Parasites with zoonotic potential found in commercially important fish in Tamaulipas, Northeastern Mexico.

Human population is exposed to numerous parasitic ichthyozoonoses. Although Tamaulipas state (northeastern Mexico) is well known for its fishing and aquaculture industry, there are few reports of this type of zoonosis. Therefore, it is imperative to investigate whether the parasites that affect these fish may represent a zoonotic risk for the inhabitants of the area. The objective of this study was to identify molecular and/or morphologically muscle parasites of fish from coastal locations in Tamaulipas, Mexico, and assess the risk of infection for humans. Between 2017 and 2018, 764 individual fish belonging to 28 species were examined for parasites. Collected worms were processed for their identification using morphological characteristics. In addition, partial sequences of the large subunit (28S) ribosomal RNA gene were obtained from some species to corroborate their identity. Prevalence and mean intensity of all registered infections were calculated. A total of seven species of parasites were found: cestodes (Poecilancistrium caryophyllum), trematodes (Clinostomum tataxumui, Clinostomum cichlidorum), nematodes (Eustrongylides sp., Contracaecum sp.) and pentastomids (Sebekia purdieae, Sebekia sp.). Parasites infected 10 species belonging to different fish families (Ariidae, Centrarchidae, Centropomidae, Cichlidae, Eleotridae, Ictaluridae, Mugilidae and Sciaenidae). Congeneric species of parasites or related to those registered in this study have been identified as zoonotic agents in other regions of the world. Despite the low levels of infection (2.6-16.6% prevalence and 1-5.5 parasites per infected host), there is a latent risk of transmission to humans, so it is recommended to avoid eating raw or undercooked fish meat.

Density-dependent condition of juvenile penaeid shrimps in seagrass-dominated aquatic vegetation beds located at different distance from a tidal inlet.

Seagrasses are critical habitats for the recruitment and growth of juvenile penaeid shrimps within estuaries and coastal lagoons. The location of a seagrass bed within the lagoon can determine the value of a particular bed for shrimp populations. Consequently, differences in the abundance of shrimp can be found in seagrasses depending on their location. As shrimp density increases, density-dependent effects on biological parameters are more likely to occur. However, knowledge about density-dependent processes on shrimp populations in nursery habitats remains limited. The present investigation was undertaken to examine the effects of population density on shrimp condition in two selected seagrass beds, located at different distance from a tidal inlet, one 25 km away (distant) and the other 1 km away (nearby), in a subtropical coastal lagoon. The study was based on monthly samplings during one year in Laguna Madre (Mexico), performing a total of 36 shrimp trawls (100 m2 each one) within each seagrass bed (n = 3 trawls per bed per month for 12 months). Shrimp density was related to the proximity to the tidal inlet (higher density was consistently observed in the nearby seagrass bed), which in turn adversely affected the condition of both species studied (Penaeus aztecus and P. duorarum). In this regard, the present study provides the first evidence of density-dependent effects on shrimp condition inhabiting a nursery habitat. Both shrimp species exhibited a negative relationship between condition and shrimp density. However, this pattern differed depending on the proximity to the tidal inlet, suggesting that shrimp populations inhabiting the nearby seagrass bed are exposed to density-dependent effects on condition; whereas, such effects were not detected in the distant seagrass bed. Shrimp density within the distant seagrass bed was probably below carrying capacity, which is suggested by the better shrimp condition observed in that area of the lagoon. Intra and interspecific competition for food items is surmised to occur, predominantly within seagrass beds near the tidal inlet. However, this hypothesis needs to be tested in future studies.

Effect of Propolis, a Honeybee Product, Against a Parasite (Ligictaluridus floridanus) from Catfish (Ictalurus punctatus) Gills.

PURPOSE: The aim of this study was to evaluate the in vitro and in vivo efficacy of propolis against Ligictaluridus floridanus on Ictalurus punctatus gills. METHODS: This study used an ethanol extract of propolis at a concentration of 300 mg mL-1, with a total polyphenol concentration of 2.77 mg mL-1 as determined by chromatography. In vitro trial used propolis concentrations at 5, 30 as well as 60 mg L-1 and a 70% ethanol control group to treat naturally infected catfish. The in vivo experiment was 16 weeks in duration, consisting of seventy-two fish infected by cohabitation and subjected to one-hour baths every 72 h during the trial. RESULTS: In vitro studies showed that parasites exposed to 60 mg L-1 of propolis displayed a significant reduction (p < 0.05) in their survival time. In vivo studies confirmed the reduction of intensity and abundance of Ligictaluridus floridanus on the gills of channel catfish. CONCLUSION: This study has provided the first challenge of propolis against L. floridanus on I. punctatus gills and shows that propolis has an anthelmintic effect.

Hematological and clinical chemistry changes induced by acute stress during handling and capture of catfish ( Ictalurus punctatus ) / Cambios hematológicos y bioquímicos provocados por estrés agudo causado por manejo y captura de bagre ( Ictalurus punctatus )

ABSTRACT Objetive . Evaluation of hematological and biochemical parameters of culture channel catfish (Ictalurus punctatus) under acute stress by management and capture practice. Materials and methods . Fish (200 g mean) were maintained in culture tanks and divided in two treatments, in duplicate, (n=15x2x2=60 fishes). Thirty catfish were exposed for 5 min to acute stress (TE) by management and capture practice, while other group not (control group, TnE). 10 fish for treatment were collected at 0, 6, and 24 h post-stress for blood collection, where TnE fishes were anesthetized along work. Complete blood count (manual method) and blood biochemical (spectrophotometry) of fish samples were evaluated and their results were analyzed using a Student's t-distribution. Results . The erythrocytes, hematocrit, hemoglobin and glucose level of TE animals was significantly higher (p<0.05) at 6 h post-stress, in comparison of TnE. Immune cells in fish TE decreased at 6 and 24 h post-stress, where leukocytes and lymphocytes were significantly lower that TnE (p<0.05) at 24 h post-stress. Other evaluated parameters did not show significant differences along this study. Conclusions . Those results suggest that several hematological and blood biochemical parameters in fish changed by acute stress generated by management and capture practice.

RESUMEN Objetivo . Evaluar los efectos del estrés agudo debido al manejo y captura sobre los parámetros hematológicos y bioquímicos en bagre de canal (Ictalurus punctatus) bajo cultivo. Materiales y métodos . Los peces (200 g promedio) fueron mantenidos en tanques de cultivo y divididos en dos tratamientos, por duplicado, (n= 15 x 2 x 2 = 60 peces). Treinta bagres fueron expuestos por 5 min a estrés agudo (TE) por manejo y captura, mientras que otro grupo no (grupo control, TnE). Diez peces de cada tratamiento fueron colectados a las 0, 6, y 24 h post-estrés para la extracción de sangre, los bagres del TnE fueron anestesiados durante su manejo y captura. Se evaluó el hemograma (método manual) y bioquímica sanguínea (espectrofotometría). Los resultados fueron analizados mediante la prueba de t student. Resultados . El contenido de eritrocitos, hematocrito, hemoglobina y glucosa de los animales TE fue significativamente mayor (p<0.05) a las 6 h post-estrés en comparación de TnE. Las células inmune en peces TE disminuyeron a las 6 y 24 h post-estrés, siendo leucocitos y linfocitos significativamente menores en el TnE (p<0.05) a las 24 h post-estrés. Otros parámetros evaluados no presentaron diferencias significativas en lo largo del estudio. Conclusiones . Los resultados sugieren que varios indicadores hematológicos y bioquímica sanguínea en los peces son alterados por el estrés agudo ocasionado por manejo y captura.

Spatial Analysis of Metal Profiles in Sediments in a Tropical Estuary: A Geostatistical Approach.

The spatial structure and distribution of heavy metals [cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), and nickel (Ni)] in sediments were geostatistically analyzed along the estuarine ecosystem of Tigre River-San Andres Lagoon (Tamaulipas, Mexico). In most cases, heavy-metal concentrations exhibited a strong spatial autocorrelation along the estuary as indicated by variogram analysis. Heavy-metal concentrations were found to be higher in the middle estuary, close to the mouth of the Tigre River, and declined as distance from the mouth increased. Metal mean levels at the middle estuary were 2.41 mg/kg Cd, 4.80 mg/kg Cu, 172.36 mg/kg Fe, 5.22 mg/kg Pb, and 2.10 mg/kg Ni. The spatial distribution of heavy metals suggests the existence of a common heavy-metal source located in this area of the estuary. The importance of wastewater discharges and open dumping in the town of El Moron, adjacent to the mouth of the Tigre River, is highlighted; these are believed to be the anthropogenic sources for heavy metals in this estuarine ecosystem.

Effects of Hydrogen Peroxide and Metrifonate on Monogenean ligictaluridus floridanus on Catfish ( Ictalurus punctatus , Rafinesque) Gills.

Hydrogen peroxide (H2O2) and metrifonate (Mtf) are common products used in ectoparasite infestations on fish cultures. The therapeutic efficacy of H2O2 and Mtf on a common monogenean parasite, Ligictaluridus floridanus, was evaluated in channel catfish ( Ictalurus punctatus ). In vitro trials were conducted using excised fish gills naturally infected with L. floridanus, which were immersed in H2O2 (150, 300, and 570 mg L(-1)) and Mtf (0.25, 0.5, and 0.75 mg L(-1)) solutions. The efficacy of the treatments was based on the survival time of the parasites, observed microscopically. In addition, an in vivo trial using catfish juveniles, naturally infected with L. floridanus, was also performed. One group received immersion baths of 570 mg L(-1) H2O2 (3%) during 4 min; the Mtf (90%) group received 0.5 mg L(-1) Mtf for 10 min. Treatments were done on days 3, 7, and 11 of the experiment. Results indicate that baths with Mtf do not significantly reduce the mean intensity of the parasite per gill arch, nor do they reduce the in vitro survival time of parasites during treatment; H2O2 baths at 570 mg L(-1) during 4 min were effective (P < 0.05) against adult and juvenile stages of L. floridanus. This study supports the use of H2O2 as an effective antiparasitic agent against I. punctatus .