Seeing the sea to be able to eat

Eating with your eyes first is something seabirds also do – but climate change is making this more difficult.

Reference: Darby J., Clairbaux M., Bennison A., Quinn J. L.and Jessopp M. J. 2022. Underwater visibility constrains the foraging behaviour of a diving pelagic seabird. Proc. R. Soc. B. 289: 20220862. 20220862.

Sensory sorrows

Senses are vital to know if something can be eaten or not. We rely on visuals, smells, taste and even touch to decide if we want to try a new dish or not. Seabirds and fishes also need their senses to feed, such as needing to see their prey to capture it. Knowing how living organisms rely on their senses to feed is extremely important to understanding how changes in the environment will affect them. In the case of seabirds, an increase in oceanic turbidity (a measure of water’s cloudiness, usually caused by small floating particles) might be making their meals more difficult to spot.

We are all aware of how climate change is modifying the world and its characteristics. One of its consequences is the increase in water turbidity due to changes in wave action. This causes a lifting in particles resting on the seafloor, bringing them back to suspension. Waves aren’t stopping long enough for these particles to go back to their resting position, which causes water to stop being as transparent–say goodbye to those beautiful, crystalline waters. Because the water is more cloudy, light can no longer penetrate the water column as well. All these particles could end up impacting the base of marine food webs – yet another climate change-induced stressor.

It’s becoming increasingly important to study the different areas in which climate change can shift ecological processes. For this reason, researchers recently explored the relationship between a seabird species’ behavior and turbidity.

The studied seabird

The seabird species studied was the Manx shearwater (Puffinus puffinus), which depends on its visual senses to dive and chase after its prey. Its behavior was observed with changing environmental variables affecting prey visibility, such as cloud cover, turbidity, and solar angle.

Manx shearwater are highly mobile to the point of taking foraging trips up to thousands of kilometers from their colonies, making them perfect for this study. Although Manx shearwaters use their sense of smell in big-scale searches, their eyes are incredibly important when capturing prey. These birds pursue their prey only during the day, and must dive to depths up to 50 m, showing just how important light is to their chase.

In this study, 36 adult Manx shearwaters were tracked from Little Saltee, Ireland, between June and August 2021. Each bird was tagged in order to track its location. In total, the researchers collected 79 foraging trips and 5472 dives.

(a) Manx shearwater foraging trips, 79 total from Little Saltee. The blue point is the colony. (b) Points represent track locations with dives. The size corresponds to the number of dives. Images by Darby et al.

Let’s see what we got

The results showed that the Manx shearwaters were more likely to take dives in transparent waters. It was also demonstrated how visibility was tightly related to how deep they went, as it affected the detection of prey underwater. Birds dove deeper when the conditions were of high solar angles, see-through waters, and low cloud cover. On the other hand, significantly less dives occurred when the sun was below the horizon, cloud cover was high, and the water was very cloudy. These results show that climate change and the rise of turbidity in water does negatively impact these birds. If prey populations were to decrease as well, it would become very difficult for these birds to capture enough prey to survive.


These results show how climate change can limit and transform the way some organisms live. This further complicates conservation in marine areas, as many waters have become more turbid in recent years, affecting coastal and offshore regions. Not only does this affect predators like the seabirds, but it also impacts photosynthesis because of the reduction of light. Climate change makes it so extreme weather events, such as heavy storms, become more frequent. This leads to increased wave action, and so low water visibility. Climate change also causes an increase in planktonic blooms, which can also contribute to cloudier waters and impact food webs.

As we can see, further study of how sensory perception can be altered due to climate change is crucial to understand marine species’ futures. Many aspects of their lives are being affected more and more each day, so learning more about this topic will help clarify their sensitivity to these changes so we can take helpful action.


Cover photo: © Jonathan Rosborough

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