Effects of post-collection storage conditions on sperm motility longevity in the blunt sea urchin Sphaerechinus granularis

The standardization of procedures for the post-collection management of semen samples is a prerequisite for the development of husbandry techniques, as well as for the use of semen in laboratory research. Despite the relevance of the sea urchin Sphaerechinus granularis as a laboratory model, the basics related to sperm collection and storage have received little attention. The aim of this research was to optimize procedures for the management of S. granularis semen, focusing on the post-collection storage of samples. Specifically, the effects of post-collection storage conditions on sperm motility parameters were evaluated; motility was assessed by computer-assisted analysis (CASA-mot) upon activation (t0), and 15 min, 30 min and 60 min after dilution in freshly collected semen, and in chilled and cryopreserved samples. Motility parameters remained unchanged for up to 60 min after activation in both fresh and chilled semen. In cryopreserved samples, sperm motility upon activation was significantly lower than in fresh semen; however, no differences with respect to t0 values were recorded when thawed semen was cold- incubated for up to 60 min post activation, thus meeting standards required by germplasm cryobanks. Post-activation longevity showed by both fresh and stored S. granularis semen, as well as its resistance to cryopreservation, are positive spermatological features that will allow the running of easy management procedures, encouraging a wider use of S. granularis in hatchery practices, as well as in laboratory activities.