Evaluación de la dieta y sobreposición trófica entre Lontra Provocax, Neovison Vison y Felis Catus en la cuenca del río Toltén y Allipén
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Fecha
2022
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es
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Universidad Andrés Bello
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Licencia CC
Licencia CC
Resumen
El huillín, Lobito de río Patagónico o nutria de río (Lontra provocax) es una de las dos especies de nutrias que habitan en Chile, como especie presenta una situación de conservación extremadamente preocupante debido al dramático declive a un 10% de su distribución en los últimos 200 años. Esta situación es el resultado de varios factores, entre los cuales se destacan la caza ilegal, destrucción de hábitat, enfermedades infecciosas y posiblemente contaminación química y patógena, debido a esto, el huillín se encuentra en estado de “Peligro” según el UICN y el Ministerio del Medio Ambiente de Chile. Otro factor importante y más
reciente es la presencia de carnívoros alóctonos invasores como los son el gato doméstico (Felis catus) y el visón americano (Neovison vison), en donde ambos casos el humano ha sido el culpable de sus introducciones. Esta situación es preocupante, debido a que ambas especies invasoras pueden llegar a tener un grado de competencia por explotación entre ellas y en particular en visón americano con el huillín, debido a que pertenecen a la misma familia, ambas son semiacuáticas, comparten hábitats y recursos alimenticios. Por lo tanto, se plantea como hipótesis: “Existe una menor sobreposición de la dieta entre visón americano y el gato doméstico, y una mayor sobreposición en la dieta entre visón americano y huillín”, esto daría indicios sobre, un potencial de
competencia por explotación entre estas tres especies, para lo cual se evaluó la sobreposición trófica entre ellas. La sobreposición de nicho se
evaluó con la técnica de isótopos estables, en la cuenca del río Toltén y Allipén, Región de la Araucanía. Con este fin, se capturaron individuos
de las tres especies, a los cuales se les tomo una muestra de vibrisas, las cuales fueron posteriormente analizadas mediante un analizador
elemental acoplado a un espectrómetro de masas “IRMS” en modo flujo continuo en el laboratorio de isotopos estables de la Universidad Andrés
Bello en Viña del Mar. De este modo se obtuvieron valores de δ13C vs δ15N, los cuales permitieron representar la trama trófica de los ríos
Toltén y Allipén, en donde no se presentaron diferencias significativas entre el visón americano y el huillín, no así entre visón con el gato
doméstico. Luego se obtuvieron las proporciones de contribución en la dieta de los tres depredadores mediante el uso del paquete para R
“SIMMR”: “Stable Isotope Mixing Models in R”, en donde el gato doméstico presentó un mayor apego por gallinas (Gallus gallus), y tanto
el huillín como el visón americano, mostraron preferencias por el salmón Chinook (Oncorhynchus sp.) y el camarón de río (Samastacus
spinifrons). Esto permitió generar un estimado del tamaño de nicho isotópico para gato doméstico, huillín y visón americano, mediante el
paquete para R “SIBER”: “Stable Isotope Bayesian Elipses in R”, con el fin de obtener el grado de sobreposición de nicho entre estas especies.
Como esperábamos (no se rechazó la hipótesis propuesta), observamos un menor grado de sobreposición entre gato doméstico y visón
americano, y un mayor grado entre huillín y visón americano. Es importante mencionar que el estudio está afectado por las limitaciones
de un bajo número de muestras, por lo que se propuso la adición de fuentes alimenticias tales como peces nativos y otros crustáceos como
Aegla spp., lo que permitiría mejorar la precisión de los resultados para futuras investigaciones.
The huillín, Patagonian River Lobito or river otter (Lontra provocax) is one of the two species of otters that inhabit Chile, as a species it presents an extremely worrying conservation situation due to the dramatic decline of 10% of its distribution in the last 200 years. This situation is the result of several factors, among which illegal hunting, habitat destruction, infectious diseases and possibly chemical and pathogenic contamination stand out, due to this, the huillín is in a state of "Danger" according to the IUCN and the Ministry of the Environment of Chile. Another important and more recent factor is the presence of invasive non-native carnivores such as the domestic cat (Felis catus) and the American mink (Neovison vison), where in both cases the human has been the culprit of their introductions. This situation is worrying, because both invasive species can have a degree of competition for exploitation between them and in particular in the American mink with the huillín, because they belong to the same family, both are semi-aquatic, they share habitats and resources. food. Therefore, it is proposed as a hypothesis: "There is less overlap in the diet between the American mink and the domestic cat, and a greater overlap in the diet between the American mink and the huillín", this would give indications about a potential competition for exploitation. between these three species, for which the trophic overlap between them was evaluated. Niche overlapping was evaluated with the stable isotope technique in the Toltén and Allipén river basin, Araucanía Region. To this end, individuals of the three species were captured, from which a sample of vibrissae was taken, which were subsequently analyzed using an elemental analyzer coupled to an "IRMS" mass spectrometer in continuous flow mode in the isotope laboratory. stables of the Andrés Bello University in Viña del Mar. In this way, values of δ13C vs δ15N were obtained, which allowed representing the trophic network of the Toltén and Allipén rivers, where there were no significant differences between the American mink and the huillín, but not between mink and the domestic cat. Then the proportions of contribution in the diet of the three predators were obtained by using the package for R "SIMMR": "Stable Isotope Mixing Models in R", where the domestic cat showed a greater attachment to chickens (Gallus gallus), and both huillín and American mink showed preferences for Chinook salmon (Oncorhynchus sp.) and river shrimp (Samastacus spinifrons). This allowed generating an estimate of the isotopic niche size for domestic cat, hoolin and American mink, using the package for R "SIBER": "Stable Isotope Bayesian Ellipses in R", in order to obtain the degree of niche overlap between these species. As expected (the proposed hypothesis was not rejected), we observed a lower degree of overlap between domestic cat and American mink, and a higher degree between whiting and American mink. It is important to mention that the study is affected by the limitations of a low number of samples, so the addition of food sources such as native fish and other crustaceans such as Aegla spp. was proposed, which would improve the accuracy of the results for future investigations.
The huillín, Patagonian River Lobito or river otter (Lontra provocax) is one of the two species of otters that inhabit Chile, as a species it presents an extremely worrying conservation situation due to the dramatic decline of 10% of its distribution in the last 200 years. This situation is the result of several factors, among which illegal hunting, habitat destruction, infectious diseases and possibly chemical and pathogenic contamination stand out, due to this, the huillín is in a state of "Danger" according to the IUCN and the Ministry of the Environment of Chile. Another important and more recent factor is the presence of invasive non-native carnivores such as the domestic cat (Felis catus) and the American mink (Neovison vison), where in both cases the human has been the culprit of their introductions. This situation is worrying, because both invasive species can have a degree of competition for exploitation between them and in particular in the American mink with the huillín, because they belong to the same family, both are semi-aquatic, they share habitats and resources. food. Therefore, it is proposed as a hypothesis: "There is less overlap in the diet between the American mink and the domestic cat, and a greater overlap in the diet between the American mink and the huillín", this would give indications about a potential competition for exploitation. between these three species, for which the trophic overlap between them was evaluated. Niche overlapping was evaluated with the stable isotope technique in the Toltén and Allipén river basin, Araucanía Region. To this end, individuals of the three species were captured, from which a sample of vibrissae was taken, which were subsequently analyzed using an elemental analyzer coupled to an "IRMS" mass spectrometer in continuous flow mode in the isotope laboratory. stables of the Andrés Bello University in Viña del Mar. In this way, values of δ13C vs δ15N were obtained, which allowed representing the trophic network of the Toltén and Allipén rivers, where there were no significant differences between the American mink and the huillín, but not between mink and the domestic cat. Then the proportions of contribution in the diet of the three predators were obtained by using the package for R "SIMMR": "Stable Isotope Mixing Models in R", where the domestic cat showed a greater attachment to chickens (Gallus gallus), and both huillín and American mink showed preferences for Chinook salmon (Oncorhynchus sp.) and river shrimp (Samastacus spinifrons). This allowed generating an estimate of the isotopic niche size for domestic cat, hoolin and American mink, using the package for R "SIBER": "Stable Isotope Bayesian Ellipses in R", in order to obtain the degree of niche overlap between these species. As expected (the proposed hypothesis was not rejected), we observed a lower degree of overlap between domestic cat and American mink, and a higher degree between whiting and American mink. It is important to mention that the study is affected by the limitations of a low number of samples, so the addition of food sources such as native fish and other crustaceans such as Aegla spp. was proposed, which would improve the accuracy of the results for future investigations.
Notas
Tesis (Licenciado en Biología)
Palabras clave
Nutrias Marinas, Visón Americano, Gatos, Investigaciones, Chile, Toltén