The interactive effect of cobalt enrichment in Artemia on the survival and larval growth of barramundi, Lates calcarifer

Cobalt is a naturally occurring element in the aquatic environment and is essential for many living functions of vertebrates. The role, retention and interactions of cobalt with other trace elements in the marine fish nutrition have been poorly documented. In this study the accumulation and effect of cobalt was investigated on the survival and larval growth of barramundi, Lates calcarifer, when fed individually and combined with zinc and manganese through a nourishment organism. Barramundi larvae from 14 to 30 dph were fed with Artemia nauplii in nine treatments (n = 3): without enrichment (control), enriched with 50 mg L− 1 and 100 mg L− 1 CoCl2 (Co-1 and Co-2), MnCl2 (Mn-1 and Mn-2), CoCl2 along with MnCl2 (CoMn-1 and CoMn-2) as well as CoCl2 along with ZnSO4 (CoZn-1 and CoZn-2) respectively. All treatments had significant effect on the cobalt, manganese and zinc level of Artemia. The concentration of these elements increased in parallel with the dose of supplementations. Our results show that a significantly higher growth performance of barramundi larvae can be achieved when cobalt and manganese supplementation is applied. No interaction occurred between the retention of zinc and cobalt, but a competitive type of interaction is assumed between the deposition of cobalt and manganese in barramundi larvae. Combined treatments of cobalt and manganese increased cannibalism and mortality significantly, while other treatments had no significant effect on the survival of barramundi. Redundancy analysis showed a strong correlation between the cobalt and manganese concentration of Artemia and barramundi larvae, as well as a total agreement between the zinc concentration of the zooplankton and the larvae.