Predators drive community reorganization during experimental range shifts.

Area of Science:

• Ecology
• Climate Change Biology
• Aquatic Ecosystems

Background:

• Climate change drives species range shifts, creating novel ecological communities.
• Species interactions, particularly trophic interactions, are crucial for ecosystem responses to climate change.
• The role of predation in facilitating or hindering range expansions remains poorly understood.

Purpose of the Study:

• To investigate how fish predation influences the establishment of range-shifting prey under climate warming.
• To test the hypothesis that fish predation facilitates zooplankton colonization by removing larger competitors.

Main Methods:

• A mesocosm experiment was conducted using zooplankton and fish from Sierra Nevada lakes.
• The study examined the impact of fish predation on zooplankton community establishment and persistence at two temperatures.
• Experimental design included interactions between higher- and lower-elevation zooplankton communities.

Main Results:

• Fish predation reduced larger, alpine zooplankton species, facilitating the establishment of smaller, lower-elevation species.
• Both warming and fish predation independently decreased average zooplankton body size.
• Reduced body size offset warming-induced growth rate increases, resulting in stable zooplankton biomass and trophic cascade strength.

Conclusions:

• Predators can accelerate species range shifts by consuming dominant native species.
• Climate warming effects on ecosystem function were dampened by size-selective predation and direct warming impacts.
• Trophic interactions are key drivers in the reorganization of ecological communities under climate change.