Surfing the red tide

Phytoplankton are tiny, plant-like organisms that live in the ocean and are, basically, at the very bottom of the food chain. But, sometimes, they get their revenge. When lots and lots and lots of phytoplankton get together, they can form what we call a "red tide," a discoloration of the water at a particular point where the plankton have become densely concentrated.

Some red tides are natural. Others happen when nutrient runoff from farm fertilizers creates a massive buffet for plankton. Some red tides can kill, as the plankton can produce toxins and their deaths reduce the oxygen content of the water. And sometimes, red tides glow in the dark.

The phytoplankton in this red tide off a California beach are bioluminescent. Their cells produce a chemical reaction that creates a soft, blue-green glow. It's basically the same thing that makes lightning bugs light. In this video by Loghan Call and Man's Best Media, you can see plankton light up in the beach (and a few surfers).

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How tide predicting, analog computers won World War II

Without Lord Kelvin, there would have been no D-Day.

There's some very cool science history in the September issue of Physics Today, centering around a collection of analog computers, developed in the 19th century to predict tides. This was a job that human mathematicians could do, but the computing machines did the job faster and were less prone to small errors that had big, real-world implications. David Kaplan, an assistant professor in the University of Wisconsin-Milwaukee physics department, sent the links over. He says that these machines ended up being crucial and are a big, in-your-face reminder of the complications of living in a world without calculators:

"... it was particularly important during WWII in order to properly plan beach landings, but even without the war part I found it fascinating. We take this so for granted now, that we can crank out sin() and cos() values instantly, but that was not always the case."

We're talking about predictions a bit more precise than simply saying, "the water is low" or "the water is high." Physics Today explains why the behavior of tides was so important at D-Day and why the tide calculators were so important to Allied success.

As an Allied cross-channel invasion loomed in 1944, Rommel, convinced that it would come at high tide, installed millions of steel, cement, and wooden obstacles on the possible invasion beaches, positioned so they would be under water by midtide.

The Allies would certainly have liked to land at high tide, as Rommel expected, so their troops would have less beach to cross under fire.

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A submarine named Alvin

I've been traveling for the last couple of weeks. One key stop: Woods Hole, Mass., where I got up close and personal with everybody's favorite research submarine. Originally commissioned in 1964, Alvin is currently disassembled as part of a regular maintenance inspection and overhaul. I got to go behind-the-scenes to check out Alvin and the RV Oceanus—a research ship also operated by the Woods Hole Oceanographic Institute. This is a window on Alvin's old manned pod, a massive sphere that can hold two scientists. It's being replaced in the current retrofit, and this sphere will go to the Smithsonian. More photos to come ... Read the rest

Human disease kills coral

In news that would be completely fascinating, were it not so damn depressing: One of the causes behind Caribbean coral die-offs seems to be a bacteria, spread from humans to the coral through sewage. It's the first time that a human disease has ever been shown to kill an invertebrate. Read the rest

Japanese tsunami and the birth of icebergs

Scientists have long speculated that large tsunamis could be linked to the calving of icebergs—where chunks of ice break off of the side of a glacier or ice shelf and float away. The Tohoku earthquake and tsunami that happened in March off the coast of Japan finally gave them much more direct evidence of this phenomenon. Fascinating stuff, and a great reminder of how interconnected the world really is.

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Algae beach party

Beachgoers in Qingdao, Shandong province, China, were met with a fuzzy, green blanket of ocean last week, as the water there exploded with algae.

You've heard before about dead zones. These are patches of coastal ocean where river runoff full of fertilizer chemicals have produced massive algae blooms. As the algae die, their decomposition reduces the oxygen level of the water to the point that many fish and other aquatic life can no longer live there.

This is what a dead zone looks like, just before the death.

It's worth noting, when I pulled this photo out of the Reuters files, I could see similar shots, taken on the same beach, in 2010, 2009, and 2008. This isn't a fluke. It's an endemic problem.

Image: REUTERS/China Daily China Daily Information Corp - CDIC

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Swim goggles made from fish scales

Neat post about an experimental plastic substitute made from fish scales over at Brian Lam's ocean-themed blog Scuttlefish. So far art student Erik de Laurens "has made not only goggles, but eye-glass frames, drinking cups, and a wooden table with a fish scale inlay" from fish scales. Read the rest