Tag Archives: ocean

Bikini Atoll 50 Years Later

Three islands of Bikini Atoll were vapourised by the Bravo hydrogen bomb in 1954, which shook islands 200 kilometres away. Instead of finding a bare underwater moonscape, ecologists who have dived it have given the 2-kilometre-wide crater a clean bill of health.

“It was fascinating – I’ve never seen corals growing like trees outside of the Marshall Islands,” says Zoe Richards of the ARC Centre of Excellence for Coral Reef Studies in Australia. Richards and colleagues report a thriving ecosystem of 183 species of coral, some of which were 8 metres high. They estimate that the diversity of species represents about 65% of what was present before the atomic tests. The ecologists think the nearby Rongelap Atoll is seeding the Bikini Atoll, and the lack of human disturbance is helping its recovery.
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“When I put the Geiger counter near a coconut, which accumulates radioactive material from the soil, it went berserk,” says Beger.

ASU Science Studio Podcasts

Science Studio offers podcasts by the Arizona State University School of Life Sciences with professors discussing science; it is another excellent source of science podcasts. Podcasts include:

Of Whales, Fish and Men: Managing Marine Reserves – With 90% of the world’s fisheries in a state of collapse, the questions around establishing marine reserves, monitoring, and species/stock recovery take on critical dimensions. But how do decision-makers, stakeholders, and the public formulate effective conservation policies; ones right for their community?
Biology on Fire – Regents’ Professor, Mac Arthur Fellow, author and a world’s expert on fire and fire ecology Stephen Pyne talks about how fire, its use, misuse, and its biological nature have shaped our world, before and because of man, and learn how policies of the past still reverberate in our present, in Arizona and globally.
Giant Insects: Not just in B movies – Professor Jon Harrison sheds light on the evolution of his scientific career and nature’s biggest order: arthropods. How big is big? In the Paleozoic, cockroaches were the size of housecats and dragonflies the size of raptors.
Special Feature: Building a science career – One of the most highly cited ecologists in the world, Jane Lubchenco trod her own unique path to success. In this live recording with the Association for Women in Science, she explains how assertiveness, the art of negotiation, and knowing the currency for promotion and tenure can make the difference between achieving balance between family and career and dropping out the leaky academic pipeline that leads to advancement.

These podcasts are great way to use the internet to serve the mission of universities: to educate. And a great way to promote science.

Mutualism – Inter-species Cooperation

Shrimp with Goby Fish

A Mutual Affair by Olivia Judson

I’d like to introduce you to one of my favorite animals: the shrimp goby. These pretty little fish lead lives of enviable indolence. As their name suggests, they live with shrimp (often, a pair). The shrimp build and maintain a burrow, which the goby and shrimp live in together. Each shrimp works hard, shoveling sand out of the front entrance like a miniature bulldozer. As soon as it’s delivered the rubble to a suitable distance, it shoots back into the burrow.

The front entrance of the burrow is often reinforced with bits of shell and coral — all of which is done by the shrimp. The goby just sits in the entrance of the burrow, keeping guard and warning the shrimp, which is nearly blind, of danger. At any sign of danger — a diver coming too close, a passing predator — the goby darts into the burrow. If the goby zooms in, the shrimp hastily retreats deep inside. And before the shrimp emerges from the burrow, it touches the goby’s tail with its long antennae. To show it’s safe to come out, the goby gently wiggles its tail. When the shrimp is out of the burrow, it keeps one antenna touching the goby. If the goby suddenly retreats, so does the shrimp.
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These animals are dependent on each other. Remove the fish, and the shrimp stops burrowing; the shrimp forage while burrowing, so without a fish, they grow more slowly, too. The shrimp need their guard goby. And the guard goby needs its shrimp: deny the goby shelter in a burrow, and it will promptly be killed by predators (yes, someone did the experiment). The shrimp keep the goby clean, too: they groom it.

photo by Boogies with Fish

Squid Materials Engineering

Scientists find that squid beak is both hard and soft

The sharp beak of the Humboldt squid is one of the hardest and stiffest organic materials known. Engineers, biologists, and marine scientists at the University of California, Santa Barbara, have joined forces to discover how the soft, gelatinous squid can operate its knife-like beak without tearing itself to pieces.
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The key to the squid beak lies in the gradations of stiffness. The tip is extremely stiff, yet the base is 100 times more compliant, allowing it to blend with surrounding tissue. However, this only works when the base of the beak is wet. After it dries out, the base becomes similarly stiff as the already desiccated beak tip.
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“You can imagine the problems you’d encounter if you attached a knife blade to a block of Jell-o and tried to use that blade for cutting. The blade would cut through the Jell-o at least as much as the targeted object. In the case of the squid beak, nature takes care of the problem by changing the beak composition progressively, rather than abruptly, so that its tip can pierce prey without harming the squid in the process. It’s a truly fascinating design!”
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“If we could reproduce the property gradients that we find in squid beak, it would open new possibilities for joining materials,” explained Zok. “For example, if you graded an adhesive to make its properties match one material on one side and the other material on the other side, you could potentially form a much more robust bond,” he said. “This could really revolutionize the way engineers think about attaching materials together.”

Ballast-free Ships

ballast-free ship’ could cut costs while blocking aquatic invaders

University of Michigan researchers are investigating a radical new design for cargo ships that would eliminate ballast tanks, the water-filled compartments that enable non-native creatures to sneak into the Great Lakes from overseas. At least 185 non-native aquatic species have been identified in the Great Lakes, and ballast water is blamed for the introduction of most—including the notorious zebra and quagga mussels and two species of gobies.

This week, the U.S. Saint Lawrence Seaway Development Corp. will implement new rules designed to reduce Great Lakes invaders. Ships will be required to flush ballast tanks with salt water before entering the Seaway, a practice corporation officials describe as an interim measure, not a final solution.
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Instead of hauling potentially contaminated water across the ocean, then dumping it in a Great Lakes port, a ballast-free ship would create a constant flow of local seawater through a network of large pipes, called trunks, that runs from the bow to the stern, below the waterline.

“In some ways, it’s more like a submarine than a surface ship,” Parsons said. “We’re opening part of the hull to the sea, creating a very slow flow through the trunks from bow to stern.

Giant Star Fish and More in Antarctica

photo of giant starfish

Photo by John Mitchell, New Zealand’s National Institute of Water and Atmospheric Research. Read a great deal about the New Zealand Census of Antarctic Marine Life project: 26 scientists and 18 crew took a 50-day voyage aboard RV Tangaroa in February-March 2008.

Benthic invertebrates in Antarctica are well known for their large size. This feature, known as “gigantism” is common amongst certain groups including sea spiders, sponges, isopods, starfish, and amphipods. The phenomenon is a subject of intense scientific investigation, but there are many contributing factors.

Slow growth rates, late reproductive maturation, prolonged periods of embryonic development, and low predation rates that are typical of Antarctic waters contribute to long life-spans for many species and can also result in large size animals. Animal physiology is thought to play a role as well, as those groups that require large amounts of calcium should not, in theory, grow well in Antarctic waters. This is because the calcium carbonate (needed for growth of shells, or starfish ‘tests’) has low solubility in very cold seawater. Yet starfish, which have a calcareous exoskeleton or ‘test’ which needs lots of calcium, can reach much larger sizes than found in New Zealand waters, as seen in [photo].

Another crucial part of the story is that the low sea temperatures allow more oxygen to be dissolved in the sea water than in warmer latitudes. Sea spiders for example are not only larger, but reach more than 1000 times the weight of most temperate species. Amphipod crustaceans in the Southern Ocean are also large; more than five times as long as the largest temperate species.

Baby Sand Dollars Clone Themselves When They Sense Danger

Baby sand dollars clone themselves when they sense danger

The odds of growing up aren’t good for baby sand dollars. Smaller than the head of a pin, the larvae drift in the ocean — easy prey for anything with a mouth.

But a University of Washington graduate student has discovered the tiny animal has a surprising survival strategy: Faced with the threat of being gobbled up, it makes like Dr. Evil from the Austin Powers movies and clones itself. The resulting “mini-me” may escape hungry fish because it is even teenier than the original — and harder to see.

“If you are eaten, but the smaller version of you survives, you’re still a winner from an evolutionary standpoint,” said Dawn Vaughn.
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Familiar inhabitants of Washington’s subtidal zone, sand dollars start life though the chance encounter of sperm and egg, simultaneously released into the water by mature adults. The larvae free-float for about six weeks before metamorphosing into miniature sand dollars that settle in colonies and eventually grow to full size.
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The white shells that wash up on the beach are the creatures’ external skeletons. Living sand dollars are covered with velvety, purple spines used to grab food particles. Vaughn knew many other marine invertebrates shift their shape to avoid being eaten. Colonial animals called bryozoans grow spikes when voracious sea slugs crawl across them. Barnacles take on a bent posture to repel snails. Vaughn’s own previous research showed periwinkle larvae narrow their shell openings to keep out marauding crab larvae.

Chinook Salmon Vanish Without a Trace

The Chinook salmon that swim upstream to spawn in the fall, the most robust run in the Sacramento River, have disappeared. The almost complete collapse of the richest and most dependable source of Chinook salmon south of Alaska left gloomy fisheries experts struggling for reliable explanations – and coming up dry.

Whatever the cause, there was widespread agreement among those attending a five-day meeting of the Pacific Fisheries Management Council here last week that the regional $150 million fishery, which usually opens for the four-month season on May 1, is almost certain to remain closed this year from northern Oregon to the Mexican border.
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So what happened? As Dave Bitts, a fisherman based in Eureka in Northern California, sees it, the variables are simple. “To survive, there are two things a salmon needs,” he said. “To eat. And not to be eaten.”

Fragmentary evidence about salmon mortality in the Sacramento River in recent years, as well as more robust but still inconclusive data about ocean conditions in 2005, indicates that the fall Chinook smolts, or baby fish, of 2005 may have lost out on both counts. But biologists, fishermen and fishery managers all emphasize that no one yet knows anything for sure.

Dolphin Rescues Beached Whales

New Zealand dolphin rescues beached whales:

The pygmy sperm whales had repeatedly beached, and both they and the humans were tired and set to give up, he said. But then the dolphin appeared, communicated with the whales, and led them to safety.

The bottlenose dolphin, called Moko by local residents, is well known for playing with swimmers off Mahia beach on the east coast of the North Island.
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Mr Smith said he felt fortunate to have witnessed the extraordinary event, and was delighted for the whales, as in the past he has had to put down animals which have become beached. He said that the whales have not been seen since, but that the dolphin had returned to its usual practice of playing with swimmers in the bay.

“I shouldn’t do this I know, we are meant to remain scientific,” Mr Smith said, “but I actually went into the water with the dolphin and gave it a pat afterwards because she really did save the day.”

Deep-Sea Denizen Inspires New Polymers

Stealing a trick from a tiny, pickle-shaped creature that dwells in the depths of the ocean, scientists have designed a new polymer that, when exposed to water, can instantly change its rigidity and strength.
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Christoph Weder, an associate professor in the same department at Case, says he and Rowan thought of copying the sea cucumber’s adaptation more than five years ago. Working with marine biologists, they determined that the deep-sea animal accomplished its transformation thanks to fibers made of a protein known as collagen. The tightness of the connections between those fibers determines how stiff the cucumber’s skin is, and is controlled by the animal’s nervous system.

To get their polymer to do the same thing, the Case scientists used fibers found in another deep sea dweller, sea squirts, and also in cotton. When they mixed those fibers – known as cellulose nanofibers – with the rubbery polymer ethylene oxide–epichlorohydrin, they formed a stiff network, “almost glued to each other,” says Weder. Due to the nature of the bonds between the polymer and the fibers, however, water gets between the two substances, weakening the fibers’ adhesion. The material then becomes soft.