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Reciprocal subsidies: dynamic interdependence between terrestrial and aquatic food webs
1Center for Ecological Research, Kyoto University, Hirano, Kamitanakami, Otsu, Shiga 052-2113, Japan.
Summary
Seasonal prey flow between forest and stream ecosystems alternately supports local wildlife. This reciprocal subsidy is crucial for maintaining energy budgets in both bird and fish populations.
Area of Science:
- Ecology
- Ecosystem Dynamics
- Food Web Interactions
Background:
- Mutual trophic interactions between contiguous habitats are vital for ecological landscapes but remain poorly understood.
- Understanding cross-habitat resource flow is key to community maintenance.
Purpose of the Study:
- To investigate the reciprocal trophic interactions between a deciduous forest and a stream ecotone.
- To quantify the contribution of cross-habitat prey subsidies to the energy budgets of forest birds and stream fishes.
Main Methods:
- Field study in a deciduous forest-stream ecotone.
- Monitoring of aquatic insect emergence and terrestrial invertebrate biomass.
- Quantification of allochthonous prey input to the stream and its contribution to predator energy budgets.
Main Results:
- Aquatic insect emergence peaked in spring when terrestrial invertebrate biomass was low.
- Terrestrial invertebrate input to the stream was highest in summer when aquatic invertebrate biomass was lowest.
- Reciprocal prey subsidies accounted for 25.6% of the annual energy budget for forest bird assemblages and 44.0% for stream fish assemblages.
Conclusions:
- Seasonal contrasts in prey availability drive the importance of reciprocal subsidies between forest and stream ecosystems.
- Cross-habitat subsidies significantly contribute to the annual energy budgets of both terrestrial (birds) and aquatic (fish) consumer assemblages.
- The findings highlight the importance of considering habitat connectivity and seasonal dynamics in ecological landscape management.