Spatial-temporal changes in dimethyl acetal (octadecanal) levels of Octopus vulgaris (Mollusca, Cephalopoda): relation to feeding ecology

Abstract

The present study aimed to identify and quantify the dimethyl acetal (DMA) levels in the muscle of Octopusvulgaris Cuvier, 1797, and to investigate the possible influence of octopus feeding ecology on their spatial and seasonal variations. The research was performed over one year in three areas of the Portuguese coast: Viana do Castelo, Cascais and Tavira. Significantly higher values of DMA were detected in Tavira (p< 0.05), an area where the importance of bivalves in the octopus’ diet was higher. The biochemical analyses performed in several prey items, belonging to five major taxonomic groups identified in octopus stomachs, revealed significant differences in DMA levels (p< 0.05). The highest values were obtained in bivalves (1.15 mg 100 g^-1 dry weight), followed by gastropods (0.74 mg 100g^-1 dw), cephalopods (0.67 mg 100 g^-1 dw), crustaceans (0.23 mg 100 g^-1 dw) and osteichthyes (0.10 mg 100 g^-1 dw). Therefore, based on these findings it can be speculated that the higher DMA levels in O. vulgaris obtained in Tavira throughout the year were evidence of its feeding ecology. Since DMAs are derived from ether glycerophospholipids, including plasmalogens (PLMs), the importance and role of this phospholipid class is discussed.