Reproductive cycle and gonadal development of the Atlantic sea urchin Arbacia punctulata in the Gulf of Mexico: changes in nutritive phagocytes in relation to gametogenesis

ABSTRACT

The annual reproductive cycle comprises steady gametogenic activities that synchronize gonadal maturation and spawning rhythms, which are important for aquatic organisms including marine echinoderms (Echinodermata, Echinoidea). In this study, we report the annual reproductive cycle, gonadal development, and changes in nutritive phagocytes (NPs, which accumulate nutrients in germ cells) in relation to gametogenesis of the Atlantic sea urchin (Arbacia punctulata, an edible echinoid) in the Gulf of Mexico. Monthly changes in gonadal development and maturation were observed morphologically and histologically. We calculated gonadosomatic index (GSI) and compared the stages of gonadal development in order to determine the NPs index, and characteristics of germ cells (eggs and sperm) during the annual reproductive cycle. According to GSI and histological analyses, gametogenic activities were classified into four stages of both sexes: mature (June–August), spent (September–November), recovery (December–March), and growing (April–May). The GSI values in both sexes were high during summer months. In males, testicular lobules were densely packed with sperm from June to August. In females, however, mature eggs first appeared in some ovaries in May, numerically increased from June to July, and decreased in August. During gametogenesis, on the other hand, NPs in both testes and ovaries were depleted from June to August. Collectively, our results suggest that the Atlantic sea urchin spawns during summer months in the Gulf of Mexico. This is the first report, to the best of our knowledge, on gonadal development and changes in NPs during the annual reproductive cycle of any Arbacia species in the Gulf of Mexico.

KEYWORDS:

• Annual reproductive cycle
• nutritive phagocytes
• the Atlantic sea urchin
• Gulf of Mexico

Acknowledgements

Thanks are due to School of Earth, Environmental, and Marine Sciences, University of Texas Rio Grande Valley (UTRGV), for the provision of academic materials, laboratory facilities, and guidance towards advanced graduate students’ research. We would like to thank Texas Parks & Wildlife Department for permission to collect wild sea urchins. We also thank Andrew Lawler, Office of Sponsored Programs, UTRGV; Sarah Nash, Mohammad Maruf Billah and Brittney Lacy, School of Earth, Environmental, and Marine Sciences, UTRGV, for their valuable comments and suggestions on the manuscript.

Disclosure statement

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

ORCID

Omar A. Vázquez http://orcid.org/0000-0003-0613-5750

Md Saydur Rahman http://orcid.org/0000-0001-6397-592X

Additional information

Funding

This research was funded in part by the start-up fund and College of Science SEED grants [grants number 210000371] to Dr. M. S. Rahman from University of Texas Rio Grande Valley.