Heavy metals uptake by Asian swamp eel, Monopterus albus from paddy fields of Kelantan, Peninsular Malaysia: preliminary study

Swamp eel, Monopterus albus is one of the common fish in paddy fields, thus it is suitable to be a bio-monitor for heavy metals pollution studies in paddy fields. This study was conducted to assess heavy metals levels in swamp eels collected from paddy fields in Kelantan, Malaysia. The results showed zinc [Zn (86.40 µg/g dry weight)] was the highest accumulated metal in the kidney, liver, bone, gill, muscle and skin. Among the selected organs, gill had the highest concentrations of lead (Pb), cadmium (Cd) and nickel (Ni) whereas muscle showed the lowest total metal accumulation of Zn, Pb, copper (Cu), Cd and Ni. Based on the Malaysian Food Regulation, the levels of Zn and Cu in edible parts (muscle and skin) were within the safety limits. However, Cd, Pb and Ni exceeded the permissible limits. By comparing with the maximum level intake (MLI), Pb, Ni and Cd in edible parts can still be consumed. This investigation indicated that M. albus from paddy fields of Kelantan are safe for human consumption with little precaution

Copper and zinc speciation in soils from paddy cultivation areas in Kelantan, Malaysia.

The purpose of this study was to investigate the present concentration of copper (Cu) and zinc (Zn), and factors controlling the bioavailability of metals in paddy cultivation soils collected from Kelantan. Cu and Zn levels in soil samples were extracted by using the sequential extraction procedures, which are namely easily or freely, leachable and exchangeable (EFLE), acid-reducible, oxidisable-organic and resistant fractions. The highest concentration of Cu was found in the oxidisable-organic fraction (19.77±1.89 µg/g) for March, while the resistant fraction (18.29±0.87 µg/g) was the highest in April. In contrast, Zn concentration was the highest in the resistant fraction for both months. Statistically, Cu and Zn results showed a non-significant difference among these two months in the fraction of paddy soil studied. These results indicate a low bioavailability of Cu and Zn in the paddy cultivation soils. Therefore, the anthropogenic-based Cu and Zn in the paddy cultivation areas of Kelantan are expected to originate from applications of chemical fertilizers and pesticide, not from the lithogenic sources

Geofractionation of heavy metals and application of indices for pollution prediction in paddy field soil of Tumpat, Malaysia

The present study investigates the concentration of Pb, Cd, Ni, Zn, and Cu in the paddy field soils collected from Tumpat, Kelantan. Soil samples were treated with sequential extraction to distinguish the anthropogenic and lithogenic origin of Pb, Cd, Ni, Zn, and Cu. ELFE and oxidizable-organic fractions were detected as the lowest accumulation of Pb, Cd, Ni, Zn, and Cu. Therefore, all the heavy metals examined were concentrated, particularly in resistant fraction, indicating that those heavy metals occurred and accumulated in an unavailable form. The utilization of agrochemical fertilizers and pesticides might not elevate the levels of heavy metals in the paddy field soils. In comparison, the enrichment factor and geoaccumulation index for Pb, Cd, Ni, Zn, and Cu suggest that these heavy metals have the potential to cause environmental risk, although they present abundance in resistant fraction. Therefore, a complete study should be conducted based on the paddy cycle, which in turn could provide a clear picture of heavy metals distribution in the paddy field soils

Health risk from Cu and Zn contamination through consumption of paddy eel, Monopterus albus

The main objective in this study is to determine Cu and Zn concentration in edible tissues (skin and muscle) of paddy eels, Monopterus albus. The collection of M. albus samples was based on four paddy seasons (plowing, seedling, growing and harvesting). A total of 163 individuals of M. albus were collected. Edible tissues were dissected, digested and analyzed using an atomic absorption spectrometer (AAS) for metal concentration. Results showed bioaccumulation of Cu and Zn in skin was higher than in muscle tissues. Comparison with the Malaysian Food Regulation showed Cu and Zn concentrations in muscle and skin tissues were within the permissible limits. The estimation of chemical doses was calculated in order to evaluate the health risk of Malaysian population via the consumption of M. albus. Result showed Cu and Zn levels were low in muscle and skin tissues, thus suggesting edible tissues of M. albus are safe for consumption

Ecology and biology of the commercially valuable freshwater Asian swamp eel, Monopterus albus

Asian swamp eel, Monopterus albus (Synbranchidae), a sex reversal, air-breathing and eel-like exotic fish is common in freshwater area of the East and Southeast Asia, and even has been reported in Florida waters in 1997. This fish is easily found in paddy fields, ponds, rivers and swampy areas. People, especially farmers, acknowledge it important for protein sources and culture. It is also tasteful, nutritionally rich and medicinally valuable fish with high export demands. However, due to several reasons especially overfishing, its population showed decline and could be potentially classified as a threatened species by IUCN in future. This manuscript will describe its ecological niche and potential for aquaculture activities

Assessment on reproductive biology of Asian swamp eel, Monopterus javanensis La Cepède 1800 in relation to the impacts of paddy practice management in Kelantan, Malaysia

In order to understand the life history of the Asian swamp eel, Monopterus javanensis found in paddy fields, the time of maturation of its gonads was studied by using the gonadal somatic index. The peak gonadal somatic index was first found during the ploughing and seedling seasons in 2011 and 2012. This was accompanied by the yellowish egg sac observation made in the eels during the ploughing and seedling seasons, which was indicative of the mid- and early maturation stages of the gonads. However, the decline in GSI from the growing until the harvesting seasons indicated the poor development of gonads since differentiating the sex of the eels was hard. This could be due to the heavy application of pesticides and fertilisers during the growing season as cadmium present as impurities in the fertilisers, which slowly accumulated in the gonads. The findings highlighted the availability of Asian swamp eels for local eel collectors as part of their income and the complexity of heavy metal bioaccumulation in their gonads for safe eel consumption. Overall, the habitat of the Asian swamp eels may induce the differences in the maturation timing for the species

Checklist of fishes at Pergau Lake, Jeli, Kelantan, Malaysia

A survey was conducted to determine the diversity of fish in Pergau Lake, Jeli, Kelantan, Malaysia from 2 September to 18 October of 2016. Fish samples were collected at seven random sampling stations around the lake by using setting trap method. The collected samples were preserved in 10% formalin solution and delivered to the laboratory for further identification process. Fourteen species, namely as Hemibagrus nemurus, Hampala macrolepidota, Clarias batrachus, Channa striata, Cyprinus carpio, Poropuntius smedleyi, Pangasius sp., Oreochromis niloticus, Oreochromis mossambicus, Leptobarbus hoevenii, Neolissochilus hexagonolepis, Tor tambroides, Osteochilus hasselti and Neolissochilus soroides, comprising of six families were collected during this study. From this study, family of Cyprinidae was the dominant species in Pergau Lake with exactly 50% of catch percentage, followed by family of Bagridae (29%), Cichlidae (10%), Clariidae (5%), Channidae (3%) and Pangasiidae (3%). This study shows that there is still a diversity of fish species in Pergau Lake, showing that the water and its environmental condition is very good

Lead concentration in long-tailed macaque (Macaca fascicularis) hair in Kuala Selangor, Malaysia

Long-tailed macaque (Macaca fascicularis) has the potential to be a good biological indicator for toxic exposure because they have an almost similar physiology and behaviour to humans. The objective of this study is to determine the concentration of lead (Pb) in hair samples of long-tailed macaques which were found in and out of the Kuala Selangor Nature Park (KSNP) area. The hypothesis is long-tailed macaques that live in the anthropogenic area (outside KSNP) may be exposed to high levels of lead compared to long-tailed macaques living in the forest area (inside KSNP). Analysis of hair samples were carried out using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The study found that the average mean of lead concentration in the anthropogenic area is 6.31 μg/g while for the forest area it is 3.16 μg/g. Lead concentration in the two areas are statistically insignificant. Nevertheless, lead concentration in the anthropogenic area recorded a slightly higher mean concentration than in the forest area. Even so, results of this study indicate that long-tailed macaques in Kuala Selangor are not exposed to high levels of lead. This study is the first in Malaysia to utilise long-tailed macaques as a biological indicator for testing the concentration of toxic substances in the environment. This study is still in its early stages; thus, future research requires improvements

Bioaccumulation of heavy metals and metallothionein effects on reproductive biology of Asian Swamp eel (Monopterus albus Zuiew, 1793) in paddy fields in Tumpat, Kelantan, Malaysia

The current application of excessive agrochemical fertilizers during the four paddy seasons could potentially elevate the concentration levels of Zn, Cu, Cd, Ni and Pb in paddy soils. Hence, concentrations of Zn, Cu, Cd, Ni and Pb in paddy soils and Asian swamp eel, Monopterus albus, were evaluated to determine the availability, distribution, overall classification and risk associated with application of agrochemical fertilizers and pesticides introduced by rice farmers. A four step sequential extraction technique (SET) was conducted to establish the speciation, mobility, availability and origin of heavy metals such as zinc, copper, cadmium, nickel and lead. These four fractions are termed as exchangeable (EFLE), acid-reducible, oxidisableorganic and resistant fractions in the paddy soil. Nine tissues of Asian swamp eel were selected, namely, gills, liver, kidneys, digestive tract, stomach contents, gonads, bone, skin and muscle; which were digested using the acid digestion method. In comparison to the values of average shale of the studied metals, total Pb and Cd were higher than the shale values, whereas the total Zn, Cu and Ni concentrations were found to be below the values. Generally, most of the metals studied were significantly associated with the resistant fraction, followed by oxidisable-organic and acid-reduction fractions. This indicates that the paddy soils of Tumpat are naturally rich with the metals studied. Meanwhile, the least average partitioning patterns in EFLE in paddy seasons indicate low Zn, Cu, Cd, Ni and Pb mobility. Among the metals studied, availability of average Cd and Pb levels was found to be abundant in most seasons based on enrichment factors and contamination factors. However, none of the studied metal concentrations in the paddy soils were as high as the toxic effect threshold (TET) value. Since Asian swamp eel is a long-lived organism, the longer the exposure to those pollutants, the higher the concentrations of metals were bio-accumulated into it. Levels of Zn, Cu, Cd, Ni and Pb in the stomach contents were found to be higher than other tissues studied. Muscle and skin were shown to have the least heavy metal concentrations. To evaluate the health risks to the Malaysian population through consumption of Asian swamp eel, daily intakes and target hazard quotient of heavy metals were estimated on the basis of the concentrations of heavy metals in muscle and skin of Asian swamp eel. Based on the estimated daily intake and THQ of Cd and Pb in skin and muscle in 2011 and 2012, the results suggest that Cd and Pb in skin and muscle of Asian swamp eel was polluted by Cd and Pb, which have higher risk to be consumed. Metallothionein (MT) concentrations in gills, liver and muscle tissues of M. albus were determined to assess the biological response of Asian swamp eel to the level of some metals. The concentrations of Zn, Cu, Cd, Ni and Pb (μg/g wet weight) in the tissues studied were correlated with MT contents. MT concentrations were found to be high in the liver, gills and muscles during plowing, growing, and harvesting seasons. However, a significant correlation (p < 0.01) was found between MTs concentrations in liver and Zn metals. No correlations were found between MTs contents in gills and muscle with the studied metals. In this study, the gonadal histological procedure was made as a basis for sex determination in Asian swamp eel, M. albus. Thirty-two females, three males and two intersexes of Asian swamp eel were considered. The presence of a high number of matured oocyte 3 and 4 during plowing and seedling seasons have shown that these seasons could be considered as breeding seasons for Asian swamp eels. The availability of food and nutrients (agrochemical fertilizers) were attributed to the ovarian development of Asian swamp eel. In conclusion, the concentrations of Zn, Cu, Cd, Ni and Pb in paddy soils varied with paddy cycles in 2011 and 2012. The presence of Zn, Cu, Cd, Ni and Pb in Asian swamp eels’ tissues indicates that these eels have the ability to accumulate and partially remove the heavy metals which required future research study

An assessment of heavy metal bioaccumulation in Asian Swamp Eel, Monopterus albus, during plowing stages of a paddy cycle

Livers and muscles of swamp eels (Monopterus albus) were analyzed for bioaccumulation of heavy metals during the plowing stage of a paddy cycle. Results showed heavy metals were bioaccumulated more highly in liver than muscle. Zinc (Zn) was the highest bioaccumulated metal in liver (98.5 ± 8.95 μg/g) and in muscle (48.8 ± 7.17 μg/g). The lowest bioaccumulated metals were cadmium (Cd) in liver (3.44 ± 2.42 μg/g) and copper (Cu) in muscle (0.65 ± 0.20 μg/g). In sediments, Zn was present at the highest mean concentration (52.7 ± 2.85 μg/g), while Cd had the lowest mean concentration (1.04 ± 0.24 μg/g). The biota-sediment accumulation factor (BSAF) for Cu, Zn, Cd and nickel (Ni) in liver tissue was greater than the corresponding BSAF for muscle tissue. For the three plowing stages, metal concentrations were significantly correlated between liver and muscle tissues in all cases, and between sediment and either liver or muscle in most cases. Mean measured metal concentrations in muscle tissue were below the maximum permissible limits established by Malaysian and U.S. governmental agencies, and were therefore regarded as safe for human consumption