Ecological and functional role of small and medium pelagic fish in the northwestern mediterranean sea
- Autores: Marta Albo Puigserver
- Directores de la Tesis: Marta Coll Montón (dir. tes.), Joan Navarro Bernabé (codir. tes.), Cesar Mösso Aranda (tut. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2019
- Idioma: español
- Tribunal Calificador de la Tesis: María Pilar Olivar Buera (presid.), Carla Susana Ferreira Garrido Coelho (secret.), Josep Lloret Romanach (voc.)
- Programa de doctorado: Programa de Doctorado en Ciencias del Mar por la Universidad de Barcelona y la Universidad Politécnica de Catalunya
- Materias:
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- Resumen
Mediterranean marine ecosystems are fundamentally driven by their pelagic communities and small and medium-size pelagic fishes (SMPF) play crucial ecological roles. Although fluctuations of the populations of these organisms have been mainly attributed to environmental variability and overfishing, there is still a lack of understanding on specific mechanisms that drive their population changes. In recent decades a decline in landings, biomass and body condition of sardine and anchovy in the Mediterranean Sea has been observed and several hypotheses to explain these changes have been formulated. Therefore, accurate scientific data at species and community level is needed in order to understand the most likely causes of these declines. Within this context, this PhD thesis aims to improve the knowledge of the seasonal dynamics and functioning of the pelagic compartment focusing in the trophic relationships and energy dynamics of SMPF in the northwestern Mediterranean Sea.
I used different methods to advance on the knowledge about the ecological and functional role of several pelagic fish species in the western Mediterranean Sea, including clupeoids, horse mackerels and mackerels. Specifically, stable isotope and stomach content analyses in combination with direct and indirect body condition indeces, were used to study seasonal variation in energy content in relation to their breeding strategies, feeding preferences and trophic role in the pelagic food-web. Results showed stability in the trophic structure through the year with a trophic segregation of small pelagic fish depending on the ontogenetic stage. Seasonal differences in energy density were highly related with the spawning season and food availability. To integrate the new findings and to test the role of potential pressures on main pelagic species, I developed qualitative food-web models. Overall, results provide pivotal information to assist the adaptive management of pelagic fish species in the region.
