Zooplankton filter huge volumes of water and passively pick up microplastic particles at roughly the water's own concentration. A small fish eats thousands of zooplankton over its life, but its body excretes plastic far more slowly than it keeps eating more — so the particles bioaccumulate in its tissue, settling at a concentration noticeably higher than any single zooplankton or the water itself. A larger fish then eats many of those already-elevated small fish and inherits — and further concentrates — their load. Repeating this hand-off at each successive trophic level is biomagnification: the concentration compounds multiplicatively with every step, so a top predator several levels up the chain can carry a load many times higher than the ambient water where it all started.
C(level i) = C(water) × Π(hop factors 1..i)
longer chain → more multiplicative hops → more extreme magnification
- Ambient concentration — how much microplastic is in the water itself; every level's load scales from this baseline.
- Trophic levels — how many consumer stages sit above the water (zooplankton → … → top predator); adding a level adds another multiplicative hop.
- The bar chart on the right shows every level's concentration on a shared scale, so the climb from base to apex is visible at a glance.
Real-world relevance: this is exactly why regulators measure microplastic and persistent-pollutant loads in top predators (tuna, seabirds, marine mammals) rather than only in seawater — by the top of the chain, a contaminant that was barely detectable in the water can reach concentrations that pose a real health risk.