Biogenic reefs at risk: Facing globally widespread local threats and their interaction

Biogenic reefs are secondary marine substrates, also referred to as bioconstructions or bioherms, made by autogenic ecosystem engineers (sensu, Jones et al., 1994) that provide habitats for various species. Their ecological role goes far beyond simple physical effects because they can modulate many resources and interactions between species inhabiting the reefs. Marine bioconstructions involve a variety of fragile three-dimensional habitats, from shallow water coral reefs to mesophotic coralligenous concretions, hosting rich, and diverse benthic assemblages (Cocito, 2004; Ingrosso et al., 2018; Cerrano et al., 2019). Biogenic reefs can be found from the intertidal to the deep sea; some are ephemeral and last a few years, while others remain active for millennia. The main framework builders are able to form bioconstructions at different latitudes, from tropical to polar zones, and include films of cyanobacteria and diatoms, calcareous rhodophytes, sponges, hermatypic symbiotic and aposymbiotic corals, polychaetes as serpulids and sabellariids, mollusks like vermetids, oysters and mussels, and bryozoans.