Pathogens trigger top-down climate forcing on ecosystem dynamics

Area of Science:

• Ecology
• Climate Change Biology
• Freshwater Ecology

Background:

• Understanding ecosystem responses to climate variation is crucial for predicting global change impacts.
• Complex food web responses to climate variations remain poorly understood.
• Intraguild predation (IGP) systems offer insights into predator-prey dynamics under environmental change.

Purpose of the Study:

• Investigate the effects of temperature variation on the intraguild-predation (IGP) system in Windermere (UK).
• Analyze how pike (Esox lucius) and perch (Perca fluviatilis) interactions are affected by climate and disease.
• Determine the role of top predators in mediating ecosystem responses to global change.

Main Methods:

• Utilized long-term time series data for spectral analysis.
• Examined the IGP system involving pike and two size classes of perch.
• Assessed the impact of a perch pathogen outbreak in 1976.

Main Results:

• Pike recruitment dynamics were found to be temperature-controlled.
• A 1976 perch pathogen outbreak shifted the IGP system, favoring pike dominance.
• This regime shift triggered a temperature-controlled trophic cascade affecting dissolved nutrients.
• Warming and pathogens showed synergistic top-down effects on ecosystem functioning in this IGP system.

Conclusions:

• Top predators significantly mediate community responses to global change.
• Size-selective agents, like pathogens, can alter food web structure and ecosystem sensitivity to climate variation.
• The IGP structure in Windermere demonstrated a unique interaction between climate, disease, and trophic cascades.