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The effects of crude oil spills are an ongoing problem for wildlife and human health in both marine and freshwater aquatic environments. Bioassays of model organisms are a convenient way to assess the potential risks of the substances involved in oil spills. Zebrafish embryos (ZFE) are a useful to reach a fast and detailed description of the toxicity of the pollutants, including both the components of the crude oil itself and substances that are commonly used for crude oil spill mitigation (e.g. surfactants). Here, we evaluated the survival rate, as well as histological, morphological, and proteomic changes in ZFE exposed to Water Accumulated Fraction (WAF) of light crude oil and in mixture with Dioctyl Sulfosuccinate Sodium (DOSS, e.g. CEWAF: Chemically Enhanced WAF), a surfactant that is frequently used in chemical dispersant formulations. Furthermore, we compared the hydrocarbon concentration of WAF and CEWAF of the sublethal dilution. In histological, morphological, and gene expression variables, the ZFE exposed to WAF showed less changes than those exposed to CEWAF. Proteomic changes were more dramatic in ZFE exposed to WAF, with important alterations in spliceosomal and ribosomal proteins, as well as proteins related to eye and retinal photoreceptor development and heart function. We also found that the concentration of high molecular weight hydrocarbons in water was slighly higher in presence of DOSS, but the low molecular weight hydrocarbons concentration was higher in WAF. These results provide an important starting point for identifying useful crude-oil exposure biomarkers in fish species.

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The oceanographic conditions of the Pacific Ocean are largely modified by El Niño (EN), affecting several ecological processes. Parasites and other marine organisms respond to environmental variation, but the influence of the EN cycle on the seasonal variation of parasitic copepods has not been yet evaluated. We analysed the relation between infection parameters (prevalence and mean intensity) of the widespread parasitic copepods Caligus bonito and Charopinopsis quaternia in the dolphinfish Coryphaena hippurus and oceanography during the strong 2015-16 EN. Fish were collected from capture fisheries on the Ecuadorian coast (Tropical Eastern Pacific) over a 2-year period. Variations of sea surface temperature (SST), salinity, chlorophyll a (Chl-a), Oceanic Niño Index (ONI), total host length (TL) and monthly infection parameters of both copepod species were analysed using time series and cross-correlations. We used the generalised additive models for determine the relationship between environmental variables and infection parameters. The total body length of the ovigerous females and the length of the eggs of C. bonito were measured in both periods. Infection parameters of both C. bonito and Ch. quaternia showed seasonal and annual patterns associated with the variation of environmental variables examined (SST, salinity, Chl-a and ONI 1+2). Infection parameters of both copepod species were significantly correlated with ONI 1+2, SST, TL and Chl-a throughout the GAMLSS model, and the explained deviance contribution ranged from 16%-36%. Our results suggest than an anomaly higher than +0.5°C triggers a risen in infection parameters of both parasitic copepods. This risen could be related to increases in egg length, female numbers and the total length of the ovigerous females in EN period. This study provides the first evidence showing that tropical parasitic copepods are sensitive to the influence of EN event, especially from SST variations. The observed behaviour of parasitic copepods likely affects the host populations and structure of the marine ecosystem at different scales.

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Introduction: Anisakidosis is a zoonotic disease caused by the consumption of raw or undercooked fish or crustaceans parasitized by nematode larvae of the Anisakidae family. In this study, the presence of anisakid larvae was identified in fish species of consumer of the Pacific coast in Ecuador and Colombia. Methods: We obtained 438 samples grouped into twenty species of fish caught in the fishing ports of Manta, Santa Rosa, Buenaventura and Tumaco. The morphological identification of the larvae was made by taxonomy and the percentage of infection, were calculated. For the identification of species, a multiplex PCR was carried. Results: The taxonomic review identified eight species of fish as hosts of the genders Anisakis and Pseudoterranova. The larvae were isolated mainly from the intestine with a percentage of infection between 18 and 100%. The percentage of infection and identification of anisakids in these fish will aid in the prevention and control of anisakiasis as a possible emerging disease for this area of the Pacific. With the multiplex PCR, A. pegreffii, A. physeteris, and P. decipiens were identified. Conclusion: The identification of these species is reported for the first time in this geographical area, providing the basis for future research into the Anisakidae family.

Introducción: La anisakidosis es una enfermedad zoonótica causada por el consumo de pescado o crustáceos crudos o poco cocinados parasitados por las larvas de nematodos de la familia Anisakidae. En este estudio, se identificó la presencia de larvas de anisakidos en especies de peces de consumo de la costa del Pacífico en Ecuador y Colombia. Métodos: Obtuvimos 438 muestras agrupadas en veinte especies de peces capturados en los puertos pesqueros de Manta, Santa Rosa, Buenaventura y Tumaco. La identificación morfológica de las larvas se realizó por taxonomía y se calculó el porcentaje de infección. Para la identificación de las especies, se llevó a cabo una PCR múltiplex. Resultados: La revisión taxonómica identificó ocho especies de peces como huéspedes de los géneros Anisakis y Pseudoterranova. Las larvas se aislaron principalmente del intestino con un porcentaje de infección entre 18 y 100%. El porcentaje de infección e identificación de anisakidos en estos peces ayudará a prevenir y controlar la anisakiasis como una posible enfermedad emergente en esta área del Pacífico. Con la PCR múltiplex, se identifico A. pegreffii, A. physeteris y P. decipiens. Conclusión: La identificación de estas especies se informa por primera vez en esta área geográfica, proporcionando la base para futuras investigaciones sobre la familia Anisakidae.

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A new caligid copepod species, Pupulinamantensissp. n. is described based on female and male specimens collected from the gills of the myliobatid elasmobranch Aetobatuscf.narinari Euphrasen, 1790 captured off the Pacific coast of Ecuador. The new species has a unique combination of characters that diverges from its known congeners, including: (i) weakly developed posterolateral processes on the genital complex; (ii) large spines on posterior surface of maxilliped basis (iii) abdomen slender, unsegmented, approximately 1/2 length and 1/5 width of genital complex; (iv) third exopodal segment of leg II with single long naked spine adjacent to minute, naked lateral spine; (v) velum of leg II with adjacent patch of denticles; (vi) caudal rami slightly less than half the length of genital complex; (vii) post-antennal process with robust, posteriorly directed tine, sclerotized stump posterolaterally, and two multi-sensillate papillae located on or near base of process (viii) post-oral process oval. The overall prevalence of P.mantensissp. n. on its host was 37.5% and its mean abundance was 1.87 specimens per host. This is the second record of the genus Pupulina from Ecuador and the second record of Pupulina infecting rays of the Myliobatinae genus Aetobatus, of the subfamily Myliobatinae, after its discovery on A.ocellatus in Australia, thus confirming this expansion of its previously known host range to a new elasmobranch subfamily.

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A new copepod species, Ergasilus curticrus n. sp. is described based on 14 female specimens collected from the gills of the characid teleost Bryconops giacopinii Fernández-Yépez, captured in the Vichada River Basin in Colombia. The new species has a unique combination of characters including: (i) 2-segmented endopods in legs 1 and 4; (ii) a semi-pinnate, falciform seta on the terminal segment of the first leg exopod; (iii) a 1-segmented fourth leg exopod; (iv) a reduced fifth leg with a single seta; and (v) a circular structure fused to a groove near the lateral margins of the second pedigerous tergite. Only two other known congeners have a 1-segmented leg 4 exopod, E. coatiarus Araujo & Varella, 1998 and E. iheringi Tidd, 1942. Among other characters, they differ from the new species by the lack of a semi-pinnate, falciform seta on the terminal exopodal segment of leg 1 and in the structure and armature of the fifth leg. The prevalence of E. curticrus n. sp. was 13.6% and its mean abundance was 0.4 specimens per host. This is the first new species of Ergasilus Nordmann, 1832 described from the Orinoco River Basin.

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A new species of Acanthocephaloides was recovered in the intestine of Symphurus plagiusa, the blackcheek tonguefish, and Cyclopsetta chittendeni, the Mexican flounder, from the Campeche coast, Mexico. The new species is characterized by having proboscis hooks arranged in 14 to 16 longitudinal rows, with 6-7 rooted hooks per row, a trunk covered with small cuticular spines (except in the zone of gonopore or bursa), a bursa without sensory structures, and the relative position of male post-equatorial reproductive system. The prevalence of Acanthocephaloides plagiusae n. sp. from S. plagiusa was low (0-7.3%) from July to October and high (29.4-40%) in November, January, and March. Similarly, the prevalence of A. plagiusae n. sp. from Cyclopsetta chittendeni was low (1.7%) in July and high (5.8%) March. Both hosts exhibited low (0.1-3.4) mean abundance. The variation in prevalence could be explained by the seasonal freshwater discharge from rivers, which affects the dispersal of parasites and the distribution of the host. Pathology changes, such as inflammation, loss of intestinal folds, increased mucous and rodlet cells, and detachment of intestinal epithelium, were associated with the proboscis hooks and spiny surface of A. plagiusae. This is the first record of an Acanthocephaloides species from a Mexican coastal zone.

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The goals of this paper were to determine whether the helminth communities of the blackcheek tonguefish, Symphurus plagiusa, exhibit a spatial structure and, if so, to determine the relative influence of selected environmental and spatial variables. The parasite communities of tonguefish and environmental data (e.g., temperature, salinity, oxygen) were sampled monthly over a network of 37 stations over 1 year (February 2006 to January 2007). Analysis of similarities (ANOSIM), non-metric multidimensional scaling (NMDS) and redundancy analysis (RDA) were used. Spatial variables were generated using the analysis of principal coordinates of neighbour matrices (PCNM) method. A total of 1,010 flatfishes and nine helminth taxa were collected. For the environmental variables, hierarchical cluster analyses produced groups of stations associated with the Yucatan dry, rainy and winter seasons. At the infracommunity level, there was no group formation as indicated by ANOSIM and NMDS nor association with environmental or spatial variables. At the component community level, there was significant group formation, and RDA analyses of core, satellite and all species produced significant associations with environmental variables. However, model fit improved substantially (from 17-52% to 49-83% of explained variance) when the spatial variables (variables generated with PCNM method) were added. Thus, the helminth component communities of S. plagiusa were affected by associated environmental variables and unknown ecological processes captured by the spatial variables acting at different spatial scales over time. In contrast, at the infracommunity level there was apparently a very fine spatial grain, where the numerical dominance of core species resulted in biased group formation.

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A new species of the cyclopoid copepod genus Ergasilus von Nordmann, 1832 is described based on adult female specimens removed from the gills of the yellow snapper Lutjanus argentiventris (Peters) and the yellowfin snook Centropomus robalito Jordan et Gilbert from a Pacific coastal system of Mexico. The new species Ergasilus davidi sp. n. has a combination of characters that includes a two-segmented first leg endopod, a three-segmented fourth leg endopod, and the presence of a single seta on the first antennular segment. These characters are shared with 14 other congeners known mainly from Brazil and North America. It differs from these other species in the armature and ornamentation of legs 1 and 4, the shape of the body, and the structure and ornamentation of the antennae. Additional characters include a maxillar basis armed with blunt teeth, distally bent maxillular setae, and naked margins of first exopodal segments of legs 2-4. Previous regional records of Ergasilus sp. from both fish species are probably assignable to E. davidi. The prevalence and intensity of infection was estimated for both teleost species and agrees to previous data. Based on other records of the genus from several other teleost species in the surveyed area and adjacent zones of the Eastern Pacific, it is presumed that the new species could have a wider range of hosts. The new species represents the first Ergasilus described from Mexican waters of the Pacific. Overall, the genus remains poorly known in Central America and Mexico.

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A new nematode species, Spirophilometra pacifica sp. n. (Philometridae), is described from gravid female specimens collected from the mouth cavity (the upper palate) of the fish (yellow snook) Centropomus robalito (Centropomidae, Perciformes) from the Chantuto-Panzacola system, Chiapas, in the Pacific coast of Mexico. Its morphology is very similar to that of the species originally described as Philometra centropomi Caballero, 1974, but the gravid females of S. pacifica are about three times longer (body length 11.63-18.17 mm); host species and the geographical distribution of both these forms also differ. Scanning electron microscope (SEM) examination of S. pacifica, used for the first time for a Spirophilometra species, confirmed the presence of numerous minute cuticular spines on the body surface, 14 cephalic papillae arranged in two circlets, and two small lateral papilla-like caudal projections. It is evident that some features of P. centropomi were incorrectly described (its types are not available) and this species is now transferred to Spirophilometra as S. centropomi (Caballero, 1974) comb. n.

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