Baetid mayflies are very messy eaters: evidence from field experiments in a tropical stream, Ilha Grande, RJ, Brazil
Abstract
Mayflies may play an important role in periphyton dynamics. In previous field exclusion experiments, we had found that baetid mayflies (Americabaetis sp. and Cloeodes sp.) had a strong negative impact on periphyton. In this study we quantified the contributions of mayfly consumptive and non-consumptive effects on periphyton in the absence of shrimp. We carried out five field experiments: an egestion rate experiment to quantify periphyton consumed by mayflies and four shrimp exclusion experiments using electricity to exclude shrimps from natural substrate to estimate total removal of periphyton by mayflies. By comparing total removal with estimated ingestion, we estimated non-consumptive loss. We starved mayflies for 0, 3 and 6 h and assumed that periphyton egested would be replaced by ingestion at the same time. We found that, after 3h, 52.8% of the initial amount of periphyton in the mayfly alimentary canal was lost due to egestion, and 77.9% after 6h. During shrimp absence mayflies accumulated over control level and significantly reduced periphyton. Estimated ingestion was 2 to 23% of the periphyton depletion, thus mayfly non-consumptive periphyton removal contributed 98 to 77% of all periphyton lost inside electrified areas. Our results suggest that mayfly have strong negative non-consumptive effects on periphyton.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2005
- Bibcode:
- 2005AGUSMNB33Q..15K
- Keywords:
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- 4815 Ecosystems;
- structure and dynamics;
- 4817 Food chains;
- 4845 Nutrients and nutrient cycling;
- 9360 South America