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AEI
Aquaculture Environment Interactions

    AEI prepress abstract   -  DOI: https://doi.org/10.3354/aei00350

    Effect of substrate type and pellet age on the resuspension of Atlantic salmon faecal material

    M. A. Carvajalino-Fernández*, N. B. Keeley, I. Fer, B. A. Law, R. J. Bannister

    *Corresponding author:

    ABSTRACT: The influence of substrate type and particle age on the remobilization of settled Atlantic salmon Salmo salar faecal material was studied through a set of controlled experiments in horizontal flow flumes, simulating different bottom conditions present under fish farming locations along the coast of Norway. Critical shear stresses ( EMBED Equation.DSMT4 ) and velocities required for resuspending the faecal pellets were strongly dependent on substrate type. There was no significant effect of the pellet age on remobilization for up to one-week old faecal material. Smooth substrates such as mud and rock slates required lower stresses for the onset of faeces resuspension ( EMBED Equation.DSMT4 ) when compared to rougher surfaces such as sand ( EMBED Equation.DSMT4 ) or fragmented rocks ( EMBED Equation.DSMT4 ), where bedforms and large fractures shield the particles from the direct influence of the drag forces. These new substrate-dependent critical resuspension stresses will contribute to the construction of more accurate numerical models that include bottom type as a parameter regulating the extent of particle spreading, in contrast to the constant-value approach that has been used to date.