Corals searching for food in the cold and dark waters of the deep sea are building high mountains to get closer to their food source. But in doing so, they may find themselves trapped when the climate changes. This is shown in the thesis that theoretical ecologist Anna van der Kaden of NIOZ in Yerske and the Copernicus Institute for Sustainable Development in Utrecht will defend on February 20 at the University of Groningen. “When the water warms up, these creatures like to go deeper, but the coral doesn’t just move under the cliff,” van der Kaden said.

Deep and dark

Unlike the famous, colorful tropical corals, cold-water corals live in deep waters a few hundred meters deep, for example off the west coast of Ireland. In the dark, they don’t live with the algae that often give tropical corals their brilliant colors. After all, these algae need light. “But that certainly doesn’t mean that cold-water corals are boring,” van der Keden emphasizes. “Sometimes they have beautiful colors of their own. And they certainly play just as important a role in the ecosystem as tropical reefs. For example, they are food oases for fish. In marine systems they have Very central location.”


Van der Kaden researched real rocks and ‘mathematical rocks’ in computational models. “In both cases, I tried to discover the spatial patterns in which corals grow. With the Australian Great Barrier Reef, for example, it’s very simple: you can see their growth patterns even from space. With cold-water corals, you have to walk around in a dark maze to identify these patterns, so to speak, with only a small flashlight. And yet, using statistical techniques and video stills, we managed to get the overall picture,” she notes. His paper, among other things, describes the regular reefs, ridges, and mountains that coral forms over thousands of years.

Taller than the Eiffel Tower

Van der Kaden also observed how corals, as true ‘ecosystem engineers’, adapt their environment, particularly water flow, to attract more food particles. “Over hundreds of thousands of years, coral reefs form mountains that can grow taller than the Eiffel Tower, so corals rise higher in the ocean, where there is more food, and those mountains also create currents that move the food. mountains.”

A cold-blooded animal

The expectation is that if the water gets too warm due to climate change, the corals will want to go down and cool down. Van der Kaden: “A cold-blooded animal like coral uses a lot of energy in warm water. But coral is a bottom-attached animal, so it can’t just go down a cliff. It’s dispersed by larvae. It happens. But for new corals, feeding conditions at the edge of coral reefs are worse because of specific flow patterns.”


Van der Kaden doesn’t want to immediately sound the alarm about the survival of cold-water corals in a changing climate. “Maybe these organisms are more resilient than we think, and if not, they can build new mountains or rocks in other places. But with this research, I want to show how an organism’s response to climate change can evolve.” “Prediction is not always easy. There are many complex processes that create unexpected constraints or opportunities. We as a society must take this into account when preparing for the impacts of climate change.”