Integrative description of changes occurring on zebrafish embryos exposed to water-soluble crude oil components and its mixture with a chemical surfactant.

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.

A new species of Ergasilus Nordmann, 1832 (Copepoda: Cyclopoida: Ergasilidae) from Bryconops giacopinii Fernández-Yépez (Characidae) in the Vichada River Basin, Colombia.

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.

The Effect of Parasitization by Trichodinid Ciliates on the Mortality of Cultured Pacific Fat Sleeper larvae (Dormitator latifrons).

Trichodinidae, a prevalent group of protozoan ectoparasites in aquaculture, cause rapid mortality in fish hatcheries. Despite their significance, knowledge about these parasites in farmed fish in South America, especially in native species that are currently being domesticated for aquaculture, remains limited. This study morphologically characterized the Trichodinid species that are infecting Pacific fat sleeper (Dormitator latifrons) larvae and evaluated their impact on larval rearing. Four pairs of broodstock were induced with GnRHA implants and placed in tanks containing 200 L of freshwater, with a water temperature of 28 ± 1.0 °C and a dissolved oxygen level of 4.00 ± 1.23 mg L-1, with partial water exchanges being performed daily. The larvae hatched 7 to 8 h after fertilization and were transferred to tanks containing water with the same quality parameters. Twelve hours post-hatching, the presence of Trichodina was observed. Every 24 h, 60 larvae per tank (n = 180 per treatment) were sedated, and larval wet mounts were prepared, air-dried at room temperature, and impregnated with silver nitrate. Infection parameters and daily mortality were calculated. Trichodina was observed to parasitize the pelvic fins, caudal fins, and heads of fish larvae, which showed lethargy and erratic swimming movements. The Trichodina species showed a daily increase in the infection parameters, and a 58% rate of larval mortality was observed at the fourth day post-hatching (dph) in the infected tanks. In captivity, D. latifrons larvae typically survive up to 7 days post-hatching (dph) before reaching their point of no return due to the lack of adequate diet and feeding regimes. However, our study indicates that Trichodina infestation accelerates mortality, causing infected larvae to die more quickly than uninfected ones.

Effect of Dietary Supplementation with Organic Silicon on the Growth Performance, Blood Biochemistry, Digestive Enzymes, Morphohistology, Intestinal Microbiota and Stress Resistance in Juvenile Hybrid Tilapia (Oreochromis mossambicus × Oreochromis niloticus).

In recent decades, interest has been aroused worldwide in the use of silicon in nutrition; however, information on its effect on nutrition and metabolism of fish is limited. The objective of the research was to evaluate the effect of dietary supplementation with organic silicon on the growth performance, blood biochemistry, digestive enzymes, morphohistology and intestinal microbiota and stress resistance in hybrid Tilapia (Oreochromis mossambicus × Oreochromis niloticus). Methodologically, six levels of organic silicon (DOS) [control (0), 10, 20, 30, 40 and 50 mg·kg-1] were used to feed juvenile fish (initial weight 7.51 ± 0.25 g) grown for eight weeks in 18 aquariums (15 fish/aquarium). The results indicated that growth performance showed differences (p < 0.05) for specific growth rate, feed conversion and survival. Triglycerides, cholesterol and glucose, transaminases and digestive enzymes were significantly influenced by DOS levels. The histological study confirmed that the administered diets did not cause damage and induced significant morphological changes in the proximal intestine. The 16S rRNA gene sequencing analysis of the gut microbiota showed a high diversity and richness of OTU/Chao-1, with Fusobacteria, Proteobacteria, Bacteroidetes and Acidobacteria predominating in the DOS treatments compared to the control (p < 0.05). Induction of hypoxia stress after the feeding period showed a significant relative survival rate of 83.33% in fish fed 50 mg·kg-1. It is concluded that the DOS treatments performed better than the control treatment in most of the variables analysed. DOS had no negative effects on the fish. The results showed that up to 50 mg·kg-1 DOS improved digestive, metabolic and growth performance in hybrid Tilapia.

Sargassum spp. Ethanolic Extract Elicits Toxic Responses and Malformations in Zebrafish (Danio rerio) Embryos.

The amount of Sargassum spp. arriving in the Caribbean Sea has increased steadily in the last few years, producing a profound environmental impact on the ecological dynamics of the coasts of the Yucatan Peninsula. We characterized the toxicological effects of an ethanolic extract of Sargassum spp. on zebrafish (Danio rerio) embryos (ZFEs) in a 96-h static bioassay using T1 (0.01 mg/L), T2 (0.1 mg/L), T3 (1 mg/L), T4 (10 mg/L), T5 (25 mg/L), T6 (50 mg/L), T7 (75 mg/L), T8 (100 mg/L), T9 (200 mg/L), and T10 (400 mg/L). In this extract, we detected 74 compounds by gas chromatography-mass spectrometry (GC-MS), of which hexadecanoic acid methyl ester, and 2-pentanone 4-hydroxy-4-methyl, were the most abundant. In ZFEs, a median lethal concentration of 251 mg/L was estimated. Exposed embryos exhibited extensive morphological changes, including edema in the yolk sac, scoliosis, and loss of pigmentation, as well as malformations of the head, tail, and eyes. By integrating these abnormalities using the Integrated Biological Response (IBRv2) and General Morphological Score (GMS) indices, we were able to determine that ZFEs exposed to 200 mg/L (T9) exhibited the most pronounced biological response in comparison with the other groups. In the comparative transcriptomic analysis, 66 genes were upregulated, and 246 genes were downregulated in the group exposed to 200 mg/L compared with the control group. In the upregulated genes, we identified several gene ontology-enriched terms, such as response to xenobiotic stimuli, cellular response to chemical stimulus, transcriptional regulation, pigment metabolic process, erythrocyte differentiation and embryonic hemopoiesis, extracellular matrix organization, and chondrocyte differentiation involved in endochondral bone morphogenesis, among others. In the down-regulated genes, we found many genes associated with nervous system processes, sensory and visual perception, response to abiotic stimulus, and the nucleoside phosphate biosynthetic process. The probable connections among the morphological changes observed in the transcriptome are thoroughly discussed. Our findings suggest that Sargassum spp. exposure can induce a wide negative impact on zebrafish embryos. Environ Toxicol Chem 2024;43:1075-1089. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Assessment of mercury and lead contamination using the bivalve Anadara tuberculosa (Arcidae) in an estuary of the Colombian Pacific.

Buenaventura Bay is considered the main estuary on the Pacific coast of Colombia, because of port and industrial activities. Mining and agriculture are major sources of contamination in the estuary. This study used the bivalve Anadara tuberculosa to evaluate the presence of mercury and lead in the Dagua River estuary (Colombia), one of the main tributaries coming into the bay. Five samplings for sediments and six for tissues of A. tuberculosa were carried out between 2016 and 2017. Additionally, a series of bioassays were conducted to determine its ability to bioaccumulate metals. A mean mercury concentration of 0.57 ± 0.74 mg*kg-1 and lead concentration of 0.87 ± 0.68 mg*kg-1 in sediment were found. Bioassays allowed us to conclude that at low mercury exposure concentrations (0.25 mg*kg-1), lesions are generated in animal tissue, mainly in sexual cells. The high concentrations of mercury found in organisms exceed the maximum permitted concentration established in Colombia. In addition, the contamination factors for mercury and lead were considered very high. This research aims at contributing to the use of Anadara tuberculosa, as prospective bioindicator for pollution biomonitoring in mangrove coastal ecosystems.

First evidence of Panulirus argus Virus 1 (PaV1) in spiny lobster from Cuba and clinical estimation of its prevalence.

The present study documents the first finding of Panulirus argus Virus 1 (PaV1) in spiny lobster Panulirus argus from Cuba. Samples originated from 2 nursery sites, Matias Keys and Bocas de Alonso Keys, and 2 fishing sites, La Grifa and El Ramajo. Lobsters from the nursery sites (artificial reefs) were collected by SCUBA diving, while those from the fishing sites were collected from artificial shelters known as 'casitas cubanas'. In these shelters it was observed that healthy lobsters tended to avoid infected lobsters. Prevalence of PaV1 in the sampling sites was assessed by using clinical signs such as lethargy, an opaque reddish shell coloration, and milky white hemolymph with loss of clotting activity. The presence of PaV1 was subsequently confirmed by histology and PCR of tissues and hemolymph samples from suspected individuals. Histological sections of the hepatopancreas, gills, gonads, and gut showed infected hemocytes with hypertrophied nuclei and eosinophilic intranuclear Cowdry type A inclusions. A 499 bp band was observed by PCR. The sequence of the amplified fragments was 96% similar to the PaV1 sequence in GenBank. The overall mean prevalence of PaV1 was 4.48% (range: 0 to 9.3%) after pooling the results of the 4 sampling sites.

The 2015-2016 El Niño increased infection parameters of copepods on Eastern Tropical Pacific dolphinfish populations.

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.

Detection of Panulirus argus Virus 1 (PaV1) in exported frozen tails of subadult-adult Caribbean spiny lobsters Panulirus argus.

The Caribbean spiny lobster Panulirus argus is a valuable fishing resource and the trade in frozen lobster tails is an important industry. However, the presence of the pathogenic virus Panulirus argus Virus 1 (PaV1), which causes systemic infection in P. argus and is particularly lethal to juvenile individuals, has not been previously examined in imported/exported lobster products. We used PCR assays to determine the presence of PaV1 in abdominal muscle tissue of 22 frozen P. argus tails exported from Belize to Mexico. Based on their size, the tails belonged to subadult-adult lobsters. Using specific primers targeted for PaV1 resulted in 11 tails showing a specific 499 bp band. The sequence of positive amplified fragments showed a high similarity to PaV1 (95% identity with GenBank accession no. EF206313.1). Although the pathogenicity of PaV1 was not evaluated in the present study, our results provide the first evidence of PaV1 in frozen lobster tails exported in the seafood industry as well as the first molecular evidence of PaV1 in adult lobsters.

A new species of Pupulina van Beneden, 1892 (Copepoda, Siphonostomatoida, Caligidae) from Aetobatuscf.narinari (Pisces, Myliobatidae) from the Pacific coast of Ecuador.

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.

Parvitaenia cochlearii (Cestoda: Gryporhynchidae) en cultivo de chame Dormitator latifrons en Ecuador

RESUMEN Objetivo. Identificar y determinar los parámetros de infección del metacestodo Parvitaenia en diferentes fases de cultivo de Dormitator latifrons y evaluar los daños histológicos. Materiales y métodos. Se revisaron 45 ejemplares, 15 en cada fase (pre-cría, pre-engorda y engorda) para identificar el metacestodo y los daños tisulares provocados. Se calculó la prevalencia, intensidad e intensidad mediana. Se evaluó la diferencia de la intensidad mediana entre fase de cultivo mediante la prueba de medianas de Mood. La longitud total, peso, factor de condición de Fulton e índice hepatosomático se correlacionó con la intensidad mediante una correlación lineal. Los daños tisulares fueron evaluados en fragmentos de hígado. Resultados. Se encontró un total de 29151 cestodos, identificados como Parvitaenia cochlearii. La prevalencia del cestodo fue de 100%, la intensidad mediana varió de 22 a 625 individuos y mostró diferencias significativas entre fases de cultivo (X2= 29.391; p<0.0001). La intensidad mostró una correlación positiva moderada con la longitud total de los peces (r2= 0.45; p<0.05) y una correlación baja con el peso (r2= 0.38; p<0.05). En hígados poco parasitados se observó fibrosis y congestión alrededor de los quistes. En hígados con altos niveles de infección se observó reducción del parénquima, fibrosis e incremento de centros melanomacrófagos. Conclusiones. Este es el primer reporte de P. cochlearii en D. latifrons de cultivo. Nuestros resultados sugieren que existe una tendencia de acumulación de cestodos durante el crecimiento de los peces, lo cual podría tener implicaciones negativas para el comercio.

ABSTRACT Objective. To identify and determine the infection parameters of the metacestode Parvitaenia in different culture stages of Dormitator latifrons and to evaluate the histological damage caused by this parasite. Materials and methods. Forty-five specimens were examined, 15 in each phase: prebreeding, pre-fattening, and fattening, to identify the metacestode and tissue damage caused using conventional parasitology and histology techniques. Prevalence, intensity, and median intensity were calculated. A Mood's median test evaluated the difference between intensity per culture phase. Total length, weight, condition factor, and hepatosomatic index were correlated with intensity by linear correlation analysis. Liver fragments were evaluated to identify the tissue damage. Results. A total of 29,151 cestodes were found and were identified as Parvitaenia cochlearii. Cestode prevalence was 100% in each culture phase. The median intensity ranged from 22 to 625 individuals and showed significant differences between culture phases (X2 = 29.391; p<0.0001). Intensity showed moderate positive correlation with total fish length (r2 = 0.45; p<0.05) and low correlation with weight (r2 = 0.38; p<0.05). In less parasitized livers, fibrosis and congestion around the cysts were observed, while in livers with high levels of infection, parenchymal reduction, fibrosis, and increase in melanomacrophage centers were observed. Conclusions. This is the first report of P. cochlearii on D. latifrons in aquaculture. We suggest that there is a tendency for cestode accumulation during fish growth, which could have negative implications for trade.

A new arhythmacanthid species (Acanthocephala) in the intestine of Symphurus plagiusa and Ciclopsetta chittendeni from the coast of Campeche, Mexico, with ecological and histopathological observations.

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.

Presence of anisakid larvae in commercial fishes landed in the Pacific coast of Ecuador and Colombia / Presencia de larvas de anisakidos en peces comercializados y desembarcados en la costa del Pacífico de Ecuador y Colombia

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.