Resumen de Diel variation in the vertical distribution of fish larvae forced by upwelling filaments off Punta Angamos (northern Chile)
- español
The role for diel vertical migration (DVM) on fish larvae assemblages off Punta Angamos (23°29'S; 70°59'W) northern Chile was examined. In September 1998 and January 1999 two bio-oceanographic surveys during coastal upwelling events were carried out. Fish larvae were collected during day/night at three depth strata (0-20, 20-80 and 80-200 m depth) inside/outside the upwelling filaments. The study area was dominated by a southward flow throughout 200 m depth, while Ekman layer did not exceed 20 m depth. Higher accumulation of fish larvae was found in the mid-depth stratum (20-80 m), where seawater speed was lower and did not interacted with circulation associated to upwelling filaments formation. Most of larval fish groups were found in nonupweling waters at mid depth. Irrespective of seawater origin (upwelling/nonupwelling), larval Diogenichthys laternatus (Myctophidae), Engraulis ringens (Engraulidae) and Bathylagus nigrigenys (Bathylagidae) showed deeper vertical distribution during day than night, suggesting diel vertical migration. This larval behaviour potentially may increase coastal retention in a productive area through the vertical avoidance of the offshore Ekman layer during upwelling events.
- English
The role of daily vertical migration (DVM) of ichthyoplanktonic associations off Punta Angamos, in northern Chile, was examined. In September 1998 and January 1999, two oceanographic surveys were conducted during coastal upwelling events. Fish larvae were collected during the day/night in three depth strata (0-20, 20-80 and 80-200 m) and inside/outside of upwelling filaments. The study area was dominated by a southward flow along 200 m depth; meanwhile, the Ekman layer did not exceed 20 m depth. The greatest accumulation of larvae was found in the middle layer (20-80 m), where the current velocity was low and did not interact with the circulation associated with upwelling the filament formation. Most fish larvae were found in non-upwelling waters in the middle stratum. Independent of the origin of water (upwelling/non-upwelling), larvae of Dioge-nichthys laternatus (Myctophidae), Engraulis ringens (Engraulidae) and Bathylagus nigrigenys (Bathylagidae) showed a deeper vertical distribution during the day, suggesting a daily vertical migration. This behavior can potentially increase retention of larvae near the coast in productive areas through vertical evasion of the Ekman layer during upwelling events
