Sea urchins Paracentrotus lividus were harvested monthly from April 2015 to March 2016 from two sites in Sardinia (Italy). The two sites, a Posidonia oceanica meadow and a rocky bottom habitat, were naturally characterized by different food sources and availability, being mainly populated by the sea grass Posidonia oceanica and the brown algaeHalopteris scoparia, respectively. Total lipids showed a minimum during winter in mature gonads, and a maximum in the summer (recovery stage). Fatty acid (FA) profiles of gut contents and gonads differed from those of the most available food sources. Levels of C18:3 (n-3) (ALA) discriminated samples from the two sites. Despite the very low amounts of C20:5 (n-3) (EPA) and C20:4 (n-6) (ARA) in P. oceanica, the main FA in gonads and gut contents were EPA and ARA in both sites. Increase in green algae intake prior to gametogenesis, especially C. cylindracea, likely affected EPA and ARA levels in gonads.
Fig: Seasonal variation of total lipids in gonads of P. lividus from P. oceanicameadow and rocky bottom habitats, compared with fitted photoperiod and seawater temperature. (a) gametogenic stages detected in the P. oceanicameadow. Fitting in (b) was performed according to Siliani et al. (c) gametogenic stages detected in the rocky bottom habitat.
The results show that P. lividus is able to concentrate lipids in gut contents and also to selectively store EPA, ARA and their precursors ALA and 18:2 (n-6) (LA). Moreover, bioconversion of ALA to EPA and of LA to ARA in P. lividus is suggested.
Anedda, R., Siliani, S., Melis, R. et al. Lipid metabolism of sea urchinParacentrotus lividus in two contrasting natural habitats. Sci Rep 11,14174 (2021). https://doi.org/10.1038/s41598-021-93669-9