Size-dependent foraging efficiency, cannibalism and zooplankton community structure

Area of Science:

• Ecology
• Aquatic Ecology
• Food Web Dynamics

Background:

• Cannibalism is a significant ecological process influencing population dynamics.
• Size-dependent interactions are crucial in structuring food webs.
• Perch (Perca fluviatilis) exhibit cannibalistic behavior, affecting different size classes.

Purpose of the Study:

• To investigate how size-dependent cannibalism in perch affects food web interactions.
• To compare zooplankton and phytoplankton communities in lakes with and without pike (Esox lucius).
• To understand the impact of cannibalism on predator-prey dynamics and community structure.

Main Methods:

• Comparative study of four lakes over two years, with varying perch and pike presence.
• Functional response experiments with different sizes of perch and zooplankton.
• Analysis of zooplankton and phytoplankton abundance and community structure.

Main Results:

• Lakes with pike had fewer older perch, while lakes with only perch had fewer young perch due to cannibalism.
• Small perch had a higher attack rate on zooplankton than large perch.
• Zooplankton communities differed, with smaller species dominating in perch-only lakes and larger species in lakes with pike.

Conclusions:

• Cannibalism in perch creates size-selective predation, altering zooplankton communities.
• The presence of pike influences perch population structure and, consequently, lower trophic levels.
• Cannibalism introduces complexity to food webs, leading to unpredictable consumer-resource dynamics.