Each colony grows logistically toward a max size, the same S-curve used for real coral-cover models:
dr/dt = k·r·(1 − r/rmax)
k = kBase · (waterQuality/100) · health
Thermal stress follows NOAA's Degree Heating Weeks (DHW) method: whenever the sea-temperature anomaly exceeds the +1 °C bleaching threshold, stress accumulates; below it, stress decays.
DHW += max(0, anomaly − 1) · dt_weeks
DHW > 4 → colony bleaches (health drops)
DHW > 8 → rising mortality probability per step
Restoration outplanting adds new juvenile colonies at the chosen rate each simulated year, seeding open substrate with full health. A surviving, un-stressed colony slowly regains health and resumes growth.
- Green→white — colony health from full to fully bleached.
- Dark skeleton — a dead colony (permanent, until a future outplant grows nearby).
- Coral cover — total colony area as a percentage of the reef footprint.