Estudi de l’edat i creixement del barb de muntanya (Barbus meridionalis): una comparativa entre rius intermitents i permanents

Pineda Merino, Laia
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The mountain barbel (Barbus meridionalis) is an endemic species of the northeastern Iberian Peninsula and southern France, currently classified as "near threatened" by the IUCN. Despite its critical status, little is known about its biology, especially regarding age and growth. Although it is adapted to the seasonality of Mediterranean rivers, in a scenario of climate change and prolonged droughts, it is crucial to compare growth between populations in permanent rivers and rivers that become intermittent during the summer due to drought. This study is conducted in four tributary rivers of the Ter River basin: two intermittent rivers (the Llémena river and the Osor stream) and two permanent rivers (the Terri River and the Brugent river). Growth patterns are analyzed using the Von Bertalanffy model, which requires knowing the age and size of each individual at each age. To determine this, the back-calculation method is used based on the growth rings of the scales. Additionally, size structure, somatic condition status, and mortality rates are analyzed. The results indicate that fish from intermittent rivers show slower growth patterns compared to fish from permanent rivers, which exhibit more sustained growth and greater longevity. Furthermore, a more structured population is observed in permanent rivers, with a wider range of sizes and individuals reaching larger sizes, as well as a greater abundance of smaller size classes, indicating higher recruitment. Intermittent rivers show lower somatic condition (Kn) values, reinforcing the hypothesis that river intermittency negatively impacts the health and well-being of fish. Moreover, it is clearly seen that the mortality rate is higher and survival lower in intermittent rivers (Llémena and Osor) compared to permanent rivers (Brugent and Terri). It is concluded that river intermittency is a critical factor affecting the biology of the mountain barbel. These results can contribute to improving conservation strategies for this threatened species, as well as a better understanding of the ecological effects of hydrological variability in Mediterranean rivers ​
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