Artificial Reefs in Marseille: From Complex Natural Habitats to Concepts of Efficient Artificial Reef Design

Abstract

With the deployment of 27,300 m³ of artificial reefs (AR) and a €6 million budget, the project “Récifs PRADO” is the largest artificial reef ever realized in the Mediterranean Sea. This large-scale program is dedicated to the restoration of an active artisanal fishery in a zone where Posidonia beds, a highly productive habitat, have previously been destroyed.

Marine biologists conceived the design of these ARs, benefiting from the feedback of field experience of the colonization of ARs immersed in the French littoral for more than 20 years. The core knowledge was based on years of underwater visual observations of fish behavior and visual censuses of fish assemblages on both artificial and natural habitats. The selected concept was to copy the most performed natural benthic habitats in order to optimize the biological efficiency of AR. Combining architectural complexity, module design and urbanism (laying out of modules on the bottom) was considered to be the key to AR effectiveness.

The reef deployment relied on the creation of horizontal and vertical discontinuities in heights, sizes, and volumes, thanks to a great variety of reef types and shapes, as well as diverse arrangements and horizontal spacing of reefs.

Three years were needed for conceiving the different reef types, the achievement of the technical and administrative folders, and overcoming the numerous technical and administrative problems.