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Published on: October 1, 2011
Large-scale manipulation of mayfly recruitment affects population size
Andrea C Encalada1, Barbara L Peckarsky
1Department of Entomology, Cornell University, Ithaca, NY, 14853, USA. aencalada@usfq.edu.ec
Oecologia
|October 22, 2011
Summary
Manipulating mayfly oviposition sites significantly altered egg and larval densities in streams. This demonstrates that recruitment, influenced by preferred habitats, can limit population size in aquatic insects.
Area of Science:
- Ecology
- Aquatic Entomology
- Population Dynamics
Background:
- Recruitment is crucial for initial population size and dynamics.
- Empirical data on recruitment and population size offer insights, but direct manipulation is needed for definitive tests.
- Understanding recruitment limitation requires studying it at relevant spatial and temporal scales.
Purpose of the Study:
- To experimentally test the hypothesis that recruitment can limit population size in mayflies.
- To investigate the impact of manipulating oviposition sites on mayfly egg and larval densities.
- To determine if recruitment manipulation affects population dynamics at the stream reach scale.
Main Methods:
- Field experiment manipulating oviposition sites for the mayfly Baetis bicaudatus in four western Colorado streams.
- Egg densities were altered by increasing, decreasing, or maintaining preferred oviposition sites.
- Larval abundance was measured after the manipulation, comparing densities before and after across treatments.
Main Results:
- Egg densities increased approximately fourfold in addition sites and decreased to zero in subtraction sites.
- Larval densities significantly increased by ~2.0 times in addition sites and decreased by ~2.5 times in subtraction sites.
- Experimental changes in recruitment directly impacted larval population size one year later.
Conclusions:
- Dramatic alterations in recruitment can limit larval population size at the stream reach scale.
- Recruitment limitation may mask other post-recruitment processes influencing stream insect abundance.
- Preferred oviposition habitats play a critical role in determining population sizes of aquatic organisms.
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