Predicting invasive species impacts: a community module functional response approach reveals context dependencies

Area of Science:

• Ecology
• Invasive Species Biology
• Community Ecology

Background:

• Predatory functional responses are crucial for predator-prey dynamics and predicting invasive species impacts.
• Interspecific interactions like parasitism and higher-order predation can modify these dynamics.
• Assessing these context dependencies enhances the predictive power of functional response approaches.

Purpose of the Study:

• To compare the predatory functional responses of native (Gammarus duebeni celticus) and invasive (Gammarus pulex) amphipods.
• To quantify the context-dependent influences of parasitism and a higher-order fish predator on these responses.
• To evaluate the applicability of comparative functional responses for predicting invasive species impacts.

Main Methods:

• Utilized a four-species community module including a higher-order predator, native/invasive focal predators, parasites, and native prey.
• Conducted functional response experiments comparing native and invasive amphipod predation on three invertebrate prey species.
• Analyzed partial prey consumption in relation to prey density, parasitism, and the presence of a higher-order predator.

Main Results:

• The invasive amphipod exhibited a higher predatory impact (shorter handling time) on two of three prey species compared to the native amphipod.
• Parasitism showed context-dependent effects, potentially reducing the invasive amphipod's impact or increasing the native amphipod's impact in the presence of a fish predator.
• Partial prey consumption increased with prey density but was not influenced by parasitism or the higher-order predator.

Conclusions:

• Comparative functional responses are valuable tools for predicting and assessing invasive species impacts.
• Interspecific interactions, such as parasitism and higher-order predation, introduce context dependencies that must be considered.
• The study highlights the complexity of invasive species dynamics within a community context.