Spermatogenesis of Bathymodiolus azoricus in captivity matching reproductive behaviour at deep-sea hydrothermal vents

This study aims to improve our knowledge on the reproduction cycles of invertebrates from deep-sea hydrothermal vents, which is fragmentary to date, owing to the prohibitive costs of regular time series sampling required for a complete assessment. However, new technologies such as acoustically retrievable cages and the long-term laboratory maintenance of vent species enabled sampling at relatively low costs. Reproductive patterns of the vent bivalve Bathymodiolus azoricus were studied with regard to the onset of spermatogenesis in captivity as compared to specimens from the wild.Following 1-year in our controlled laboratory set-up, spermatogenesis started in January–February, as “naturally occurs” in mussels at hydrothermal vents, which provide further supporting evidence for an annual reproduction in B. azoricus.In addition, we describe a functional methane-feeding system for the long-term maintenance of the hydrothermal mussel that represents great potential for post-capture experimental investigations.