Assessment of stress and nutritional biomarkers in cultured Octopus

Abstract

The common octopus (Octopus vulgaris) is a promising species for aquaculture diversification, but massive mortality during the first life-cycle stages (paralarvae) is the main bottleneck for its commercial production in captivity. The aim of this study was to assess stress and nutritional condition biomarkers (HSP70, ROS enzymes and lipid peroxidation) (RNA/DNA, RNA/protein, protein/DNA and protein) in O. vulgaris paralarvae from different geographical origins and fed with Artemia enriched with marine phospholipids or microalgae (control group). To this end paralarvae were cultured for 30 days, in three different centres in Spain (Tarragona-Mediterranean area, Tenerife-Central Atlantic area and Vigo-North Atlantic area), under the same protocol, and fed on Artemia enriched with marine phospholipids (LC60) (Marine Lecithin LC 60®, PhosphoTech Laboratoires) or microalgae (control group). Dry weight and most biomarkers analysed in hatchlings showed significant differences related to their origin (centre). Fifteen day old paralarvae presented significant differences in specific growth rate (SGR) associated with their dietary regime, and also showed differences in biomarkers associated both with their geographical origin and dietary regime. The results suggest that the SGR of paralarvae were positively influenced by LC60, promoting growth and in agreement with the results of nutritional condition biomarkers (nucleic acids ratios). The antioxidant defences against oxidative damage were also boosted in the LC60 paralarvae group, possibly as a result of the elevated content in highly polyunsaturated fatty acids. In addition, the partial correlations found between biomarkers varied according to diet. However, no positive effect of LC60 on survival was observed. The high variability found among geographical origins, despite the use of the same rearing protocol, highlights the need to clarify the sources of such variability. Statement of relevance: Stress status varies among geographical origins and diets.