Abstract
Metabolic modifications associated with natural environmental conditions were assessed in the meagre Argyrosomus regius cultured in earthen ponds under natural photoperiod and temperature. Juvenile specimens (90-100 g initial weight) were sampled (plasma, liver and muscle) every two months for 18 months (between December 2004 and May 2006). Specimens showed seasonal variations in growth rate, with the highest values in spring and summer. Plasmatic, hepatic and muscular metabolite levels and hepatic and muscular metabolic enzymes also showed significant variations throughout the year. Enzymatic activity related to carbohydrate metabolism in the liver (HK, FBPase and G6PDH) showed great modifications in summer, increasing glycogenogenic pathways, while amino acid metabolism (GDH and GOT activity) was enhanced in spring and summer. However lipid-related (G3PDH activity) metabolic enzymes did not show a clear seasonal pattern. In muscle, enzymatic activity related to amino acid, lipid and lactate metabolism (LDH-O activity), but not carbohydrate metabolism, showed seasonal changes in parallel with changes in growth rate. Thus A. regius specimens showed a trend to grow in summer months and mobilize their energy reserves in winter. Differences in the hepatic level were observed between the first and the second year of the study, suggesting the possible existence of metabolic changes related to specimen age or size. Our results indicate that growth and metabolic responses in A. regius are environmentally dependent and that this species is a very good candidate for diversification in aquaculture.
Highlights
The meagre Argyrosomus regius (Asso 1801) is a widely distributed sciaenid along the Atlantic coast and in the entire Mediterranean Sea (Chao 1986)
A. regius became a suitable candidate species for aquaculture diversification (Cárdenas 2010) for several reasons: i) its easy adaptability to captivity (Quéméner 2002); ii) its high capacity to tolerate a wide range of temperatures and salinities (Lavié et al 2008, Márquez et al 2010); iii) its high growth rate, reaching 1 kg in ten months of culture (Calderón et al 1997 Jiménez et al 2005); and iv) its excellent flesh quality, with high nutritional value and good acceptance by consumers (Quéméner 2002, Poli et al 2003, Roo et al 2010, Grigorakis et al 2011, Giogios et al 2013)
Muñoz et al (2008) analysed the growth of A. regius juveniles (22-30 g weight) maintained in these earthen ponds (November 2006 to December 2007) under two different environmental salinities, finding better responses in specimens grown under isosmotic environments
Summary
The meagre Argyrosomus regius (Asso 1801) is a widely distributed sciaenid along the Atlantic coast (northward to southern Norway and southward to the Congo) and in the entire Mediterranean Sea (Chao 1986). In recent years stagnant markets in the Mediterranean have stimulated the diversification of aquaculture to novel species such as flatfish (Scophthalmus rhombus, Dicologoglossa cuneata, Solea senegalensis), sea bream (Pagrus pagrus), and croakers (Umbrina cirrosa) In this context, A. regius became a suitable candidate species for aquaculture diversification (Cárdenas 2010) for several reasons: i) its easy adaptability to captivity (Quéméner 2002); ii) its high capacity to tolerate a wide range of temperatures and salinities (Lavié et al 2008, Márquez et al 2010); iii) its high growth rate, reaching 1 kg in ten months of culture (Calderón et al 1997 Jiménez et al 2005); and iv) its excellent flesh quality, with high nutritional value and good acceptance by consumers (Quéméner 2002, Poli et al 2003, Roo et al 2010, Grigorakis et al 2011, Giogios et al 2013). In a preliminary study, Muñoz et al (2008) analysed the growth of A. regius juveniles (22-30 g weight) maintained in these earthen ponds (November 2006 to December 2007) under two different environmental salinities (sea water 35.7±2.0‰ and brackish water 13.1±2.8‰), finding better responses in specimens grown under isosmotic environments
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