Roles of dispersal mode, recipient environment and disturbance in the secondary spread of the invasive seaweed Codium fragile

摘要: Secondary spread largely determines the distribution and success of invasive species depends ultimately on capacity invader to disperse colonise over multiple scales. Spread seaweed Codium fragile ssp. (Codium) can occur through dispersal vegetative fragments, which be buoyant or non-buoyant depending environmental conditions. This study examined factors influencing dispersal, settlement, establishment these two types propagules in eelgrass (Zosteramarina) meadows iles de la Madeleine, Canada, where lives epiphytically rhizomes. To measure ~1,400 fragments were marked, released, tracked under different hydrodynamic conditions areas high low density. Under all conditions, dispersed one orders magnitude further than fragments. Dispersal distance was positively correlated with wind speed (a proxy for surface currents this system) current For latter, also negatively height Natural deposition drifting experimentally-manipulated variable space time, but not affected by shoot Experimental disturbance enhanced density, biomass, percent cover Codium, suggesting that exposure rhizomes natural anthropogenic promotes invasion Codium. Our results highlight importance small-scale field experiments determining local affecting species.