Relationships between spawn quality and biochemical composition of eggs and hatchlings of Octopus vulgaris under different parental diets

Three frozen mono-diets (sardine, crab and squid) were supplied to Octopus vulgaris broodstocks, and their effects on the spawn quality and biochemical composition of eggs and hatchlings were studied. Squid and crab diets achieved superior spawn quality, producing in general significantly larger eggs, as compared to sardine diet. Similar differences were also observed in the biometric parameters of hatchlings (ventral and dorsal mantle lengths and dry weight) as well as in the survival of fasted hatchling which were greater in the squid and crab groups with respect to sardine treatment. On the other side, a strong and significant relationship between the mentioned biometrical measures and hatchlings survival was found, suggesting that eggs and hatchlings early biometrical measures can be utilized as a predictor for larval viability. Statistical techniques as multivariate and correlation analyses were used to distinguish dietary groups based on protein content and lipid and fatty acid composition of achieved eggs and hatchlings as well as to relate this composition with spawn quality parameters. The analyses allowed to discriminate the nutrient composition of the early stages which was also found to be significantly correlated to the differences in the spawn quality of the different dietary groups, thereby underlining the importance of the protein content, and lipid classes like phosphatidylethanolamine, phosphatidylcholine, cholesterol and triacylglycerol, as well as docosahexaenoic (22:6n-3) and eicosapentaenoic (20:5n-3) fatty acids in the reproduction of O. vulgaris. Statement of Relevance It has been demonstrated that biochemical composition of the broodstock diet is a major determinant of successful reproduction and offspring survival in teleost fish (Watanabe & Vasallo-Agius, 2003; Bobe and Labbe, 2009). For Octopus vulgaris, our data suggest that the broodstock diet influenced the protein content and lipid composition of eggs and hatchlings, and these nutrients are related to the differences found in the spawn quality. A strong and significant relationship between the measured biometrical parameters and hatchlings survival was also found, suggesting that eggs and hatchlings early biometrical measures can be utilized as a predictor for larval viability. On the other side, the utilization of nutrients during the embryo development can also be seen as an indicator of the nutritional requirements during the early stages of development and be useful for a future advance in the formulation of paralarvae artificial diets. Our results pointed to an embryo catabolismmainly based on proteins, as previously suggested (Lee, 1994; Villanueva and Norman, 2008). Data also suggest that triacylglycerol, sterol ester and phosphatidylcholine were specifically catabolized for energy and/or used to de novo synthesize lipid classes such as PS or PE. With in fatty acids, we found that arachidonic acid was strongly reduced (50-51%) during embryonic development. Further studies on the particular role of AA and the n-3 HUFA (mainly EPA and DHA) for early stages of O. vulgaris are needed, specially taking into account that these FAs are essential for this species (Monroig et al., 2012a,b). (C) 2015 Elsevier B.V. All rights reserved.