On the reproduction of two deep-sea Arctic holothurians, Elpidia heckeri and Kolga hyalina (Holothuroidea:Elpidiidae)

ABSTRACT

Internal gonad morphology was examined in two species of elpidiid holothurians, Elpidia heckeri and Kolga hyalina, commonly occurring in the Central Arctic Ocean. The holothurians were sampled in August – September 2012 and in August 2018, at several locations in the Nansen and Amundsen Basins, in areas under the constant ice cover and in areas free of ice. Both species were observed at different reproductive stages and both are presumed to reproduce periodically. In 2012, spawning occurred at the beginning of September in Elpidia heckeri and from late August to early September in Kolga hyalina. There are reasons to believe that gametogenesis in K. hyalina depends on the availability of freshly deposited phytodetritus. The maximum oocyte size in Kolga hyalina (240 μm) was smaller than in Elpidia heckeri (390 μm).

KEYWORDS:

• Abyssal Arctic
• deep-sea species
• reproduction biology
• Elasipodida
• Echinodermata
• sea cucumbers

Acknowledgments

We thank Antje Boetius for organizing the Polarstern cruise XXVII-3 and sampling; Ivan Ryzhov, Renate Degen and crew of RV Polarstern for their great help in sampling and further work on the deck; Andrey Vedenin for collection of samples in the RV Akademik Mstislav Keldysh cruise 72. We are grateful to two anonymous reviewers for their valuable comments to the manuscript. This study was funded by RFBR, project No 17-05-00787 and 18-05-60228. Histological preparation of the material by O. E. was supported by the Russian Science Foundation (project No 18-74-10025).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was funded by RFBR, projects No 17-05-00787 and 18-05-60228. Histological preparation of the material by O. E. was supported by the Russian Science Foundation, project No 18-74-10025.