The Royal Netherlands Institute for Sea Research (NIOZ) started the ‘Tree Reefs’ project in 2022 to place artificial reefs in the Wadden Sea. The aim is to bring back the mussel and oyster reefs that used to exist on the bottom and to restore marine life there.
“Many of those reefs, and with them the natural structure in the Wadden Sea floor, have disappeared due to fishing, dredging activities and disease,” says Jon Dickson, who leads the Tree Reefs project.
Cuttlefish
In April last year, Dickson and his fellow researchers at NIOZ converted 192 trees into 32 artificial reefs and placed them in the Wadden Sea.
After four months, the researchers hoisted up part of the reefs to see if anything could live on them. “There were already mussels growing on the reef. There were also several types of fish and other animals around the reef,” says Dickson.
Last week was the second time that the artificial reefs were checked. The researchers were surprised by the results: 20 animal species were found, including butterfish and sea squirts. They also found squid eggs, and crabs crawling around the reefs. “We’ve seen fish use the reefs for shelter, but also to find food,” says Dickson.
He is delighted: “It is encouraging that these reefs generate so much biodiversity in such a short time. We see them creating a small ecosystem.”
Natural materials
“We have previously tested different types of material to see which would be best suited for the artificial reefs,” says Oscar Franken, scientific coordinator of the Wadden Mozaïek project, which includes the ‘Tree Reefs’ project.
Wood used to contribute to the reefs in the Wadden Sea. “It is therefore also an ideal material from a historical point of view. It used to be transported via rivers into the sea. But due to the dams that people have built on the rivers, there is no longer any wood in the area,” explains Franken .
According to Dickson, it is the first time humans have built artificial reefs from fruit trees. The choice of pear trees is because they sink and stay intact longer. “Moreover, a pear tree consists of natural materials. And animals love it.”
Doctor of people
Although the project so far shows that pear trees can help restore nature in the Wadden Sea, pear tree reefs should not become the means of preserving nature. That is the opinion of Lars Soerink, of ARK Rewilding, which organizes initiatives for nature conservation and nature management.
Soerink says ‘a push in the back for nature’ is not so bad, as long as nature can continue to recover afterwards.
2023-08-25 17:32:54
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