Global warming affects foraging efficiency of fish by influencing mutual interference

Area of Science:

• Ecology
• Behavioral Ecology
• Physiological Ecology

Background:

• Predator-prey dynamics are fundamental to ecosystem stability and population regulation.
• The functional response (FR) approach models resource use, but the impact of temperature and multiple predators is understudied.
• Climate warming may alter foraging behavior and inter-predator interactions.

Purpose of the Study:

• To investigate the combined effects of elevated temperature and predator/prey densities on fish foraging efficiency using the FR approach.
• To determine how intraspecific competition and temperature interact to affect predator foraging.
• To assess if single-predator experiments overestimate temperature effects.

Main Methods:

• Laboratory experiment with pumpkinseed (Lepomis gibbosus) predators at three densities (1, 2, 4) and two temperatures (25°C, 28°C).
• Six prey densities were used to calculate functional responses.
• Analysis focused on foraging efficiency, encounter rates, and inter-predator interactions.

Main Results:

• Higher temperatures reduced maximum feeding rates for single predators.
• Group foraging efficiency decreased due to antagonistic interactions, which were reduced at higher temperatures.
• Antagonistic interactions increased with predator density and peaked at intermediate prey densities, overriding temperature effects.

Conclusions:

• Conspecific presence negatively impacts individual predator performance, but this effect lessens with increasing temperature.
• Predators may limit food intake and reduce interactions as an adaptive response to warming.
• Including intraspecific competition in functional response studies provides more realistic ecological insights than single-predator experiments.