Frontiers in Marine Science (Nov 2015)
Growth plasticity of the southern Iberian barbel along longitudinal gradients in a highly regulated Mediterranean basin.
Abstract
Human induced flow regulation has been suggested as a driver of life history differences among freshwater fish populations. The purpose of the present study is to assess the influence of hydrological flow variability along the longitudinal gradient in the age structure and annual growth rates of a sentinel Iberian fish species, the southern Iberian barbel Luciobarbus sclateri Günther. We analysed populations at site level (25 sampling localities in fluvial sectors) along the longitudinal gradient in the main rivers of the Segura River basin, which is one of the most regulated basins in the Iberian Peninsula. A total of 1560 specimens caught during autumn 2009 and were in situ measured for length. Additionally, a sample was processed in the laboratory to obtain sex determination and growth parameters (age structure and growth rates). The life history of the species was characterized by a medium life span, with at least eleven age-classes detected showing high variability in age structure depending of fluvial sector. The fish growth rates showed significant differences mainly in younger individuals showing highest values in Mundo River, a fluvial sector dominated by high monthly flows. Both the longitudinal gradient pattern and the hydrological variables that accounted for most of the variation in L. sclateri growth traits were difficult to explain probably because the relationships were clouded by the high complexity of the ecological interactions. At the present, studied parameters show that L. sclateri presents a great phenotypic plasticity to adapt to flow changes. This study offers a multi sites perspective of the relationships between barbel growth traits and hydrological variability, providing water resources managers with needed perspective about the effect of human induced alteration of flow magnitudes and regimes.
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