Datos de investigación
First record of endoparasites in Magellanic penguin (Spheniscus magellanicus) nest soil in one of the southernmost breeding colonies at Martillo Island, Tierra del Fuego, Argentina
Publicador:
Consejo Nacional de Investigaciones Científicas y Técnicas
Fecha de depósito:
12/05/2025
Fecha de recolección:
01/12/2022-01/04/2023
Clasificación temática:
Resumen
This study provides the first comprehensive analysis of endoparasite diversity associated with Magellanic penguins (Spheniscus magellanicus) at the southernmost extent of their distribution, within the Beagle Channel , Argentina. Using nest sediment sampling, multiple parasite genera were identified, including Corynosoma, Cosmocephalus, and Contracaecum, alongside various taxonomic groups like trematodes, cestodes, and acanthocephalans. These findings indicate that penguins in this colony are exposed to a wide range of parasites, with nematodes being the most prevalent. Endoparasite abundance was higher during chick rearing than after breeding, likely due to increased fecal deposition and favorable environmental conditions. Significant variations in parasite loads were observed across three previously identified erosion level zones of the colony, suggesting that microhabitat characteristics influence parasite persistence. This research highlights the effectiveness of non-invasive soil sampling in detecting parasite exposure over time and underscores the importance of continued monitoring of penguin health and parasite exposure, particularly in response to anthropogenic stressors. Future studies should integrate direct parasitological methods and molecular techniques to further understand host-parasite interactions.
Tabla de contenidos
Study took place at Martillo Island (54°53'S, 67°34'O) where a small Magellanic penguin colony breeds (3000 breeding pairs, Scioscia et al. 2024). Three zones were identified within the colony according to burrow nest ground cover based on the following erosion percentage categories (following Quiroga et al. 2020): Medium-high erosion (50-70%, zone A), Medium erosion (30-50%, zone B) and Low erosion (0-30%, zone C) (Fig. 1). During chick rearing (December 2022-January 2023) and after breeding (April 2023), a sample of soil was taken from 20 nests randomly selected from each of the three mentioned zones at each of the two time periods (n = 20 in each zone each time period, out of which a total of 115 samples were finally used). Zone A was also distinguished from the remaining zones as it is visited by tourists during the breeding period. For the extraction of soil samples, a superficial portion of soil (less than 1 cm deep) was taken from the internal section of the burrow nest with a 15ml falcon tube. Samples were kept in alcohol 70% at room temperature. Separation of egg and larval stages of parasites from soil was done with the modified Ritchie method of the sedimentation concentration technique (Hawksworth et al. 2012). A few drops of resulting sediment were taken, placed on a slide with a drop of glycerin and observed under an optical microscope at 40X (Leica DM2500 Wetzlar, Germany). All eggs and larvae present in the smear were counted. Parasites were differentiated at different taxonomic levels using the cited bibliography of parasite groups present in the genus Spheniscus as reference. From the existing bibliography, we identified certain characteristics in eggs and larvae that suggest their classification into the following genera: Corynosoma, Cosmocephalus, and Contracaecum. The remaining parasite eggs, whose genus could not be determined, were grouped into broader taxonomic classes: trematodes, nematodes, cestodes, and acanthocephalans, based on their distinctive morphological features. Additionally, a separate category was assigned for nematode larvae, which included first-stage (L1) and gastrointestinal-type larvae. Eggs were classified according to size: trematode eggs (20 to 200 μm), nematode eggs (30 and 100 μm), cestode eggs (20 to 60 μm) (Vila et al. 2009). In addition, eggs were distinguished by taxon-specific features based on Bowman, 1995. Nematode larvae shed in feces are typically identified based on their hosts, and in domestic animals, they tend to measure approximately 300 μm in length. A total of 60 breeding Magellanic penguins were sampled during chick rearing, corresponding to 20 individuals (one per nest) for each of the three previously defined erosion zones (a total of n = 50 samples were finally used). Blood samples were extracted from the tarsal vein of the individuals, needle puncture was performed, a drop of blood was extracted with a capillary and placed on a slide and a blood smear was performed in the field (in duplicate). Smears were fixed with 95% ethanol and stained in the laboratory with Giemsa diluted 1:7 with distilled water for 13 minutes (Giemsa, 1909). Finally, leukocyte counting and differentiation was performed under an optical microscope (Leica DM2500, Wetzlar, Germany) with immersion oil at 100x. For each sample a minimum of 100 leukocyte cells were counted,the number of lymphocytes (L) and eosinophils (E) were identified and the E/L value was estimated.
Palabras clave:
Erosion,
Magellanic penguins,
Nematodes,
Parasites,
soil sampling
Alcance geográfico
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Identificador del recurso
Colecciones
Datos de Investigación(CADIC)
Datos de Investigación de CENTRO AUSTRAL DE INVESTIGACIONES CIENTIFICAS
Datos de Investigación de CENTRO AUSTRAL DE INVESTIGACIONES CIENTIFICAS
Citación
Montangero, Milena; Harris, Sabrina; San Martín, Analía Anahí; (2025): First record of endoparasites in Magellanic penguin (Spheniscus magellanicus) nest soil in one of the southernmost breeding colonies at Martillo Island, Tierra del Fuego, Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. (dataset). http://hdl.handle.net/11336/261001
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