Reproductive timing and synchronized reproduction of the sea urchin Pseudechinus magellanicus (Echinoidea: Temnopleuridae) in central Patagonia, Argentina

ABSTRACT

The reproduction of the sea urchin Pseudechinus magellanicus and the influence of environmental factors were studied during a 27-month period in central Patagonia, Argentina, where this species is among the dominant grazers in kelp forests and tide pools. The monthly variation in the gonad dry weights, gonadal stages and other quantitative reproductive variables (oocyte diameter, density and thickness of spermatogenic columns) indicated a clearly annual gametogenic cycle and revealed a high level of spawning synchrony. A main spawning event occurs between August and September, and a minor and asynchronous spawning event was recorded during the austral summer (January–March). The highest gonadal growth rate occurs between late spring and summer, accompanied by growth and early prematurity gonadal stages, indicating active vitellogenesis. The accumulation of ova begins in autumn and shows a peak during winter. After spawning, the recovery stages are not extended in time and ovaries do not show a complete meshwork of nutritive phagocytes within the acinus, suggesting simultaneous reabsorption and inversion processes. Spermatogenesis shows a higher maturation rate than oogenesis, and a higher temporal prevalence of premature and mature stages. Major spawning coincides with the first rise in seawater temperature, the maximum rate of increase in day length and the maximum peak of chlorophyll a. Results also revealed some temporal differences in the gonadal cycle, vitellogenesis and spawning periods compared with other P. magellanicus populations from different latitudes. This could be attributed to individual differences in the acquisition and allocation of energy for gametogenesis, as well as to local environmental factors.

KEYWORDS:

• Echinodermata
• histology
• gametogenesis
• spawning synchrony

Acknowledgements

We dedicate this manuscript to the memory of our friend and co-author Dr Héctor E. Zaixso, who passed away in 2015 but initiated this and other related echinoderm studies in the Patagonian region. We are grateful to Omri Bronstein and two anonymous reviewers for insightful comments, to Paula Stoyanoff and Javier Tolosano for their help during field sampling, and Vanina Tartalini and Alejandra Martinez for their support in the histological procedures.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by a Universidad Nacional de la Patagonia San Juan Bosco (UNPSJB) research grant provided to DGG (R/7-486/13).