HR: 15:45h
AN: NB14G-01    [Abstracts]
TI: Channel Realignment Increases Multi-Scale Sensitivity to Floods in Benthic Snails in a Puerto Rico Stream
AU: * Blanco, J F
EM: jblanco@LTERnet.edu
AF: Department of Biology, University of Puerto Rico, Rio Piedras, PO Box 23360, University Station, San Juan, PR 00931-3360 Puerto Rico
AB: The impact of hydromodifications such as channel realignment on diadromous fauna is poorly understood in tropical streams. This study documented the impacts of channel realignment performed at lower Rio Mameyes (NE Puerto Rico) on local and upstream populations of the diadromous Neritina virginea (Gastropoda: Neritidae). The streambed was dredged and leveled during the realignment (Summer 2002) promoting small-substrate patches, and increasing reach-scale heterogeneity. Snail density and size, streambed and channel properties were monthly recorded in a reference reach, and in situ and upstream the realigned reach during the following 18 months. After realignment, the local density was lower compared to previous surveys, and to the reference reach. It was due to individual wash out during flashfloods on gravel patches at the realigned reach. Increased mortality in juvenile snails migrating upstream through the realigned reach was responsible for gradual density decline, and low recovery after a major flood in the upstream population. However, existing data before the realignment showed that this population recovered from storm floods in less than two months. This study evidenced that civil works in flashy streams promote long-lasting negative effects on local populations that may propagate upstream when diadromous species are compromised, and may provide restoration guidelines.
DE: 4804 Benthic processes/benthos
DE: 9902 NABS Student Award Applied Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly