Mechanisms for longitudinal transport on early life stages in benthic-pelagic fishes within a tide-dominated estuary

Mechanisms that control the longitudinal transport of larvae and juveniles in nursery grounds such as estuaries are reported for some species. However, behaviour population consequences these mechanisms still uncertain. In this study, we tested selective tidal-stream from along-channel (up- downstream) cross-channel (from one margin to other) perspectives two kinds fish: estuarine-resident gobies ( Pomatoschistus spp.) marine estuarine-opportunistic anchovies Engraulis encrasicolus ). Three cruises were conducted lower Guadalquivir estuary, on ebb flood spring tides summer. Plankton samples collected across a channel section, at three stations (one middle adjacent shallower areas), near surface bottom simultaneously. addition, multiple physico-chemical variables (temperature, turbidity, dissolved oxygen, pH, salinity, chlorophyll-a, along with wind current direction velocity) measured examine different correlations used by studied fish their strategies. The benthic distribution indicated they currents lateral (shallow) areas ingress into remain temperature and/or oxygen being main possible cues. On contrary, more abundant surface, especially tide, showing downstream advection, which was mainly influenced salinity. largest individual lateral/shallow zones suggested behavioural ontogeny, which, together induced transport, could contribute retention. This comparison also enhanced knowledge habitat species common estuaries, gobies. • anchovy moves longitudinally through layers. spp. move Anchovy showed behavioral ontogeny preferences individuals. Salinity influences while