Studies by the Woods Hole Oceanographic Institute have shown that the powerful, low-frequency sound pulses disrupt the ability of marine mammals to communicate, feed, and migrate. The system has also been implicated in the mass strandings and ear hemorrhaging deaths of whales in the Bahamas and the Canary Islands.
The system dangles 18 compact car-sized speakers below a surface ship and emits rumbles at 250-500 hertz. The sound is so loud it can be heard halfway across ocean basins. Judge Elizabeth Laporte of the U.S. District Court in San Francisco recommended the Navy be prevented from using the system in about 40 percent of the Pacific Ocean but would permit its use in areas with less ocean life.
The decision is only the latest ruling in a decade of struggles between the Navy and environmentalists. Congress may still pass legislation widening the scope of the sonar’s deployment.
Overfishing Causes Coral Reef Dieoffs
If humans don’t stop plundering fish from the oceans, coral reefs will disappear in just a few decades. That’s the conclusion of a dozen marine researchers, who report in the journal Science that millennia of overfishing have driven reef communities to the brink.
For example, they found colonial-era documents suggesting native Bahamians had killed off most of the islands’ green turtles before Europeans arrived. Around the world, larger reef species such as sea turtles and manatees were decimated first. Many are now so scarce that they have virtually no impact on their ecosystems. Their functional disappearance has been disastrous.
Removal of some species in tightly-knit reef ecosystems knocks conditions out of whack for dozens of others. Reefs are critical because they serve as nurseries, food, and shelter for the majority of ocean fish.
One remedy, scientists say, could be to vastly expand marine reserves. Designated no-fish areas make up only 1/10th of 1 percent of the world’s coral reefs. Scientists say protected areas must be boosted to nearer 50 percent if reefs ﾗ and the ecotourism-dependent economies of countries such as Australia and Belize ﾗ are to be saved.
Oystercatchers Divorce for Muddier Pastures
Oystercatchers can be shameless social climbers. If one of the red-billed shorebirds gets wind of a higher ranked partner, it’ll dump its previous mate and shack up with the new bird.
In so doing, found Dik Heg of the University of Bern, Switzerland, and colleagues, divorcees snag superior nesting spots closer to mudflat feeding grounds and hatch up to 20 percent more chicks. The find supports the theory that birds will break up to increase their reproductive success. The researchers report in the journal Animal Behavior that oystercatchers stuck in undesirable nesting neighborhoods and whose fledgling success is falling are the most likely to leave.
The birds who are abandoned ﾗ mostly males ﾗ fare far worse. Rejected oystercatchers build nests far from the mudflats, which forces them to spend more time and effort obtaining food. While they’re out, their mates have more chances to cheat, and their young are more vulnerable to predators.
Even Whales Pass Gas
A photo snapped off Antarctica has answered an important fact about marine mammal digestion: even whales pass gas. The photo shows a minke whale trailing a plume of poop, followed by a perfectly spherical bubble of gas breaking the surface.
Joe Borkowski III, captain of a research vessel with the Australian Antarctic Division, was standing on the bow of his ship when the momentous event occurred. Intrepid Borkowski braved the stink just long enough to snap the image, then hightailed it for fresher air inside.
Marine mammal scientists are in the area to collect fecal samples from passing whales and identify their prey using DNA analysis. The results could help whale conservation. Norway, Japan, and other nations that have resumed whaling say the animals are reducing fish harvests, while other scientists contend that the relationship is more complex and indirect.
Adapted by Kathleen M. Wong, California Academy of Sciences
