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Thursday, May 29, 2008 - 11:30 AM
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Influence of flow and temperature on the temporal variability in leaf processing rates in atlantic headwater streams
Isabel Pardo, Liliana Garcia, and Maruxa Alvarez. Departamento de Ecología y Biología Animal, University of Vigo, Vigo, Spain
Leaf processing dynamics are affected by abiotic and biotic factors over bioclimatic scales. Headwater streams in Northwest Spain are heterotrophic systems depending on riparian input for their functioning. Long lasting leaf inputs in combination with the existence of more benign environmental conditions during late spring-summer causes an increase in invertebrate production. We incubated two leaf species (alder and eucalyptus) in three similar headwater streams. Three in-stream continuous incubations during the period of leaf inputs were done in each stream per year for two years. Temperature was recorded with continuous dataloggers and flow was estimated bi-weekly. Our results indicate an increase in leaf decay rate with flow, mostly due to autumnal differences in flow between years. However, the temperature gradient (10.2-16.4 ºC) did not influence decay rate. Changes in the amount and timing of seasonal runoff can result in both increased flow and longer low-water periods in Atlantic streams. Variation in seasonal timing of floods during the litterfall season also influence physical processing and export of organic matter, increasing environmental variability in resource availability. Therefore, floods challenge life histories and production of invertebrate in many Atlantic headwaters, either disrupting detritivores during their productive season or allowing longer production times.
Web Page: Atlantic, streams,processing