Reproductive biology of the starfishPharia pyramidatus(Echinodermata: Asteroidea) from the Mexican tropical Pacific

Abstract

<jats:p>The starfish<jats:italic>Pharia pyramidatus</jats:italic>is a tropical species of high ecological importance, mainly because of its role as generalist predator. Nevertheless, there are no studies about its reproduction. This study analysed the reproductive biology of<jats:italic>P. pyramidatus</jats:italic>based on monthly time-series samples from April 2008 to March 2009 at Isla Montosa in the Mexican tropical Pacific. The gonad index (GI), and pyloric caecum index (PCI) were determined and the results were corroborated by histological examination of the gonads.<jats:italic>Pharia pyramidatus</jats:italic>is a gonochoric asteroid and the ratio of males to females was not significantly different throughout the year. Gametogenesis showed high synchrony among males and females and five stages were recognized for both sexes. Spawning occurred from July to September. Maximum oocyte size was ~150<jats:italic>μ</jats:italic>m and mean fecundity was 7.3 ± 1.2 millions of oocytes per female. GI and PCI showed seasonal variations and an inverse relationship from May to August. Sea-bottom temperature and photoperiod showed a direct relationship with GI, and apparently constitute the proximate causes of the seasonal reproductive pattern observed in<jats:italic>P. pyramidatus</jats:italic>, while the highly seasonal rainfall and strong upwelling probably act as ultimate causes.</jats:p>

Growth and reproductive biology of the sea star Astropecten aranciacus (Echinodermata, Asteroidea) on the continental shelf of the Catalan Sea (northwestern Mediterranean)

“…Results showed that both A. aranciacus sexes had a synchronous gametogenesis but females reached the maturity stage slightly earlier than males, in accordance with previous results obtained in Asterias amurensis by Byrne et al [9]. The studied A. aranciacus population did not differ significantly in the male-female proportions, coinciding with previous results in other sexually reproducing asteroids (since sex-ratios can be highly biased in the case of asexual asteroids) [4,26]. The development of the A. aranciacus gonads reflected that mature and partially spawned individuals remained for an extended period of time.…”

“…However, this interaction has not been observed in species inhabiting areas with stable environmental conditions [4]. This relationship was not observed in the studied A. aranciacus population despite the fact that it inhabits a seasonally changing environment, in accordance with the results obtained by Ventura et al [48] in A. cingulatus.…”

“…Relations among PCI, temperature, photoperiod and Chl a (independent variables) with the reproductive cycle represented by GI (dependent variable) were assessed through a step-by-step multiple linear regression analysis (GLM) using STATA v1.2 statistical Software (Stata Corporation, College Station, TX, USA). Statistical significance was accepted at p < 0.05 [4].…”

“…Microscopic examination of the sections allowed sex determination and assignation of each individual to a gonad maturation state. Development was divided into five stages based on an adaptation of scales used for other asteroid species, where each stage is determined according to the frequency and characteristics of gametes, presence of phagocytes and cell remains, as well as thickness and shape of the gonadal wall [4,9,10,32,38].…”

Reproductive biology of Ophiocoma aethiops and O. alexandri (Echinodermata: Ophiuroidea) from Estacahuite Bay, Oaxaca, Mexico

“…When our results were compared with those of Hendler (1979) for Panama, it was evident that the reproductive cycles of the populations coincide, which led us to conclude that the reproductive patterns of Ophiocoma aethiops and O. alexandri are not determined by local dynamics, as otherwise occurs with other echinoderm species in the area (Benítez-Villalobos & Martínez-García 2012). Consequently, we propose that the general pattern of reproduction has a high genetic (endogenous) element, because different populations of these ophiuroids living at dissimilar latitudes show very comparable reproductive patterns.…”