Masculinization of Red Tilapia (Oreochromis spp.) Using 17α-Methyltestosterone-Loaded Alkyl Polyglucosides Integrated into Nanostructured Lipid Carriers.

The aim of the present study was to optimize a masculinization platform for the production of all-male red tilapia fry by oral administration of 30 and 60 ppm of MT and alkyl polyglucoside nanostructured lipid carriers (APG-NLC) loaded with MT, respectively, for 14 and 21 days. The characterization, encapsulation efficiency and release kinetics of MT in lipid-based nanoparticles were assessed in vitro. The results showed that the MT-loaded nanoparticles were spherical, ranging from 80 to 125 nm in size, and had a negative charge with a narrow particle distribution. The APG-NLC loaded with MT provided higher physical stability and encapsulation efficacy than the NLC. The release rate constants of MT from MT-NLC and MT-APG-NLC were higher than those of free MT, which is insoluble in aqueous media. There was no significant difference in survival between the fish administered MT or the those fed orally with MT-APG-NLC fish. According to the logistic regression analysis, the sex reversal efficacy of MT-APG-NLC (30 ppm) and MT (60 ppm), resulted in significantly higher numbers of males after 21 days of treatment compared with the controls. The production cost of MT-APG-NLC (30 ppm) after 21 days of treatment was reduced by 32.9% compared with the conventional MT treatment group (60 ppm). In all the treatments, the length-weight relationship (LWR) showed negatively allomeric growth behavior (b < 3), with a relative condition factor (Kn) of more than 1. Therefore, MT-APG-NLC (30 ppm) would seem to be a promising, cost-effective way to reduce the dose of MT used for the masculinization of farmed red tilapia.

Development of a TaqMan quantitative reverse transcription PCR assay to detect tilapia lake virus.

Tilapia lake virus disease (TiLVD) is an emerging viral disease associated with high morbidity and mortality in cultured tilapia worldwide. In this study, we have developed and validated a TaqMan quantitative reverse transcription PCR (RT-qPCR) assay for TiLV, targeting a conserved region within segment 10 of the genome. The RT-qPCR assay was efficient (mean ± SD: 96.71 ± 3.20%), sensitive with a limit of detection of 10 RNA viral copies per reaction, and detected TiLV strains from different geographic regions including North America, South America, Africa, and Asia. The intra- and inter-assay variability ranged over 0.18-1.41% and 0.21-2.21%, respectively. The TaqMan RT-qPCR assay did not cross-react with other RNA viruses of fish, including an orthomyxovirus, a betanodavirus, a picornavirus, and a rhabdovirus. Analysis of 91 proven-positive and 185 proven-negative samples yielded a diagnostic sensitivity of 96.7% and a diagnostic specificity of 100%. The TaqMan RT-qPCR assay also detected TiLV RNA in infected Nile tilapia liver tissue extracts following an experimental challenge study, and it successfully detected TiLV RNA in SSN-1 (E-11 clone) cell cultures displaying cytopathic effects following their inoculation with TiLV-infected tissue homogenates. Thus, the validated TaqMan RT-qPCR assay should be useful for both research and diagnostic purposes. Additionally, the TiLV qPCR assay returns the clinically relevant viral load of a sample which can assist health professionals in determining the role of TiLV during disease investigations. This RT-qPCR assay could be integrated into surveillance programs aimed at mitigating the effects of TiLVD on global tilapia production.

The effect of feeding black soldier fly larvae on growth performance, protein, and fat content of red hybrid tilapia (Oreochromis spp.).

Background and Aim: In the aquaculture industry, the crucial goal is to minimize production costs, especially feeding costs, without significant side effects. Black soldier fly larva (BSFL) is a locally available, eco-friendly, and sustainable source that is high in crude protein (42% dry matter [DM]) and fat (35% DM). This study aimed to determine the growth performance along with the composition of crude fat and protein in red hybrid fingerlings after the addition of BSFL into the diet. Materials and Methods: A total of 120 fingerlings of uniform size (mean initial weight of 1.46 ± 0.06 g) were randomly assigned to one of four groups (n = 10) (A, B, C, and D) per tank (1 m × 2 m × 1 m). For 21 days, Group A (control group) was fed with 100% commercial diet; Group B was fed with 90% commercial fish diet + 10% BSFL; Group C was fed with 80% commercial fish diet + 20% BSFL; and Group D was fed with 70% commercial fish diet + 30% BSFL. Feed efficiency, growth performance, and proximate composition analysis were performed on the fish. Results: The results displayed that the group with the highest BSFL percentage had a greater effect on protein and fat composition than the control group. The proximate composition analysis of fish-fed diet revealed that an increase in the level of BSFL inclusion increases the protein content in the fish. In comparison to the other groups, the experimental diet with 30% BSFL inclusion has the highest levels of crude protein (80.30% DM) and fat (2.90% DM). Conclusion: It is concluded that incorporating BSFL into a commercial diet for red hybrid tilapia fingerlings increased crude protein and fat composition, providing an alternative protein and fat source in fish diets.

Physicochemical Water Quality Influence on the Parasite Biodiversity in Juvenile Tilapia (Oreochromis spp.) Farmed at Valle Del Mezquital in the Central-Eastern Socioeconomic Region of Mexico.

Aquaculture parasite biodiversity dependents on multiple environmental characteristics, including water quality. The analysis of this relationship aims to support improvements in the production management of tilapia. For this purpose, a total of 100 juvenile fishes (Oreochromis spp.) and 30 water samples were collected at Valle del Mezquital in the Central-Eastern socioeconomical region of Mexico. A study of parasite biodiversity was carried out and water quality parameters were determined. Biodiversity in the habitat was measured using the Simpson diversity index, which considers the number of species present and the abundance of each one; we also calculate the Berger-Parker index to estimate the proportional importance of the most abundant species. In general, it was found that 86% of the examined specimens were parasitized. Parasite biodiversity was 11 genera (Simpson index = 0.55). Trichodina spp. (Ciliophora) was the dominant genus (Berger-Parker index = 0.51). The protozoa Apiosoma spp. was associated with the water hardness (Berger-Parker index = 0.57). Furthermore, the presence of monogeneans showed a positive correlation with the levels of nitrites and ammonium in the water (Berger-Parker index = 0.06-0.55). This characterization may represent a useful tool in the comprehensive management of parasites that affect the farmed tilapia. However, new data is necessary to expand the knowledge about the environment-host-parasite relationship.

Antibacterial Potential of Caesalpinia coriaria (Jacq) Willd Fruit against Aeromonas spp. of Aquaculture Importance.

Aquaculture is an important source of food and livelihood for hundreds of millions of people around the world, however, aquaculture systems are affected by different factors, among them the appearance of resistant or multiresistant bacteria to antimicrobials. The secondary metabolites of plants have been proposed as alternatives for the treatment of these bacteria. The aim of the present study was to determine the antibacterial activity of Caesalpinia coriaria fruit hydroalcoholic extract and gallic acid over Aeromonas hydrophila, Aeromonas veronii,  and Aeromonas dhakensis to identify new molecules for the treatment of diseases caused by Aeromonas spp. The C. coriaria fruit hydroalcoholic extract (HECc) was obtained by hydroalcoholic maceration and subjected to bipartition with ethyl acetate and water to obtain an aqueous fraction (Ac-FrCc) and an organic fraction (Ac-FrEtCc); gallic acid was purchased commercially. The Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), MBC/MIC ratio, and cytotoxicity of HECc, its fractions, and gallic acid were determined. The results indicate that HECc fractions (Ac-FrCc and Ac-FrEtCc) and gallic acid have bactericidal activity against A. hydrophila and A. dhakensis, but only gallic acid showed bactericidal activity against A. veronii. The HECc and Ac-FrCc showed no toxicity, Ac-FrEtCc showed low toxicity, and gallic acid showed medium toxicity. The HECc, Ac-FrCc, and Ac-FrEtCc may be alternatives for the treatment of diseases caused by the genus Aeromonas, however, in vivo assays are necessary to corroborate these results.

Rapid genotyping of tilapia lake virus (TiLV) using Nanopore sequencing.

Infectious diseases represent one of the major challenges to sustainable aquaculture production. Rapid, accurate diagnosis and genotyping of emerging pathogens during early-suspected disease cases is critical to facilitate timely response to deploy adequate control measures and prevent or reduce spread. Currently, most laboratories use PCR to amplify partial pathogen genomic regions, occasionally combined with sequencing of PCR amplicon(s) using conventional Sanger sequencing services for confirmatory diagnosis. The main limitation of this approach is the lengthy turnaround time. Here, we report an innovative approach using a previously developed specific PCR assay for pathogen diagnosis combined with a new Oxford Nanopore Technologies (ONT)-based amplicon sequencing method for pathogen genotyping. Using fish clinical samples, we applied this approach for the rapid confirmation of PCR amplicon sequences identity and genotyping of tilapia lake virus (TiLV), a disease-causing virus affecting tilapia aquaculture globally. The consensus sequences obtained after polishing exhibit strikingly high identity to references derived by Illumina and Sanger methods (99.83%-100%). This study suggests that ONT-based amplicon sequencing is a promising platform to deploy in regional aquatic animal health diagnostic laboratories in low- and medium-income countries, for fast identification and genotyping of emerging infectious pathogens from field samples within a single day.

Antimicrobial activity of characterized Leuconostoc spp. as novel probiotics isolated from Oreochromis spp. (red tilapia) against fish pathogen Edwardsiella tarda

Aims@#This study aimed to isolate and characterize putative new probiotic with antimicrobial properties against common fish pathogens from the gut of Oreochromis spp. (red tilapia). @*Methodology and results@#A total of 28 colonies were isolated from gut of Oreochromis spp. and characterized phenotypically. Eight isolates were selected for probiotic characterization. Temperature, salinity, pH and bile salt tolerance, antibiotic susceptibility and antimicrobial test against selected fish pathogens (Aeromonas hydrophila, Edwardsiella tarda and Staphylococcus aureus subsp. aureus ATCC 25923) were conducted. Characterization studies revealed isolates suited for freshwater environment and exhibited tolerance against wide range of salinity, pH and bile salt. Isolates displayed different antibiotic susceptibility profile, with six exhibited antimicrobial properties against E. tarda. Molecular identification based on 16S rRNA gene sequencing showed 99.44%, 98.59% and 91.21% sequence similarity with Leuconostoc pseudomesenteroides strain 3832T, Leuconostoc lactis strain KCC202369T and Leuconostoc mesenteroides strain 4332T, respectively as compared to known sequence in the GenBank. When identified Leuconostoc spp. were coated on feed pellets, no major decrease in viability over 21 days of storage at 4 °C were observed, with an average of 8 log CFU/mL.@*Conclusion, significance and impact of study@#The characterized species allow further application assessment of the probiotic-supplemented tilapia feed. Host-originated Leuconostoc displayed potential antimicrobial properties against fish pathogen E. tarda. The isolates Leuconostoc is expected to provide protective effect for Oreochromis spp. against edwardsiellosis and to exert beneficial effects more efficiently as compared to commercial probiotics which are not specifically target for Oreochromis spp., thereby indirectly helping fish farmers in achieving economic sustainability and increase affordability of fish.

Probiotics Modulate Tilapia Resistance and Immune Response against Tilapia Lake Virus Infection.

Tilapia lake virus (TiLV) causes an emerging viral disease associated with high mortality and economic damage in tilapia farming around the world. The use of probiotics in aquaculture has been suggested as an alternative to antibiotics and drugs to reduce the negative impact of bacterial and viral infections. In this study, we investigate the effect of probiotic Bacillus spp. supplementation on mortality, viral load, and expression of immune-related genes in red hybrid tilapia (Oreochromis spp.) upon TiLV infection. Fish were divided into three groups, and fed with: control diet, 0.5% probiotics-supplemented diet, and 1% probiotics-supplemented diet. After 21 days of experimental feeding, the three groups were infected with TiLV and monitored for mortality and growth performances, while organs were sampled at different time points to measure viral load and the transcription modulation of immune response markers. No significant difference was found among the groups in terms of weight gain (WG), average daily gain (ADG), feed efficiency (FE), or feed conversion ratio (FCR). A lower cumulative mortality was retrieved from fish fed 0.5% and 1% probiotics (25% and 24%, respectively), compared to the control group (32%). Moreover, fish fed with 1% probiotic diet had a significantly lower viral load, than those fed with 0.5% probiotic and control diet at 5, 6, 9, and 12 days post infection-challenge (dpc). The expression patterns of immune-related genes, including il-8 (also known as CXCL8), ifn-γ, irf-3, mx, rsad-2 (also known as VIPERIN) showed significant upregulation upon probiotic treatment during the peak of TiLV pathogenesis (between 9 and 12 dpc) and during most of the study period in fish fed with 1% probiotics-supplemented diet. Taken together, these findings indicate that dietary supplementation using Bacillus spp. probiotics may have beneficial effects to strengthen tilapia immunity and resistance against TiLV infections. Therefore, probiotic treatments may be preventively administered to reduce losses caused by this emerging viral infection in tilapia aquaculture.

In Vitro Antibacterial Potential of Salix babylonica Extract against Bacteria that Affect Oncorhynchus mykiss and Oreochromis spp.

Aquaculture development is limited by bacteria associated with several diseases; antibiotics are used for the treatment of these affections, but bacteria have developed resistance to these drugs. It is important to develop effective treatments that allow the production of antibiotic-free food. The aim of the present study is to evaluate the in vitro antibacterial effects of Salix babylonica hydro-alcoholic extract (SbHE) against Aeromonas hydrophila, Listonella anguillarum, Edwarsiella tarda, and Streptococcus iniae, bacteria that affect Oncorhynchus mykiss and Oreochromis spp. production. SbHE was obtained through the maceration technique. Reference strains were used and their sensitivity to antibiotics was determined. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of SbHE were determined. Results showed that three of four evaluated bacteria were multidrug resistant, except S. iniae. SbHE showed antibacterial activity against all bacteria. Results indicate an MIC of 1.56 to 25 mg/mL and an MBC of 3.12 to 100 mg/mL. The greatest inhibitory activity occurred against L. anguillarum obtaining a MIC of 1.56 mg/mL and an MBC of 3.12 mg/mL. Results indicate that SbHE has bactericidal activity against A. hydrophila, L.anguilalurm, and S. iniae as well as bacteriostatic activity against E. tarda and could be an alternative treatment against these bacteria.

Characterization and susceptibility of streptococci and enterococci isolated from Nile tilapia (Oreochromis niloticus) showing septicaemia in aquaculture and wild sites in Egypt.

BACKGROUND: The present investigation was an endeavor into the elucidation of the disease-causing pathogen of streptococcosis in Nile tilapia (Oreochromis niloticus) in Egypt affecting adult fish cultured and wild fish in the Nile river. Fish were obtained from commercial fishermen, collected as part of their routine fishing activities. The researchers observed the routine fishing process and selected fish for use in the study, at the point of purchase from the fisherman. RESULTS: Diseased fish showed exophthalmia with accumulation of purulent and haemorrhagic fluid around eyes, and ventral petechial haemorrhages. The Post mortem examination revealed, abdominal fat haemorrhage, pericarditis and enlargement of the liver, spleen and kidney. Gram-stained smears revealed the presence of Gram-positive cocci, ß-hemolytic, oxidase and catalase negative. Analysis of the 16S rRNA gene confirmed that the 17 tilapia isolates studied were 6/17 Enterococcus faecalis, 2/17 Enterococcus gallinarum, 3/17 Streptococcus pluranimalium, 2/17 Aerococcus viridans, 1/17 isolate of each Streptococcus dysgalactiae, Streptococcus anginosus, Lactococcus garvieae and Granulicetella elegans/Leuconostoc mesenteroides cremoris. It should be noted that there was no mixed infection. Multiple resistance was observed and the most frequent antibiotic combination was penicillin, ampicillin, vancomycin, chloramphenicol, rifampicin, ofloxacin, clindamycin, erythromycin and tetracycline representing eight classes. CONCLUSIONS: Consequently, we concluded that Streptococcus species are an emerging pathogen for Nile tilapia aquaculture in Egypt and to be considered as a new candidate in the warm water fish diseases in Egypt with special reference to L. garvieae, S. dysgalactiae in addition to L. mesenteroides cremoris which was not reported before from tilapia and taking into consideration their zoonotic implications for public health.

Gill monogeneans of Nile tilapia (Oreochromis niloticus) and red hybrid tilapia (Oreochromis spp.) from the wild and fish farms in Perak, Malaysia: infection dynamics and spatial distribution.

Tilapia is one of the commercially important fish in Malaysia as well as in other parts of the world. An understanding of monogenean infection dynamics in tilapia fish may assist us in searching for some intervention measures in reducing the loss of fish caused by parasitic diseases. The present study aimed (1) to compare infection level of monogeneans between the wild and cultured Oreochromis niloticus, and between the cultured O. niloticus and cultured red hybrid tilapia, and (2) to examine the spatial distribution of monogenean species over the gills of the different host species. From a total of 75 fish specimens, six species of monogeneans from two genera: Cichlidogyrus (C. halli, C. mbirizei, C. sclerosus, C. thurstonae, C. tilapiae) and Scutogyrus (S. longicornis) were identified. Data showed that the infection level of cultured O. niloticus was higher than that of the wild O. niloticus, however, the former was lower than that of the cultured red hybrid tilapia. Higher species richness of monogeneans was observed in the cultured red hybrid tilapia as compared to the others. Results for spatial distribution showed that the monogeneans have no preference on the left or right sides of the gills. However, C. halli, C. mbirizei, and C. tilapiae showed preferences on specific gill arches in the cultured O. niloticus and red hybrid tilapia. In general, the gill arch IV harboured the least number of monogeneans. The susceptibility of monogenean infection between the different types of tilapia is discussed.

Caracterización de la composición en proteína, lípidos, energía y perfiles de ácidos grasos en huevos de tilapia roja (Oreochromis spp.) / Characterization of the Protein, Lipid, Energy and Fatty Acid Profile Composition in Red Tilapia (Oreochromis spp.) eggs / Caracterização da composição em proteína, lipídios, energia e perfis de ácidos gordurosos em ovos de tilápia vermelha (Oreochromis spp.)

Luego de considerar el significado de las tilapias en el escenario piscícola nacional, la posibilidad de mejorar los índices de producción es un imperativo técnico y, dentro de estos, focalizar esfuerzos experimentales en la semilla resulta ser una opción estratégica. Con el fin de establecer un referente de base se utilizaron las puestas individuales de 50 hembras de tilapia roja (Oreochromis spp.) para determinar los contenidos en los huevos de proteína (%MS), extracto etéreo (%MS), energía (cal g-1) y los perfiles de ácidos grasos (%), con algunas relaciones de interés analítico. Salvo ciertas variaciones menores, los valores encontrados se ajustan a los registros disponibles para la especie en diferentes estudios, lo que sugiere que las dietas ofrecidas a los reproductores experimentales contienen los mínimos necesarios para asegurar una provisión de nutrientes y energía suficientes para los embriones y las larvas en formación. Se analiza que, como punto de partida, esta serie de datos tiene utilidad para el desarrollo de trabajos destinados a mejorar los estándares de producción de alevinos, considerando que las variaciones en la composición, que pueden ser determinadas sobre los huevos, se pueden utilizar y tienen validez como un indicativo directo de su calidad.

After considering the meaning of tilapia in the national piscicultural scenario, the possibility of improving production rates is a technical imperative and, among these, focusing experimental efforts in the seed turns out to be a strategic option. In order to establish a base model, individual laying of 50 female red tilapia (Oreochromis spp.) were used to determine the content of protein in eggs (%MS), ether extract (%DM), energy (cal g-1) and fatty acid profiles (%) with some relations of analytical interest. Except for minor variations, the values found are consistent with the available records for the species in different studies, suggesting that diets offered to experimental breeders contain the minimum necessary to ensure provision of sufficient energy and nutrients for embryos and larvae in formation. It is analyzed that, as a starting point, this series of data is useful for the development of work to improve the standards of fingerling production, considering that variations in the composition, which can be determined on the eggs, can be used and have validity as a direct indication of its quality.

Depois de considerar o significado das tilápias no cenário da piscicultura nacional, a possibilidade de melhorar los índices de produção é um imperativo técnico e, dentro destes, focalizar esforços experimentais na semente resulta ser uma opção estratégica. Com a finalidade de estabelecer um referente de base, se utilizaram as postas individuais de 50 fêmeas de tilápia vermelha (Oreochromis spp.) para determinar os conteúdos nos ovos de proteína (%MS), extrato etéreo (%MS), energia (cal g-1) e os perfis de ácidos gordurosos (%), com algumas relações de interesse analítico. Com exceção de algumas variações menores, os valores encontrados se ajustam aos registros disponíveis para a espécie em diferentes estágios, o que sugere que as dietas oferecidas aos reprodutores experimentais contêm os mínimos necessários para assegurar uma provisão de nutrientes e energia suficientes para os embriões e as larvas em formações. Analisa-se que, como ponto de partida, esta série de dados tem utilidade para o desenvolvimento de trabalhos destinados a melhorar os padrões de produção de alevinos, considerando que as variações na composição, que podem ser determinadas sobre os ovos, se podem utilizar e têm validade como um indicativo direto de sua qualidade.

Evaluación de la calidad alimentaria de la harina de Lemna obscura como ingrediente en la elaboración de alimento para tilapia roja (Orechromis spp) / Feeding quality evaluation of Lemna obscura meal as ingredients in the elaboration of food for red tilapia (Orechromis spp)

El presente trabajo se realizó con la finalidad de evaluar la calidad nutricional de la harina de lenteja de agua (Lemna obscura) como ingrediente en la elaboración de alimento para tilapia roja (Oreochromis spp.). Se prepararon 3 dietas con niveles de inclusión de 15 por ciento (dieta A), 25 por ciento (dieta B) y 35 por ciento (dieta C) y una dieta control exenta de harina de Lemna. Estas fueron isocalóricas e isoproteicas con un nivel de 30 por ciento de proteína. Además se utilizó una dieta comercial (dieta D), con 40 por ciento de proteína, para compararla con las dietas experimentales. Los alevines se alimentaron durante 10 semanas consecutivas y cada catorce días, se evaluaron los parámetros más importantes como ganancia de peso, alimento consumido, factor de conversión alimentaria (FCA) y la relación eficiencia-proteica (REP). La comparación estadística reveló que no hubo diferencias significativas (P>0,05) en los valores de los resultados finales de la conversión entre las dietas Control A, B, C y D. En relación al peso promedio final, hubo diferencias significativas (P<0,05) entre los peces alimentados con la dieta B, con respecto a la dieta control y dieta comercial. No hubo diferencias significativas entre las dietas experimentales (P>0,05). Se demuestra en este estudio que la dieta con un 25 por ciento de inclusión resultó ser más eficiente en cuánto a los parámetros evaluados que la dieta control. Los excedentes de Lemna crecidos en el lago de Maracaibo o cultivados pueden ser utilizados como harina en las dietas para tilapia roja y representa una alternativa para reducir los costos de alimentación, siempre y cuando se utilice en combinación con otros ingredientes de alto contenido proteico.

The present work was carried out with the purpose to evaluate the nutritional quality of duckweed (Lemna obscura) meal as ingredient in the food elaboration for red tilapia (Oreochromis spp.). Three diets were prepared with inclusion levels of 15 percent (diet A), 25 percent (diet B) and 35 percent (diet C) and a control diet free of Lemna meal. The diets were isocaloric and isonitrogenous with 30 percent of protein. Furthermore, commercial diet (diet D) with 40 percent protein was used to compare with experimental diets. The fingerlings were fed during 10 weeks consecutive and fourteen days, were evaluated the most important parameters as weight gain, consumed food, feed convertion ratio (FCR) and the protein efficiency ratio (PER). The statistical comparison revealed that there were no significant differences (P>0.05) in the values of final results of convertion among diets control, A, B, C and D. In relation to weight average final there were significant differences (P<0.05) among the fish fed with the diet B with respect to the control diet and commercial diet. There were no significant differences among experimental diets (P>0.05). This study showed that diet with inclusion level 25 percent resulted to be more efficient in how much to the evaluated parameters that the diet control. The excesses of Lemna grown in the Maracaibo lake or cultivated can be used as meal in the diets for red tilapia and represents one alternative to reduce the feeding costs, as long as it used in combination with other ingredients of high protein content.

Organochlorine pesticides in lacustrine sediments and tilapias of Metztitlan, Hidalgo, Mexico

The organochlorine pesticides (OP) are very stable molecules, due to this stability; they are very resistant in the environment and highly related to fat tissues with a wide diffusion property and an average time life higher then 10 years. We studied sediments (November 2001, April and June 2002) and organisms collected in April and July (2002) from the lacustric zone of Metzitlán, Hidalgo, Mexico. The analysis was performed according to UNEP/IAEA (1982) (sediments) and UNEP/FAO/IOC/IAEA (1986) (organisms) methods. Three chemical families of organochlorine pesticides were identified and analyzed to determine posible toxicological risk. The principal organochlorine compounds found in sediments were g-HCH, d-HCH, p,p’-DDT and the endosulfan sulfate; these xenobiotics come from agriculture lands near the river and lake, used intensively, and most probably carried by the rain and rain flows into the main water body. In the tilapias tissue, p,p’-DDD y d-HCH were detected. The average concentrations of organochlorine pesticides in sediments were within the internacional limits for freshwater benthonic fauna, although lindane (g-HCH) was near the limit. The fish were above the criteria established in the local legislation (NOM-027-SSA1-1993 y NOM-028-SSA1-1993). Rev. Biol. Trop. 56 (3): 1381-1390. Epub 2008 September 30.

El presente trabajo se llevó a cabo en la cuenca lacustre de Metztitlán, Hgo. Se realizaron tres colectas de sedimentos recientes en noviembre (2001), abril y julio (2002) y dos colectas para organismos en abril y julio (2002). Los análisis se hicieron siguiendo la metodología para sedimentos propuesta por UNEP/IAEA (1982) y para tejido de organismos por UNEP/FAO/IOC/IAEA (1986). Se identificaron y cuantificaron tres familias químicas de plaguicidas organoclorados, para determinar el posible riesgo toxicológico de los sedimentos y de organismos en capturas comerciales. Los principales compuestos clorados en sedimentos fueron el g-HCH, d-HCH, p,p’-DDT y el sulfato de endosulfán; estos xenobióticos provienen de las zonas de cultivos aledañas al río y al lago, con un uso intensivo, probablemente transportados por lluvias y descargas fluviales hacia el cuerpo lacustre y en el tejido de organismos se detectaron principalmente el p,p’-DDD y d-HCH. Las concentraciones promedio de plaguicidas clorados en sedimentos no rebasaron los límites establecidos en los criterios de calidad ambiental internacionales para provocar efectos nocivos en la biota bentónica de los sistemas dulceacuícolas, aunque de manera puntual el lindano (g-HCH) registró niveles cercanos a dichos límites. Las tilapias rebasaron los criterios existentes en las Normas Oficiales Mexicanas (NOM-027-SSA1-1993 y NOM-028SSA1-1993).