National Geographic : 2013 Nov
NEXT photo: GeorGe Steinmetz. Graphic: meSa Schumacher. art: marc JohnS Beach Bumming the bigger a beach, the more tourists’ towels to fit on it—and the more money, in turn, for local business. that calculation can be complicated by erosion. unwilling to build seawalls that, among other things, prevent beach goers from enjoying waves, cities in hawaii and north carolina periodically renourish their beaches. the process involves dredging millions of cubic yards of sand offshore and depositing it on land. more cities are investing in the method, according to the army corps of engineers. Yet considering constant wave motion, the replenishment is often only temporary. Last fall the San Diego area fortified five miles of its coast at a cost of $28 million. project man agers say they’ll need to do it again in about five years. — Daniel Stone Portions of the shore in Virginia Beach, Virginia, have been rebuilt 49 times since 1951. Night Shift For some people shortened day lengths bring on the blues. For rats it’s the opposite. Neurobiologist Davide Dulcis found that when rodents are exposed to prolonged periods of light, their dopamine production gets thrown off. A chemical switch occurs, says Dulcis, that creates “depressive-like behav- iors in the animals.” Since rats and humans have similarly structured brains, the research could help scientists better understand dopamine-related illnesses, including Parkinson’s and schizophrenia. —Catherine Zuckerman the world’s largest organism is the fungus Armillaria ostoyae, one of which covers 2,384 acres in oregon’s Blue mountains.