CONICET | Buscador de Institutos y Recursos Humanos

The kelp gull (Larus dominicanus) is an opportunist predator with a wide distribution in the south hemisphere, breeding in a pristine sites as Antarctic coastal areas or in highly polluted as urban landfills. When some Antarctic populations seemed to decline, bacterial infections and presence of pathogens were mentioned as possible causes. In this work, we used samples from different organs (liver, stomach, intestine and cloaca) of L. dominicanus obtained from pristine (Esperanza Station, Antarctica) and contaminated (landfill near Buenos Aires city) areas to analyze the cultivable fraction of bacterial flora associated to mature individuals. We analyzed samples from six Antarctic and three urban landfill-associated specimens. General and selective culture media were used to evaluate total cultivable bacterial flora and presence of selected groups of microorganisms. Qualitative analysis included conventional biochemical tests and commercial phenotypic identification kits (API20 system). Results showed that total aerobic bacterial counts of the liver were high and variable in specimens from polluted area (values between 1x103 and 1x106 CFU/g) but absents in the Antarctic ones. The digestive tract showed very high counts from landfill-associated individuals (between 1x107 and 1x108 CFU/g), while the Antarctic specimens showed heterogeneous but smaller values (between 1x102 and 1x105 UFC/g). The qualitative study showed a wide diversity and heterogeneity in all the organs of specimens from Buenos Aires, while the Antarctic ones presented predominance of one or two groups. This study showed a higher bacterial load and a greater biodiversity in the individuals of the polluted area than the Antarctic individuals.

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