Instituto de Ciencias Naturales Alexander von Humboldt

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Physiological capacity of Pinctada mazatlanica to receive xenografts from Pteria sterna, as a criterion to improve pearl production and quality
(Elsevier, 2025) Trejo-Rodriguez, Karla; Granados-Amores, Andres; Arellano-Martinez, Marcial; Acosta-Salmon, Hector; Campa-Cordova, Angel I; Rojas-Figueroa, Alejandro; Saucedo, Pedro E
This study reports the survival, hemocyte count and physiological response indicators of pearl oysters Pteria sterna and Pinctada mazatlanica seeded with allografts and xenografts for pearl culture. Two treatments of oysters receiving an allograft (both donor and host were Pt. sterna) or a xenograft (donor was Pt. sterna and host was P. mazatlanica) were compared against two control groups of unseeded oysters (allografts and xenografts) at 0, 0.5, 2, 24, and 72 h. While survival was not affected by any particular treatment, the number of circulating hemocytes was inversely proportional in both species; it did not vary in Pt. sterna after allografting from t0 to 2 h, but then gradually increased and reached a 4-fold peak at 72 h that differed significantly from its control group and t0. In P. mazatlanica, the hemocyte count increased significantly (3-fold) at 0.5 h after xenografting, but then gradually decreased to equal the value of its control group and t0 at 72 h. In Pt. sterna, glycogen and mucopolysaccharide indices decreased >50 % at 2 h and gradually returned to the initial value at 72 h. In contrast, neither index varied significantly in P. mazatlanica, indicating almost no use of energy stores to compensate for the effects of xenografting, as well as little mucus production due to tissue irritation, compared to allografting in Pt. sterna. The lipofuscin index followed a relatively stable pattern over time in treatments A and X and changes with respect to their control groups CA and CX were not significant up to 72 h. Our results indicate that P. mazatlanica responded significantly faster to xenografting and wound healing than Pt. sterna to allografting, and may be a viable host to receive Pt. sterna xenografts. This could contribute to improve pearl yield and quality in Pt. sterna.
Morphological and molecular characterization of Neodiplostomum vaucheri Dubois, 1983 (Digenea: Diplostomidae) from Trachops cirrhosus (Spix, 1823) (Chiroptera: Phyllostomidae) in the southern Peruvian Amazon using third-generation sequencing (Oxford Nanopore)
(Cambridge University Press, 2025) Cacique, E. R; Barriga, N; Bello, R; Pino, J; Salcedo-Mejia, L; Nacari, L; Cruces, C; Mondragon-Martinez, A; Chero, J. D
Neodiplostomum vaucheri Dubois, 1983 is a digenean trematode originally described from the intestine of the woolly false vampire bat, Chrotopterus auritus (Peters, 1856), in the northwestern Peruvian Amazon. Decades later, it was also reported from the fringe-lipped bat, Trachops cirrhosis (Spix, 1823), in Ecuador. During a helminthological survey of phyllostomid bats at the Kawsay Biological Station in Madre de Dios, southeastern Peruvian Amazonia, specimens of Neodiplostomum Railliet, 1919 were recovered from the intestine of T. cirrhosus. Morphological comparisons with the holotype confirmed these specimens as conspecific with N. vaucheri. Phylogenetic inference supported the morphological identification, recovering the Peruvian isolate with an N. vaucheri isolate from another South American region within the same clade, with strong support (ML = 90; BI = 0.9587). The observed genetic divergence (4.47% under the Kimura two-parameter model and 4.27% based on uncorrected p-distances) in the partial cox1 sequence may indicate cryptic diversity, as previously noted in congeners. This represents the first integrative characterization of a digenean from a bat host in Peru, contributing to our understanding of parasite diversity in neotropical chiropterans. Furthermore, the use of third-generation sequencing technology (Oxford Nanopore) proved effective for generating reliable partial gene sequences, underscoring its applicability in molecular helminthology.
Modelling 22-years of changes in productivity of the red sea urchin Loxechinus albus in southern Chile using the pre-image population analysis: insights for fishery and conservation management
(Elsevier, 2025) Ortiz, Marco; Diaz, Josue
Pre-image population analysis (PPA) corresponds to a graphic method which allows modelling population dynamics, being able to estimate local population growth parameters using time series of biomass and/or abundance. In this work, PPA was performed using two different types of biomass time series of the exploited red sea urchin Loxechinus albus (Molina, 1782) that inhabit three geographical areas in southern Chile estimating changes in productivity over a period of 22 years. Although the magnitudes of biomass in the time series seem to fluctuate in the analyzed time period, the PPA model parameters in terms of x* (equilibrium values) and r (growth rate, used as a proxy for productivity) showed a reduction between ~15 - 37 % and ~60 - 71 % respectively, highlighting that the Aisen Region (XI) showed the lowest values in both model parameters. Despite the above, the productivity (r) exhibited chaotic dynamics, reaching a flat level in last years. Based on current outcomes, it is suggested to consider the inter-annual magnitudes of equilibrium values (x*) and productivity (r) when determining the exploitation levels for L. albus. Likewise, the direction of change in transient values of productivity (r) could facilitate the monitoring of local populations of L. albus, providing useful information for the adoption of management decisions, such as the setting of fishing quotas and bans. Therefore, PPA could be a useful and complementary technique in estimating dynamic reference points that improve fisheries-management and conservation programs. Finally, it is recommended that PPA could be used as an easy single-species technique to assess the population dynamics of exploited and protected species.
Exploring sustainable scenarios for the brown algae fishery in the intertidal zone along the central Chilean coast (Maule region)
(Elsevier, 2025) Berrios, Fernando; Ortiz, Marco
This work presents the outcomes from five semi-quantitative loop models of different levels of complexity, built to explore and quantify the stability and resilience (used as proxies for sustainability) of the ecological and eco-social systems where intensive artisanal fishing activity of the algae Durvillaea incurvata (Di) and Lessonia spicata (Ls) is occurring in central Chile (Maule Region). The average values for Routh-Hurwitz local stability criterion 1 (Fs) and for Levins’ criterion (Fn) showed that the model systems achieved the desired stability and resilience only when both algae exhibit asymmetric level of abundance (avoiding symmetric competition). Furthermore, both species should exhibit self-negative feedback, that is, their abundances should fluctuate between k/2 and maximum abundance (according to logistic growth). The latter results imply that both algae were the most sensitive to perturbations, regardless of their level of complexity, which limits exploitation strategies and emphasizes the need for integrated management. The substrate (S) also emerged as sensitive in the system. When fishers (F) and demand (D) are dominated by self-negative feedback, the average values of local stability (Fs) and resilience (Fn) were higher than when F and D exhibited self-positive feedback. Therefore, to ensure a sustainable exploitation of both algae, it would be necessary to: maintain the asymmetry of abundance (regardless of which of the two dominates), monitor the quality of the coastal rocky substrate to ensure the colonization of new plants, particularly L. spicata and D. incurvata, and design and implement policies that promote control over the activity of fishers and demand.
High rate of ship strike to large whales off Chile: Historical data and proposed actions to reduce risk
(Elsevier, 2025) Toro, Frederick; Buchan, Susannah J; Alvarado-Rybak, Mario; Bedrinana-Romano, Luis; Garcia-Cegarra, Ana M; Hucke-Gaete, Rodrigo; Olavarria, Carlos; Sepulveda, Maritza; Galletti-Vernazzani, Barbara; Sielfeld, Walter; Aguayo, Anelio; Capella, Juan; Perez-Alvarez, Maria Jose; Viddi, Francisco; Caceres, Benjamin; Gibbons, Jorge; Acevedo, Jorge; Guzman, Hector; Guerra, Jorge; Saez, Ricardo; Seguel, Mauricio; Fishbach, M. Michael
Ship strikes are a worldwide threat to large whales as a major cause of mortality and injury. In the Southeast Pacific, this has been poorly studied. In the last decade, an increase in ship strikes has been observed off Chile. This study assesses ship strike mortality in large whales off Chile using data on fatal strandings from the past 52 years, (1972-2023) and vessel traffic patterns. In 63 out of 226 strandings (28 %), ship strike was the direct or probable cause of mortality, i.e. the primary cause of non-natural death in whales. Fin whales (B. physalus) suffered highest total ship strikes (n = 23; 37%), followed by humpback (M. novaeangliae) (n =13; 21 %), blue whales (B. musculus) (n = 7; 11 %), sei (B. borealis) and sperm whales (P. macrocephalus) (n = 6; 10 %). Ship strikes were highest in the Regions of Valparaiso, Coquimbo, Atacama and Antofagasta (Central-Northern Chile), Los Lagos, Aysen and Magallanes (Southern Chile). Since 2013, when necropsies began to be systematically performed, an average of 5 individuals/year have been killed by ships, mostly between January and May. We review all ship strike studies globally and compare rates in Chile with those elsewhere. Based on data between 2013 and 2023, Chile is the country with the highest ship strike mortality globally; considering the entire time series since 1972, Chile ranks number six worldwide. We identify major knowledge gaps and recommend policy measures, including establishing High-Risk Areas and the implementation of shipping lanes modifications and vessel speed restrictions.
Assessing the food web structure of the mesozooplankton community in the highly variable coastal upwelling system of the southeast Pacific
(Elsevier, 2025) Cabrera-Nunez, Susana; Fernandez-Urruzola, Igor; Bode, Antonio; Hernandez-Trujillo, Sergio; Hidalgo, Pamela; Escribano, Ruben
Zooplankton are a key component in the food web of highly productive coastal upwelling systems linking primary producers to higher trophic levels. However, the complex taxonomy, wide size spectrum, and diverse trophic behaviors of zooplankton make it challenging to characterize their food web structure. This study proposes a Trophic Behavior Index (TBI) to assess the trophic structure of zooplankton and test the hypothesis that key biological attributes such as body size, diel vertical migration (DVM) behavior and trophic interactions, rather than environmental factors, primarily shape the food web dynamics of mesozooplankton communities. To this end, we analyzed depth-stratified daytime and nighttime samples of mesozooplankton collected from the upper 900 m at three oceanographically contrasting stations in the Southeast Pacific upwelling system. Vertical gradients in temperature, chlorophyll-a and dissolved oxygen were examined in relation to zooplankton abundance and composition, their DVM behavior, biomass size spectra and trophic position. The proposed TBI was constructed from zooplankton body size assessed by automated image analysis, DVM amplitude and trophic position of taxonomic groups derived from nitrogen stable isotope composition. This index was then compared across environmental conditions, allowing the classification of mesozooplankton into four major trophic functional groups: low predators (primary consumers), moderate predators, strong predators and top predators (very strong predators). Variability in oceanographic conditions influenced the zooplankton community composition and size spectrum; however, our findings suggest that zooplankton body size, DVM behavior and trophic position are the primary determinants of trophic structure. This is reflected in the relative abundance of functional groups, with strong and very strong predators prevailing in offshore areas, whereas the coastal zone was dominated by primary consumers and moderate predators. Overall, our findings support the TBI as a robust community descriptor of zooplankton trophic structure across highly variable oceanographic settings.
Environmental Stability Drives and Maintains the Global Patterns of Phylogenetic Endemism in the Marine Realm
(Wiley, 2025) Rivera, Reinaldo; Gonzalez, Carolina E; Hidalgo, Pamela; Urbina, Mauricio A; Escribano, Ruben
Aim: Endemism is a critical aspect of biological diversity, yet the mechanisms driving it remain unclear. The leading hypoth-esis posits that prolonged environmental stability fosters speciation and reduces extinction rates, promoting endemism. Whileterrestrial studies exist, marine environments remain underexplored. This study analysed the global distribution and drivers ofphylogenetic endemism in two marine taxa: Calanidae copepods and Blenniidae fish.Location: Global.Time Period: From the Last Glacial Maximum (LGM, past 24,000 years) to the current period.Taxa: Calanidae copepods and Blenniidae fish.Methods: We assessed taxonomic and phylogenetic diversity, endemism and areas of paleo- and neo-endemism usingCategorical Analysis of Neo- and Paleo-Endemism and Piecewise Structural Equation Modelling to evaluate the influence ofpresent-day and historical environmental variables.Results: Results showed consistent diversity patterns and significant endemism hotspots, with Calanidae in the SouthernHemisphere and Blenniidae in the Northern Hemisphere. Tropical regions, particularly the Indonesian-Australian Archipelago(IAA), exhibited high species richness and endemism for both groups. Paleo- endemism was observed in the Pacific for Calanidaeand the IAA for Blenniidae, suggesting that these areas are either relict diversity centres or diversification hubs.Main Conclusions: The Mediterranean and Caribbean Seas emerged as biodiversity cradles for Calanidae and Blenniidae re-spectively. Phylogenetic endemism is driven by both historical and contemporary factors, with centres of endemism emergingin regions where past environmental fluctuations have been moderate (hypothesis 1) and where cold, productive ocean currentsfoster the development of endemic areas (hypothesis 2). These findings underscore the importance of historical stability in oceantemperatures in shaping phylogenetic endemism, indicating that long-term environmental stability sustains marine endemism
Fishery biology of the Crevalle jack Caranx hippos (L) from the Colombian Caribbean
(Elsevier, 2025) Pacheco, Carlos; Cusba, Jose; Bustamante, Carlos
The crevalle jack Caranx hippos is a significant fishery resource in the Caribbean Sea; however, biological information necessary for its effective management is currently lacking. To address this gap, this study conducted an integrated multiannual analysis of fishery-dependent data on the size structure, maturity, and spatiotemporal dynamics of landings in six Colombian Caribbean regions. This study found that encircling gillnets, drift gillnets, and seine nets yielded a higher catch in terms of mass, whereas handlines, encircling gillnets, and fixed gillnets captured small and immature specimens. These practices, which affect both adult and immature populations, appear to pose a significant threat to stock health, highlighting the need for preventive approaches to fishery management in Colombian waters. Additionally, the results revealed sexual dimorphism, with females being smaller than males, and the size at maturity of females was estimated at 54.2 cm LT (81 % immature and 19 % mature). Furthermore, this study recorded annual fluctuations in the number of landed specimens at all sites, with La Guajira in the northeastern area of the Colombian Caribbean and Atlántico in the southwest area showing the highest values. The findings suggest a decrease in the size at maturity of C. hippos over a span of ten years, with an average reduction of 2.25 cm LT per year, in response to fishing pressure. In addition, spatiotemporal factors that affect fleet operations play a key role in these fluctuations. This study emphasises the need to adopt comprehensive approaches to improve our understanding of the reproductive dynamics of crevalle jack stocks to ensure the sustainability of artisanal fishing.
Is parasitic infection a buffer against metal pollution?
(Cambridge University Press, 2025) Leiva, N. V; Montenegro, D; Castro, C; Silva, M; Vidal, R; Gonzalez, M. T
Metal pollution is a major global issue in aquatic environments, affecting environmental quality and potentially altering host-parasite dynamics. This study evaluates the buffering role of a larval trematode Himasthla sp. under experimental conditions to test the effect of copper (Cu) exposure on the survival of the marine snail Echinolittorina peruviana. Snails were collected from intertidal rocky pools over a two-month period from Coloso (23 degrees 45'S, 70 degrees 28'W), northern Chile, and identified as parasitized or unparasitized. Both groups were then exposed to Cu concentrations (3 and 6 mg/L). Kaplan-Meier curves were used to determine the percentage of survival over time and the respective confidence intervals (CI). A nested ANOVA was conducted to assess whether rediae abundance per snail varied by experiment time, snail status, and Cu concentration. Snail survival was affected by both Cu-concentrations, but the effect was greater at 6 mg/L. At 3 mg/L, 57% (CI: 49.9-66.6%) of unparasitized snails were alive at 192 h, while 56% (CI: 46.6-67.4%) of parasitized snails survived at 216 h. At 6 mg/L, 42% (CI:35-51%) of unparasitized snails survived at 192 h, while 48% of parasitized snails survived at 216 h (CI:39-59%). Regardless of Cu concentration, after 240 h, all unparasitized snails had died, while 15% of parasitized snails remained alive. Dead snails harboured 125 +/- 53 rediae, while survivors had 194 +/- 73 rediae, with no significant differences between treatments. Our results show that parasitized snails survived longer than unparasitized snails, suggesting a trade-off between parasitism and host survival in polluted environments.
Site fidelity and external health of two distinct fin whale populations from the Northeast and Southeast Pacific Ocean
(Elsevier GmbH, 2025) Guevara, Consuelo; Arriagada, Aracelli; Fishbach, Michael; Van Bressem, Marie-Francoise; Van Waerebeek, Koen; Garcia-Cegarra, Ana M
Human activities such as marine traffic, fishing, and pollution are the main threats to large cetaceans, especially to resident whale populations inhabiting heavily exploited enclosed seas or gulfs. Skin is indicative of whale health status because it can display wounds and scars from interactions with fishing gear, boat strikes and natural predators as well as infectious diseases. We evaluated the residence time of two fin whale, Balaenoptera physalus (Linnaeus, 1758) populations: one resident in the Gulf of California (GC), Mexico, and another potentially migratory found at Mejillones Peninsula (MP), Chile. We also compared skin conditions by analyzing photographs for the period 2016–2022. The results show that the GC population is closed while the MP population has a low residence time (5–6 months). The GC population has a significantly higher prevalence of the mesoparasite Pennella sp., commensal Xenobalanus globicipitis and scars from collision with vessels than its MP counterpart. The MP population has a significantly higher prevalence of skin conditions of natural origin such as cookie-cutter shark (Isistius sp.) bites, predation by killer whales, Orcinus orca (Linnaeus, 1758), and orange-brown and green–brown diatom patches than the GC population. These results show that a fin whale population residing year-round in an area with high industrial, fishing, and marine traffic presents more skin conditions related to anthropogenic origin than an oceanic migratory population, which mainly presents scars of natural origins (predation). It is recommended to review the conservation status of the GC resident fin whale population and propose management strategies to guarantee their long-term conservation and welfare.
A genome-based phylogeny for Mollusca is concordant with fossils and morphology
(American Association for the Advancement of Science, 2025) Chen, Zeyuan; Baeza, J. Antonio; Chen, Chong; Gonzalez, Maria Teresa; Gonzalez, Vanessa Liz; Greve, Carola; Kocot, Kevin M; Arbizu, Pedro Martinez; Moles, Juan; Schell, Tilman; Schwabe, Enrico; Sun, Jin; Wong, Nur Leena W. S; Yap-Chiongco, Meghan; Sigwart, Julia D
Extreme morphological disparity within Mollusca has long confounded efforts to reconstruct a stable backbone phylogeny for the phylum. Familiar molluscan groups-gastropods, bivalves, and cephalopods-each represent a diverse radiation with myriad morphological, ecological, and behavioral adaptations. The phylum further encompasses many more unfamiliar experiments in animal body-plan evolution. In this work, we reconstructed the phylogeny for living Mollusca on the basis of metazoan BUSCO (Benchmarking Universal Single-Copy Orthologs) genes extracted from 77 (13 new) genomes, including multiple members of all eight classes with two high-quality genome assemblies for monoplacophorans. Our analyses confirm a phylogeny proposed from morphology and show widespread genomic variation. The flexibility of the molluscan genome likely explains both historic challenges with their genomes and their evolutionary success.
Mild Impact of the 2023 El Niño on Oceanographic and Biological Conditions in the Humboldt Current System
(American Geophysical Union, 2025) Aguilera, Victor M; Barranco, Linda; Dewitte, Boris; Gonzalez, Carolina E; Oerder, Vera; Escribano, Ruben
El Niño is an oceanographic‐atmospheric perturbation that originates atthe equator and subsequently moves poleward along the coasts of the American continent, alteringenvironmental and biological conditions of marine ecosystems. Upwelling supplies nutrients and concentratesplankton near the surface in some of these ecosystems, although it also promotes the transport of water andplankton to the open ocean. We recorded the ecosystem alterations associated with the El Niño 2023 in theHumboldt Archipelago, a biodiversity hotspot situated in a Chilean upwelling region of the Humboldt CurrentSystem. To this end, the abundance of plankton organisms (both phytoplankton and zooplankton), particulatecarbon and oceanographic conditions were assessed during eight nearly‐monthly campaigns. Planktonabundance in the archipelago depends also on local currents that disperse or concentrate particles. Thesecurrents originate from the interaction of winds and a canyon crossing the archipelago. Upwelling persistedduring the period despite the arrival of a warm Kelvin wave in June–July that elevated the sea level andtemperature. The phytoplankton abundance was the lowest after the warm wave, whereas particulate carbon andzooplankton were stable, but there was a significant surface increase during spring. The zooplankton abundancewas related to local environmental conditions, such as food and currents.
Origin, trophic transfer and recycling of particulate organic matter in two upwelling bays of Humboldt Current System: Insights from compound-specific isotopic compositions of amino acids
(Public Library of Science (PLOS), 2025) Srain, Benjamin; Flores, Edgart; Valdes, Jorge; Camano, Andres
The Chilean upwelling bays are highly productive ecosystems shaped by their inter-actions with the open ocean. Although significant knowledge exists regarding their hydrodynamic and ecological processes, the spatial dynamics of trophic transfer and heterotrophic resynthesis of organic matter remain insufficiently understood. To address these knowledge gaps, we conducted a compound-specific isotope analysis of amino acids (CSIAA) on suspended and sinking particulate organic matter from Mejillones and Antofagasta bays, two oceanographic environments characterized by contrasting hydrodynamic conditions and topographic orientations. In Mejillones Bay, the CSIAA trophic positions for metazoan (1.7 ± 0.5) and protozoan (2.3 ± 0.3) were significantly higher compared to those in Antofagasta Bay (metazoans: 1.3 ± 0.6; protozoans: 1.5 ± 0.3), highlighting protozoans as primary trophic vectors. MixSIAR analysis indicated that phytoplankton is a key source of particulate organic matter in both bays; however, Mejillones Bay exhibited a greater proportion of microbially degraded organic matter. Enhanced heterotrophic resynthesis in Mejillones Bay (ΣV: 1.9–2.5) was associated with lower oxygen levels, increased concentrations of NO₂⁻ , and heightened stratification of the water column. Additionally, depth-dependent variations in δ15N for phenylalanine and threonine indicated a greater solubilization of particles, which contributed to a reduction in the export of particulate organic matter (averaging 9 ± 2 mg C/m²/d). These findings underscore the critical role of the intricate interactions between the bay’s topographic features and the physical and biological processes that ultimately influence the cycling trajectories of particulate organic mat-ter in upwelling bays
Unveiling a new species of Trapania (Gastropoda: Nudibranchia: Goniodorididae) from the South-eastern Pacific using anatomical and molecular tools
(Cambridge University Press, 2025) Uribe, Roberto A; Mendivil, Alejandro; Pastor, Ruslan; Atoche-Suclupe, Dennis; Aleman, Solange; Flores, Lorenzo; Sepulveda, Fabiola
Morphological and molecular methods were used to describe a new species ofTrapaniaPruvot-Fol, 1931 from shallow water kelp forests on the north-central coast of Peru. Thenew species,Trapania huarmeyana sp. nov., is distinguished from other species along theEastern Pacific by external morphological characters such as its translucent white bodywith brown stripes and small spots on the dorsum, blotches on the base of the extra-branchialprocesses, extra rhinophoral processes and gill branches. Internally,T. huarmeyanasp. nov. isdistinguishable by several morphological characteristics of the radula, jaws and genital organs.Phylogenetic trees recovered using Bayesian Inference and Maximum Likelihood analysis ofDNA sequences support its distinct status and clarify its relationship to other species fromthe Eastern Pacific. This new species constitutes the first record ofTrapaniafrom theHumboldt Current Ecosystem, contributing to our understanding of the distribution of thegenus in the South-eastern Pacific.
Metazoan Parasite Communities of Two Sympatric Shortnose Chimeras (Holocephali: Chimaeridae) from Deep Waters Associated with the Humboldt Current System: Ancient Fishes Harbor Ancient Parasites
(MDPI, 2025) Oliva, Marcelo E; Nacari, Luis A; Espinola-Novelo, Juan F
A total of 61 specimens of deep-sea chimaeras (Hydrolagus melanophasma = 41; Chimaera sp. = 20) were obtained during September 2017 as by-catch of the local fishery of the Patagonian toothfish (Dissostichus eleginoides, Pisces: Nototheniidae) along the northern Chilean coasts (≈22°20′ S) at depths ranging from 950 to 1500 m using a deep-sea longline. Nine species of metazoan parasites were found in H. melanophasma and seven in Chimaera sp. Four species were shared between both host species. Gyrocotyle sp.1 (Cestodaria) and Multicalyx elegans (Aspidogastrea) showed the higher prevalence H. melanophasma (68.3% and 65.38%, respectively), whereas Plectognathotrema hydrolagi (Digenea), Gyrocotyle sp.1 (Cestodaria), and Chimaericola sp. (Monogenea) showed higher prevalence in Chimaera sp. (90%, 55% and 55%, respectively). Beta diversity analysis reveals that the parasite communities of these two related and sympatric species are strongly differentiated. Our results suggest a strong relationship between the ancient Holocephali, which harbor ancient parasites belonging to Rugogasteridae and Multicalycidae (Aspidogastrea), and two Cestodaria species. Chimaera spp. are also parasitized by some highly specific monogeneans, such as Chimaericola spp. Our results demonstrate the differences in the parasite community structures—both of ecto- and endoparasites—of two related and sympatric hosts.
Impact of multiple-factors on health and infections in marine mussels (Perumytilus purpuratus) inhabiting contaminated sites in the Humboldt Current System
(Nature Portfolio, 2025) Montenegro, Diana; Gonzalez, Maria Teresa
Marine organisms are increasingly exposed to a combination of environmental stressors. However, most studies focus on single factors, limiting our understanding of real-world ecological challenges. This study investigates the combined effects of metal pollution, parasites, pathogens, and environmental variables on the health of Perumytilus purpuratus, a mussel species inhabiting the coast of northern Chile. The upwelling system in this area, combined with low water turnover, creates a unique environment in which to study how multiple factors interact. Mussels were sampled from several sites affected by metal discharges. Analyses revealed that individuals from central and northern sites exhibited the highest levels of parasites, pathogens, and tissue lesions. These health impacts were strongly associated with elevated pH, salinity, cadmium and copper concentrations in the water. Findings emphasise the synergistic effects of chemical and abiotic factors, underscoring the importance of incorporating multiple factors interactions into monitoring programmes. Such an approach can enhance predictions of ecological responses, inform conservation efforts, and guide policies addressing global challenges like aquatic pollution. Our study provides critical insights into how combined factors threaten aquatic ecosystems, offering a framework for more comprehensive environmental assessment.
New record of Frilled shark Chlamydoselachus anguineus Garman, 1884 (Chondrichthyes: Hexanchiformes) in the South Pacific Ocean
(PeerJ Inc., 2025) Indurain, Maria J; Mancilla, Angel; Brizuela, Leandro; Vargas-Caro, Carolina; Bustamante, Carlos
Frilled sharks are rarely observed and limited information is available regarding their life history. The global number of records for these sharks does not exceed 40, with most sightings reported in the Western Pacific Ocean. In 1976, one specimen was recorded for the first time in the South East Pacific Ocean; however, this study provides new evidence for the presence of Chlamydoselachus anguineus in Chilean waters, extending its distribution range 850 km south of the previous record. The morphological features of all specimens from Chile are discussed, supplementing previous observations and adding to the existing knowledge on this species in the Pacific Ocean.
Pingers as a potential deterrent tool to mitigate Burmeister's porpoise (Phocoena spinipinnis) bycatch while foraging nocturnally in the Humboldt Current System: a pilot study
(Frontiers Media SA, 2025) Diaz, Diego; Garcia-Cegarra, Ana M
Fisheries bycatch is one of the main threats for porpoise species worldwide. In the Humboldt Current system of northern Chile, the elusive Burmeister’s porpoise (Phocoena spinipinnis) inhabits the coastal waters of Mejillones Bay and suffers bycatch mortality in purse seine fishing nets and coastal gillnets. In order to mitigate bycatch of this near-threatened species, this study aimed to (1) analyze the diurnal and nocturnal acoustic behaviors of the Burmeister’s porpoise and (2) evaluate the potential of banana pingers as acoustic deterrent tools. For 27 days during austral summer, a full wave form capture porpoise detector was anchored 7 m above sea level in Mejillones Bay where Burmeister’s porpoises are frequently observed. During this time, the detector registered acoustic activity continuously over 13 days, and a banana pinger deployed over 100 m away from the detector emitted high frequency sounds continuously for 14 days. The results show that the number of clicks and detection-positive minutes were significantly higher while the inter-click intervals and high click rate feeding buzz were significantly lower at night, indicating that Burmeister’s porpoises forage mainly nocturnally in this bay. With pingers present, the probability of detection of Burmeister’s porpoise acoustic activity decreased by 20%, suggesting that pingers could be an effective tool to avoid Burmeister’s porpoise mortality in fishing nets. Future studies should implement pingers in artisanal purse seine fishing nets and coastal gillnets in order to mitigate Burmeister’s porpoise bycatch in northern Chile.
Biogeographic Insights Into the Late Miocene Diversification of the Giant Deep-Ocean Amphipod Eurythenes
(Wiley, 2025) Gonzalez, Carolina E; Weston, Johanna N. J; Rivera, Reinaldo; Oliva, Marcelo; Escribano, Ruben; Ulloa, Osvaldo
Mechanisms driving the spatial and temporal patterns of species distribution in the Earth's largest habitat, the deep ocean, remainlargely enigmatic. The late Miocene to the Pliocene (~23–2.58 Ma) is a period that was marked by significant geological, climatic,and oceanographic changes. This transitional period spurred widespread species diversification, particularly among widely dis-tributed benthic scavengers, such as amphipods. Here, we take step toward understanding the long-term evolutionary processesof amphipod colonization and diversification in the deep ocean by focusing on the model genus Eurythenes S. I. Smith in Scudder,1882. These large-bodied scavengers play key roles in benthic communities. We constructed a time-calibrated phylogeny usingtwo mitochondrial DNA genes by analyzing publicly available data on 14 species of Eurythenes across a global depth range from839 to 8081 m. The resulting phylogenetic tree reveals a diverse clade, with a common ancestor originating around 11.81 Ma. Agradual increase in the effective population size of Eurythenes was observed, particularly during the Pliocene (~4 Ma). The netdiversification rate remained almost constant, with slight increases between the Miocene and Pliocene (~8–4 Ma), and most newspecies appeared during the latter period. Additionally, reconstruction of the ancestral area suggested that the common ancestorof Eurythenes had a global distribution. A combination of dispersal and sympatric processes, along with environmental factors,such as changes in ocean temperature and sea level, contributed to the present biogeographic distribution of these species. Ourfindings highlight the importance of historical events, such as plate tectonics and changes in deep-water circulation, in drivingthe rapid speciation of Eurythenes and underscore their essential role in shaping deep-ocean biodiversity
Heavy metals and trace elements in a threatened population of guanay cormorants (Leucocarbo bougainvilliorum) from an industrialized bay in the Humboldt Current System, Chile
(Elsevier GmbH, 2025) Carretero, Jorge; Garcia-Cegarra, Ana M; Martinez-Lopez, Emma
Metal contamination from industrial and mining activities threatens coastal and marine ecosystems, leading to bioaccumulation in marine organisms and biomagnification through the trophic chain. The Guanay cormorant (Leucocarbo bougainvilliorum), an endemic species of the Humboldt Current System, is experiencing population declines and serves as a key bioindicator of heavy metal contamination due to its high trophic position, reliance on commercially exploited pelagic fish, and capacity to accumulate contaminants over time. This study analyzed the concentrations of five heavy metals (Hg, As, Pb, Cr, Cd) and three trace elements (Cu, Zn, Se) in liver, muscle, feathers, and kidney of 10 Guanay cormorants found dead in Mejillones Bay, Chile, a highly industrialized area. Feathers exhibited the highest concentrations of Cr (2.03 ± 0.63 mg/kg), Cu (19.72 ± 3.82 mg/kg), and Zn (109.84 ± 11.95 mg/kg), emphasizing their role in detoxification. Females showed significantly higher Cu and Pb concentrations in muscle and Cr in kidneys, likely due to physiological and hormonal differences related to reproduction. Correlations between metal concentrations across tissues suggest shared bioaccumulation mechanisms, while the Hg:Se molar ratio (e.g., 0.25 ± 0.04 in liver) indicated a protective role of Se against Hg toxicity. Metal concentrations were comparable to those reported in other marine cormorants but differed from freshwater populations, highlighting the influence of habitat on metal accumulation. Although current levels do not indicate acute toxicity, the ongoing population decline of Guanay cormorants underscores the need for long- term biomonitoring. Future research incorporating biochemical and enzymatic biomarkers is essential to assess potential sublethal effects and long-term ecological risks associated with heavy metal exposure in this species.

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