Coastal reef restoration in temperate waters: Counteracting fish habitat loss with the construction of artificial stone reefs

Tim J.G. Wilms

Publication Date:

Coastal marine ecosystems are facing increasing levels of degradation worldwide as a consequence of anthropogenic activities. The extraction of marine substrate is particularly damaging as it permanently alters the seabed structure, and recovery is unlikely to occur without human intervention. In Denmark, large-scaled extraction of marine boulders occurred for over a century until it was banned in 2010. Since then, a number of restoration projects have been initiated in an attempt to recover this important habitat type and its functions. In this study, we restored a series of coastal stone reefs in Flensborg Fjord, South Denmark. Field sites were monitored with the use of remote underwater video stations (RUVS) in a before-after control-impact (BACI) experimental design. Artificial reefs were constructed either as a large dense reef or as multiple scattered reefs in an attempt to address the ongoing “Single Large or Several Small” (SLOSS) debate in conservation biology. Our results show that the reef restoration efforts had a significant positive effect on total fish abundance. Species richness was also higher on artificial reefs compared to control sites. In terms of reef design, the single dense reefs promoted the abundance of commercially important species, e.g. codfishes (Gadidae), whereas overall species diversity was higher on scattered reefs. Our study provides pertinent information for future marine habitat assessments and emphasizes the importance of considering reef design when constructing artificial reefs. Efforts to recover important fish habitat worldwide are increasing, highlighting the need for effective restoration methodologies.

Resource Type:
Audio/Video, Conference Presentation, SER2019

Society for Ecological Restoration