News

Dolphins and turtles and oil – oh my!

By: Larissa Graham / Published: Apr 12,  2017

I always get excited when I’m walking along the beach and see dolphins off in the distance or – better yet – am lucky enough to catch a glimpse of a sea turtle swimming in shallow waters. I can’t help it! There’s just something special about stumbling upon such unique creatures in the wild.

As you could imagine, many people expressed concern about the impact the Deepwater Horizon oil spill had on dolphins and sea turtles. Both of these animals are long-lived and slow to mature, so the death of even a few individuals can have a ripple effect on the overall population. Now, almost seven years after the spill, scientists have a better handle on some of its short-term impacts.

Young bottlenose dolphins died in areas affected by the 2010 Deepwater Horizon oil spill. Unborn dolphins from the northern Gulf Coast were 18 times more likely to show signs of fetal distress than those from the other areas. Photo credit: NOAA
Young bottlenose dolphins died in areas affected by the 2010 Deepwater Horizon oil spill. Unborn dolphins from the northern Gulf Coast were 18 times more likely to show signs of fetal distress than those from the other areas. Photo credit: NOAA

From 2010 to 2014, scientists documented more than 1000 stranded dolphins and whales along the northern Gulf of Mexico. This unusual mortality event began a month before the oil spill. However, the largest increase in stranded dolphins occurred in oiled areas following the Deepwater Horizon blowout. Overall, scientists believe that dolphin populations in oiled areas declined from 30 to 70 percent and could take 30 to 50 years to recover.

Scientists examined the health and stranding patterns of dolphins along the coasts of Louisiana, Mississippi and Alabama and discovered oiled areas had more sick and dead dolphins than other areas. Dolphins from oiled areas suffered from infectious diseases, had lung problems and their adrenal glands were not working properly. They also had excessive tooth loss, were in poor condition, and were underweight compared to dolphins in unoiled areas.

Scientists found many sick and stranded perinatal dolphins - young dolphins that were just born or about to be born. Young dolphins found in oiled areas were eight times more likely to have inflamed lungs or pneumonia or and 18 times more likely to show signs of fetal distress than those from areas outside the Gulf.

The Deepwater Horizon oil spill also affected sea turtle populations. In total and across all Gulf sea turtle species, scientists estimate that the Deepwater Horizon oil spill and related response activities killed about 35,000 hatchling sea turtles, between 55,000 and 160,000 small juvenile sea turtles, and between 4,900 and 7,600 large juvenile and adult sea turtles.

A National Oceanic and Atmospheric Administration (NOAA) veterinarian prepares to clean an oiled Kemp's Ridley turtle as part of the Deepwater Horizon oil spill animal rescue and rehabilitation efforts. Photo credit: NOAA and Georgia Department
A National Oceanic and Atmospheric Administration (NOAA) veterinarian prepares to clean an oiled Kemp's Ridley turtle as part of the Deepwater Horizon oil spill animal rescue and rehabilitation efforts. Photo credit: NOAA and Georgia Department

Although scientists understand some of the short-term impacts, long-term impacts may take time before they are revealed. For example, scientists do not fully understand oil’s impacts on sea turtles’ health and reproduction. They continue to monitor sea turtle populations by counting numbers of nests, hatchlings and adult females on beaches to monitor populations. Scientists also continue to monitor the number of strandings and health of dolphin populations in the Gulf.

Want to learn more? Check out our full publications on the impacts to sea turtle and dolphin populations. We also recently hosted a science seminar on sea turtles. You can view the recordings of the presentations online. As always, feel free to email or call (251-438-5690 x21) if you have any questions or need more information. 

Comments

comments powered by Disqus