Recently we had the opportunity to necropsy birds that were released from evidence from the Deepwater Horizon oil spill. You may be thinking; “Wait! He can’t mean Deepwater Horizon! That spill was 9 years ago!” You’d be right to think that. However, it’s true. A little comparative pathology policy for you:
With marine mammals, all animals that are found dead or that die during an oiled wildlife event are necropsied. Pathologists are brought on early in the spill, samples are collected, and assessments are made regarding cause of death, impacts from disease, and effects of oil. This is to provide evidence and guide treatment of animals impacted by the spill.
In the past, oiled birds during declared spills were not necropsied without specific dispensation from the Unified Command (UC) to do so. Instead any carcass was considered dead from oil, and immediately became evidence. By legal standards, an oiled bird is considered a dead bird. Those of us that work in the field, and anyone who’s read the research (see the references below) know that isn’t necessarily the case. The upside of this policy is a reduction in the up-front costs and logistics of hiring staff and setting up necropsy areas. The downside impacts however are much greater; there is a lot we can learn from carcasses. This information can guide rehabilitation and help us to understand and reduce impacts on animals in the wild. How much and what depends a lot on the condition of the animals when we get them.
If we are able to examine animals after they first die, we can find out the most about them. Fresh tissues give us the best chance to look for signs of disease exposure and infection, understand the physiological impacts of oil, assess injuries, and see the impacts of oil. If tissues are stored for a long time or frozen, they become harder to evaluate. Subsequent changes in microscopic structure of tissues introduces artifacts and reduces our ability to determine what changes are associated with disease or injury versus storage and post-mortem breakdown. Over time freezing and drying will cause the breakdown of bacteria, viruses, parasites, proteins, and other complex molecules. This decreases our ability to detect these important players in health and disease.
The goal of this recent work was to try and evaluate what we can learn from carcasses collected or stored under less than ideal conditions. The OWCN and OSPR along with a great group of dedicated volunteers necropsied over 100 animals including clapper rails, least terns, sanderling, Northern gannets, and other species impacted by the Deepwater Horizon Oil spill. We collected tissues and samples to start to answer the question of what we can learn from these animals, and how we can use that information to help the animals we care for in the future.
Thankfully, our access to carcasses and our ability to evaluate them may be changing. During a meeting last week between the OSPR and the OWCN, we started to look into the possibilities of getting earlier access to carcasses, and even to do necropsies immediately once animals die. Generally, the opinion was that we have valuable information for research and animal care. Changing this paradigm would be a boon for rehabilitators and researchers alike, leading to a better understanding of the impacts of oil, the health of wild birds, and our ability to care for these animals.
I also wanted to take a moment to thank a lot of people who helped with this effort. There are a lot of logistics, equipment, and time required for a project like this. Thank you to Mike Ziccardi and Laird Henkel for moving this project along and providing the resources to make it happen. Thanks to all the fantastic prosectors from SPCA for Monterey County, Monterey Bay Aquarium and the MWVCRC for their assistance. Melissa Miller, OSPR Pathologist was (as always) a tremendous resource and a wealth of information. And extra thanks to Corrine Gibble for sorting samples, helping organize data, and generally keeping the project moving and on track.
– Greg Frankfurter