The nutritional quality of non-calcified macroalgae in Guadeloupe (Lesser Antilles) evaluated by their biochemical composition

International audienceBiochemical compositions of 15 species and 1 genus of macroalgae were studied. Concentrations of macronutrients were measured to evaluate their nutritional quality. High concentrations of proteins, lipids and soluble carbohydrates generally indicate a high nutritional quality because these compounds are readily metabolically available for consumers and provide a large proportion of energy. Insoluble carbohydrates are more difficult to digest and high concentrations indicate a low nutritional quality.Three groups of macroalgae were identified according to their biochemical characteristics. The first group clusters Ceramium cf nitens, Ulva cf lactuca and Lobophora cf variegata due to their high concentrations of proteins and soluble carbohydrates, and low proportion of ashes. These species presented high nutritional qualities and, according to previous studies, are preferredby herbivorous fishes. A second group constituted by Dictyota cf pulchella, Caulerpa cupressoides, C. sertularioides and Sargassum cf polyceratium presented intermediate nutritional qualities due to higher concentrations of lipids and insoluble carbohydrates. Finally, the others species and genus are characterized by a high proportion of ashes and a low nutritional quality. However, some of these species (Acanthophora spicifera, Padina cf sanctae-crucis or Laurencia cf chondrioides) are cited as preferred macroalgae for some herbivorous fishes.The present study indicates that the biochemical composition in macronutrients only partially explains the food choice made by fishes. The consumption of macroalgae by herbivores depends also on the presence of deterrent molecules, the composition in micronutrients, and their palatability that often decreased with increasing size. Most of macroalgae are preferentially consumed when young and small