Hydrodynamic modulation of Microcystin-LR effects on golden mussel filtration: implications for biocontrol

Golden mussel (Limnoperna fortunei) is a filter-feeding invasive bivalve causing extensive biofouling in water infrastructure across South America and Asia. Conventional control methods are often unsustainable, necessitating environmentally compatible alternatives. This study examines the combined effects of microcystin-LR (MC-LR) and flow velocity as potential biocontrol factors. Adult mussels (shell length 1.5 ± 0.2 cm) were exposed to MC-LR (0 ∼ 50 μg/L) under controlled flow velocities (0.00 ∼ 0.60 m/s). Filtration rates consistently declined with increasing MC-LR concentrations, showing over 95 % reduction at 50 μg/L under static conditions. Flow velocity exhibited unimodal effects, with peak filtration rate occurring at the flow velocity of 0.15 ∼ 0.17 m/s, with magnitude decreasing as MC-LR concentration rose. Dose-response analysis revealed that filtration declined logistically at low flow velocities (0.00 ∼ 0.28 m/s) but exhibited exponential decay at higher velocities (0.46 ∼ 0.60 m/s). Response surface analysis identified three functional regimes for biocontrol: optimal filtration (0 ∼ 15 μg/L; 0.10 ∼ 0.25 m/s), transitional inhibition (15 ∼ 35 μg/L), and severe inhibition (>35 μg/L). Concentration-time (C × T) analysis indicated a flow-robust inhibition threshold of approximately 63 μg·h/L. These findings demonstrate that golden mussel toxin sensitivity is strongly modulated by hydrodynamic conditions, providing a mechanistic basis for environmentally sustainable biocontrol strategies that integrate hydrodynamic manipulation with natural algal toxins.