Sara M. Rodríguez

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.

Anomalies in skin or plumage pigmentation have been recorded across various vertebrate species, albeit infrequently. Factors such as pollution and genetics are indicated as the causes. This study reports for the first time, a case of color aberration (albinism or Brown) in a juvenile Humboldt penguin Spheniscus humboldti individual on the Hualpén Peninsula, Chile, along with an update of the literature comprising 25 reported cases of these anomalies in the Chilean wildlife.

Balancing sample sizes between infected and uninfected hosts is a common challenge in ecological parasitology, particularly when dealing with intermediate hosts involved in complex life cycles. In these life cycles, common in nature, the intermediate hosts accumulate parasites across their ontogeny, making it difficult to obtain similar numbers of naturally infected and uninfected individuals across full host body-size spectra. Here, we present a standardized and repeatable method to experimentally infect and re-infect intermediate hosts using parasite eggs derived directly from the fresh faeces of definitive hosts. We tested this methodology in a marine host–parasite system involving the acanthocephalan Profilicollis altmani , the mole crab Emerita analoga , and the grey gull Leucophaeus modestus . Crabs were raised in controlled laboratory conditions from early juvenile stages, ensuring no prior infections, and exposed to parasite eggs through filtered faecal suspensions. Larval development was tracked across two inoculation events. The first larval stage (acanthellae) appeared six days after inoculation and matured into cystacanths within the following week. After the first exposure, 55% of inoculated hosts were infected; after the second, infection prevalence reached 100%. Larger crabs acquired more parasites than smaller ones, likely due to higher filtration rates. The method closely mimics natural faecal-oral transmission while avoiding the need to isolate or handle parasite eggs directly. It also overcomes the common issue of parasite overdispersion in natural populations by enabling controlled infections across host size classes and experimental replicates. This technique is particularly useful in species with opaque cuticles, where internal parasites cannot be visually identified in vivo. Additionally, it can be extended beyond acanthocephalans to other helminth taxa (e.g., nematodes, cestodes, and digeneans) whose eggs are also shed in vertebrate faeces. Our results establish a reliable, ecologically relevant protocol for experimental parasitology in marine and freshwater systems.

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.

Intersexuality is a reproductive phenomenon that occurs in some gonochoric species and refers to the simultaneous presence of both male and female gametes within the same individual. Although this phenomenon has been reported in various invertebrate species, many aspects remain poorly understood, especially in marine mussels. However, it has been suggested that the prevalence of parasites within populations could induce the occurrence of intersex animals. We studied intersexuality in the marine mollusk Perumytilus purpuratus, a key species of the rocky intertidal zone on the southeastern coast of the Pacific Ocean. A total of 6472 mussels from eight locations in northern and southern Chile were analyzed. We estimated the size of the specimens, the sex ratio of the population, and the prevalence of parasites. Additionally, we examined the germ cells of intersex mussels. The results showed that the male-to-female sex ratio (1:1) was maintained in the populations. Intersex mussels were found in six of the eight locations, representing 0.19% of the mussels analyzed. However, no parasites were found in the intersex animals. Additionally, the abundance of intersex individuals was not correlated with parasitism levels in the population. In intersex mussels, the gonadal tissue was compartmentalized, with male and female germ cells remaining separate. It is concluded that intersexuality in Perumytilus purpuratus is a low-frequency reproductive phenomenon, likely resulting from an alteration in the sex determination mechanism. Intersexuality offers a valuable opportunity to explore the biological aspects of sex determination in mussels. Therefore, further research in this area should be pursued.

Profilicollis rancoensis n. sp. is the tenth species of Profilicollis Meyer, 1931 which includes 9 other species mostly known from marine decapod crabs and shore birds. Cystacanths of P. rancoensis are described from the dominant freshwater crab Aegla abtao in Ranco Lake, Chile and are morphologically distinguished from cystacanths of the 9 other species based on a combination of 4 characters. These are body size, number of proboscis hook rows, number of hooks per row, and length of the largest anterior 2–4 hooks. Male and female cystacanths of P. rancoensis are 2.10–3.33 mm long having an ovoid proboscis with 14 rows of 6–7 hooks per row, with the largest anterior 2–4 hooks being 105–110 micrometers long; the anterior trunk has many small spines in 70–80 concentric rings, each with 50–60 spines around them; hook roots are simple, directed posteriorly, about as long as the blades anteriorly with unremarkable anterior manubria; the cephalic ganglion are in mid-receptacle just anterior to the level of the anterior trunk; the lemnisci are long and slender; the testes are in the anterior trunk, posterior trunk, or one in each; the primordia of 2 tubular cement glands are evident; strong bundles of fibers link the anterior and posterior trunk; and the posterior trunk has a corrugated surface cuticula. Molecular analysis (COI and 18S) sequences coincided with the morphology and support its taxonomy. The phylogenetic profile revealed that P. rancoensis n. sp. fell into the Profilicollis clade. Both sequences showed low genetic variation, and three different haplotypes were found. The new species was more closely related to P. botulus (Van Cleave, 1916) Witenberg, 1932 than to other Profilicollis species.

Resumen: La rentabilidad es uno de los factores que más influye en la selección de presas. Este factor varía en función del tamaño de la presa y del tiempo de manipulación. Por lo tanto, generalmente las presas grandes son altamente rentables para los consumidores e intensifican la competencia. El cleptoparasitismo es una forma de competencia en la que un individuo roba alimento previamente obtenido por otro individuo. En consecuencia, la manipulación de presas grandes debería aumentar la probabilidad de ocurrencia de cleptoparasitismo, sin embargo, estas relaciones siguen siendo poco conocidas. En este trabajo estudiamos la ocurrencia de cleptoparasitismo de la Gaviota Cáhuil (Chroicocephalus maculipennis – Laridae) sobre Zarapitos (Numenius phaeopus hudsonicus – Scolopacidae) que se alimentan de chanchitos de mar (Emerita analoga) en una playa arenosa expuesta al oleaje en el sur de Chile. Los modelos lineales generalizados, ajustados a los datos de video secuencias focales‐individuales, mostraron que la probabilidad de cleptoparasitismo tuvo una respuesta sigmoidal positiva al tiempo de manipulación. Además, con un aumento de un segundo en el tiempo de manipulación, los Zarapitos duplicaron su probabilidad de ser cleptoparasitados. Además, la probabilidad de ser cleptoparasitado fue un 17% más alta con un aumento de 10 mm en la longitud de la presa y un 47% más alta con un aumento de una gaviota por hospedador. Sin embargo, el efecto del tiempo de manipulación sobre la probabilidad de cleptoparasitismo disminuyó ligeramente (2%) con un aumento de 10 mm en la clase de tamaño de la presa. Nuestros resultados sugieren la existencia de un umbral de tiempo en el que los consumidores pueden manipular a sus presas antes de que la probabilidad de cleptoparasitismo sea demasiado alta. Sin embargo, la tasa media de ingesta de los zarapitos alcanzó 0,15 ± 0,13 kJ s⁻¹, permitiendo que los zarapitos cumplan, en teoría, con sus requerimientos energéticos a pesar de perder algunas presas a causa de los cleptoparásitos. Este estudio proporciona una nueva visión sobre una forma común de competencia entre consumidores, destacando la importancia del tiempo de manipulación de presas para las aves playeras con un tiempo de alimentación restringido a causa de los ciclos de marea.

Previous descriptions of Corynosoma bullosum (Linstow, 1892) show that specimens vary greatly in the proportions of different body structures, measurements of females and males, number of rows of hooks, and egg measurements, among other features. We redescribe this species from specimens found in southern elephant seal faeces from King George Island. We also provide a molecular characterization, in addition to 5.8S and internal transcribed spacer (ITS) existing sequences. We examined 41 elephant seals, and 30 adult acanthocephalans were found in 15 of them. The specimens were identified as belonging to the genus Corynosoma due to each having a tubular body with an inflated anterior part forming a thorny disk and the posterior part bearing somatic spines on the ventral surface, and genital spines surrounding the genital pore. Individual morphology corresponded to C. bullosum: large size, marked sexual dimorphism, and proboscis with 16–18 rows of spines with 11–15 spines per row. The molecular profile of three specimens of C. bullosum was analysed using 18S rDNA. We inferred phylogenetic relationships of the family Polymorphidae using maximum likelihood and Bayesian inference. We provide an updated morphological redescription for C. bullosum including electron microscopy photographs and molecular data. The 18S gene sequences showed low genetic variation and supported that C. bullosum is a sister to Corynosoma australe.