Living between sand and waves: Age and feeding habits of sand sole (Pegusa lascaris, Risso 1810) and brill (Scophthalmus rhombus, Linnaeus, 1758) on the beaches of the Gulf of Cádiz (Southwest Iberian Peninsula)

Abstract

Within ecosystems that are used as nurseries, surf zones are crucial for many species due to the protection and sustenance these areas provide. Many commercially important species live in these zones during their early years, including the sand sole (Pegusa lascaris) and the brill (Scophthalmus rhombus). The objective of this study was to determine the age and feeding habits of individuals from both species living in the surf zone, as well as any potential variations with the environmental variables such as time of the day, lunar phases or season. The average size was 15.66 ± 3.71 cm (TL) for the sand sole and 11.49 ± 5.66 cm (TL) for the brill. The length-weight relationship for the sand sole was TW = 0.005*TL3.230 (parameter a: 95 % C.I.: 0.004–0.006 and parameter b: 95 % C.I.: 3.134–3.326), while for the brill it was TW = 0.013*TL3.048 (parameter a: 95 % C.I.: 0.012–0.016 and parameter b: 95 % C.I.: 2.988–3.108). In both the sand sole (92.4 %) and the brill (85.6 %), the most abundant age classes were 0+ and 1+, with significant differences in the abundance of age classes, depending on the season, in the case of the brill. The sand sole primarily feeds on cumaceans and bivalves, with significant variations in diet based on the time of the day, moon phases, and season, whereas the brill preys on mysids. This research provides new insights into how both species utilize the surf zone, using these areas as nurseries in their early years of life. This underscores the importance of these zones and the potential of the ecosystem services they offer.