CONICET | Buscador de Institutos y Recursos Humanos

The long snouted seahorse Hippocampus guttulatus is a recent candidate in the ornamental trade and its rearing will help in both the experimental assessment of ecological hypothesis and further development of conservational plans. Since there is a lack of information on many biological and physiological subjects, including developmental features, we assessed the ontogenetic development and functionality of the digestive system in this species by means of conventional and innovative techniques. The digestive tract of H. guttulatus develops with age from a short and straight tube to a long and segmented duct. Histological techniques showed a general increase in the intestinal absorptive surface close to 15 and 30 days, with the formation of intestinal loops. The liver parenchyma showed a significant increase in lipid deposits in early stages, which persisted until day 15. From 20 days onwards, lipid deposits were no longer observed in liver. The effect of the diet was assayed in juveniles submitted to three different diets (copepods, Artemia nauplii or both). Liver biochemical composition was analysed by means of Focal Plane Array-Fourier Transform Infra-Red (FPA-FTIR) spectroscopy. The results achieved evidenced changes in liver biochemical composition when challenged with different type of diet, prior to day 20, depending on the type of diet. Phospholipids increased with copepods administration whereas Artemia mainly provided higher content in carbohydrates and lipids. The digestive system of H. guttulatus was functional at first feeding, although not fully developed. As in adults, the liver plays a key role as energy reservoir in juveniles and its macromolecular composition may depend on both the diet provided and the digestive capabilities of fish. Inadequate diets delivered to fish when the gastrointestinal motility, digestion and absorption are not fully developed, might influence growth and survival rates with development.