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We traced the food sources of mussel Mytilus galloprovincialis cultured in suspension in Ría Ares-Betanzos (N.W. Spain) by means of fatty acid (FA) biomarkers. The FA profile of seston, mussels' mantle, digestive gland and feces was analyzed during five seasons. Due to the proximity of a fish farm to the bivalve aquaculture site, we also tested if mussels and seston situated 170 m distant from the fish cages incorporated fish feed FA markers compared with samples obtained 550 m away. The principal FA in the mussels' organs were 16:0, 16:1ω7, EPA (20:5ω3) and DHA (22:6ω3), while 16:0 predominated in the feces. Seasonal fluctuations in the seston composition were mirrored in the FA signature of mussels' organs and feces, although the digestive gland had the closest resemblance to the seston FA profile. In general, diatom and bacteria derived-biomarkers predominated in mussels' organs and feces during the upwelling period (spring-summer), while dinoflagellates were the dominant dietary source during downwelling (autumn-winter). The higher concentration of EPA and DHA in both organs and the feces compared with the seston suggested a preferential accumulation of these ω3 FA in the mussels' tissues. The results showed a lack of assimilation of fish feed FA biomarkers in the seston and mussel samples. This might be due to the dispersion of uneaten feed particles by high current velocity, substantial distance between the fish and mussel culture, the limited amount of nutrient waste released by the fish farm and dilution of feed particles in the large mussel standing stock., (Copyright © 2014 Elsevier Inc. All rights reserved.)

We examined the influence of the reproductive cycle and environmental variables on the gonadal fatty acid profile in the tropical scallop Nodipecten nodosus. Individuals from a natural population in north-eastern Venezuela (Caribbean Sea) were sampled monthly during one year. The gonadosomatic index (GSI) and a visual assessment of gonadic status are also reported. The environmental conditions characterized by chlorophyll a, temperature and seston concentration were measured in parallel. The highest reproductive activity, with a GSI of 13-18%, was observed from November 2003 to April 2004, and a decrease in GSI, taken as an indication of three spawning periods, was recorded in October, January and May-June. The GSI was 5-8% outside these intervals. A similar trend was observed in maturity stage frequency. Statistical analysis (MDS-ANOSIM) established two different periods; one dominated by upwelling (January to July) and the other characteristic of non-upwelling conditions (August to December). The fatty acids 16:0, 22:6n-3, 20:5n-3 and 16:1n-7 were responsible for the differences between two periods and explained 50% of the observed variance. Accordingly, during the upwelling period, fatty acids such as 22:6n-3 were positively correlated with temperature, organic seston and bivalves in the spent sexual stage and inversely related to the GSI. Furthermore, individuals in the ripe sexual stage were positively related to 20:5n-3 and 18:3n-3, whereas chlorophyll a was directly related to 18:1n-7 and 16:1n-7. In the non-upwelling period, a significant and positive correlation was obtained between fatty acids such as 20:5n-3 and 22:6n-3 and the GSI and the bivalves in the ripe sexual stage, whereas these acids were inversely correlated with the spent sexual stage. In addition, chlorophyll a was positively related to 18:1n-9 and 18:2n-6. Changes in the gonadal fatty acid profile of N. nodosus were influenced by the environmental variables (exogenous factors) during the upwelling and non-upwelling periods and by reproductions (endogenous factors)., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Fatty acid profiles of seeds of the mussel Mytilus galloprovincialis originating from two habitats (rocky shore and subtidal) were compared after transfer to the same habitat (subtidal). The objective was to study the initial levels of different fatty acids of metabolic importance and, furthermore, the variability of these fatty acids over the experimental period. The results show that of all fatty acids identified in both seed groups, the polyunsaturated fatty acids (PUFA) is the group with highest percentage. Within this group, the C20:5n-3 and C22:6n-3 fatty acids show the highest levels. Additionally, the mussels of subtidal origin presented higher initial levels than the rocky shore mussels with regard to fatty acids characterised by energetic-type functions, such as the C14:0, C16:0, and the C20:5n-3 fatty acids, among others. Fatty acids characterised by structural-type functions, e.g. C18:0, C22:6n-3 and non-methylene interrupted dienoic (NMID) with 20 and 22 carbons in rocky shore mussels presented higher levels than those of the subtidal mussels. However, it has not been ruled out that aside from influences relating to the functional aspects of the different fatty acids, the initial differences were also associated with the quantitative and qualitative differences of the available food in both habitats. Nevertheless, 22 days into the experiment (in the majority of cases) the initial differences disappear in the different fatty acids with metabolic importance. On the basis of these results, the influence that mussel origin could exercise on the variability of the fatty acid profiles of recognised metabolic importance is discussed.