HR: 1330h
AN: NB33G-02    [Abstracts]
TI: Is the Seasonal Water Flow a Regulator of Zoobenthos Movements in the Colonization Process of a Stream Sandy Substrate?
AU: * Anaya, M
EM: manaya@unicid.br
AF: University City of São Paulo, Rua Cesário Galeno, 448/475, Sao Paulo, SP 05132-000 Brazil
AU: Shimizu, G Y
EM: yuka@ib.usp.br
AF: Dept. of Ecology University of São Paulo, Rua do Matão, Travessa 14, 317, Sao Paulo, SP 05508-900 Brazil
AB: This work aimed to evaluate the importance of routes of colonization of sandy substrate in an urban Atlantic forest stream (Cantareira State Park, São Paulo, Brazil), during low and high flow seasonal conditions. Natural sediment of the stream was boiled, filled in perforated plastic baskets and implanted in the stream bed. The baskets were modified in two ways, one to restrict upward subsurface colonization and other to restrict water route of colonization (aerial, drift and downstream and upstream movements). Baskets without restriction were implanted as control. Three sampling units of each basket were exposed for 7, 14, 21 and 28 days, during three sampling periods of low and high flow seasonal conditions respectively. In both seasons, zoobenthos densities and family richness were frequently higher in water route colonized baskets than in subsurface route colonized baskets. However, benthic families' persistence in subsurface samples increased conspicuously in the end of rainy season, in spite of no significative correlation between this community parameter and any water movement variable has been founded. These results indicates subsurface route as more important in the process of colonization in dry season. Just Orthocladiinae showed preference on water route and Tanytarsini on interstitial route.
DE: 9810 New fields (not classifiable under other headings)
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly