Spatio‐temporal distribution of early life stages of the European anchovy Engraulis encrasicolus L. within a European temperate estuary with regulated freshwater inflow: effects of environmental variables

摘要: The spatio-temporal distribution of the anchovy Engraulis encrasicolus in its early life stages was related to environmental conditions within Guadalquivir River estuary (south-west, Spain) by monthly field surveys during nine periods recruitment (May 1997 December 2005). Anchovy post-larvae showed a consistent seasonal pattern abundance throughout study period: each year, high period (HARP) occurred from late May November, with main peak July, coinciding when were more stable. Results stepwise multiple regression analysis indicates that density prey, Mesopodopsis slabberi, explained 45% total variance. Furthermore, after removing effect this variable, interannual differences estuarine not significant. Clear spatial and tidal trends also observed for both prey predator: at sampling date, decreased outer inner estuary; site, higher ebbs than floods. Field distributions gradients HARP indicated populations E. M. slabberi seemed hold steady position point on salinity gradient longitudinal displacement estuary. Since freshwater management actions affect as well input nutrients adjacent coastal areas, it is hypothesized factor may be relevant recruitment.