A team of researchers from several institutions in the U.K. has found evidence that suggests some seabirds may benefit from the existence of human-built offshore structures. In their paper published in the journal Communications Biology, the group describes their study of foraging seabirds in a tidal channel near Northern Ireland and what they learned.
As we look for ways to replace energy sources such as gasoline with renewables such as solar, wind and hydro, conservationists worry that we might be causing harm to the environment. Birds being killed by wind turbines or fried by solar farms are well-known examples. But building renewable structures offshore might actually be helping some wildlife, the researchers found. They conducted a study of a type of seabird as it foraged around a man-made structure jutting up from the sea—a decommissioned tidal energy turbine just off the coast of Strangford Lough in a channel that empties into the Irish Sea.
The study started with the knowledge that terns tend to forage for fish over parts of the sea where there is some bit of turbulence—water moving around objects is forced to move up in some scenarios, bringing fish with it, making them easy prey for terns. The researchers refer to such turbulence as a wake. To find out if man-made objects might provide the same benefits, the researchers used drones to watch terns forage around the abandoned tidal energy turbine, around a small island, and near a natural whirlpool—each forced seawater into a unique type of wake.
The researchers report that they found the terns used all three sites as a hunting ground, but the man-made wake created by the tidal energy turbine was the clear favorite. They note that other studies have shown that wakes created by man-made objects are attractive to predators, but point out that theirs is the first example in which wildlife actually prefer them to natural sites. They suggest their findings indicate that adding more offshore structures is likely to have a larger impact on marine life than has been previously thought, and some of it can be positive.
More information: Lilian Lieber et al. Localised anthropogenic wake generates a predictable foraging hotspot for top predators, Communications Biology (2019). DOI: 10.1038/s42003-019-0364-z
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