Predator foraging behaviour drives food-web topological structure.

Area of Science:

• Ecology
• Aquatic Ecology
• Food Web Dynamics

Background:

• Predator foraging behaviors are critical in structuring prey populations and food webs.
• Distinct predator foraging types can influence biodiversity, food-web architecture, and ecosystem functioning.
• Limited research exists on how different predator foraging strategies impact these ecological aspects.

Purpose of the Study:

• To experimentally compare the effects of two distinct planktivore foraging types—size-selective visual feeding and filter feeding—on lake food-web architecture.
• To analyze how these foraging behaviors influence topological descriptors of the food web over time.
• To determine if predator biomass affects food-web topology.

Main Methods:

• A 1-month mesocosm experiment was conducted using model planktivore species: bluegill (visual feeder) and gizzard shad (filter feeder).
• The experiment involved cross-classifying biomass gradients of each predator type.
• Food-web architecture was analyzed by computing topological descriptors (connectance, link density, omnivory index) from predator-prey matrices.

Main Results:

• Visual feeders (bluegill) led to more inedible primary producer species and reduced food-web complexity (lower link density, connectance, omnivory, generalism) compared to filter feeders (gizzard shad).
• Predator biomass did not significantly alter food-web topology in this experiment.
• Filter feeders supported a more complex and interconnected food web structure.

Conclusions:

• Top-predator foraging behavior is a key functional trait that significantly drives food-web topology.
• Different foraging strategies, like visual vs. filter feeding, have distinct and measurable impacts on ecosystem structure.
• Understanding predator foraging behavior is crucial for predicting and managing aquatic ecosystem functioning.