Trimmed Spearman-Karber Research Articles

Assessing the toxicity of peracetic acid to early Atlantic salmon Salmo salar life‐stages

Bacterial and fungal pathogens in recirculating aquaculture and egg incubation systems can cause elevated mortality and decreased production. Peracetic acid (PAA) is a relatively low-cost, safe, and effective disinfectant; however, its toxicity to early life stages of the Atlantic salmon (Salmo salar) has not been assessed. The 24-h LC50 value of PAA was determined for three early life stages of Atlantic salmon: eyed eggs, fry (~0.17 g), and fingerlings (~16.3 g). LC50 values were calculated using the Trimmed Spearman-Karber (TSK) method and Toxicity Relationship Analysis Program (TRAP). TRAP LC50 values for eyed eggs treated for 5 and 10 min were 781.5 and 485.0 mg/L PAA, respectively, while TSK LC50 values for eyed eggs treated for 5 and 10 min were 771.1 and 462.1 mg/L PAA, respectively. TRAP LC50 values for fry and fingerlings were 4.0 and 5.3 mg/L PAA, respectively, while TSK LC50 values for fry and fingerling were 4.1 and 5.3 mg/L PAA, respectively. The no observed effect concentration (NOEC) values for eyed eggs treated for 5 and 10 min were 500 and 300 mg/L PAA, respectively. These LC50 and NOEC values provide guidance for developing safe PAA treatment protocols Atlantic salmon eggs, fry, and/or fingerlings.

Attenuation of Microcystins Using Electron Beams and Gamma Radiation: A Study with Environment-Bound Conditions

Microcystins (MCs) are toxins profusely synthesized by cyanobacteria, causing livestock poisonings and endangering human health. We design and execute an experiment to investigate the attenuation (degradation) of microcystins by exposing them to gamma radiation and electron beams at doses of 0 (control), 3, 5, 10 and 15 kGy. The experimental conditions simulate microcystin contamination of aquatic environments; we thus consider (1) microcystins inside whole cells and extracellular dissolved in water, simulated by non-sonicated and sonicated cells, respectively, and (2) two acute microcystin concentrations within water. Toxicity tests of Microcystis aeruginosa detected immobilization (i.e., paralysis) of Ceriodaphniasilvestrii exposed to aqueous crude extracts of irradiated and non-irradiated M. aeruginosa (NPLJ-4 strain) at concentrations of 45 and 90 mg.L-1 (mg dry weight of freeze-dried material), and the results were analyzed using the Trimmed Spearman-Karber statistical program to obtain 48-h EC50, the average effective concentration causing immobility in 50% of organisms after 48 hours. We conclude that electron beams are effective physical agents for toxin attenuation (degradation) and reach 100% effectiveness at 5 kGy and above; their efficiency is two orders of magnitude greater than that of gamma radiation. This new body of information contributes to (1) remediating environmental water sources; (2) designing water/wastewater treatment facilities; (3) combatting chronic microcystin environmental contamination; and (4) inspiring further studies to promote the use of biomonitors (e.g., Cladocerans) to detect and evaluate microalgae contamination.

Acute Toxicity (LC50) Of Cyhalofop Butyl on Gambusia Holbrooki

Cyhalofob butyl is a synthetic herbist. This herbicide is a systemic herbicide and is used in weed control especially on celtic agriculture. In this study, the acute toxicity (LC50) of this herbist (Chillinger 200 EC 200, cyhalofob butyl) was investigated, which is currently used intensely in the fight against herbists in Thrace region, including Cyhalofob butyl. Acute toxicity (LC50 value) for this herbicide has been investigated in the common mosquito fish (Gambusia holbrooki) in Thrace Region. Lethal Dose 50 experiments were performed in 3 replicates in static test runs (water temperature 27.70 ±0.56 C, water pH 8.88± 0.37, and conductivity 718.25±21.113 µhos). The experiment results obtained for Chillinger 200 ec during the experiments were evaluated by Trimmed Spearman–Karber method. 96-hour LC50 value for the mosquito fish Gambusia holbrooki was calculated as 4.140 ppm.

The efficacy and dosage of Mentha piperita essential oil in the control of Monogenean parasites in Oreochromis niloticus.

This study determined the safe dosage of Mentha piperita essential oil in Oreochromis niloticus and tested its effectiveness against gill monogeneans. In the acute toxicity trial in fingerlings, seven oil concentrations (20, 25, 30, 35, 40, 45 and 50mg/L) were evaluated with two controls, one positive (water) and one negative control (water with addition of 35mL/L of absolute ethyl alcohol-99.8% PA). It was tested the lethal concentration for 48h (LC50-48h), and during this period we recorded the behavior and mortality of individuals. After the acute toxicity trial, histological analyzes were performed on the gills of specimens submitted to acute toxicity concentrations and controls. To test the efficacy of the essential oil against the parasite in the live host, it was performed an in vivo trial with 27 naturally infected juvenile Nile Tilapia. A three-replicate treatment was carried out, where the fish were submitted to 60-min baths with essential oil of M. piperita at a concentration of 35mg/L (value determined by the acute toxicity trial), and two controls, one positive and a negative. The LC50 was determined using the Trimmed Spearman-Karber program with a 95% confidence interval. No behavioral changes were observed in the controls or in the 20mg/L concentration, but it occurred in the other concentrations. Among the 270 individuals, 20 presented depigmentation. We found the following histological changes in the fingerlings gills: lamellar epithelium removal, partial lamellar fusion, generalized epithelial tissue proliferation, total lamellar fusion. In the in vivo trial, after 1h of therapeutic bath at the concentration of 35mg/L, no efficacy of the essential oil of M. piperita was verified against the monogeneans. According to this study, M. piperita essential oil demonstrated toxic to O. niloticus fingerlings at concentrations of 40, 45 and 50mg/L, causing histological changes, changes in the color of the animal and death, and ineffectiveness against the monogeneans parasites after therapeutic bath in the highest concentration of essential oil tolerated by the studied fish specimens.

Antioxidant and anti-termite activities of the ethanol extract of cibotium barometz (L.) J. Sm.

The antioxidant and anti-termite activities have been considered on the ethanol extract of Cibotium barometz (L.) J. Sm rhizome. An antioxidant assessment was carried out using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method and measured the absorbance at λ = 517 nm. An anti-termite assay was carried out by the force-feeding method using concentrations of 0, 10, 20, and 30 ppm. The results of phytochemical screening indicated that the extracts contained secondary metabolites of flavonoids, polyphenols, tannins, saponins, steroids, and triterpenoids. The antioxidant trial for which data were processed by the linear regression showed IC50 values of 8.20 and 5.04 ppm for the extracts and the vitamin C (as a standard) respectively. The IC50 value of the ethanol extract of the C. barometz rhizome exhibited the strongest antioxidant activity. The anti-termite assay whose data was processed by the Trimmed Spearman-Karber (TSK) program showed an LC50 value of 28.88 ppm. The termite mortality data for 96 hours were analyzed statistically using one way ANOVA with α = 0.05 demonstrated that the given treatments exposed very significant differences in termite mortality [F(3, 16) = 293, p <0.0001]. Based on the results of the study, it might be firmed that the ethanol extract of C. barometz rhizome could be exploited as antioxidant and anti-termite stuff.

Acute toxicity of non-ionized ammonia on tambacu (Colossoma macropomum x Piaractus mesopotamicus)

Ammonia is a toxic compound to aquatic organisms and at high concentrations in water, it can cause various changes in the animal. Therefore, it becomes important to determine the tolerance of farmed aquatic animals for that substance. Thus, the aim of this study was to determine the mean lethal concentration (LC50-96 h) of un-ionized ammonia (NH3) in tambacu fingerlings (Colossoma macropomum x Piaractus mesopotamicus) in acute toxicity test. The fingerlings were exposed to ammonia at concentrations of: 0.09 (control); 0.54; 1.23; 2.52; 3.44 and 3.66 mg L-1 NH3, which were obtained from the application of NH4Cl. The test lasted 96 hours and mortalities were recorded over that period. The LC50 was determined by the Trimmed Spearman Karber statistical method. The LC50-96 h of non-ionized ammonia (NH3) for fingerlings of the tambacu hybrid was 1.63 mg L-1.

Nitrate acute toxicity to post larvae and juveniles of Macrobrachium amazonicum (Heller, 1862).

The objective was to determine the median lethal concentration (LC50) of nitrate for post-larvae and juveniles of Macrobrachium amazonicum exposed for 96 h, and to identify histopathological alterations in the gills of juveniles exposed to nitrate. Post-larvae and juveniles of M.amazonicum were exposed to seven different concentrations of nitrate (0, 50, 100, 500, 1000, 1500 and 2000 mg.L-1) with four replicates (n = 10 prawn/experimental unit). The degree of damage to the branchial structure of juveniles was evaluated using standard histological processing with hematoxylin and eosin (H&E), subjected to the Organ Index (Iorg). LC50 values at 24, 48, 72 were estimated by the Trimmed Spearman Karber Method software and were respectively 1574, 638, 237, and 194 mg.L-1 for post-larvae and 1070, 286, 185 and 155 mg.L-1 for juveniles, respectively. From these results, the safety level of nitrate was estimated at 157, 64, 24 and 19 mg.L-1 for post-larvae and 107; 27; 18 and 16 mg.L-1 for juveniles, respectively for 24 h, 48 h, 72 h and 96 h. Damage to the gills in treatments with 100% mortality for nitrate corresponded to the high occurrence of progressive, regressive, circulatory and inflammatory damages. The other treatments, which caused lower mortality, mainly resulted in inflammation and regressive damage, whose occurrence increased with increasing concentration of nitrate. However, in closed systems, the use of anaerobic denitrifying filters or aquatic macrophytes is necessary to provide suitable water quality for the best productive performance, avoiding the negative influence of the accumulated nitrate.

Effects of Phenanthrene on the Amazonian Fish Tambaqui Colossoma macropomum: LC&lt;sub&gt;50&lt;/sub&gt;, Growth and Haematology

Oil spills have increased in frequency worldwide and biodiversity hotspots, such as the Amazon Basin, are under increasing threat of oil spills. The toxic effects of polycyclic aromatic hydrocarbons are poorly known for Amazonian fish species. The acute and sublethal effects of phenanthrene (Phe) on tambaqui (Colossoma macropomum), an important Amazonian food fish, were analyzed in the present study. The Trimmed Spearman-Karber method was used to determine 96h-LC50 for Phe, which was 940 ug/L and represented roughly 70% of its regular water solubility at 30℃. Tambaqui specimens were exposed to 47, 235 and 470 ug/L, representing respectively, 5, 25 and 50% 96h-LC50 for Phe, for four weeks to analyze Phe effects on growth and haematological properties. Fish exposed to Phe showed high mucus production, expansion of lower lips, and the loss of both hydrodynamic balance and orientation. The condition factor has decreased by over 10% during the last two weeks of exposure to all Phe concentrations. After four weeks of exposure to 47 ug/L Phe (5% 96h-LC50), there was observed a decrease of nearly 47% for final weight gain, 55% for specific growth rate, and 9% for blood haemoglobin. Additionally, plasma glucose increased up to 49% in animals exposed to 470 ug/L Phe (50% 96h-LC50) and lactate increased up to 37% in animals exposed to 235 ug/L Phe (25% 96h-LC50). The main finding was that tambaqui exposed to Phe even at the lowest level analyzed (47 ug/L Phe, 5% of the 96h-LC50 Phe) exhibited disturbances of basic biological and physiological functions.

Toxicity of Peracetic Acid to Fish: Variation among Species and Impact of Water Chemistry

AbstractThere has been strong interest in the use of peracetic acid (PAA) in aquaculture as it can be used to disinfect water and hard surfaces and thereby eliminate or lower the burden of fish pathogens. Unfortunately, there has been little research on the toxicity of PAA to fish. Twelve species of fingerling fish that are important to aquaculture were exposed to PAA for 24 h in static toxicity bioassays in well water. These fish were: fathead minnow, Pimephales promelas; black‐nose crappie, Pomoxis nigromaculatus; bluegill, Lepomis macrochirus; blue tilapia, Oreochromis aureus; channel catfish, Ictalurus punctatus; golden shiner, Notemigonus crysoleucas; goldfish, Carassius auratus; grass carp, Ctenopharyngodon idella; largemouth bass, Micropterus salmoides; rainbow trout, Oncorhynchus mykiss; sunshine bass, Morone chrysops × M. saxatilis; and walleye, Sander vitreus. Median lethal concentration (LC50) values were estimated with the trimmed Spearman–Karber method using nominal PAA concentrations. The mean 24‐h LC50 values ranged from 2.8 to 9.3 mg/L PAA. Fathead minnow were very sensitive and blue tilapia were very tolerant to PAA exposure; LC50 values of other species tested were within the range of 4.1–6.2 mg/L PAA. More importantly, the 24‐h no‐observed‐effect concentration (NOEC) ranged from 1.9 to 5.8 mg/L PAA; the NOEC would be considered as the safe range for culturists to investigate the use of PAA. Decreased alkalinity/hardness increased the toxicity of PAA, while a small increase of dissolved organic content had no effect on PAA toxicity. Results of the present study are important information on the safe application of PAA for the aquaculture industry.

Toxicidade aguda da amônia em juvenis de sardinha-verdadeira Sardinella brasiliensis

A sardinha-verdadeira (Sardinella brasiliensis) é o principal recurso pesqueiro do Brasil, sustentando diretamente a indústria de enlatados, como matéria prima, e indiretamente a pesca dos tuní­­deos, pois juvenis são utilizados como isca-viva. A UFSC, através do Projeto Isca-Viva, vem desenvolvendo técnicas de produção de sardinha-verdadeira em cativeiro com vistas ao uso sustentável do recurso, entretanto não existem informações sobre a toxicidade dos compostos nitrogenados no cultivo desta espécie. O objetivo deste estudo foi estimar a toxicidade aguda de amônia (NH3-N) em juvenis de sardinha-verdadeira. Grupos de cinco peixes (1,04 ± 0,20 g) foram expostos a cinco concentrações de NH3-N (0,60 a 1,47 mg L-1) durante 96 h, mais um grupo controle em triplicata. Os testes foram conduzidos em um sistema semiestático com renovação diária total dos meios experimentais. Os resultados foram apresentados como dados de mortalidade, registrados nas diferentes concentrações testadas, utilizando o software Trimmed Spearman Karber Method. A concentração letal (LC50) após 96 h de exposição a NH3-N foi estimada em 0,74 (0,61-0,90) mg L-1. Os resultados indicam que juvenis de sardinha-verdadeira são relativamente sensí­­veis í­Â amônia em relação a outros peixes marinhos e que atenção especial deve ser dada a este composto em sistemas de cultivo.

Median Lethal Concentration (LS-50) of Lead and the Effect on Osmoregulation of the “Red Tilapia” Fish (&lt;i&gt;Oreochromis&lt;/i&gt; sp.)

The aims of this study are analyzing the score of median lethal concentration (LC50) of lead on the red tilapia fish and also test the influence of Pb exposure on osmoregulation of the red tilapia. This study consists of two steps. The first step is finding out the values of median lethal concentration (LC50) of lead on the red tilapia. The second step is finding out the influence of toxicity of lead metal exposure by giving the metal to the red tilapia maintained in the fresh water for 60 days. The lead concentration used are sub-lethal concentration 0 mg Pb/L, 1.7 mg Pb/L, 2.9 mg Pb/L, 4.9 mg Pb/L, 8.3 mg Pb/L and 14.1 mg Pb/L. The influence of lead metal exposure observed in this observation are the mortality of red tilapia fish and osmoregulation. The data of mortality are analyzed by Trimmed Spearman Karber (TSK) version 1.5 from EPA, the data of osmoregulation are analyzed by variant analysis with SPSS version 16. The result of the first step study was the values of LC50 due to the exposure of Pb metal was 13.12 mg Pb/L. The result of the second step study showed that the exposure of Pb metal also caused the disturbance of osmoregulation of red tilapia fish shown by the increase of osmotic pressure blood of red tilapia fish.

Effect of pesticides 2, 4-on hematological parameters of channa punctatus

Pesticides are chemicals used for pest control in the agricultural fields. Modern agricultural pesticides result in indiscriminate use of various pesticides. Which usually enter into the aquatic environment? They finally reach the surrounding water bodies through surface runoff affecting the aquatic fauna. 2, 4-D is frequently used pesticides due to its effectiveness and rapid breakdown into environmentally safe products. A 96hr static sub-lethal concentration toxicity test was carried out to determine the LC50 value of 2, 4-D on the snake head fish channa punctatus. The fish were exposed to 5 different concentrations of 2, 4-D (40, 45, 50, 55 &amp; 60ppm) for toxicity. Control (0.0ppm) was also carried out. The data were subjected to Finney’s Probit analysis and processed with Trimmed Spearman-Karber statistical software. The LC50 values for 2, 4-D for 24, 48, 72 and 96hr were 4.87, 3.12, 2.69 and 1.92 mgl-1 respectively. At higher concentration of 2, 4-D (3.25 mgl-1 and above) the fish showed uncoordinated behavior such as erratic and jerky swimming, attempt to jump out of water, frequent surfacing and effected the allover of body.

Toxicity Of Sodium Dodecyl Sulfate tO Federally Threatened and Petitioned Freshwater Mollusk Species

Anthropogenically caused physical and chemical habitat degradation, including water pollution, have caused dramatic declines in freshwater mollusk populations. Sodium dodecyl sulfate (SDS), a surfactant with no USEPA Water Quality Criteria (WQC), is commonly used in industrial applications, household cleaners, personal hygiene products, and herbicides. In aquatic habitats, previous SDS studies have associated deformities and death to mollusks found in these systems. The objective of this study was to determine EC50 values for two freshwater juvenile unionids (Villosa nebulosa and Hamiota perovalis) and two freshwater caenogastropods (Leptoxis ampla and Somatogyrus sp.) endemic to the Mobile River Basin, USA, to SDS. Using the Trimmed Spearman-Karber method, EC50 values were calculated. Results found that EC50 values were: V nebulosa = 14,469 µg/L (95% CI: 13,436 – 15,581 µg/L), H. perovalis = 6,102 µg/L (95% CI: 4,727 – 7,876 µg/L), Somatogyrus sp. = 1,986 µg/L (95% CI: 1,453 – 2,715 µg/L), and L. ampla = 26 µg/L (95% CI: 6 – 112 µg/L). Freshwater gastropods were more sensitive to SDS than freshwater unionids. Leptoxis ampla was the most sensitive species tested and had such a low EC50 value that more protective regional criteria may be required. Therefore, future research should include additional testing on mollusk species, particularly regionally isolated species that may display increased sensitivity.

Acute and chronic effects of acidic pH on four subtropical frog species

Acidic precipitation is implicated as a possible cause of global amphibian decline. Even protected areas such as Kruger National Park receive acid rain which may lead to possible negative effects on the park’s natural amphibian populations. We conducted acute (LC 50 ) and chronic acid tolerance bioassays on embryos and tadpoles of four frog species found in the park, i.e., Chiromantis xerampelina (Southern Foam Nest Frog), Pyxicephalus edulis (African Bullfrog), Amietophrynus maculatus (Flat-backed Toad) and Hildebrandtia ornata (Ornate Frog), using survival, deformities and growth as endpoints. Chronic exposure pH-values were selected based on the results of the acute assays. Trimmed Spearman-Karber LC 50 s were 4.07, 4.55, 3.75 and 3.747 for C. xerampelina , P. edulis , A. maculatus and H. ornata , respectively, and were all below the pHs in the natural ponds of the KNP. For chronic exposures tadpole size decreased and tadpole deformities increased with decreasing pH. Metamorphosis of tadpoles was also delayed by increasing acidity. In conclusion, the current buffering capacity of water bodies, which serve as habitat for amphibians, negates the effects of decreasing pH from acid precipitation. Keywords: low pH, acid precipitation, amphibians, mortality, developmental deformities, delayed metamorphosis, Kruger National Park

Toxicity of cryoprotectants agents in freshwater prawn embryos of Macrobrachium amazonicum.

The process of cooling and cryopreservation of prawn embryos is a viable alternative for a continuous supply of larvae for freshwater prawn farming ponds. However, studies involving the application of those techniques as well as on toxicity of cryoprotectants in freshwater prawn embryos are scarce. Thus, this study aims to test the toxicity of methylic alcohol (MET), dimethyl sulfoxide (DMSO) and ethylene glycol (EG) on Macrobrachium amazonicum embryos. For the present experiment, pools of embryos were taken from 15 M. amazonicum females and were divided into three groups and tested in duplicate at concentrations of 10, 5, 3; 1, 0.5 or 0.1%. Toxicity tests were conducted for 24 h in Falcon® pipes to obtain the lethal concentration for 50% of the larvae (LC50). After the set period for testing, random samples of embryos were removed for morphological analysis under stereoscopic microscopes. Results were analysed using analysis of variance (ANOVA) and Tukey's test at a 5% significance level and Trimmed Spearman-Karber Analysis to determine LC50-24 h. DMSO toxicity tests revealed that 5% and 10% concentrations showed the highest toxicity and differed from the control (P ≤ 0.05), 24h-LC50 was 437.4 ± 14.4 µL. MET was less toxic among the tested cryoprotectants and concentrations did not allow the determination of its LC50-24h. For tests with EG, concentrations of 3, 5 or 10% solutions resulted in a 100% mortality to tested embryos; EG was the tested cryoprotectant with the highest toxicity, with an LC50-24h average of 81.91 ± 35.3 µl.

Genotoxicity of chlorpyrifos in freshwater fish Labeo rohita using Alkaline Single-Cell Gel Electrophoresis (Comet) assay

Chlorpyrifos is a widely used insecticide of organophosphate group, which causes severe toxicological effects in non target aquatic organisms especially in fish. In the present study the genotoxic effects of sublethal concentrations of chlorpyrifos were observed in the erythrocytes and gill cells of Labeo rohita (commonly known as rohu) using the Alkaline Single-Cell Gel Electrophoresis (Comet) assay. Effects of chlorpyrifos on the behavior of the fish were also investigated. The 96 h LC50 value of chlorpyrifos, estimated by Trimmed Spearman-Karber (TSK) in static bioassay, was found to be 442.8 µg/L. On the basis of LC50 value, the fish were exposed to three sublethal concentrations of chlorpyrifos (SL-I ∼221.4 µg/L, SL- II ∼110.7 µg/L and SL-III ∼73.8 µg/L) for 96 h. Blood and gill samples were collected at every 24 h and were subjected to the Comet assay. The observed DNA damage was concentration dependent and time dependent and those levels of DNA damage in between the tested concentrations and times were significantly different (p < 0.01). It was also found that the gill cells are more sensitive to chlorpyrifos, though; it revealed more DNA damage as compared to the erythrocytes of fish. Fish exposed to different concentrations of chlorpyrifos showed different neurotoxic behavioral responses. It was concluded that chlorpyrifos is a genotoxic and neurotoxic insecticide causing DNA damage and neurotoxic effects in Labeo rohita.

Evaluation of the Genotoxicity of Chlorpyrifos in Common Indus Valley Toad, &amp;lt;i&amp;gt;Bufo stomaticus&amp;lt;/i&amp;gt; Using Alkaline Single-Cell Gel Electrophoresis (Comet) Assay

Chlorpyrifos is a commonly used pesticide of organophosphate group, which causes toxicological effects in non-target organisms especially fish and frogs. In the present study, the genotoxicity of sublethal concentrations of chlorpyrifos was observed in the erythrocytes of common Indus valley toad, Bufo stomaticus, using the Alkaline Single-Cell Gel Electrophoresis (Comet) assay. In the first step, acute toxicity of chlorpyrifos was evaluated by exposing the tadpoles to high concentrations of the pesticide. The acute LC50 value of chlorpyrifos, calculated by Trimmed Spearman-Karber (TSK) in static bioassay, was found to be 930.0 μg/L. On the basis of acute LC50 value, the tadpoles were exposed to three sublethal concentrations (155, 233 and 465 μg/L) of chlorpyrifos for 96 h. Blood cells were collected at every 24 h interval and were subjected to the Alkaline Single-Cell Gel Electrophoresis assay. The observed DNA damage was concentration and time-dependent, and those levels of DNA damage in between the tested concentrations and times were significantly different (p Bufo stomaticus.

Comparison of Synthetic and Natural Organic Polymers as Flocculant for Textile Wastewater Treatment

Performance of synthetic organic polymer (polyacrylamide) and natural organic polymers (pectin) as flocculant in coagulation-flocculation treatment will be assessed. Analysis of functional group of organic polymer was done by Fourier Transform Infrared Spectroscopy - Attenuated Total Reflectance (FTIR-ATR). Response Surface Methodology - Central Composite Design (RSM-CCD) was used to evaluate the interaction effects of pH, coagulant dose and flocculant dose. The experiment was conducted in lab scale of 500mL of sample textile wastewater with six paddle of conventional jar test. Trimmed Spearman-Karber method has been used to estimate median lethal concentration (LC ) values and their confidence intervals. The result shows 50 polyacrylamide added in the treatment was the best at optimum pH 5, coagulant dose at 275 mg/ L and flocculant dose at 35 mg/ L with 88 and 80% removal. In contrast, additions of natural organic flocculant only manage to remove 54.2 and 67 % at the optimum pH 5, coagulant and flocculant dosage at 427.4 and 21.9 mg/ L respectively. However, polyacrylamide treatment claimed to be more toxic based on lethal concentration (LC ) 50 at 17 % compare to natural organic flocculant at 34%.

Comparative Susceptibility of Freshwater Fish Species to Metals from Ultramafic Soils

Soils derived from ultramafic rocks have a mineralogy rich in metals like Co, Cr, Fe and Ni, and the process of extracting these metals from soil generates highly metallic waste. When disposed near of water bodies these residues pose a risk on the aquatic environment. Two fish species are used in ecotoxicity tests worldwide: Danio rerio (zebrafish), an Asian species, and Oreochromis niloticus (tilapia), an African one. However, Hyphessobrycon eques (mato grosso), a native of South America and found in Brazilian rivers, is as yet little used in ecotoxicity tests. The aims of this study were to evaluate the acute toxicity of the metals Co, Cr, Fe and Ni to the fish D. rerio, O. niloticus and H. eques, and compare its susceptibility. Tests were conducted following the recommendations of the Brazilian Association for Technical Standardization (ABNT). Stock solutions were prepared with the analytical reagents CoCl2.6H2O; K2Cr2O7; FeCl3.6H2O e NiCl2.6H2O. The quantification of metals was carried out in the stock solutions by ICP-AES. The dilution water used was synthetic softwater pH 7.3±0.1, hardness 43 mg L-1; DO 95% and temperature 25±1°C. To perform static tests 10 fish from each species were exposed for 96 hours, in duplicate, to different concentrations of the metals tested. The measured 96-hr initial lethal concentrations LC(I)50 of metals Co, Cr, Fe and Ni, calculated by the Trimmed Spearman Karber method, were 35.7, 35.9, 5.6 and 15.0 mg L-1 for D. rerio, 79.8, 32.6, 8.8 and 49.7 mg L-1 for O. niloticus and 104.1, 23.7, 8.5 and 34.5 mg L-1 for H. eques, respectively. The data showed that D. rerio has greater susceptibility to the metals tested, which justifies its increased use as a test species, except concerning Cr, for which H. eques was the most sensitive species.

Uji selektivitas ekstrak etil asetat (EtOAc) biji putat air (Barringtonia racemosa) terhadap keong mas (Pomacea canaliculata) dan ikan lele lokal (Clarias batrachus)

Abstract. This study examined the selectivity of ethyl acetate extract of putat air (Barringtonia racemosa) in controlling Pomacea canaliculata compared to local catfish (Clarias batrachus). Five concentration of putat air (25, 50, 100, 200, and 400 ppm) with triplicate were tested in this study. The powder of putat air kernel was extracted through increasing the polarity of solvent, i.e. dichloromethane, ethyl acetate, and methanol. The mortality data were analyzed using Trimmed Spearman Karber (TSK) program version 1.5. The selectivity value was calculated based on LC50 values obtained from TSK. The results showed that (1) LC50 values of putat air's kernel extract of putat air to P. canaliculata and C. batrachus were 25.00 and 87.06 ppm, respectively, (2) the selectivity value of putat air's kernel extract as molluscicide of P. canaliculata was 3.48. Key words: Pomacea canaliculata, local catfish (Clarias batrachus), putat air (Barringtonia racemosa).