Integrated ecosystems: linking food webs through reciprocal resource reliance

Area of Science:

• Ecology
• Ecosystem Science
• Conservation Biology

Background:

• Ecosystems are often studied within defined boundaries, but resource exchange across these limits can obscure distinctions.
• Trophic transfers of organic matter can integrate distinct ecosystem compartments.
• Understanding cross-boundary resource reliance is crucial for ecosystem management.

Purpose of the Study:

• To develop and test a framework for quantifying reciprocal reliance on cross-boundary resource exchange.
• To measure ecosystem integration based on permeable boundaries and significant bidirectional resource exchange.
• To assess the impact of integrated ecosystems on food webs and consumer support.

Main Methods:

• Developed a framework to quantify reciprocal reliance on cross-boundary resource exchange.
• Calculated the contribution of adjacent primary production to food webs at different trophic levels.
• Applied the framework to a desert river-riparian zone case study and analyzed published lake ecosystem data.

Main Results:

• Demonstrated that resources exchanged across the aquatic-riparian boundary cycle through multiple trophic levels.
• Found that predators on both sides of the river-riparian boundary were similarly supported by external resources, indicating tight integration.
• Showed that benthic and pelagic compartments in lake ecosystems are likely not fully integrated, but differences can be leveraged for ecological hypotheses.

Conclusions:

• Defined an integrated ecosystem as one with permeable boundaries and significant bidirectional resource exchange sustaining both food webs.
• Highlighted the tight integration of river-riparian ecosystems, where changes in one compartment substantially impact the other.
• Proposed the framework's applicability to diverse ecosystems (urban-preserve, field-forest) for research and global management strategies facing novel pressures.