by Linda DaVolls
In November 2002 a vast coastal area extending from northern Portugal to Brittany (France) was contaminated by 59 000 tonnes of oil, spilled from the Prestige tanker. A recent study, published in the Journal of Zoology, examined changes in the diet of otters Lutra lutra before and after the spill in a coastal lagoon (1 sample point) and a stretch of rocky coast (5 sample points). Diet was assessed from 1103 spraints, 553 collected in 2000 before the spill, and 550 in 2003 after the spill. In the coastal lagoon, after spill, spraints contained more shrimp and prey of marine origin, and fewer gobies and eels. A decline of the eel population in the coastal lagoon may have resulted in otters making more frequent visits to the sea. On the rocky coast, spraints contained more blennids in 1 of the 5 sampling points, however, the seasonal patterns of the principal prey species (Blennidae, Gadidae and Labridae) were similar across the 2 years of study. This study of the short-term effects of a marine oil spill on the diet of coastal otters suggests that otters were able to cope with a huge pollution pulse such as the Prestige oil spill. Hydrocarbons derived from oil may have long-term impacts on marine ecosystems, including delayed effects on top predators, such as coastal river otters L. canadensis, but the short-term effects were small.
Photo: Mike Pennington [CC-BY-SA-2.0 (www.creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons