By Henry Fountain
Published: November 23, 2004
Sperm whales, like other marine mammals, use echolocation when they are diving for food. These sonar signals take two forms: ''clicks,'' short-duration noises at intervals of up to two seconds, and ''creaks,'' continuous clicking that sounds more like a buzz.
While scientists have long suspected that the whales use both sounds to locate sources of squid or other food, little has been known about the details. It's not easy to find out what an animal is doing 2,000 feet or more below the surface.
Using a new kind of monitoring tag, scientists from St. Andrews University in Scotland and the Woods Hole Oceanographic Institution in Massachusetts have come up with a much fuller picture of how sperm whales use echolocation while foraging.
Their conclusion, reported in The Proceedings of the Royal Society, is that the creaks are used when the whale is closing in for capture.
The tags, which mount on a whale's skin with suction cups, record depth, sound and the animal's orientation in three dimensions. The researchers attached them to 23 whales in the Mediterranean and the Gulf of Mexico.
They recorded information during 103 dives, and logged a total of 1,670 creaks that lasted, on average, about 9 seconds. But what was more interesting was where the creaks were produced: almost all were from the deepest part of the dives. The whales swam actively during these bottom phases, constantly changing their orientation, often within 10 seconds of a creak.
All this, the researchers say, supports their hypothesis that the creaks are used for maneuvering to capture prey. In this respect, the whales are similar to bats, which produce buzzes as they close in on food. For both animals, the continuous clicking produces a more rapid updating of the prey's location.
All the Fish in the Sea
The sperm whale is only one species in the ocean. There are many more, though exactly how many is an open question.
An ambitious project is under way, however, to catalog the number and distribution of marine species worldwide. The project, the Census of Marine Life, has passed a milestone of sorts, compiling more than five million records in its database, the Ocean Biogeographic Information System. Those records show the distribution of more than 38,000 species, including about 15,500 fish.
The census (www.coml.org) is actually a network of research projects in more than 70 countries. Database records come from many sources, involving both current research and historical data from projects like one that has been monitoring plankton growth in the North Atlantic and North Sea for more than 70 years.
The 40,000 species cataloged so far represent less than one-fifth of the number of described marine species. And most scientists believe there are many more remaining to be discovered, particularly in the deep oceans.
So the census, currently in the fourth year of a 10-year program, faces a major challenge. Dr. J. Frederick Grassle, a professor at Rutgers who is chairman of the project's steering committee, said he expected it to continue indefinitely, and to continue to add records at a high rate.
''We feel we're in an exponential growth phase,'' he said. ''The major obstacle wasn't technical. It was getting people to understand the value of making their databases publicly available.''
Saving the Shark Fin
Several of those marine species got some help on Sunday, when more than 60 countries agreed to ban the killing of sharks for their fins in the Atlantic.
The ban was approved at a meeting of the International Commission for the Conservation of Atlantic Tunas in New Orleans. It was proposed by the United States, which has banned shark finning, as the practice is know, for a decade.
Shark fins are a valuable delicacy in Asia, so commercial shark boats cut off the fins and throw the carcasses overboard. It is widely practiced in the Pacific as well, but conservationists hope that the new ban may be a first step toward a worldwide prohibition.
The 1380's: Hot Times in the Vineyard
A toast, please, to the humble pinot noir grape, and its long service to the cause of science.
French researchers have used records of the grape harvest to determine annual spring-summer temperatures in eastern France over the past six centuries. They show several warmer periods over the centuries, and a cool trend of nearly 300 years that ended when temperatures rose in the 1970's.
The study, reported this week in the journal Nature, is one of many that use proxies like tree rings and ice cores to study past climate change. Dr. Pascal Yiou, the lead researcher, said French grape harvests were a good proxy because harvest dates were set by official decree and archived records went back centuries. Dr. Yiou, of the Laboratory for the Science of Climate and the Environment, part of the French atomic energy agency, said pinot noir, the major variety grown in Burgundy, was particularly useful. ''It's known that pinot noir was used constantly in Burgundy since the Middle Ages,'' he said. ''And it's always been the same vine type. That's not necessarily true for other regions.''
Dr. Yiou and his colleagues studied the biology of ripening in the pinot noir. ''We were able to compute exactly the state of ripeness of the vine from the temperature,'' he said. Then, using information from church and municipal archives, they compiled a record of harvest dates since 1370.
From that data they could estimate the date of veraison, when the grapes begin to ripen and turn from green to black. This, Dr. Yiou said, is about 23 days before the decreed harvest date. ''Then from the model of grape growth, we can estimate the temperature of the warm season,'' he added.
The researchers found a few periods of high temperatures. The 1380's were warm -- about 3 degrees Fahrenheit above the norm -- as were the 1420's, the 1520's and the half-century from the 1630's to the 1680's. But after that temperatures turned cooler, with a few brief exceptions, until the past 30 years, when things really began to warm up.
''The late 20th century is exceptional,'' Dr. Yiou said. While this is only a local trend for eastern France, it is comparable to findings from global studies. ''The trend is quite stable and unprecedented,'' he said.
Drawing (Drawing by Chris Gash)