Warmer and Murkier Waters Favor Predators of Guppies, Study Finds
Published:26 Jul.2023 Source:University of Bristol
Changes in water conditions interact to affect how Trinidadian guppies protect themselves from predators, scientists at the University of Bristol have discovered.Known stressors, such as increased temperature and reduced visibility, when combined, cause this fish to avoid a predator less, and importantly, form looser protective shoals.The findings, published today in the journal Proceedings of the Royal Society B, show guppies' responses are more affected by the interaction of these stressors than if they acted independently.
The team observed the reciprocal responses between a predator and a shoal of prey under four treatments, optimal housing conditions (as a control), and in treatments where either temperature or cloudiness of water was increased. They were then tested with an interaction treatment where both temperature and turbidity were increased at the same time.This took several weeks of trials in the lab involving 36 predators and 288 prey fish. The animals were separated so they did not come to any harm.All the video recordings were then processed to obtain fine scale movements of all the fish so that the researchers could calculate the swimming speeds of all fish and how they related to one another: how close together the prey stayed and how far from the predator each prey tried to remain.
Now the team plan to test whether the decrease in anti-predator behaviour is as negative for the prey as it may seem and not a clever adaptation to allow prey fish to worry less about predators in an environment that keeps them safe. By using a wider range of predators, they will also investigate whether these changes can affect multiple species differently.