Marine noise pollution and seamount destruction highlighted at AAAS meeting

Science magazine’s awesome blog, ScienceNow, just held a contest for the best bloggers covering the 2010 AAAS meeting.  The third place winner Daniel Stolte, a science writer at the University of Arizona, made two excellent posts on two very depressing aspects of ocean degradation.  The first, “Blinded by the Noise”, is on marine noise pollution interfering with whale communication and the second, Oases of Life in Perpetual Darkness”, is about the destruction of ocean seamounts via bottom trawling. Ill excerpt them below, but both are worth reading in full.

Blinded by the Noise

A new visualization reveals the dramatic impact of shipping traffic on Right Whales in New England

Before the invention of the Diesel engine, life was good for the Right Whales living off the coast of Boston. For thousands of years, the calls and songs they produced to keep track of each other over great distances were the only sounds probing the murky depths.

“The place in which these animals live is defined not only in terms of space, but in terms of sound – they live in an acoustic habitat,” says Christopher Clark from Cornell University, who has been listening in on the whales to get a better understanding of how noise impacts their acoustic habitat. “Imagine living in a village where people can’t see each other or where they’re going. They have to rely on sounds and calls to keep track of each other and go about their lives.”

Once a shire shrouded in peace and quiet, the Right Whales’ village has since been drowning in the cacophony of cargo ships’ and ocean liners’ propellers that churn the waters

Using an array of underwater listening devices installed on the sea floor, Clark and his research team have been able to record and monitor the sounds that define the Right Whales’ acoustic seascape over long periods of time.

What the researchers found is alarming: Just like terrestrial habitats shrink in space, the whales’ acoustic habitat is being destroyed.

“Each time a ship passes through the area, the acoustic habitat around the whales basically collapses,” Clark says.

And see our post on the effects of ocean acidification on marine acoustics here

Oases of Life in Perpetual Darkness: Seamounts are being destroyed faster than they are discovered

Unlike on land, where every peak, every mountain, every hill and every valley has been discovered, described and mapped, the deep ocean floor, which makes up the largest portion of the earth’s crust, is mostly terra incognita. Exactly how many seamounts there are and where, nobody knows.

“We estimate there are fifty thousand or more seamounts out there,” says Hall-Spencer, a lecturer at the University of Plymouth in the U.K and a member of the project CenSeam, a census exploring seamounts and the marine life associated with the newly discovered oases beneath the sea. “But less than 0.1 percent of them have been surveyed.”

Only problem: even faster than seamounts are being discovered, they are being destroyed, and with them entire ecosystems that we hardly know anything about.

big threat comes from destructive fishing practices. In the 1970s, fishing fleets struck unexpected riches below their hulls. Whenever they hauled their nets near the slopes of a seamount, chances were they came back on board bursting at the seams, spilling hundreds of tons of deep-sea fish across the deck. Because of their stark topography, seamounts attract large numbers and unusually diverse arrays of marine life.

“Some seamounts are so big that they divert ocean currents upward and send them swirling over the top,” says Hall-Spencer. The resulting vortices trap plankton and other drifting organic matter and concentrate it on the mountain.

“One trawl bulldozes deep-sea coral forests that took more than 4,000 years to grow in some cases,” says Hall-Spencer. “Since most known seamounts are being trawled we have to ask ourselves whether the catches are worth the destruction of seamount habitats?”

His next slide, in the brief and factual language of science states what should give us the only necessary clue to find the answer: “Worldwide catches landed each year: 80 million tons. Estimated total seamounts catch (read: ALL seamount catches EVER MADE, taken together) 2 – 2.5 million tons, a fraction that seems meaningless in the big picture.


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