Evaluation of different procedures for fertilization and larvae production inHediste diversicolor(O.F. Müller, 1776) (Nereididae, Polychaeta)

Abstract

Different experimental trials were performed to clarify some aspects of the biology of the polychaete Hediste diversicolor (O.F. Müller, 1776) as a further step towards the development of appropriate breeding protocols for indoor farming systems. In particular, the trials were addressed to evaluate the effectiveness of two fertilization conditions (in vitro and “natural‐like”); induce gamete spawning by exposing mature individuals to thermal shock or to tissue homogenates; estimate the density effects on larval growth and survival; and evaluate the most suitable parameters to be used as proxy for biomass assessment. The highest percentages of fertilized eggs and larvae were obtained by the in vitro fertilization condition. Mature organisms were induced to spawn by exposure to thermal shock although the spawned eggs revealed low rates of fertilization and hatching. The treatment with male tissue homogenates induced females to successful spawning, and the resulting eggs showed high fertilization and hatching rates. The density of larvae in the rearing phase had no effect on growth or on survival rates of juveniles. Finally, allometric evaluations showed that fresh weight and L3 length are the most reliable parameters to be used as proxy for biomass assessment of this species.

Embryonic and larval development in the semelparous Nereid polychaete Hediste diversicolor (OF Müller, 1776) in Norway: Challenges and perspectives

“…The coloration of the adult worm can be picked out 1 or 2 months before the spawning seasons, which was considered the suitable time to collect the parental worms. Nesto et al (2018) kept the maturing worms in glass pipes (5 mm) placed in 50 ml tubes to prevent asynchronous spawning. We tested several glass pipettes with a diameter of around 5 mm placed in a plastic rectangle box to shelter the parental worms (Appendix Figure A3).…”

“…Dales (1950) and Smith (1964) did not observe natural spawning under laboratory conditions, but Dales (1950) distinguished ripe females as reddish brown and the males as bright green which enabled the selection of broodstock for artificial fertilization. Nesto, Simonini, Prevedelli, and Da Ros (2018) used naturally spawned eggs in the laboratory to breed, but the natural spawned eggs had lower fertilization rates compared with in vitro fertilization. Ozoh and Jones (1990) found that fertilization of H. diversicolor was not affected in the ranges of temperature from 12 to 22°C, while the capacity adjustment of embryonic cleavage to increasing temperature deceased with increasing salinity.…”

Insight into aquaculture's potential of marine annelid worms and ecological concerns: a review

“…), extend of breeding season and/or cryopreservation of larvae to achieve larval supply all year round, develop appropriate breeding protocols (Nesto et al . ), optimize growth through control of nutrition with new diets (Santos et al . ), temperature and, if appropriate, photoperiod (Olive ), all contributing to improve the production of polychaetes.…”

“…Polychaete aquaculture has been developed for several species but there are hurdles to develop this activity. Research that allowed knowledge to produce new native species can enhance the diversification of the bait produced, develop simple inexpensive systems for rearing juveniles (Garc ıa-Alonso et al 2013), extend of breeding season and/or cryopreservation of larvae to achieve larval supply all year round, develop appropriate breeding protocols (Nesto et al 2018), optimize growth through control of nutrition with new diets (Santos et al 2016), temperature and, if appropriate, photoperiod (Olive 1999), all contributing to improve the production of polychaetes.…”

“…Larvae can be obtained naturally with males and females in the same tank (Santos et al 2016) or with artificial fecundation (Serebiah 2015). Nesto et al (2018) evaluated the effectiveness of two fertilization conditions, in vitro and natural, using tissue homogenates or thermal shock. Percentages of fertilized eggs and number of larvae were higher using in vitro fertilization, while low rates of fertilization and hatching were observed when mature individuals were induced with thermal shock.…”