Scientists dumped 192 old pear trees into the Wadden Sea, and something special happened

The corals seem to come alive after only a few months. It shows that the original marine biodiversity can be restored in an amazing way.

Coral reefs, both natural and man-made, are hotspots for marine biodiversity. Unfortunately, the bottom of the Wadden Sea is mainly sandy at present. That was different though. In recent centuries, many solid foundations have gradually disappeared. In a new study, researchers attempted to create a new “reef” by throwing nearly 200 pear trees into the water. whether this works? definitely!

Coral reefs
Hard surfaces such as driftwood, peat bogs, and stones were common in the Wadden Sea. They formed the basis of many animal species such as mussels and oysters. The coral reefs also attract different types of fish, crabs and shrimps. But especially in soft-bottomed seas, these corals are now rare. Many solid anchors have been lost to shellfish overfishing, dredging and trawling, and deep-sea mining. “Before humans domesticated landscapes through agriculture, logging and river management, trees would fall into rivers in large numbers and find their way to the sea,” says John Dixon, a researcher at the Royal Netherlands Institute for Marine Research. “We know that such sunken wood has been present in marine ecosystems since the Jurassic period, providing shelter, shelter and food for marine animals.”

pear trees
in New study The researchers wondered how they could restore this lost biodiversity. In a new experiment, they decided to drop 192 old pear trees into the Wadden Sea. They were transported by ship to the open waters between Texel and Vlieland. There, the “reef” was anchored to concrete feet and lowered to the soft sea floor in four different locations, at a depth of about three to four metres.

And after a few months…
Four months later, the pear trees were briefly lifted aboard a ship. In this way, the researchers were able to count the number of different types of organisms – such as shellfish, algae and polyps – that had adhered to the wood. Then the team took down the pear trees again. After two months, three fish traps were placed around each tree. All fish and shellfish in the traps were identified, counted and measured before being released unharmed.

It explodes with life
To the great surprise of the researchers, the corals exploded within six months after life was found. “Within six months, the reef was covered in an abundance of organisms and algae,” Dixon says. “Moreover, it harbors more fish than the surrounding areas.” In all, the researchers found fifteen species of sessile organisms, such as barnacles and polyps. They also found algae animals, seaweeds, and starfish. In addition, six species of fish (including perch, grebe, and eel) and four crustaceans appear to live around the reefs. And that only 200 meters away, in a place devoid of coral reefs, only two species of fish and five species of crustaceans were found.

Biodiversity
Through the study, the researchers showed that removing pear trees is a cheap and effective way to create coral reefs, which increases the local diversity of marine life. And that too within a very short period of time. “We have shown that native marine biodiversity can be restored in a severely degraded ecosystem such as the Dutch Wadden Sea by using trees as corals,” Dixon concludes.

This means that corals can serve as an interesting recovery measure. Although, of course, we now have only the Wadden Sea as an example. “Since we only conducted our experiment in one sea, we don’t yet know how effective coral reefs are off the coast of other continents,” Dixon says critically. “And how long will they function as corals, given that they are biodegradable? What species will they live in, in and around them in the long term? These are questions we need to answer.”