Patterns of larval growth, lipid composition and fatty acid deposition during early to mid stages of development in Panulirus ornatus phyllosoma

Abstract

The tropical spiny lobster, Panulirus ornatus, is a commercially important Palinurid marine lobster species of high market value with wild populations distributed throughout the tropical and sub-tropical Indo-Pacific region. As wild populations of P. ornatus has been over-exploited, so there is interest in the development of this lobster aquaculture to meet current and rising market demand for supply. However, a major challenge for closed-life cycle production of Palinurid lobsters is the development of a commercially viable hatchery technology. There is minimum knowledge of larval nutrition, and in particular, the lipid requirements. The current study focused on investigations into the growth pattern and ontogenetic changes of lipid composition for early–mid stage P. ornatus (stages I–VI) under controlled laboratory conditions. Body wet weight (WW), dry weight (DW) and total body length (TBL) increased exponentially with the number of stages. There were large increases in WW, DW and TBL between stages I and VI, with increases of 4092%, 3864% and 504%, respectively. The greatest increase in DW and WW was noted between stages III to IV while the greatest specific growth rate (SGR) was noted during stages I to II. The lipid class profile of phyllosoma was dominated by phospholipids (PL) for all early stages (I–V) despite the high triacylglyceride (TG) content of Artemia; which was the primary food source. The newly hatched phyllosoma contained higher percentages of total saturated fatty acids (SFA), 20:5n3 (EPA), 22:6n3 (DHA) and total highly unsaturated fatty acids (HUFA) compared to that found in all other stages. From stages II to V, the total lipid, lipid class and fatty acid profile of phyllosoma resembled those of their diet with the exception of 20:4n6 (ARA). The increase in ARA concentration during phyllosoma development (stages II–V) suggested that mid-stage phyllosoma (IV and V) had a higher requirement compared to that noted in early-stage (II and III) phyllosoma. It was noted that early-stage (II and III) phyllosoma preferentially sequestered and accumulated a higher proportion of EPA and DHA compared to that present in their diets. These data indicate that early–mid stage P. ornatus phyllosoma have an ability to preferentially sequester, store or modify their dietary lipid composition to support normal growth and development. These results provide important morphometric date useful in the evaluation of larval feed and culture conditions as well as, providing baseline larval lipid nutrition data required for the development of artificial diets for P. ornatus phyllosoma.