Mario George-Nascimento

Heavy metal contamination represents a persistent threat to coastal ecosystems due to its toxicity, environmental persistence, and potential transfer through marine food webs. This study evaluated the accumulation of copper (Cu), cadmium (Cd), and lead (Pb) in a host–parasite system composed of the red cusk-eel Genypterus chilensis and its parasitic nematode Phocanema cattani, together with associated environmental matrices (water and sediment) collected from four coastal localities of the Biobío Region, Chile (Tomé, Talcahuano, Coronel, and Punta Lavapié). Metal concentrations were determined by atomic absorption spectrophotometry following acid digestion of biological and environmental samples. Differences among matrices and localities were assessed using generalized linear models. Copper exhibited significant variation among localities and matrices, with markedly higher concentrations in parasites than in host muscle tissues. Cadmium showed significant differences among matrices, reaching its highest concentrations in seawater and displaying elevated accumulation in parasites. Lead differed significantly among localities, with the highest levels recorded in Coronel and the lowest in Punta Lavapié. Overall, metal accumulation patterns reflected the combined influence of local anthropogenic sources and regional oceanographic processes. The high concentrations of Cu and Cd detected in P. cattani demonstrate its strong metal accumulation capacity and support its use as a sensitive bioindicator of coastal contamination. Integrating environmental matrices, host tissues, and parasites provided a comprehensive assessment of contaminant dynamics and trophic transfer in coastal ecosystems. These findings contribute to the understanding of heavy metal pollution in the Biobío coast and highlight the value of host–parasite systems for environmental biomonitoring in industrialized marine environments.

Invasive species can disrupt disease dynamics in new areas. Upon introduction, an invasive species in its new range may be colonised by novel parasites that normally infect native fauna. If the infected invasive host then helps to spread and boost the parasites to native hosts, this is known as spillback. Chinook salmon (Oncorhynchus tshawytscha) were released into rivers in southern Chile around 1924 and became invasive from 39°S to 53°S. Its anadromous migration and predatory behaviour involve multiple interactions with various native species. We examined the digestive tracts from 114 adult Chinook salmon returning from the sea to the estuary in the Toltén River, Chile to characterise their enteroparasite diversity, classify parasite developmental stages and assess Chinook’s potential as a definitive host for local, native parasites. We enumerated 12,277 larvae of parasitic individuals belonging to the genera Anisakis and Hysterothylacium (Nematoda), Nybelinia (Cestoda) and orders Pseudophyllidea, Tetraphyllidea and Trypanorhyncha (Cestoda). Amongst these, we also found adults — one immature female, four gravid females and eight males of the nematode Hysterothylacium sp., six adults of the trematodes Lecithaster sp. and one Lampritrema sp. Finding advanced and adult stages suggests chinook are a competent non-native host for Hysterothylacium, Lecithaster and Lampritrema, as well as a non-native host for larval stages of Nybelinia sp., Pseudophyllidea and Tetraphyllidea. Our study demonstrates the integration of native parasites into an invasive host along the coast of Chile. Namely, Chinook salmon are now acting as a novel host that is positioned as a new node in trophic interactions and host-parasite networks. Additionally, our study provides valuable baseline data for further research on the impact of these parasites on native species and ecosystem dynamics, including the extent to which spillback is occurring.

Las especies del género Anisakis (Nematoda: Anisakidae) son parásitos marinos con ciclo de vida indirecto. Los crustáceos planctónicos actúan como primeros hospedadores intermediarios, mientras que peces y cefalópodos intervienen como segundos hospedadores intermediarios o paraténicos, finalmente el ciclo se cierra en los cetáceos, mamíferos marinos que son los principales hospedadores definitivos del género. En el ciclo de vida, las larvas de Anisakis pueden ser ingeridas por el hombre interviniendo como huésped accidental, lo que puede ocasionar anisakiasis, una zoonosis adquirida a través del consumo de peces y cefalópodos crudos o marinados. Estos nemátodos tienen una distribución cosmopolita, sin embargo, su diversidad ha sido escasamente estudiada en el hemisferio Sur. Por tanto, se evaluó la diversidad de las larvas de Anisakis spp., presentes en dos especies de hospederos de Chile, combinando el análisis morfométrico y genético. Para ello, se recolectaron larvas de Anisakis spp. en la cavidad abdominal de la merluza Merluccius gayi y el calamar Dosidicus gigas, procedentes de terminales pesqueros de la región del Biobío, Chile. La caracterización morfométrica de las larvas de Anisakis spp., consistió en la medición de la longitud del esófago, ventrículo esofágico, cola, longitud total y ancho máximo del cuerpo. Para los análisis genéticos se usó la región molecular nuclear ITS (ITS1-ITS2) y mitocondrial COX2. Los resultados morfométricos revelaron que las larvas extraídas de D. gigas son significativamente de mayor longitud que las recolectadas en M. gayi, sugiriendo una alta variabilidad fenotípica hospedador-dependiente. Los análisis moleculares y filogenéticos determinaron la presencia de Anisakis pegreffii en ambos hospedadores, sin embargo, demostraron una baja diferenciación genética y diversidad nucleotídica entre las secuencias, indicando una escasa variabilidad genética para el conjunto de datos. Este trabajo constituye el primer registro molecular de A. pegreffii en hospedadores intermediario o paraténicos de la costa de Chile.