Nature today | Nature restoration through fruit tree reefs

Granted, it sounds strange to place trees on the ocean. And if you can, then why would you want it? To understand this, according to Tjeerd Bouma – NIOZ researcher, professor at Utrecht University and lecturer at HZ in Vlissingen – we must think of tropical reefs. ‘Anyone who thinks of a coral reef imagines a lot of fish. You see a similar picture around shipwrecks in the North Sea. These examples show how important it is as a fish to be able to hide well for hunters who want to eat you, “says Bouma.

But how to recover foxes? Inspired by bike rides in Zuid-Beveland with its many orchards, Bouma got the idea to use felled low-stemmed fruit trees as a TreeReef. “In the Netherlands, we have about 100,000 hectares of orchards. About 250 hectares of this are cleared each year for new planting. These dead fruit trees are a natural by-product with a complex reef structure in itself.” In the past, there were also far more washed-up trees in the Wadden Sea. So Bouma’s idea does not sound so crazy after all.

An experiment

But an idea is, of course, far from an experiment. Fortunately, colleague Tjisse van der Heide – researcher at NIOZ and professor at the University of Groningen – saw opportunities. In the project ‘Vademosaik’ we are looking for ways to improve the underwater nature. And this idea fits in perfectly. Therefore, with the help of the Vade Foundation, we have now started a unique experiment: a small TreeReef. It took PhD student Jon Dickson many tests to arrive at a good design, for the dead trees must remain on the seabed. But everything is in place now, and it is super exciting to see what types of fish will swim in TreeReef, and what will grow on the trees ”.

The concept is appealing, which is why a small piece of TreeReef has been placed in Grevelingenmeer in Zeeland. Less like an experiment, but primarily to inspire people. “In addition to gaining scientific knowledge, it is important to show people what reefs can mean for biodiversity recovery,” says Van der Heide.

Strengthening biodiversity

“Although it sounds very strange to plant trees at sea, this approach fits well with our past,” says Albert Oost from Staatsbosbeheer. “In the past, there were many places with tree remains on the bottom, in the Wadden Sea and Zuiderzee as well as in the North Sea. Therefore, this experiment is interesting: can it help to improve the underwater nature? “

“It could actually be a good way to improve biodiversity and fisheries richness in areas such as the North Sea, the Wadden Sea and the Oosterschelde. And active nature development is crucial to prepare areas such as the North Sea for major challenges such as climate change, huge areas with wind farms, sand extraction, etc., says Gijs van Zonneveld from ARK Nature Development, an organization that is actively involved. for nature restoration. This is further confirmed by Christiaan van Sluis from the De Rijke Noordzee program: “The Dutch part of the North Sea alone is twice as large as the Netherlands inhabited by us. The vast majority of the bottom is a sand plain. Now that we begin to designate protected areas, “It would be great to plant some TreeReefs there right away. Even if it’s just an experiment to see what it does to underwater life.”

Mussels, seaweed and an anemone

Organic North Sea divers Karin Didderen and Wouter Lengkeek from Bureau Waardenburg have high expectations: “Such a tree reef in the North Sea provides shelter for species such as dog hat, cod, stingray, North Sea crab and lobster. In addition, the trees will act as spawning grounds for endangered species such as sharks and rays or other special animals such as squid. In addition, you will see the growth of anemones and cold-water corals, and it will abound with species such as tulips and snails. ”

Upscaling to the North Sea is exactly where scientists Bouma and Van der Heide want to go. “The discarded fruit trees can really be used there ‘fruit the more’ be; reefs full of diversity and a valuable source of marine life ”.

Text: Royal Netherlands Institute for Sea Research (NIOZ)
Photos: Jon Dickson; Oscar Franken

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