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

Abstract

SUMMARY: The present study aimed to identify and quantify the dimethyl acetal (DMA) levels in the muscle of Octopus vulgaris 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.Key words: Octopus vulgaris, dimethyl acetal, plasmalogens, phospholipids, feeding ecology. RESUMEN: CAMBIOS ESPACIO-TEMPORALES EN LOS NIVELES DE DIMETIL ACETAL (OCTADENAL) DE OCTOPUS VULGARIS(MOLLUSCA: CEPHALOPODA): RELACIÓN CON LA ECOLOGÍA TRÒFICA. -El presente trabajo ha tenido como objetivo la identificación y la cuantificación del nivel de dimetil acetal (DMA) en el músculo de Octopus vulgaris Cuvier, 1797, e investigar la influencia de la ecología alimentaria del pulpo en los variaciones espacio-temporales de este compuesto. El estudio ha sido realizado durante un año en tres zonas de la costa portuguesa: Viana do Castelo, Cascais y Tavira. Se han obtenido valores significativamente superiores del DMA (p<0.05) en Tavira, un área donde la importancia relativa de los bivalvos en la dieta fue superior. Los análisis bioquímicos realizados en distintos tipos de presas, pertenecientes a los cinco grupos taxonómicos identificados en los contenidos estomacales del pulpo, han revelado la existencia de diferencias significativas en los niveles de DMA entre los grupos (p<0,05). Los valores más elevados han sido obtenidos en los bivalvos (1.15 mg 100 g -1 ), seguidos de los gasterópodos (0.74 mg 100 g -1 ), cefalópodos (0.67 mg 100 g -1 ), crustáceos (0.23 mg 100 g -1 ) e osteichthies (0.10 mg 100 g -1 ). En base a estos resultados se puede especular que los valores más elevados obtenidos en Tavira a lo largo de todo el año constituyen una evidencia de la ecología alimentar del pulpo. Dado que los DMA son derivados de los eter glicerofosfolípidos, donde se incluyen los plasmalogénos (PLM), se discute la importancia y el papel funcional de esta clase de fosfolípidos.

Seasonal patterns of polycyclic aromatic hydrocarbons in digestive gland and arm of octopus (Octopus vulgaris) from the Northwest Atlantic

“…These results suggest that the exposure to PAHs in the NW Portuguese coast is moderate; however it must be taken into account that octopuses used in this study were captured around 10 km offshore and the contamination levels decrease with increasing distance from the pollution sources (Baumard et al, 1999). The high metabolism of PAHs in fish might have also contributed to the low levels found in the octopus digestive gland since Osteichthya species makes up a great part of the octopus diet in the NW Portuguese coast (Rosa et al, 2004a).…”

“…As referred above, the octopus diet in the NW Portuguese coast is constituted mainly of Osteichthya species (Rosa et al, 2004a) that directly absorb PAHs from the water column, supporting the greater contribution of LMW than HMW PAHs observed in the digestive gland of the octopus (Nakata et al, 2003;Perugini et al, 2007;Webster et al, 2002). Naphthalene was the most abundant PAH in the octopus digestive gland in the different sampling periods.…”

Identification of a Δ5-like Fatty Acyl Desaturase from the Cephalopod Octopus vulgaris (Cuvier 1797) Involved in the Biosynthesis of Essential Fatty Acids

“…Whereas the small amount of solutes meant it was not possible to unequivocally confirm the double-bond structure for 20:2 and 22:2 NMI, the 20:3 NMI was confirmed as Δ5,11,14 20:3. Dimethylacetals (DMA) of 16 and 18 carbons were also detected as previously described (Rosa et al 2004). …”

Cephalopods as Vectors of Harmful Algal Bloom Toxins in Marine Food Webs

“…Although some studies point out that benthic species tend to prey mainly on crustaceans while fishes predominate the pelagic species [95,96,97], others studies indicate that the prey spectrum in the diet is related to the most readily available prey (Table 2) [93]. For instance, Smale and Buchan [98] and Ambrose and Nelson [99] showed that octopus had a greater preference for bivalves, forming up to 88% of its diet.…”

“…High variable DA levels, ranging from 1.1 to 166.2 μg DA g −1 were found in the digestive gland (DG) of the common octopus ( Octopus vulgaris ) off the Portuguese coast (Figure 7A; Table 1). The highest DA levels are observed in DG because this organ is the primary site of digestive absorption and intracellular digestion in cephalopods [93,111]. Thus, it may act as a DA reservoir, as it is for other substances (lipids, contaminants, etc .)…”