Narwhals Display Perplexing Escape Responses to Human-Induced Stress

By Olivia Schuitema, SRC intern

Narwhals (Monodon monoceros) are Arctic marine mammals that have traditionally been relatively isolated from anthropogenic contact, making them particularly vulnerable to disturbance (Williams, 2017). The lack of ecological interference also makes narwhals adequate study organisms regarding anthropogenic effects. With larger declines in Arctic sea ice, narwhals have been increasingly exposed to predation, human hunting and seismic exploration (Williams, 2017). For example, seismic surveys in the Arctic aim to pinpoint fossil fuel reserves and in the process release high-energy noise that can affect marine mammal migration and behavior (Jørgensen, 2013). Scientists aimed to gauge the stress responses of release after entanglement or stranding by monitoring the behavior and the cardiovascular and energetic responses of narwhals inhabiting East Greenland (Williams, 2017).

Figure 1: Study area in eastern Greenland with GPS tracks for five instrumented narwhals, Williams, 2017

When exposed to stressful conditions, animals tend to respond in one of two ways: 1) “fight or flight” reaction; stay to fight the threat or flee from the threat, or 2) freeze reaction; extreme decrease in heart rate. Mammals who flee their situation show signs of tachycardia (elevated heart rate) and increased rates of respiration (Williams, 2017). Conversely, mammals that “freeze” tend to show signs of bradycardia (slowed heart rate) and slowed behavior. These two escape systems stem back to two different anatomical positions in the mammalian brain, making fleeing and freezing simultaneously very unlikely.

Scientists placed electrocardiograph-accelerometer-depth monitors on five narwhals immediately released from entanglement and stranding (Williams, 2017). These devices were attached via suction cup for varying amounts of time (0.4-3 days) and measured heart rate, speed, and depth of the escaping narwhals. The studied organisms showed a paradoxical response upon release; a fleeing response with high stroke frequencies immediately followed by heightened bradycardia (“cardiac freeze”), a freezing response (Williams, 2017). Data also showed that the longer it took to release the entangled narwhals, the more likely they were to undergo cardiac freeze (Williams, 2017). These results show the negative effects of human-induced stress, but also highlight the inconsistencies of marine mammal responses to such stress.

Figure 2: Narwhal with ECG-ACC recorder (Electrocardiograph-accelerometer-depth monitor) on dorsal side of the body, Williams, 2017

The profound melting of sea ice due to climate change has opened up the Arctic to a variety of stressors including human influence. Arctic predators such as killer whales have increased access to Arctic prey items like narwhals (Breed, 2017). More research must be conducted in order to further explore the effects of anthropogenic stress on marine mammals like the narwhal in the Arctic. This example showcases the connection between rise in global temperature and melting sea ice due to climate change. “Climate change” can be a broad and sometimes obscure topic, but as seen by the paradoxical narwhal escape responses, the effects of this phenomena can extend to very specific organisms.

Works Cited

Breed, G., Matthews, C., Marcoux, M., Higdon, J., Leblanc, B., Petersen, S., . . . Ferguson, S. (2017). Sustained disruption of narwhal habitat use and behavior in the presence of Arctic killer whales. Proceedings of the National Academy of Sciences of the United States of America, 114(10), 2628-2633.

Heide-Jørgensen, Hansen, Westdal, Reeves, & Mosbech. (2013). Narwhals and seismic exploration: Is seismic noise increasing the risk of ice entrapments? Biological Conservation, 158, 50-54.

Williams, Terrie M., Blackwell, Susanna B., Richter, Beau, Sinding, Mikkel-Holger S., & Heide-Jorgensen, Mads Peter. (2017). Paradoxical escape responses by narwhals (Monodon monoceros). Science, 358(6368), 1328.

Marine Biota and The Well Being of Humans

By Melissa Soto, SRC Intern

A small dose of nature can go a long way. Studies show that exposure to nature has a significant calming and stress reducing effect on humans. A recent study published in the United Kingdom examined how people’s behavior, physiological, and psychological reactions varied when exposed to an aquarium. The researchers recorded the participant’s reactions when the aquarium was unstocked (meaning no marine life), partially stocked (some marine life), and fully stocked (with plenty of marine life).

Previous research suggests that humans inherently want to be surrounded by nature. Taking place in the United Kingdom’s National Marine Aquarium, researchers wanted to see how much time people would spend in front of the large restocking exhibit along with any stress and emotional changes people experienced at the three stages of restocking.

Screen Shot 2015-10-19 at 5.47.58 PM

There are three main ways to determine stress recovery with the assistance of nature. They are the Biophilia Hypothesis, the Psychophysiological Stress Recovery Theory (PSRT), and Attention Restoration Theory (ART). Biophilia is the emotional connection humans have with nature, PRST says humans are predisposed to react positively to nature, and ART suggests that mental irritability and distraction can be reduced with a nature setting. Although these three theories apply, ART is the one that worked best with this experiment as there are four parts. Fascination, being away, extent, and compatibility all resemble what people experienced as they view an aquarium. Here are the direct examples for these four components. 1. People were fascinated as they viewed the marine life 2. The everyday setting of their life was removed 3. They had the opportunity to be educated 4. They choose to visit the exhibit.

The scientists created three different hypotheses’ and explore them. The first was to see if voluntary exposure time would reflect intrinsic fascination and be positively correlated with the level of biota present within the exhibit. Second, there would be a positive relationship between psychophysiological responses and viewing the exhibit when it contained marine life. The final hypothesis was to see if longer exposure time to the exhibit would improve psychophysiological responses.

The participants entered the aquarium and stood in front of the exhibit when it was unstocked, partially stocked and fully stocked. Each participant stood alone while the aquarium transitioned into the different conditions. Measurements were taken twice weekly at different times of the day. Following this, the participant’s psychological mood was measured based on a “The Feeling Scale”. The scale showed whether the participants had a positive mood with high arousal, negative mood with high arousal, positive mood and low arousal or negative mood with low arousal.

Participants then made their way from the aquarium into a room where their blood pressure and heart rate was monitored. Blood pressure and heart rate monitoring was conducted for a total of five-minutes. Measurements were taken at the two-minute mark and at the five minute mark.

Screen Shot 2015-10-19 at 5.49.24 PM

The results of this study showed that the participants stayed in front of the exhibit longest when it contained the highest level of marine life further supporting Hypothesis 1. The more biota allowed for more interest and willingness to watch. Hypothesis 2 and 3 were weaker but did show significant blood pressure and heart rate drops demonstrating that the exposure was calming and physiologically restorative.

Although this study was unsuccessful in determining a measurable effect on elevated stress, it did find new data to add to past studies. Overall, the participants left the aquarium feeling relaxed, in a positive mood, and slightly aroused. It also showed that an individual does not need to spend a long time in front of the exhibit, just five minutes, to gain significant benefits.



Cracknell, D., White, M., Pahl, S., Nichols, W., Depledge, M. (2015). Marine biota and psychological well-being: a preliminary examination of dose-response effects in an aquarium setting. Environment and Behavior, 1-28. doi: 10.1177/0013916515597512