Comparació de la capacitat crítica de natació i la morfologia de sis espècies de peixos d’aigües continentals

Abstract

Swimming capacity is a vital function for aquatic organisms because it is essential for obtaining food, reproduction and survival. This is estimated from the critical swimming speed (Ucrit), the maximum metabolic rate (MMR) and the standard metabolic rate (SMR), which can be influenced by the total length (TL), the total weight (BW) and the morphology of the species. These parameters have been analyzed by six species, three cyprinids (Alburnus alburnus, Phoxinus bigerri and Rutilus rutilus), a centrurid (Lepomis gibbosus), and two cyprinodontides (Aphanius iberus and Gambusia holbrooki). The measurements of critical swimming speed (Ucrit), the maximum metabolic rate (MMR) and the standard metabolic rate (SMR) have been obtained experimentally in the laboratory through swimming tunnels coupled to a respirometer. For the morphological measures, we have used the "tpsDig232" program, which can measure areas and perimeters from the photographs of the specimens. The statistical analysis consisted in the application of Covariance Analysis (ANCOVA) between the physiological and morphological variables with the total length and the total weight of the individuals, analysis of the Variance (ANOVA) when there was no linear regression between the variables physiological and morphological factors with total length and total weight and, also, an analysis of correlations between the physiological and morphological variables. Finally, we have used the Analysis of Main Components (PCA) for all the species and the variables studied. The results obtained showed an increase in Ucrit as the total length increases and an inversely proportional relationship between Ucrit and MMR. MMR and SMR have been found to be related to total weight so that individuals with higher weight present higher oxygen (mg O2/h) intake. High values of Fineness ratio, Aspect ratio, Propulsive ratio and Caudal peduncle factor are determinants of hydrodynamic morphology of species, and therefore they were related with the Ucrit, the MMR and the SMR. High values of Muscle ratio have been observed in non-migratory species which showed low Ucrit. Furthermore, high values of Aspect ratio have been observed in migratory species which showed a high Ucrit. The life style of the species and its morphology seemed to play a key role in determining the swimming capacity (Ucrit) and metabolic rates (MMR and SMR) of the species studied