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Dolphins may be dying due to U.S. oil spill, study finds

March 26, 2012
Courtesy of NOAA
and World Science staff

Dol­phins in Barataria Bay, in the Gulf of Mex­ico, are show­ing signs of se­vere ill health in the wake of the 2010 Deep­wa­ter Ho­ri­zon oil spill in the Gulf, U.S. gov­ern­ment bi­ol­o­gists say.

The sci­en­tists from the Na­t­ional Oce­an­ic and At­mos­pher­ic Ad­ministra­t­ion, work­ing with col­leagues from oth­er gov­ern­ment agen­cies, are in­ves­ti­gat­ing bot­tle­nose dol­phins at the bay off the Lou­i­si­ana coast. The an­i­mals re­ceived heavy and pro­longed ex­po­sure to oil dur­ing the spill, ac­cord­ing to pre­lim­i­nar­y re­sults re­leased by the re­search­ers.

Based on com­pre­hen­sive phys­i­cals of 32 live dol­phins from Barataria Bay in the sum­mer of 2011, pre­lim­i­nar­y re­sults show many of the dol­phins in the study are un­der­weight, ane­mic, have low blood sug­ar and/or some symp­toms of liv­er and lung dis­ease, the in­ves­ti­ga­tors said. Nearly half al­so were found to have ab­nor­mally low lev­els of hor­mones that help with stress re­sponse, me­tab­o­lism and im­mune func­tion.

Re­search­ers fear some of the study dol­phins are in such poor health that they will die. One of them, last ob­served and stud­ied in late 2011, was found dead in Jan­u­ary.

The sci­en­tists started the Barataria Bay dol­phin study in 2011 as part of the Nat­u­ral Re­source Dam­age As­sess­ment, the pro­cess for stu­dying the ef­fects of the Deep­wa­ter Ho­ri­zon oil spill. 

Since Feb­ru­ary 2010, more than 675 dol­phins have stranded in the north­ern Gulf of Mex­i­co from Frank­lin Coun­ty, Flor­i­da, to the Lou­i­si­an­a-Texas bor­der, the sci­en­tists said. That’s a much high­er rate than the usu­al av­er­age of 74 dol­phins per year, and it prompted the agen­cy to de­clare an “Unu­su­al Mor­tal­ity Event” and in­ves­t­i­gate the cause of death for as many of the dol­phins as pos­si­ble. The vast ma­jor­ity of stranded dol­phins were found dead, but 33 were stranded alive and sev­en have been tak­en to facil­i­ties for re­ha­bilita­t­ion, the re­search­ers said.


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Dolphins in Barataria Bay, Louisiana, are showing signs of severe ill health in the wake of the 2010 Deepwater Horizon oil spill in the area, U.S. government biologists say. Scientists from the National Oceanic and Atmospheric Administration, with colleagues from other government agencies, are investigating bottlenose dolphins at Barataria Bay, in the northern Gulf of Mexico. The animals received heavy and prolonged exposure to oil during the spill, according to preliminary results released by the researchers. Based on comprehensive physicals of 32 live dolphins from Barataria Bay in the summer of 2011, preliminary results show many of the dolphins in the study are underweight, anemic, have low blood sugar and/or some symptoms of liver and lung disease, the investigators said. Nearly half also were found to have abnormally low levels of the hormones that help with stress response, metabolism and immune function. Researchers fear some of the study dolphins are in such poor health that they will die. One of them, last observed and studied in late 2011, was found dead in January. The scientists started the Barataria Bay dolphin study in 2011 as part of the Natural Resource Damage Assessment, the process for studying the effects of the Deepwater Horizon oil spill. Since February 2010, more than 675 dolphins have stranded in the northern Gulf of Mexico from Franklin County, Florida, to the Louisiana-Texas border, the scientists said. That’s a much higher rate than the usual average of 74 dolphins per year, and it prompted the agency to declare an “Unusual Mortality Event” and investigate the cause of death for as many of the dolphins as possible. The vast majority of stranded dolphins were found dead, but 33 were stranded alive and seven have been taken to facilities for rehabilitation, the researchers said.