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

Marc Baeta,Eve Galimany,Montserrat Ramón

doi:10.1186/s10152-016-0453-z

Abstract

The growth and reproductive biology of the sea star Astropecten aranciacus was investigated on the continental shelf of the northwestern Mediterranean Sea. Sea stars were captured monthly in two bathymetric ranges (5–30 and 50–150 m) between November 2009 and October 2012. Bathymetric segregation by size in A. aranciacus was detected: small individuals inhabit shallow areas (5–30 m), while large individuals inhabit deeper areas of the continental shelf (50–150 m). Recruitment was recorded twice nearshore but no recruitment was detected offshore during the whole study period. Three cohorts were identified in each bathymetric range and growth rates were estimated. A. aranciacus population exhibited a seasonal growth pattern, being higher from June to October in the nearshore cohorts and from February to October in the offshore ones. Histology and organ indices revealed that spawning likely started in March, coinciding with the spring phytoplankton bloom and the increase in sea water temperature, and extended until June–July. Ratio between males and females was approximately 1:1 throughout the year and in both bathymetrical ranges. The size at first maturity (R50 %) was estimated to be R = 112 mm. A. aranciacus did not show an inverse relationship between gonad index and pyloric caeca index.

Highlights

Sea stars play an essential ecological role as high-level predators in the structure and function of intertidal and subtidal benthic communities, where they promote heterogeneity and diversity [23]
Offshore, we observed the presence of Luidia ciliaris and Tethyaster subermis, potential predators [23] that could play an important role in the recruitment failure of A. aranciacus. 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 gonadal index (GI) value was highest in March, indicating that during that month the gonads of A. aranciacus were in maximum development

Summary

Introduction

Sea stars play an essential ecological role as high-level predators in the structure and function of intertidal and subtidal benthic communities, where they promote heterogeneity and diversity [23]. Astropecten (Fam. Astropectinidae) is one of the most species-rich genera among sea stars and its members are distributed worldwide, from polar to tropical seas and from intertidal areas to the deep sea [49]. Astropectinidae) is one of the most species-rich genera among sea stars and its members are distributed worldwide, from polar to tropical seas and from intertidal areas to the deep sea [49] They are voracious predators, feeding mainly on gastropods and bivalves. They have an intra-oral feeding mechanism, swallowing prey intact [11]. In general they exhibit a patchy spatial distribution as a consequence of a combination of biotic (e.g., prey and congener abundance) and abiotic factors (e.g., depth and sediment properties) [36]. Resources stored in pyloric cecum seem to play an important role in the seasonal production of gonads in some asteroid species [29]

Methods

Results

Conclusion