Phytoplankton are microscopic algae that form the base of nearly every marine food web. Their growth is limited by two things that trade off with depth: light, which is strongest near the surface and fades with depth, and nutrients like nitrate and phosphate, which are usually scarcer near the surface and richer in deep water. When winds or seasonal mixing bring nutrients up into a sunlit layer, cells divide rapidly — a bloom. Grazing zooplankton and nutrient exhaustion eventually end it.
A single spring diatom bloom can strip a water column of nearly all its dissolved nitrate within two to three weeks — visible from space as vast green-blue swirls in satellite chlorophyll imagery.
A 3D ocean water column split into depth layers, each running a simplified nutrient–phytoplankton–zooplankton model so a bloom's rise, peak and crash can be watched forming in real time.
Phytoplankton growth is capped by whichever is scarcer, light or nutrients, at each depth. Nutrient upwelling fuels growth, grazing zooplankton with a saturating response can trigger a bloom crash, and clearer water lets light — and growth — reach deeper layers.
Raise nutrient input to fuel a bloom, adjust water clarity to control how deep light penetrates, and dial grazer population up to watch predation cap or crash the bloom. Reset to restart from a pre-bloom baseline.
Large spring diatom blooms are visible from orbit as swirling green-blue patches in satellite chlorophyll maps, and can strip a water column of nearly all dissolved nitrate within a few weeks.