Newspaper article The Christian Science Monitor

On the Horizon

Newspaper article The Christian Science Monitor

On the Horizon

Article excerpt

Fewer sharks = fewer scallops Tourists may have been unhappy with "Jaws" roiling the waters, but scallops didn't mind. Researchers have found that, at least off North Carolina, overfishing of the largest sharks has led to the inadvertent collapse of scallop populations. Fish that the big sharks once ate are thriving, feasting on scallops and other shellfish. The results highlight the ecological - and economic - damage that comes when people skim off an ecosystem's top predators, the researchers say. The team, led by scientists from the United States and Canada, found that from 1970 to 2005, fishing had decimated some key shark species, essentially knocking them off their perch at the top of the food chain in North Carolina's coastal ecosystems. On-site observations that began in the early '80s showed that at the time, migrating cownose rays had little effect on the long-term scallop population. As sharks dwindled, cownose rays surged. By 2004, the cownose had virtually cleared the sampling areas of scallops - except for control sites protected by pens. This "collateral" ecological damage from commercial shark fishing points to the need to manage fisheries as whole ecosystems, not by species, according to the researchers. Their results appear in the current issue of the journal Science. A long look back at C02's impact Just how sensitive is the climate to changes in carbon dioxide? It's a key question for scientists trying to gauge the impact of burning fossil fuels on today's climate. Now a team has looked at patterns over the past 420 million years and found that when CO2 concentrations double, the global average temperature rises by at least 1.5 degrees Celsius (2.7 degrees FahA- renheit). The best estimate: 2.8 degrees C. February's report from the InterA-governA-mental Panel on Climate Change (IPCC) gave a range of 1. …

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