The National Institute of Oceanography and Fisheries (NIOF) at El-Anfoushy depends mainly on seawater (SW) from the Eastern Harbor in its marine fish hatchery for marine fish aquaculture. On the other hand, the El-MAX facility which is not located directly on any marine SW source provides an alternative source of water: groundwater (GW) for the marine fish aquaculture. Although the EL-MAX facility provides a new source of water for aquaculture, the properties and suitability of its GW for marine fish production and larval rearing is still under examination. Groundwater from the El-Max facility was used in comparison with SW in two different water systems: a running flow-through system and a static system for assessing their potentiality in European sea bass Dicentrarchus labrax aquaculture. The current research studied brood stock spawning, egg incubation, larval and post larval rearing until 60 days post hatch (dph) in both marine water types and rearing systems.
The results revealed that D. labrax brood stock did not spawn in GW while spawning and hatching was 95-100% for eggs held in SW. Yolk-sac larvae that were transferred to GW tanks suffered high mortality that extended to the newly mouth opened larvae until 7th dph in which the larvae in GW showed normal viability and survival as those in SW tanks. The results of the current research revealed that by 60 dph the marine water source in combination with the water rearing systems significantly affected post-larvae survival (fig. 1), final weight, and composition (total lipid, total protein and fatty acid profile) but did not affect the growth in length.
The results of the current study do not recommend GW water from El-MAX facility for D.labrax brood stock spawning. Urgent need for more research is required for enhancing GW with nutrients or new technologies should be considered to accommodate early larval rearing stages, especially newly hatched larvae. Authors suggest using stressed GW in the EL-MAX facility in D. labrax larval rearing starting from the 7th dph while applying a running water system to achieve better larval survival and quality.