"Taxocene surrogation" and "taxonomic sufficiency" concepts were applied to the monitoring of soft bottoms macrobenthic assemblages influenced by fish farming following two approaches. Polychaete assemblage evaluation through multivariate analysis and the benthic index BOPA were compared. Six fish farms along the Spanish Mediterranean coast were monitored. Polychaete assemblage provided a suitable picture of the impact gradient, being correlated with total free sulphides. BOPA did not support the impact gradient described by the polychaete assemblage, providing erroneous categorizations. The inclusion of several polychaete families, which were locally identified as indicative of affection to recalculate BOPA, resulted in an improved diagnosis and correlation with the impact gradient. Nevertheless, frequent misclassifications occurred. These results suggest that the structure of polychaete families, sulphides and granulometry conform an appropriate strategy for fish farming monitoring. Biotic indices need to be specifically designed for concrete activities, and regionally validated, because of the environmental plasticity of benthic invertebrates.
A 5-factor design survey was carried out to examine the spatial distribution at different scales of amphipod assemblages and sedimentary variables in soft bottoms adjacent to coastal aquaculture installations. Natural variability of sediment variables showed the highest values at the scales of sites (10s of meters) and locality (1 to 10 km), while the greatest component of variation of amphipod assemblages occurred among replicates (on the scale of meters). Regarding the influence of coastal aquaculture, the highest variability of the environmental variables was observed among the different fish farms. On sandy localities, the influence gradient of coastal aquaculture was determined by total free sulphides, whilst, in muddy localities, the main variable was δ 15 N. This study has important consequences for the establishment of a clear and effective methodology for studying and monitoring the impact of fish farming, highlighting the complicated establishment of a widespread pattern of effects by coastal aquaculture. The necessity to apply a high replication effort at several spatial scales, especially at the scales of meters and 10s of meters, to increase the precision of estimates of assemblage composition should be taken into consideration.
Cerezo Valverde, J.; Martínez-Llorens, S.; Tomás Vidal, A.; Jover Cerda, M.; Rodriguez, C.; Estefanell, J.; Gairin, JI.... (2013). Amino acids composition and protein quality evaluation of marine species and meals for feed formulations in cephalopods. Aquaculture International. 21(2):413-433. doi:10.1007/s10499-012-9569-6. The amino acid composition and protein levels of three species of cephalopods 5 (Octopus vulgaris, Loligo gahi and Todarodes sagittatus), the natural diets of common 6 octopus (O. vulgaris) and different kind of meals were determined in order to optimize 7 the content of these nutrients in artificial feeds. Arginine, leucine and lysine were the 8 most abundant essential amino acids in cephalopods, while glutamate and aspartate 9represented the main non-essential amino acids. Arginine and leucine were the limiting 10 amino acid in most samples, with maximum Chemical Score values for mussel (79-11 98%), squid (84%) and crustaceans (65-91%), medium for fish (41-70%) and minimum 12 for meals (29-64%). Mussel, squid, crustaceans and fish showed a high essential amino 13 acid index according to Oser (OI: 88-99%) suggesting a suitable amino acid balance.
In this study, HPTLC was used to make a quantitative analysis of the total lipid content (TL dry weight) and their classes in 39 samples, including molluscs, crustaceans, fish and meals in an attempt to identify those most suitable for formulating diets for cephalopods by reference to an index of nutritional quality (OI LC : Oser's index modified for lipid classes). All the crustaceans analysed (\10% TL), fish from artisanal fisheries such as Boops boops, Gadus poutassou, Mugil sp. and Gadus minutus (\10% TL) and the plant meals (TL \ 5%) would cause fewer digestive problems than the fish that were a by-catch from fish farms (B. boops or Sparus aurata), pelagic species (Sardina pilchardus or Trachurus trachurus) or krill meal, which are characterised by their high lipid content (20-60% TL). These latter feeds were associated with neutral lipids, mainly triglycerides during the summer. Mytilus galloprovincialis, Carcinus maenas, G. poutassou, Mugil sp., S. pilchardus and G. minutus had a more appropriate lipid content and profile during the winter, when they showed a higher OI LC due to the greater variety of polar lipid classes they contained. Phospholipids like PS, PI and PE seem to be limiting nutrients in cephalopods because of their high content (78-542, 41-309 and 152-2,114 mg/100 g, respectively) compared with the rest of the samples. None of the meals analysed showed a good nutritional balance per se and should only be used in conjunction with other foods.
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