Research organisation DHI and state-owned Danish infrastructure company Sund & Bælt are mapping marine life near the construction site of the Fehmarnbelt tunnel to learn how the environment adapts to changes from human activities.

Researchers are collecting water samples along the southern coast of Lolland and analysing genetic traces, known as eDNA, from numerous species.

The method for analysing DNA traces in sea water is still evolving but it offers a better understanding of marine life.

DHI marine biologist Ole Brodnicke said using the eDNA method, the species inhabiting the area could be identified from just one cup of sea water.

“These could range from birds and fish to crustaceans and molluscs, including species that are elusive and rarely observed. Moreover, we don’t require a full team of marine biologists or ornithologists to identify the species,” he said.

He relies on an open, international research database containing DNA profiles of the majority of known marine species. However, precision is paramount during both sample collection and the analysis of the DNA mix extracted from the samples.

“The method of sample collection is crucial. We can’t simply gather water from the surface, as it contains DNA traces from seagulls and various other species that may not necessarily reflect life deeper down. We collect samples closer to the seabed, yielding precise local results,” said Brodnicke.

The research team focuses primarily on certain fish species and common eider ducks. However, they also study mussels, worms and crustaceans, which are food sources for larger animals and so provide insights into the development of the coastal marine environment.

DHI will collect and analyse water samples to identify the development among the species and diversity in the project area, which has been altered by the tunnel works. Excavated materials from the tunnel trench have been used for land reclamation, with approximately 7km of coastline extended 500m into the sea, and new stone barriers erected.

“The fascinating question is how quickly nature can establish itself in an entirely human-made environment. But we also want to understand the sequence in which organisms and species appear and replace each other over time until we have a robust environment along the coast,” said Brodnicke,

The research findings will provide insights for Sund & Bælt in planning future coastal infrastructure projects. These could include projects like the proposed Eastern Ring Road, a tunnel east of Copenhagen from Nordhavn to Amager.

“As the developer, we see immense potential in eDNA and the findings from the Fehmarnbelt tunnel project. Understanding the natural progression of an ecosystem in a human-made area can guide us to build in harmony with nature from the onset. This aligns with our experiences from previous large-scale projects such as the Great Belt Bridge and the Øresund Link, and it’s also what we anticipate the eDNA project will demonstrate,” said Lars Hansen, project co-ordinator in Sund & Bælt’s environmental department.