Collection information of the genus Geodia from boreo-arctic North-Atlantic deep-sea sponge grounds

Boreo-arctic sponge grounds are essential deep-sea structural habitats that provide important services for the ecosystem. These large sponge aggregations are dominated by demosponges of the genus Geodia (order Tetractinellida, family Geodiidae). However, little is known about the basic biological features of these species, such as their life cycle and dispersal capabilities. Here, we surveyed five deep-sea species of Geodia from the North Atlantic Ocean and studied their reproductive cycle and strategy using light and electron microscopy. We confirmed that these five species were oviparous and gonochoristic and that their reproductive season spanned similar periods: from late spring to early autumn. Concerning their reproductive strategy, the high abundance of lipid yolk observed in the female gametes could indicate both a necessity for rapid fuel during embryogenesis in the water column and increased buoyancy for drifting over longer times. Overall, the investment in reproduction was lower for all the surveyed species compared to similar shallow-water species. Given the present hazards that threaten sponge grounds, it becomes crucial to understand the processes behind the maintenance and regeneration of populations of keystone deep-sea species in order to predict the magnitude of human impacts and estimate their ability to recover. The information provided in this study will be useful for developing adequate conservation strategies for these vulnerable deep-sea habitats.