Does the trophic habitat influence the biochemical quality of the gonad of Octopus vulgaris

Octopus vulgaris is a merobenthic octopus with high growth rates, and an opportunistic predator of a wide range of species which adapts the reproductive cycle to the oceanographic characteristics of their habitats. Trophic habitat and gonad quality of two neighbour populations of the Portuguese coast, subject to different oceanographic regimes, one inhabit a productive system with strong seasonality, and the other a oligotrophic system with punctual upwelling events, were compared using the digestive gland and beaks as recorders of trophic and habitat preferences, and gonads as indicators of egg quality. Cholesterol and phospholipids content, fatty acid (FA) profile of the digestive gland and stable isotopes, δ15N and δ13C, in the flesh and beaks were used as indicators of possible differences in the trophic habitat between populations. For gonad quality, the same bio-indicators were used to identify differences during maturation. The populations present similar trophic positions, with the south population presenting higher δN signature. The cholesterol content is significantly different between populations as the FA profile of the digestive glands mainly in the EFA 14:0, 16:1n-7, 20:1n-9, ARA, EPA and DHA. The lipid classes’ content in the gonad doesn’t show a clear influence of environment although the major FA profile of the gonads is dependent of both maturity and region, showing that both timing of maturity and feeding influences the quality of gonads as proxies of eggs.