Tuesday, April 20, 2010

Post-Katrina Gulf Coast Baby Boom for the Bottlenose Dolphin

Nearly five years after Katrina, the region is still in recovery mode but the dolphin population appears to be doing great.The city of New Orleans and the wider Gulf Coast region continue the slow march of recovery nearly five years after the disastrous storm unleashed its fury on the coast and its inhabitants. Those who earn a living from the sea took an especially hard hit as the storm wiped out an estimated 87 percent of the commercial fishing fleet according to Discovery News, who reports of a small, silver lining to be found in the ongoing challenges faced by Gulf Coast residents: the marine life has fared pretty well, and in particular, the dolphins.Jessica Marshall, writing for Discovery, reports that a marine biological survey study initiated prior to the 2005 hurricane revealed some striking differences when additional surveys were conducted after the storm. Biologist Lance Miller of the San Diego Zoo, then a graduate student at the University of Mississippi, found that subsequent to the storm, births of bottlenose dolphins have risen dramatically.Explanations for the increase point to some obvious suggestions: the steep decrease in boat traffic and fishing activities have resulted in a diminished impact on the ecosystem as well as in a much richer bounty of available food. Also possibly in play are the variable fertility capabilities of the animal itself. Dolphins are known to become and remain fertile for extended periods of time following the loss of a calf. A broad loss of young dolphins to the storm and might have led to a higher population of fertile females."What's great about this study is that it shows us some potential effects of this hurricane, and indirectly, potentially, effects of human disturbance," Miller explains to Discovery. "I think this allows us to look at some more specific questions: How does decreasing commercial fisheries intake affect dolphin populations? How does the number of boats or density of boats affect populations?"It remains unknown if the bump in dolphin births since Katrina is likely to lead to an overall dolphin population increase, or if it represents a short-term spike unlikely to be sustained over time. The increase in available food will likely back down as fishing activity picks back up, and if the greater number of youngsters did result from a mortality-induced increase in fertility, that too would likely ultimately be shown to be a short-lived change.For now though, these highly intelligent marine mammals are finding themselves living large in a Gulf of Mexico that was dramatically impacted by a storm whose effects continue to be felt.

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