‘Otter’ Ways of Assessing Species Vulnerability to Climate Change


Cianfrani, C., O. Broennimann, A. Loy, and A. Guisan. More than range exposure: Global otter vulnerability to climate change. Biological Conservation221: 103-113.

PSA: Prepare for an ‘otterly’ ridiculous amount of otter puns!

How Does Climate Change Impact Species Vulnerability?

It’s no mystery that climate change has lasting impacts on our planet, and scientists are still learning how to forecast its consequences. One of their goals is to understand if plant and animal species can adapt to climate change, or if they’ll be forced into extinction. Usually, scientists will determine how vulnerable a certain species is by predicting how much of their habitat will change as a result of climate change. This can help scientists forecast if that species will have a home, or if they’ll be exposed to the threats of a changing climate and environment. But they might be leaving out some ‘otterly’ important clues to solving this mystery.

Figure 1: North American river otter, L. canadensis.
Source: By Attribution is to be given to Dmitry Azovtsev. When using on the Web, a link to http://www.daphoto.info is appreciated., CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=297924

What Do ‘Otter’ Scientist Have to Say?

Scientists are realizing that it’s not just how a species’ habitat changes, but how sensitive the species is to that change.

For example, freshwater otters love rivers, streams, wetlands, lakes, and ponds. They’re most comfortable in large, undisturbed areas because it gives them access to an abundance of food, space to play, and plenty of borrowing options.

Climate change could alter environmental conditions with irregular temperatures and precipitation, which would have a trickle-down effect to other parts of their ecosystem, such as changes to food sources, diseases, parasites, and other predators. Some otters may be more sensitive to these changes than others and may not be able to tolerate the new conditions. Climate change may also physically shift suitable habitat to a new location, forcing otters to stay and adapt, or move to where temperature, food, and other environmental conditions are more favorable. Lastly, human pollution and development could taint the water quality and food sources, destroy their large, pristine freshwater habitats, and stress otters even further!

Figure 2: Habitat fragmentation by numerous roads in the Indiana Dunes National Lakeshore.
By Digital File:hcl00027ID. Hill, C.L. 27cpOriginal found at [1] using keywords “Indiana” and “Dunes.”, Public Domain, https://commons.wikimedia.org/w/index.php?curid=17267246

What ‘Otter’ Factors Should Scientists Include?

With so many influences to consider, Dr. Ciafrani and colleagues decided to incorporate six factors that they felt were key to predicting how vulnerable a species might be to climate change.  The first two focus on how sensitive a species is to climate change, and the last four account for how exposed a species might be as habitat ranges change.

  1. Environment/Climate Requirement– the type of climate and environmental conditions (temperature, precipitation, food, etc.) a species needs to survive.
  2. Environment/Climate Tolerance– tolerance level of a species to changes in their environment.
  3. Changes in Habitat Size– will a habitat grow, shrink, or change shape.
  4. Fragmentation– will a habitat get cut into smaller, separate chunks, challenging a species to find food, mates, and homes.
  5. Overlap of Protected Areas– will a habitat be closer or further from wildlife preserves, national parks, etc.
  6. Human Pressure– will a habitat shift closer to cities, highways, or other human-impacted areas.

Some ‘Otterly’ Surprising Results!

The researchers concluded that all freshwater otters are predicted to be negatively impacted by climate change, but the impacts are mixed and will vary from species to species.

Climate change would not affect the habitat range size of an endangered Latin American otter species,but it would increase fragmentation, a factor already threatening the species. One Asian otter species would see their habitat range shrink, but it would also shift towards more protected areas with less human impact. Unfortunately, two African otter species would see their range shrink and shift away from protected areas and towards more human-impacted areas. Interestingly enough, a Eurasian otter species would benefit the most with their range increasing with climate change and shifting towards areas with more protection and less human impact.

…it’s not just how a species’ habitat changes, but how sensitive the species is to that change.

Lastly, a third African otter species relies on a highly sensitive food (they love earth worms!) and requires specific environmental conditions, which makes it difficult to adapt to climate change. Their habitat is also predicted to shift towards more human-impacted areas.  The researchers realized that this combination of sensitivity to climate change and exposure to a changed climate is what makes a species most vulnerable to climate change, and thus this species needs to be a conservation priority. ‘Otterly’ fantastic!

Figure 3: A green forest corridor in Brazil connecting two fragmented habitats.
Source: By Ipe-institutodepesquisasecologicas – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=40983443

Conservation Strategies? Target Specific Threats.

The study yielded an excellent model that can not only help otters, but other species too! By accounting for several key factors and predicting how they’ll change with time, scientists and conservationists can reveal the main issues that will threaten a species. If a species’ habitat is predicted to move towards more human-impacted areas, a solution could be to implement policies and practices to reduce pollution or habitat destruction. If fragmentation is the issue, finding a way to connect those habitats may help to mitigate species declines (Figures 2 and 3). Some issues, such as specific food and habitat requirements, may be out of our control, but being armed with this framework can at least inform decisions-makers of where problems lie, and help direct future conservation strategies.

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Nick Iraola

Nick has a Master of Science in Marine Science from UNC Wilmington. His master's thesis research pertained to eutrophication and nutrient cycling within an urban blackwater lake in Wilmington, NC. Currently, Nick works for the Cape Fear Public Utility Authority testing drinking and waste water for safe consumption and discharge (respectively!!). Nick also works as a part-time research scientist at UNCW's Center for Marine Science in the Aquatic Ecology Laboratory and the Nutrient Analysis Core Facility. When he's not sciencing, Nick enjoys running, swimming, cooking, sailing, and catching up with friends and family. His favorite candy is Reese's pb cups, because what is there not to like!?

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