth of the Ganges River, is the world’s largest single block of mangrove forest. Mangroves are found at the inter-tidal region between land and sea, and not only serve as breeding grounds for fish but help protect coastal regions from natural disasters such as cyclones, storm surges and wind damage.

Providing the habitat for between 250 and 400 tigers, the Sundarbans is also home to more than 50 reptile species, 120 commercial fish species, 300 bird species and 45 mammal species. While their exact numbers are unclear, the tigers living in the Sundarbans of India and Bangladesh may represent as many as 10 percent of all the remaining wild tigers worldwide.

Using the rates of sea level rise projected by the Intergovernmental Panel on Climate Change in its Fourth Assessment Report (2007), the study’s authors wrote that a 28 cm sea level rise may be realized around 2070, at which point tigers will be unlikely to survive in the Sundarbans. However, recent research suggests that the seas may rise even more swiftly than what was predicted in the 2007 IPCC assessment.

sundarbans-map

This satellite image shows the forest in the protected area. The Sundarbans appears deep green, surrounded to the north by a landscape of agricultural lands, which appear lighter green, towns, which appear tan, and streams, which are blue. Ponds for shrimp aquaculture, especially in Bangladesh, sit right at the edge of the protected area, a potential problem for the water quality and biodiversity of the area. The forest may also be under stress from environmental disturbance occurring thousands of kilometers away, such as deforestation in the Himalaya Mountains far to the north. Image and caption: Wikipedia.

In addition to climate change, the Sundarbans tigers, like other tiger populations around the world already face tremendous threats from poaching and habitat loss. Tiger ranges have decreased by 40 percent over the past decade, and tigers today occupy less than seven percent of their original range. Scientists fear that accelerating deforestation and rampant poaching could push some tiger populations to the same fate as their now-extinct Javan and Balinese relatives in other parts of Asia.

Tigers are poached for their highly prized skins and body parts, which are used in traditional Chinese medicine. The 2010 Year of the Tiger marked an important year for conservation efforts to save wild tigers, with WWF continuing to play a vital role in implementing bold new strategies to save this magnificent Asian big cat.

Recommendations in the study include:

· Locally, governments and natural resource managers should take immediate steps to conserve and expand mangroves while preventing poaching and retaliatory killing of tigers.

· Regionally, neighboring countries should increase sediment delivery and freshwater flows to the coastal region to support agriculture and replenishment of the land;

· Globally, governments should take stronger action to limit greenhouse gas emissions;

“It’s disheartening to imagine that the Sundarbans, which means ‘beautiful forest’ in Bengali, could be gone this century, along with its tigers,” Loucks said. “We very much hope that in this, the Year of the Tiger, the world will focus on curtailing the immediate threats to these magnificent creatures and preparing for the long-term impacts of climate change.”

Original Article

The original report: Sea level rise and tigers: predicted impacts to Bangladesh’s Sundarbans mangroves, PDF File

Sinking Sundarbans, A Photo Gallery By Peter Caton

Bangladesh’s Project to Develop and Protect Southern Coastal Region

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Bangladesh Coastal Erosion. Photo Source: Laman/National Geographic Image Collection

Excerpt from The Financial Express, Dredging Today

Bangladesh’s coastal area covers about 20% of the country and over thirty percent of the net cultivable area. It extends inside up to 150 km from the coast. Out of 2.85 million hectares of the coastal and offshore areas about 0.83 millions hectares are arable lands, which cover over 30% of the total cultivable lands of Bangladesh. A part of the coastal area, the Sundarbans, is a reserve natural mangrove forest covering about 4,500 km2. The remaining part of the coastal area is used in agriculture. The cultivable areas in coastal districts are affected with varying degrees of soil salinity. The coastal and offshore area of Bangladesh includes tidal, estuaries and river floodplains in the south along the Bay of Bengal.

Barisal division, Khulna division, and some districtsin the Patuakhali and Noakhali areas, form the southern region of Bangladesh. The greater part of this region that roughly is equally to one fourth of the country spatially, is coastal in nature or relatively closer to the sea than other regions. It shares common economic prospects and challenges. The vast region is expected to be affected by the worldwide climate change. The southern region of Bangladesh is already undergoing the adverse effects of interventions in the free-flow of waters.

Structures built on the other side across the border have adversely affected the free flow of river waters into lower riparian Bangladesh. Already, there is an alarming fall in such flows, impacting very unfavourably the environment, ecology, habitat and people’s livelihood, particularly in the district of Khulna. The saline sea waters have been pushing up inland because of the poor flow in the rivers that cannot adequately flush out the sea waters. Big areas near the coasts have been affected by salinity and progressively more and more areas are meeting a similar fate.

Not only salinity, the leaner flow in the rivers of the southern region has also meant faster deposition of silt and the raising of their beds. Thus, the rivers across the region needs comprehensive dredging. Two consequences can be expected from such dredging. The flows in them could improve having a better effect in reducing salinity. Flood protection to some extent may also be achieved from the same. Government in Bangladesh appears to have firmed up a plan to engage in thorough river dredging in this area.

Salinity is not only threatening agriculture in the area, it is also posing as a serious threat to various flora and fauna in the Sunderbans forest which Bangladesh is otherwise proud of, as one of its great possessions.

Salinity has been such a problem for the region that in large tracts of what had been once cultivable lands, nothing of much value grows nowadays. People on a large scale were pushed to the brink and migrated to other areas of the country. The saline taste of even the underground tubewell water is a risk to public health. Thus, apart from river dredging, it should be planned whether fresh water from other areas of the country can be diverted to this region. Preservation and use of rain water need to be promoted here. Success was achieved in recent years in developing new and study varieties of rice plants that can grow well even under saline conditions. These varieties of rice and their cultivation will have to be popularized in this region. Storms and surges from the sea also pose big threats. Clearly, any overall plan for the development of the southern region, must incorporate the building of coastal embankments, sea walls, etc., both to hedge people against storms like the devastating storm, Alia and also from the looming threat of sea-level rise. Bangladesh is expected to be a major recipient of funds from donors to protect itself from climate change. A big part of such funds should be spent in the southern area considering its special vulnerabilities.

In this context, Prime Minister Sheikh Hasina spoke about an integrated plan for the development of the southern region. For any plan for development of the southern region cannot be isolated in its parts. All segments under a comprehensive plan must be simultaneously attempted or integrated to get the best results. All concerned would now expect the government to firm up actions for such an area-focused comprehensive plan of action in an integrated way in order to help reverse the present situation in the region of the country and to provide a strong base for its steady and sustained growth.

Original Article

Salinity Problems In Coastal Regions of Bangladesh

Finding Sustainable Ways to Cope With Sea Level Rise, in Coastal Care

68 Percent of New England and Mid-Atlantic Beaches Are Eroding

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Considerable beach erosion at Surf City, New Jersey. Photo Source: Jim Phillips

By Cheryl Hapke, U.S. Department of the Interior, U.S. Geological Survey

An assessment of coastal change over the past 150 years has found 68 percent of beaches in the New England and Mid-Atlantic region are eroding, according to a U.S. Geological Survey report released February 23rd.

Scientists studied more than 650 miles of the New England and Mid-Atlantic coasts and found the average rate of coastal change, taking into account beaches that are both eroding and prograding, was negative 1.6 feet per year.

Of those beaches eroding, the most extreme case exceeded 60 feet per year.

The past 25 to 30 years saw a small reduction in the percentage of beaches eroding, dropping to 60 percent, possibly as a result of beach restoration activities such as adding sand to beaches.

“This report provides invaluable objective data to help scientists and managers better understand natural changes to and human impacts on the New England and Mid-Atlantic coasts,” said Anne Castle, Assistant Secretary of the Interior for Water and Science. “The information gathered can inform decisions about future land use, transportation corridors, and restoration projects.”

Beaches change in response to a variety of factors, including changes in the amount of available sand, storms, sea-level rise and human activities. How much a beach is eroding or prograding in any given location is due to some combination of these factors, which vary from place to place.

The Mid-Atlantic coast, from Long Island, N.Y. to the Virginia-North Carolina border, is eroding at higher average rates than the New England coast. The difference in the type of coastline, with sandy areas being more vulnerable to erosion than areas with a greater concentration of rocky coasts, was the primary factor.

The researchers found that, although coastal change is highly variable, the majority of the coast is eroding throughout both regions, indicating erosion hazards are widespread.

“There is increasing need for this kind of comprehensive assessment in all coastal environments to guide managed response to sea-level rise,” said Dr. Cheryl Hapke of the USGS, lead author of the new report.”It is very difficult to predict what may happen in the future without a solid understanding of what has happened in the past.”

The researchers used historical data sources such as maps and aerial photographs, as well as modern data like lidar, or “light detection and ranging,” to measure shoreline change at more than 21,000 locations.

This analysis of past and present trends of shoreline movement is designed to allow for future repeatable analyses of shoreline movement, coastal erosion, and land loss. The results of the study provide a baseline for coastal change information that can be used to inform a wide variety of coastal management decisions, Hapke said.

The report, titled “National Assessment of Shoreline Change: Historical Shoreline Change along the New England and Mid-Atlantic Coasts,” is the fifth report produced as part of the USGS’s National Assessment of Shoreline Change project. An accompanying report that provides the geographic information system (GIS) data used to conduct the coastal change analysis is being released simultaneously.

Original Article

Reefs at Risk Report, Revisited: A Wakeup Call to Protect Coral

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Coral Reef, Strait Islands, Australia

By Robert Lalasz, Nature Conservancy, An Interview with Mark Spalding, Conservancy marine scientist

The new Reefs at Risk Revisited report is out, 13 years after the original Reefs at Risk, which was the first global assessment of the threats to Earth’s coral reefs and painted an alarming picture of their future. Today’s edition is even less rosy: It reports that 75% of the planet’s reefs are threatened, not just by unsustainable fishing practices and development but also by the effects of climate change.

Amazingly, Mark Spalding, Conservancy marine scientist and a co-author for both editions, is still optimistic we can save coral reefs. I asked him why and to tell us what’s in the new report.

Amazingly, Mark Spalding, Conservancy marine scientist and a co-author for both editions, is still optimistic we can save coral reefs. I asked him why and to tell us what’s in the new report.

You were part of the first Reefs at Risk report, published more than a decade ago. What’s changed? Are things that much worse for coral reefs now, and why?

Mark Spalding : The 1998 report was a wakeup call. It was the first reliable assessment of the scale of the problems facing reefs, and we found those problems, such as unsustainable fishing, coastal development, pollution and sediments sweeping off the land, were truly global and piling up to create huge challenges.

Our findings spurred vast efforts that spent hundreds of millions of dollars to deal with these problems. But while I’d love to tell you we’ve turned things around over the last decade, we haven’t. In fact, there’s been a 30% increase in the area of threatened reefs. Oceans have warmed because of climate change, and that’s caused devastating coral bleaching in many areas.

It would be wrong to talk about failure, though. Reefs would be in much worse condition in many places if we hadn’t done what we’ve done. There are now literally thousands of examples of good reef management worldwide, and of how to turn coral reefs around. We need to pick up these examples and see them as a tool-kit, something we can turn into standard management practice across the globe. For peoples’ sake.

The report says 75% of the world’s reefs are threatened. What does “threatened” mean, exactly, are they on the verge of disappearing, or no longer functioning?

Mark Spalding : A bit of both. Some of our “threatened” reefs are to all intents and purposes lost, while others on the map still appear to be in good health. But most of that 75% are degraded to some degree: fewer fish, fewer corals, banks of seaweed smothering the sea floor.

Reefs at Risk isn’t a measure of conditions in the water, it’s a scientific best estimate of how things could affect reefs. In some cases, these threats are like shadows, waiting in the wings; elsewhere, they have begun to tip the balance. And as these reefs decline, coastal people start to lose out too, from declines in fishing, failing tourism revenues, or weakening protection against storms by the ramparts of living reef.

If you had to pick one threat that’s gotten dramatically worse over the last 10 years, which would it be?

Mark Spalding: Coral bleaching, without a doubt. Bleaching is a stress response: when the water gets just a bit too warm, the corals pale to a bleached white and lose the important algae that normally live inside their bodies. Bleaching can kill corals over vast areas in extreme cases.

We knew bleaching was a threat as we worked on the last study, but no reef scientist had predicted the scale of the problem. It has just come on so fast, so strong, it’s hammered many reefs, and left other corals more susceptible to disease or other impacts.

Recent bleaching has increased the percentage of threatened reefs from 61% to 75%. Future projections of bleaching’s effects are even scarier. Until we get global change and carbon emissions under control, the threats from coral bleaching — and ocean acidification, as the ocean absorbs more CO2, will continue and accelerate.

Let’s do a thought experiment: Coral reefs have vanished overnight. What are the results? What do we lose? Who suffers? How would it affect the developed world?

Mark Spalding : First off, the 275 million people who live near coral reefs would be devastated. There are 150,000 km of worldwide coastline sheltered behind reefs, which provide storm and wave protection. And these aren’t just people on remote islands, while coral reefs provide critical food and shelter for villages and farms, they’re also critical to the functioning of countless towns, businesses and even cities from Miami to Manila. There are entire nations built from coral reefs, whose land surface is nothing more than the accumulated remains of corals shaped into islands by storms and currents. So all that would go away.

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Healthy coral reefs provide a living for about 275 million people, with many more dependent on them. Photo Source: National Geographic

But the ramifications are so much bigger than the local. Tourism, for one: Reef tourism is a massive industry, bringing international travellers to 100 coral reef nations around the world, and providing one-third of all export earnings to around 20 of these countries. And there are the vicarious benefits from the reefs’ supplies, from exotic food to aquarium fishes.
Equally important are the potent chemicals of the reefs and their medicinal uses and potential. Like rainforests, coral reefs host a bewildering diversity of plants and animals. In systems this diverse, the struggle for survival leads many species to develop complex adaptations, from skeletal structures to poisons and venoms. There might be 1 million different animal species on the world’s reefs, and we have only just begun to look at them. But they’ve already yielded active compounds with considerable promise for the treatment of certain cancers, HIV and malaria.

It’s frightening to think of coral reefs disappearing. The flip side: Give reefs a chance and the payback to people could be vast, and could continue in perpetuity.

The report calls for increased protection of coral reefs, but 27% of the world’s reefs are already inside marine protected areas (MPAs), and you write those aren’t completely effective. How do we increase the effectiveness of existing MPAs for reefs as well as their coverage?

Mark Spalding : It’s true. We found that only 6% of reefs were in fully effective MPAs, sites that allow fish and other organisms to thrive without any significant human impact. And quite a lot of those effective sites are very remote from the threats.

We know that MPAs are good for reefs. We also know that, as fish stocks recover in MPAs, they allow increased catches for fishers and better diving for tourists. So we need more MPAs close to people, precisely in the places that the threats are highest.

But these aren’t easy fixes, there is competition for use in these places, and some will resist any efforts to restrict or control fishing or other impacts. The Conservancy has been working around the world with fishers as well as with governments to design protected areas, and, indeed, comprehensive ocean zoning, to lead to benefits for all. Success breeds success in these matters, and the best emissaries for MPAs are their beneficiaries. Marine conservationists should be using fishers from successful locations to spread the word to others.

Given the dramatic decline in the condition of reefs since the last Reefs at Risk appeared, why should we be optimistic that we can avoid widespread disaster for coral reefs?

Mark Spalding : It would be foolish to simply wear a happy smile and pretend “all shall be well”, this report clearly points to a very sobering reality. But the report is also filled with success stories, everything from inspiring community leaders and well-managed local areas through to large-scale marine parks and international agreements such as the Micronesia Challenge. We can turn things around. We can manage reefs for survival, or even for rapid recovery. And in so doing, we can strengthen our coastlines and feed more hungry mouths.

Climate change hangs over such optimism, though, our projections suggest that reefs may be defenseless against its worst ravages. But we can certainly buy ourselves time. Some reefs have shown remarkable resilience and a great ability to bounce back from bleaching impacts to date, so if we can persuade the global community to act on climate change soon there’s certainly hope.

There are more than 60 recommendations in this new report for policymakers, scientists, industry. What can ordinary people do to help coral reefs? Anything?

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Photo Source: National Geographic

Mark Spalding : Individuals have a critical part to play. If you live near a reef, get involved. Help local communities and organizations with reef conservation and lobby leaders for better management. Fish with due caution and be careful not to drive overfishing when you buy fish from others.

And even if you live far from reefs, you can help, too. Do you holiday in reef areas, or know people who do? Think about where you stay and don’t be afraid to ask questions, choose hotels and restaurants that do not pollute and that make a positive contribution to the environment. Support NGOs such as The Nature Conservancy, which are making a real difference to coral reef conservation on the ground. Reduce your own personal carbon footprint, too, this step is urgent and, while it won’t be enough, it sends a powerful message. Finally, tell others what you are doing and encourage them to do the same.

Original Article

Coral reefs heading for fishing and climate crisis, BBC

The Last Of The Sea Nomads, Destroying The Reefs That Sustain Them, in Coastal Care

Testing the Limits of Where Humans Can Live

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Kuril Islands. Photo Source: RIA Novosti. Alexandr Grashenkov
The Kuril Islands are a chain of volcanic islands between Russia’s Kamchatka Peninsula and Japan’s Hokkaido Island, which separate the Okhotsk Sea from the Pacific Ocean. The coastal waters of the Kuril Islands are home to seals, sea otters, killer whales and sea lions.
Kuril Islands. Photo Source: RIA Novosti. Alexandr Grashenkov

Excerpt from The University of Washington

On an isolated segment of islands in the Pacific Ring of Fire, residents endure volcanoes, tsunamis, dense fog, steep cliffs and long and chilly winters. Sounds homey, huh?

At least it might be for inhabitants of the Kuril Islands, an 810-mile archipelago that stretches from Japan to Russia. The islands, formed by a collision of tectonic plates, are nearly abandoned today, but anthropologists have learned that thousands of people have lived there on and off as far back as at least 6000 B.C., persevering despite natural disasters.

“We want to identify the limits of adaptability, or how much resilience people have,” said Ben Fitzhugh, associate professor of anthropology at the University of Washington. “We’re looking at the islands as a yardstick of humans’ capacity to colonize and sustain themselves.”

kuril islands
Photo Source: Sergei Krasnoukhov

Understanding what made residents stay and how they survived could inform how we adapt to modern vulnerabilities, including climate change. The findings also have implications for how we rebound from contemporary catastrophes, such as the Indonesian tsunami in 2004, hurricanes Katrina and Rita and last year’s earthquake in Haiti.

Fitzhugh is leading an international team of anthropologists, archaeologists, geologists and earth and atmospheric scientists in studying the history of human settlement on the Kuril Islands.

The team’s findings will be discussed Feb. 20 during a lecture, Scales of Vulnerability and Resilience in Human Settlement of the Kuril Islands, at the American Association for the Advancement of Science’s annual meeting in Washington, D.C.

The scientists are studying islands in the central portion of the Kurils, from Urup Island in the south to Onekotan Island in the north, about 75 percent of the island chain. During three expeditions, they’ve found small pit houses, pottery, stone tools, barbed harpoon heads and other remnants of the islanders’ fishing and foraging lifestyle.

The scientists believe that human settlements existed in three different waves, the earliest in 6000 B.C., the most recent in 1200 A.D.

Fitzhugh finds evidence that following volcanic eruptions and tsunamis, people left the settlements but eventually returned. Fitzhugh and his research team have found that mobility, social networks and knowledge of the local environment helped indigenous people survive.

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“Having relatives and friends on other Kurils meant that, when something disastrous happened locally, people could temporarily move in with relatives on nearby islands,” he said.

Understanding the local environment also helped people survive the persistently foggy, dark and chilly environment. Since fog can shroud the islands, residents couldn’t navigate between islands by simply pointing their boats toward destinations. Fitzhugh and his collaborators suspect that indigenous Kurilians instead used bird behavior, water currents and water temperature to navigate.

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Photo Source: Sergey Krivosheyev

Fitzhugh says that the Kurils’ population decline has less to do with environmental challenges and more to do with changes in social and political influences, such as skirmishes between Russia and Japan over control of the Kurils.

He adds that as a global society in a time of environmental changes, we have to protect abilities of small and vulnerable populations to sustain themselves.

“This is not something that will naturally rise to the top of priorities of large political systems without concerted effort,” Fitzhugh said.

kuril-islands
Photo Source: Sergey Krivosheyev

Original Article

Tokyo’s unlearned history lessons, Kuril Islands Dispute, by Yuri Rubtsov, PhD, International Affair Magazine

Why Kuril dispute will not end any time soon, BBC

The Kuril Islands Dispute, Wikipedia

The Kuril Islands Photos Gallery, Ria Novosti

Impacts Of Intensive Salmon Farming On Coastal Ecosystems

fish-farm
The use of chemicals in Scotland’s salmon farming industry has risen sharply, according to an investigation. East Loch Tarbert, Scotland. Photo source: ©© IrenicRhonda

Excerpts;

A new salmon-farming trade deal with China has terrifying implications on Scotland’s coastal ecosystem.

But first, for readers who are not familiar with the war between the salmon farming industry on the one hand and those trying to protect wild salmon and sea trout runs on the other, here is a brief summary of the problem…

Read Full Article, Guardian Uk

Scotland’s wild salmon face calamity from trade deal with China

Impacts of Salmon Farms on Coastal Ecosystem Discovered Accidentally

The Horrors Of Salmon Farming, Explained

50 million environmental refugees by 2020, experts say

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A boat full of illegal immigrants enters the port of the Italian island of Lampedusa escorted by a Coast Guard vessel on February 20. Photo Source: AFP/File/Roberto Salomone

Excerpts;

Fifty million environmental refugees will flood into the global north by 2020, fleeing sparked by climate change, experts warned at a major science conference that ended Monday.

“In 2020, the UN has projected that we will have 50 million environmental refugees,” University of California, Los Angeles professor Cristina Tirado said at the annual meeting of the American Association for the Advancement of Science (AAAS).

Read Full Article, PhysOrg

The Human Face Of Climate Change, in Coastal Care

If An Island Vanishes Is It Still a Nation?, in Coastal Care

Is Climate Change Disinformation a Crime Against Humanity?, in Coastal Care

Pilot Whales Die on New Zealand Beach

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Beached pilot whales, New Zealand. Photo source: ©© Angieandsteeve

Excerpts;

All members of a pod of 107 pilot whales that stranded on a remote New Zealand beach have died, including 48 that were euthanised.

The stranded whales were discovered by hikers on Sunday near Cavalier Creek on Stewart Island, off the southern tip of New Zealand’s South Island…

Read Full Article, Guardian UK

Whales Stranded On Beach, New Zealand

New Zealand Rescuers Save 14 Beached Whales

Where Call Reception Fades for Pilot Whales, The New York Times

Darwin’s Elevation Changes Theory Confirmed, Cape Verde

Porto Praia
Porto Praia

Excerpt from NASA Earth Observatory

Born on February 12, 1809, Charles Darwin is best known for his theory of natural selection as a driving force in evolution. Yet he was also an accomplished geologist, studying earthquakes and the formation of coral atolls, among other topics.

When he set sail on the Beagle in December 1831, he was determined to understand the geologic history of the places he visited. He did some of his first digging in Cape Verde, specifically on the islands of Santiago (St. Iago or St. Jago) and Ilhéu de Santa Maria (Quail Island in Darwin’s day).

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Fig.1: close-up of Porto Praia (also Porto Praya). Image Source: NASA

The Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite captured these natural-color images of Santiago and Ilhéu de Santa Maria. The top image (Fig.1) is a close-up of Porto Praia (also Porto Praya), the harbor where the Beagle anchored in January 1832. The bottom image (Fig.2) shows the rugged topography of Santiago. The area of the close-up is outlined in white in the wide-area view.

Only about 1 mile (1.6 kilometers) in circumference, Ilhéu de Santa Maria was small enough for Darwin to study in detail. He mapped rock layers and collected samples from each one, using the island as a key to understanding the much larger Santiago, which held tantalizing geologic clues of its own. On a cliff face near Porto Praia, Darwin noticed a bed of marine shells resting roughly 45 feet (14 meters) above sea level. He concluded that both islands “are volcanic islands that were submerged for some period beneath the sea, where they collected marine beds and then another layer of melted volcanic material.” He concluded that both islands had gained and lost elevation over time.

To support his hypothesis, Darwin pointed to the Temple of Serapis along the coast of Italy, which Charles Lyell had described in his recently published Principles of Geology. The land under the temple had previously sunk below the water line, enabling mollusks to bore into the temple’s stone pillars. After the land rose again, the borehole layers appeared as dark bands.

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Fig.2: shows the rugged topography of Santiago. Image Source: NASA

More recent geologic studies in Cape Verde have confirmed Darwin’s conclusions, not only about the islands’s volcanic origin, but also about elevation changes. A 2006 study published in Geology found that Cape Verde sits over a relatively stationary hotspot where magma pushes up through Earth’s crust. Hotspot melting has thickened the crust in the area, the study found, buoying the ocean floor underneath the islands of Cape Verde. A 2010 study published in Nature Geoscience concluded that multiple geologic processes under the ocean floor have raised Cape Verde at varying rates over the past 6 million years.

Original Article

The mission of the Santa Aguila Foundation is to raise awareness of and mobilize people against the ongoing decimation of coastlines around the world.

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