Seasonal variation in fatty acid profiles of Holothuria poli (Delle Chiaje, 1823) from Monastir Bay (Tunisia): implications for trophic markers and lipid nutritional quality assessment

This study investigated the seasonal variations in the proximate composition, fatty acid profile, lipid nutritional quality, and diet composition of Holothuria poli collected from Monastir Bay. Our findings revealed significant seasonal variations in protein, lipids, and ash contents, with the highest protein levels recorded during the summer and peak lipid levels observed in winter. Total monounsaturated fatty acids peaked in both winter and summer, while total saturated fatty acids reached their maximum in autumn. These variations in biochemical compositions were closely linked to the sea cucumber's dietary preferences. Our results demonstrated that H. poli exhibits a diverse diet, consuming bacteria, detritus, diatoms, zooplankton, and algae, with notable seasonal fluctuations. Moreover, the EPA + DHA content and the atherogenic (AI), thrombogenic (TI), and hypocholesterolemic/hypercholesterolemic (H/H) indexes align with the ranges characteristic of high-quality seafood, though marked variations are evident among seasons. A principal component analysis illuminated the dynamic seasonal shifts in Holothuria poli's dietary habits and lipid nutritional characteristics, offering valuable insights into its ecological adaptations and potential repercussions for marine food webs. These findings underscore the intriguing interplay between fatty acid composition, lipid nutritional quality, dietary preferences, and environmental factors in sea cucumbers.