Gonad development stages and reproductive traits of Diadema mexicanum (Echinodermata: Echinoidea) from Oaxaca, Mexico

Abstract

Diadema mexicanum is a common inhabitant of the Mexican Pacific coast and a key species for coral reefs dynamics. Several reproductive traits of D. mexicanum throughout one year at La Entrega Bay, Oaxaca (15°44′N), in the Mexican tropical Pacific, were analyzed. Maturity index or microscopic maturity index “MI” was calculated. Annual ratio of males to females (1:1) was not significantly different. Five gonad development stages “GDS” (i.e. development, mature, spawning, post-spawning, nutritive) were recognized. The nutritive stage was noticeably later to post-spawning. High values of gonadosomatic index “GSI” in December 2008 and February/March 2009 did not correspond to maturity but to the nutritive stage. MI values ratified the periodicity of each GDS and spawning preparedness. MI was a better descriptor than GSI for reproductive season of D. mexicanum, and probably for all sea urchins exhibiting the nutritive stage. D. mexicanum has a single annual reproductive season (maturity/spawning) from April to October, similar to the population of Panama (9°00′N), without a second season, as proposed previously for the population of Colima, Mexico (19°10′N). Previous disparities in its reproductive season reflect differences of the environments it inhabits, rather than an effect of the latitudinal gradient in the tropical region.

Keywords:

• reproductive cycle
• gonadosomatic index
• maturity index
• fecundity
• histology
• sea urchin

Acknowledgements

This work is part of the BSc thesis of Bravo-Ruiz AR at the Universidad del Mar “UMAR”. The Project PROMEP-SEP-2IR0707 to Benítez-Villalobos F., financed this research. The specific research permit (No. DGOPA.02934.250308.0646) for the collections of the specimens was acquired with the project. The histological procedure and analyses were done at the histology laboratory of the UMAR. An “old” reference that is not available online neither in Scopus or Web of Science, was granted by Yuko Nagai, General Secretary of The Zoological Society of Japan (http://www.zoology.or.jp/en/). Avila-Poveda OH is commissioned as CONACYT Research Fellow–UAS-FACIMAR (project No. 2137).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Programa de Mejoramiento del Profesorado, Secretaria de Educación Pública (PROMEP-SEP) [Project number 2IR0707].