Ecologia tròfica d’una població autòctona d ’alburn (Alburnus alburnus)

Abstract

The bleak (Alburnus alburnus) (L.) is a cyprinid specie that can inhabit both lotic and lentic environments. They follow a generalist diet, since they can feed on multiple dams preys: from terrestrial insects to zooplankton, algae or detritivores. This specie, native to most of Europe, was introduced to the Iberian Peninsula during the 90's, where it has expanded and become invasive. The main objective of this study is to determine the trophic ecology of a native population of alburn based on the characterization of the diet through different trophic parameters (prey richness, Shannon’s index and trophic niche width) and with Fulton's physical condition index. It is also analyzed whether there are differences between the trophic parameters based on sex. Finally, Finally, different trophic parameters are compared between this native population and different introduced populations The specimens were captured with electric fishing during the spring of 2014. They were later processed in the laboratory, obtaining the following parameters: furcal length (FL), eviscerated weight, sex and size structure. All the procedures carried out during the sampling and the laboratory work comply with the regulations for animal welfare and use. The obtained results suggest that the size structure of the population in males and females follows a unimodal pattern, indicating that we find only one cohort. Ingested and occurrence biomass percentages show a lesser diversity in the diet compared to invasive populations, and reveals that one of the secrets of the success of the bleak is its opportunism according to the conditions of its habitat. Statistically no significant differences are observed in any of the diet-related parameters between the sexes, but they are noticed in their condition. Males have a better physical condition than females because the sampling was performed after the egg-laying period