Wind Up

Wind Up: upwelling and coastal productivity for Cambridge IGCSE Marine Science

This free game is part of our Cambridge iGCSE Marine Science (0697) course for exams in EXAM YEARS 2027-2029.

Be the trade wind

In Wind Up you are the trade wind over the coast of Peru. The front of the 3D model is cut away, so you can see a slice through the sea: warm surface water on top and cold deep water below the thermocline. Swipe from the coast out to sea and you watch upwelling happen live: the wind moves the surface water away from the coast, and cold, nutrient-rich water rises from below to replace it. The game covers the Cambridge IGCSE Marine Science (0697) points on how winds cause upwelling, productivity, the importance of local upwellings to coastal ecosystems and the role of bacteria in cycling nutrients.

• A coast buoy shows the temperature of the surface water at the coast: about 23 °C when the wind drops, about 15 °C when cold water wells up.
• Blow the other way, towards the coast, and you see downwelling: warm surface water piles up and sinks, and the nutrient-rich water is pushed down.
• On Peru's coast the real trade wind blows along the shore, and the Earth's spin (the Coriolis effect) turns the surface water out to sea. Either way, it is the wind that moves the surface water away from the coast.

Productivity and the bloom

When the nutrients reach the sunlit surface, phytoplankton bloom and the sea turns green. Phytoplankton are producers: they photosynthesise, using energy from light to make glucose from carbon dioxide and water. A productivity bar shows the rate at which producers transfer energy into carbohydrates. It only stays high while the wind keeps bringing up nutrients, so in Mission 2 you keep it in the green through gusts and lulls. Stop blowing and productivity crashes within seconds, because warm surface water has plenty of light but very few nutrients.

The nutrient loop: marine snow and bacteria

Mission 3 follows nutrients all the way round the cycle. You tap a glowing clump of marine snow (dead phytoplankton, waste and other remains) and watch it sink. Bacteria decompose it, so the nutrients become available again in the deep water. Then you blow the wind to return them to the surface by upwelling, where they are taken up by phytoplankton and passed up the food chain to zooplankton and anchovy. Close the loop three times to finish the mission.

Why upwelling matters to coastal ecosystems

Upwelling zones cover less than 1% of the ocean's surface but provide about a fifth of the world's fish catch. In Mission 4 the bloom feeds zooplankton, the zooplankton feed shoals of Peruvian anchovy, and Peruvian boobies dive on them from a guano island. You tap the shoals to send the village's purse seiners out and land 500 tonnes. Let the wind drop and the bloom fades, the shoals scatter and the nets come back empty. Other big upwelling zones include the California, Canary and Benguela currents, all on the west coasts of continents.

El Niño

In the last mission the trade winds weaken and reverse. Warm water spreads east, the surface of the eastern Pacific off Peru warms by several degrees and the thermocline gets deeper, so upwelling is reduced and what does rise is warm and low in nutrients. The bloom fades, the anchovy scatter, the seabirds leave, and heavy rain falls on Peru's desert coast while Australia and South East Asia get less rain than usual. Then the trade winds return and you restart the upwelling. Every mistake brings up a short explanation with a link to the lesson, and the recap at the end lists everything you need to remember.