Dietary fatty acid composition significantly influenced the proactive–reactive behaviour of Senegalese sole (Solea senegalensis) post-larvae

Abstract

Few studies have examined the influence of diet on larval proactive–reactive behavioural dimension of stress coping style responses. The present study evaluated the influence of using different vegetables oils (Linseed; Soybean; Olive) and fish oil (Cod liver) for Artemia metanauplii nutritional enrichment on the proactive–reactive behavioural responses of Senegalese sole (Solea senegalensis) post-larvae (40 days post hatch). Forty-two Senegalese sole larvae from each of the four replicate tanks per treatment were tested. Two tests were performed: a new environment individual-based test, which evaluate the larvae latency time to move, total activity time and total distance moved; and a risk group-based test, which consisted in evaluating the larval capacity to cross from a “comfort” zone to a “risk” zone. In the group-based test, proactive, intermediate and reactive individuals were identified depending on the time taken to cross between two zones. Larvae fed with Artemia metanauplii enriched with the cod liver oil emulsion were significantly (P=0.01) larger and in the individual-based test presented significantly higher total activity time (P=0.08) and total distance moved (P=0.01) than larvae from the other dietary treatments. No significant correlations (P>0.05) were observed between larvae total length and latency time to move, total activity time or total distance moved across all treatments or within any dietary treatment. In the group-based test, fish fed with Artemia enriched with the cod liver oil emulsion presented a significantly higher proportion of proactive larvae (P=0.02) and the lower proportion of reactive larvae. The present study showed for the first time that (i) Senegalese sole presented a defined proactive–reactive behaviour from early ontogenesis and (ii) dietary fatty acid composition significantly influenced the proactive–reactive behavioural dimension of stress coping style of sole larvae. The current study has practical implications that open the possibility to produce organisms that have behavioural styles that could ultimately result in improved aquaculture productivity.