Deployment of a remote underwater video system to monitor a reef restoration site in Flensborg Fjord. Photo: Casper Tybjerg (

PhD defence about restoration and monitoring of rocky reefs

Wednesday 26 Jan 22


Jon Christian Svendsen
Senior Researcher
DTU Aqua
+45 93 51 16 63

On 9 February 2022, Tim Wilms from DTU Aqua will defend his PhD thesis. It is possible to attend the defence online.

Reefs consisting of marine rocks or hard-bottom substrate (i.e. geogenic reefs) are an important type of coastal habitat on which a wide variety of marine species depend for foraging, shelter and reproduction. However, marine rocks have been extracted from the Baltic Sea for more than a century to serve as material for the construction of e.g. jetties and piers, a practice that was eventually banned by Danish law in 2010. The removal of marine rocks has resulted in large areas of degraded or permanently lost habitats with detrimental effects to inhabiting flora and fauna. 

In his PhD project, Tim Wilms has investigated the potential for recovering geogenic habitats by focusing on two independent reef restoration projects conducted within degraded coastal areas in the western Baltic Sea (in the waters at the east coast of southern Jutland, Denmark). 

Furthermore, Tim Wilms has evaluated various techniques to monitor the restoration efforts with a minimal impact to study organisms and habitat, i.e. non-invasive monitoring. 

The results of the research show that geogenic reef restoration can provide suitable habitat for a range of reef species and even for some soft-bottom organisms, with a potential to strongly enhance the abundance of commercially important cod fishes and to benefit species diversity. 

The PhD project identifies baited video systems as a particularly useful method to monitor restored habitats in aquatic systems by producing high-quality data with a minimal impact on the surroundings. However, Tim Wilms also points out that sampling of environmental DNA is rapidly evolving to further expand our knowledge on marine species and their association with surrounding habitats. 

About the PhD defence

Tim Wilms will defend his PhD thesis "Restoration and non-invasive monitoring of geogenic reefs in temperate waters" on Wednesday 9 February 2022, 13:00 (CET) on Teams (find link below).


  • Principal Supervisor: Senior Researcher Jon C. Svendsen
  • Co-supervisor: Senior Researcher Josianne G. Støttrup
  • Co-supervisor: Senior Researcher Henrik Baktoft


  • Senior Researcher Niels Jepsen, DTU Aqua (chair)
  • Professor Peter Grønkjær, Aarhus University, Denmark
  • Senior Scientist Even Moland, Institute for Marine Research, Norway

Chair at defence

  •  Senior Researcher: Martin Lindegren
Learn more

A popular science summary of the thesis can be downloaded here

A copy of the thesis is available by e-mail on request. Please contact Tim Wilms,

Link to Teams and guidelines for online attendance

Everybody is welcome to join the defence on Teams. Click here to attend Tim Wilms’ defence via Teams

Please, enter the meeting no later than 12:50 (CET). All participants are muted per default, but we ask you to double check that your microphone is turned off at all times.

There will be instructions regarding the proceedings in the beginning of the defence.