Ekologisk design som metod för anpassning av konstruktioner i kustvatten: en kunskapsöversikt

Humans have a long history of influencing coastal and marine landscapes. Large parts of the world's coastline have been modified due to constructions. This development is expected to intensify with increased needs for infrastructure for housing, transport and energy production, as well as coastal protection from the effects of climate change. All types of structures introduced into the aquatic environment can affect aquatic life by causing the loss and alteration of natural environments. Hydrodynamic conditions and biogeochemical processes can also be affected. Artificial structures that are placed in the aquatic environment create a new type of habitat that may resemble, but are not full equivalents, to natural habitats. Under certain conditions, their effects can be perceived as positive by humans. The introduced hard structures create surfaces to which organisms can attach themselves, and fish can be attracted to the area. These processes give rise to what is known as an artificial reef effect, which can locally lead to more species. It is common for the species composition that arises around artificial structures to differ from natural environments in their vicinity, as the structure and habitat are different. The same applies to effects on other ecological characteristics such as biodiversity, dispersal conditions and ecosystem function. If the artificial structure is more similar to a natural habitat, there is a greater chance that the colonising plant and animal communities will also develop to resemble those in a natural habitat. With increased building in the aquatic environment, there is a growing need and to be able to influence the ecological effects using ecological engineering. A common method is to increase the structural complexity of surfaces, for example by providing gaps, holes and varying surface structures. Species richness is often higher in such ecologically designed structures than in structures with traditional design, which are more homogeneous with smooth surfaces. Surfaces can also be designed to promote specific species, for example by adapting their dimensions and complexity to their needs. Another way is to actively seed in the desired species at an early stage. It may be particularly interesting to promote habitat-forming species, such as mussels and macroalgae, which in themselves can further contribute to creating a more varied habitat. An overall goal is to reduce the negative impact of artificial environments on biodiversity, which also means preventing or counteracting the establishment of undesirable species. For all constructions in the aquatic environment, it is essential to follow up on how biodiversity is are affected and how species interact with the added structures. Increasing our understanding of how ecological designs affect aquatic life is important for further developing them as a method for counteracting biodiversity loss. They can also potentially strengthen certain ecosystem services. The number of available studies evaluating ecological designs has increased in recent years, but there are still many knowledge gaps. Comparatively few studies internationally are directly applicable to Swedish conditions. A general shortcoming is that artificial structures are often compared with nearby areas instead of considering what the built area looked like before the intervention. There is also a particular need for long-term studies and a better understanding of the large-scale effects of increased building in water.