Well, today was a better day for the OMTU. Less chaos, less aggravation, positive work and still no oiled mammals or turtles! This has allowed us to continue to plan (including honing in on a plan for manatees), welcome Barbara Schroeder (NOAA’s national sea turtle coordinator) to the OMTU in person at Houma, and also begin to examine the animals we have in hand more thoroughly.
Brian Stacy and his tech Jennifer Muller have joined us on the Gulf coast and are making fast work of evaluating the stranded turtles (which have no apparent external oil) through performing complete necropsies, or animal autopsies. This may seem simple (especially for those of you who watch “CSI”), but the process is fairly laborious, as our protocols require full external and internal examinations, measurements, and collecting numerous samples of organs for microscopic examination and (possibly) chemical evaluation. The entire exam is fully photodocumented and all samples, paperwork and images are considered evidence should these “cases” be taken to court. This elaborate process makes sure we get the best answers, but also ensures the validity of the results.
Another challenging fact related to this spill is the numbers of turtles we will be evaluating. More than 70 dead turtles have been collected (to date) ranging from LA to FL. You may ask why we are concerned about turtles that strand as far away as Appalachicola, FL or the Texas-Louisiana border (and, yes, I have finally learned how to spell Louisiana without spellchecker squawking at me – though the word squawking did). The issue is that we are not entirely certain how far a dolphin or sea turtle may swim after being impacted by oil exposure. When they are externally coated, or even when oil is found in the mouth, it is easy to assess exposure. However, unlike birds and heavily furred mammals, turtles and cetacea they are not prone to hypothermia with exposure, having greater internal effects from breathing fumes and ingesting tarballs. Therefore, these species do not rapidly beach themselves, and may travel miles before subsequent toxic effects occur. By our making the “margins” of our search area broad, we can be more certain of finding and treating (or pathologically evaluating) impacted mammals and turtles that might be impacted.
The most challenging aspect of this exercise, though, is trying to ascertain oiling in animals that do not have apparent oil either externally or internally. While you can see changes to the architecture of the different organ systems with oil exposure, there is no “smoking gun” of a single change or sign seen in all cases. Tissue levels of certain oil components can be increased in oil-affected animals, but not always, as the animal’s metabolic pathways are trying to get rid of these compounds as quickly as possible before they can wreak havoc in the body. Additionally, we often often do not know what “background” levels of these compounds are in the species that we are examining. Many researchers use biomarkers, or different inherent changes to the animal’s systems (such as cancers) related to exposure to these compounds, but these measures are often non-specific, as the changes can also be seen with exposure to other natural and man-made compounds. Sound like fun research? This is what my PhD work was on and it can be hair-pullingly maddening at times.
So, what can we do? Well, we can build the best case possible for exposure to oil using what evidence we have. We look at all of these things – how the animal looks, what the tissues look like under the microscope, what the lab tells us about the contaminant levels – and come up with a probability of that animal dying due to oil exposure. We also overlay this information over what levels of natural mortality we would expect in this area at this time of year to get an estimate of the increased mortality due to the spill.
Why is this important – after all, the animal is already dead, right? Well, this can be important from a response perspective because we can get a sense for where oil is impacting animals the worst, and possibly try to use more proactive capture methods and provide more intensive care to animals collected in those areas. It also can help in a more holistic way, as a spiller is responsible not only for cleanup costs (of which animal rehabilitation is included) , but also costs associated with restoring the environment back to pre-spill conditions. Animals found damaged by the spill can contribute to a monetary “penalty” that is added to the response costs – funds that then can go towards environmental projects. This evaluation process, called Natural Resource Damage Assessment, can help fund broad-based initiatives to assist habitat, individual species, or entire ecosystems, depending on the project. A key ingredient of this assessment is the data, samples and information that the wildlife rehabilitation program provides to these scientists so that more accurate estimations of impacts might be developed. A further review of this can be found on the OWCN website via an excellent piece by Dr. Steve Hampton, or on DFG OSPR’s website.
So science does exist in the wildlife rehab arena during spills. Who would have thought it? Many don’t, this being one of the many fallacies of wildlife rehabilitation lingering from when our field was young. Another of these falsehoods is a topic I intend to tackle tomorrow on my blog: the danger of putting a per-bird pricetag on oil spill response and undervaluing the impact of oiled wildlife rehabilitation within a spill effort. Sleep well, bring your popcorn, and enjoy the show tomorrow!