Benthic communities inhabiting the continental shelves and slopes worldwide are in a poor conservation state, with fishing practices having greatly contributed to the degradation of deep-water habitats to a point where the abundance of benthic megafauna has declined dramatically. As a result, most deep-sea benthic habitats are considered by FAO as Vulnerable Marine Ecosystems (VMEs): groups of species, communities or habitats highly vulnerable to fishing impacts.

Amongst these, sponge communities are both drivers of many key biological processes for deep-sea ecosystems as well as particularly vulnerable to bottom-contact fisheries, as the latter can trigger a rapid reduction in their structural complexity and diversity by vast biomass removal as bycatch. This results in an impoverishment of their associated biodiversity and of the many Ecosystem Services they provide. In this sense, during the past decades there has been a surge regarding the potential restoration of VMEs worldwide, yet almost all attention has been focusing on corals, despite sponges and other benthic taxa being key players in these structural habitats. Successful application of most restoration efforts will first require a deeper understanding of biodiversity and ecology of deep-sea ecosystems, and a better knowledge of ecosystem resilience and recovery rates of its fauna. Currently, knowledge of the faunal composition, areal extent, or the effects of human impact on sponge communities is almost non-existent for most of the deeper areas of the Portuguese continental shelf and slope. This knowledge gap already hampers the development and implementation of management and restauration tools, limiting the capacity to achieve positive and sustained long-term conservation efforts. It is therefore of an outmost priority to get a sound understanding of the survival potential of by-caught sponges and explore the viability of restoration actions aimed at the recovery of these habitats. In this context, the overarching goal of the SpongeREST project is to get a sound understanding of the basic ecological and physiological traits of habitat-forming sponges to assess their restoration potential. In order to do such, we will i) analyze the by-catch rates of VME habitat-forming sponges by bottom fisheries in northern Portugal while, parallelly, evaluating for the very first time their survival rates upon their accidental capture, by measuring their survivability to air exposure. Later on, we will ii) explore the propagation capabilities of selected species ex-situ in aquaria facilities through explants, while trying to determine the environmental factors (e.g. temperature) and explant characteristics (e.g. shape, size) that maximise survivorship. Ultimately, in order to assess the sponge’s restoration potential, we aim iii) to develop a sponge Restoration Potential Index (sRPI) to determine, based on cost-efficient and easily-obtainable characteristics, the potential of any given species for future restoration actions.