Sea turtles in a landscape of fear

by Wageningen University
December 22, 2022

Many sea turtles live their adult lives in predator-free environments due to overfishing of their main predator, the tiger shark. Because of this, it is largely unknown how sharks impact turtle grazing behaviour. Wageningen researchers have discovered how turtles change their grazing behaviour when they feel safe, and as a result increase their grazing pressure on seagrass meadows.

The ‘landscape of fear’ is an established concept on land, where for instance the presence of wolves influences the risk-avoiding behaviour of deer. This can result in variation in plant abundance and diversity and prevent overgrazing of plants. In the marine environment, it is challenging to detect and map such a landscape of fear, because of the high mobility of large animals in the ocean and unknown cues between predators and prey. Researchers of Wageningen University & Research together with Florida International University and the Centre for Ocean Research and Education in The Bahamas have recently published a paper in the journal Ecology on a field study in the Bahamas. It describes that sea turtles had a vigilant grazing strategy and spread themselves out over the lush seagrass meadows. This was most likely because of the high densities of predators – large sharks – reported in this area, having an impact on turtle movements and behaviour.

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