Best in Class: Amphibia

A Green Frog is washed during an oil spill. Credit: Tri-State Bird Rescue 2014

Today, February 19th marks my 1 year anniversary with the OWCN. The year flew by and I’ll be honest—I only know the date because Facebook was kind enough to remind me. So in recognition of my 1 year, I’d like to blog about one of my favorite topics… Amphibians!

Growing up, I spent many summer days watching and sometimes catching the Southern Leopard Frogs in my backyard in New Jersey. I was thrilled to get my first pair of hip waders on my thirteenth birthday. I got my first pet frog when I was 15—an albino

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Kevin, my pet African Bullfrog

African Clawed Frog named Steve. He joined me when I attended college and lived to the ripe old age of 11. I’ve owned several species of frogs and salamanders over the years. Currently, my 5 year old African Bullfrog, Kevin, is buried deep in the substrate of his tank, hibernating for the winter. He was the size of a grape when I first brought him home, but now he’s roughly the size of a salad plate and eats a variety of invertebrates and occasionally a small rodent. There’s just something about amphibians that I find fascinating. They are the first ever tetrapods and they evolved almost 400 million years ago. What’s not to love?! Okay, so now that we’ve established that I’m a crazy frog lady…

Amphibians and Oil Spills

How often are amphibians actually affected by oil spills anyway? The answer… often enough. As you probably already know, thousands of oil spills occur in U.S. waters every year. Thankfully, most of these spills are a small volume and not all spills result in wildlife becoming oiled. You might not have heard of amphibians getting oiled. That could be because media attention surrounding small, inland oil spills tends to diminish after a day or two, but these spills still have the potential to affect a wide variety of species, including amphibians. But why should we care? Aren’t there enough amphibians out there? An oil spill couldn’t wipe out that many of them, could it? Unfortunately we don’t really know how many amphibians are directly or indirectly impacted by spills. Historically they comprise just a fraction of the total number of wildlife captured for treatment during spills. This doesn’t necessarily mean that they aren’t being impacted, however. While California’s response system is quite robust and the OWCN could be activated for amphibians alone, the rest of the country operates differently. Oiled wildlife responders outside of California might only be activated if a spill is large enough or affects more charismatic species such as birds and mammals. Amphibians can easily be overlooked in the field and someone unfamiliar with their life history may have a difficult time identifying their habitat.

Populations Are Declining

In 2004 the International Union for the Conservation of Nature (IUCN) completed a comprehensive assessment of global amphibian populations. Their findings were alarming. The assessment found that 42% of amphibian species were in decline, 32% of species were threatened, and at least 159 recorded species have gone extinct. I’d venture a guess that things aren’t looking any better for our amphibian friends in the sixteen years since the IUCN’s assessment came out. The biggest threats to amphibian populations are habitat loss and pollution. Other threats include human disturbance, disease, and changes in native species dynamics. Oil spills have the capacity to contribute to each of the above.

Experience with Oiled Frogs and Salamanders

In 2014, California’s Office of Spill Prevention and Response (OSPR) expanded the OWCN’s response range from marine to statewide, including all California state surface waters. This means that inland spills affecting amphibians (and other taxa) now fall under the network’s umbrella. Several OWCN staffers, myself included, have experience handling oiled amphibians. In 2014, when I was working on Tri-State Bird Rescue, Inc.’s oil spill response team I gained valuable experience responding to a pipeline rupture in Ohio. I had the opportunity to collect, wash, and rehab several dozen salamanders and frogs. Unlike a traditional oiled wildlife event with birds or marine mammals, this response effort happened on a small scale—within a single wide trailer on a nature preserve. Each salamander and frog was house individually, but even dozens of these small patients didn’t take up much room.

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Salamander housing during a spill. Credit: Tri-State Bird Rescue

Some of the unique challenges with amphibians during an oil spill include:

Their life history is quite different than other taxa.
  • The Ohio spill coincided with the salamander’s natural breeding season during which they congregate in vernal pools to spawn. The oil was in the vernal pool so there was an ongoing concern of new animals becoming oiled throughout the cleanup. This was mitigated with the installation of a drift fence and pit fall traps which allowed un-oiled salamanders to be collected and relocated.
Amphibians are ectothermic, meaning that the regulation of their body temperature depends on external factors.
  • The spill occurred in late March. Daytime temperatures fluctuated between 40-50°F with nighttime temps dipping below freezing. This complicated the overnight collection of the nocturnally active salamanders because there was a risk of them and other non-target species freezing in the pit fall traps.
  • The metabolism of amphibians varies with the season of the year. It was important to minimize disturbance to their environment in order to keep them in their winter state of lower activity=lower metabolism. One way that we addressed this was by maintaining the rehabilitation center (trailer) at a temperature close to the outside conditions.
Amphibians have a unique and delicate integumentary system.
  • Both gas and water are exchanged through their skin. This permeability potentially makes them much more vulnerable to oiling. They also shed their skin periodically as they grow or in response to irritation. Some species will consume their shed skin to conserve the nutrients it contains. We found that many of the oiled salamanders shed their skin after decontamination and when possible, we elected to remove the shed skin from their housing before it could be consumed.

Where Do We Go From Here

There is still so much to be learned about amphibians in oil spills. Until now, ecotoxicology research on them has been focused on larval development in the presence of petroleum products rather than the direct effects of oiling. We still have many questions.

What kinds of internal and external effects of oiling do amphibians experience?
Are there long term effects if they survive the initial oiling?
Are existing wash protocols sufficient? How can they be improved?
What can be done to better plan and prepare for amphibians before and during spills?

The OWCN is working to provide some answers. In 2019 the OWCN funded a research project to investigate “The short-term effects of petroleum exposure and the process of petroleum removal on Northern Leopard Frogs.” We look forward to sharing the project’s findings when they become available.

The OWCN sponsors up to $200,000 annually to support research and technology development efforts in order to ensure that oiled wildlife receive the best-achievable capture and care. Since 1996, over 170 projects have been sponsored, and over $4 million has been allocated to improve our understanding of how oil affects wildlife. Perhaps there will come a day when amphibians are as valued and protected as their more charismatic avian and mammalian counterparts. I am honored to be part of an organization that is helping to make that happen!

The OWCN also sponsors sessions at wildlife conferences such as the National Wildlife Rehabilitators (NWRA) Symposium. Curt and I will be heading to the NWRA Symposium in South Padre Island, Texas next week. Will we see you there? If you aren’t already sick of hearing me ramble on an on about frogs and salamanders, you can come to my talk “Considerations for Treating Oiled Amphibians” on Friday!

–Crazy Frog Lady

–Sam

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Sam and baby Kevin

 

 

 

 

 

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