Habitat (macro-)characteristics are currently widely used to infer species assemblagesassociated to them in the context of marine protection extension and Marine SpatialPlanning directive implementation by institutional stakeholders. However, large gapsremain to explicitly link species functional traits and habitat properties (see Axis 1).This issue is particularly tricky in habitats hosting ecosystem engineer species whichstructure co-evolves with the ecosystem engineer population and individual growth.Ecosystem engineer refers to organisms that, through causing changes in the local physicalor biogeochemical conditions, directly or indirectly control the availability of resources(other than themselves) to other organisms and, thus, modify, maintain, or create habitats(Lawton 1994). Autogenic engineers modify their environment through physical changes, whileallogenic engineers do so through chemical transformations (Jones et al. 1994).

In fact,gorgonians, corals or other large symbiotic invertebrates interact with their physical andchemical environment by controlling the gradient of oxygen, CO2/pH, and organic and inorganicnutrients at their interface (Buhl Mortensen et al. 2009). Environmental modifications by ecosystemengineers have been largely studied at a macroscopic scale, but much less is known at the micro-scalewhere these exchange occur and the effect on associated biota. The hypothesis put forward in this axisis that hydrodynamical or biochemical micro-climates associated to particular benthic ecosystemengineers are key to facilitate or inhibit the functions that allows species assemblages to respondto environmental fluctuations (including natural and anthropogenic disturbance).