Distribution And Accumulation Of Heavy Metals In Fish in Cage System in Linggi Estuary, Malaysia

Kuala Linggi is developing into potential aquaculture area in the west coast of Peninsular Malaysia but this area is facing ecological pressures. In Malaysia, data on heavy metals in aquaculture area and the cultured organisms are lacking. This study is aimed to evaluate the metal levels in fish cage ecosystem and to investigate the exposure route of metals to the cultured fish. Samples of three different sizes of cultured Nile tilapia (Oreochromis niloticus), river sediment, cage sediment, river water and periphyton were analysed for Cu, Zn, Cd and Pb content using atomic absorption spectrophotometer. The cultured fish Hg content was also determined using mercury analyser. Heavy metals (Cu, Zn, Cd, Pb and Hg) are present in the aquaculture area in Linggi Estuary. Concentrations of Cu and Zn in the Linggi River water in the estuary are below the standards outlined by the Malaysian Department of Environment, but Cd and Pb concentrations are above the standards. Sediment Cu and Zn concentrations are at safe levels but Cd and Pb concentrations are above threshold levels. Sediment Cu and Zn are due to anthropogenic origin while large percentage of Cd and Pb in the sediment occurs naturally. There is a similar trend of Cu, Zn, Cd and Pb accumulation in three components of the aquaculture area environment, the periphyton, the cage sediment and the river sediment. This reflects close relationship of these components in cycling of the heavy metals. These three components, plus the commercial fish feed contribute heavy metals to the cultured fish. Different metals accumulate in different organs of the cultured fish. Copper is concentrated in the liver, Zn in the bone, Pb in the operculum, Cd in the gills and Hg in the kidney. Copper, Zn, Cd and Pb were also found to accumulate with age of fish. With respect to Cu, Zn and Hg, the fish cultured in Linggi Estuary is safe for consumption but their Cd and Pb levels are above the permissible level set by the Malaysian Government. Elevated levels of these of nonessential elements may pose threats to human health through consumption of the fish. These results indicate that some measures should be taken to prevent the contamination of the estuarine environment for human and animal health

Effect of mercury and cadmium on early life stages of Java medaka (Oryzias javanicus): a potential tropical test fish.

Several organisms have been used as indicators, bio-monitoring agents or test organisms in ecotoxicological studies. A close relative of the well established Japanese medaka, the Java medaka (Oryzias javanicus), has the potential to be a test organism. The fish is native to the estuaries of the Malaysian Peninsula, Thailand, Indonesia and Singapore. In this study, newly fertilised eggs were exposed to different concentrations of Cd and Hg. Observations were done on the development of the embryos. Exposure to low levels of Cd and Hg (0.01-0.05 ppm) resulted in several developmental disorders that led to death. Exposure to ≥1.0 ppm Cd resulted in immediate developmental arrest. The embryos of Java medaka showed tolerance to a certain extent when exposed to ≥1.0 ppm Hg compared to Cd. Based on the sensitivity of the embryos, Java medaka is a suitable test organism for ecotoxicology in the tropical region

Utilization of Java medaka (Oryzias javanicus) in ecotoxicological studies

An increasing number of chemicals due to human activities enters our environment every day. This study promotes Java medaka (Oryzias javanicus) as test organism for the impacts of these chemicals. Java medaka is a small tropical fish native to Malaysia, Indonesia, Singapore, Thailand and Vietnam, commonly found in abundance in estuaries. The fish have been successfully cultured in the laboratory in ambient temperature and controlled photoperiod of 14 hours light and 10 hours dark. Some ecological aspects of the fish in their natural habitat were studied in order to understand their response to chemicals. The fish occur abundantly all year round in the west and south coasts of Peninsular Malaysia. They migrate tidally within a large salinity range (1.2 – 29.0 ppt), making them suitable to represent the coastal environment. The sensitivity of different life stages of Java medaka to environmental pollutants was tested. All life stages of the fish have been utilized and they have shown particular sensitivity. The embryos were sensitive to low concentrations (0.01 – 0.05 ppm) of heavy metals (Cd, Hg, Pb, Cu and Zn) in terms of developmental impairments. In exposure to glyphosate-based herbicide embryonic death was found to be the most prominent response while swimming disorder was observed in the juveniles. Teratogenecity is another developmental endpoints in embryos exposed to the pollutants tested. The responses shown by all the life stages of the fish indicated that this fish species can be a useful to investigate short term and long term effect of pollutants in the future

Effect of imazapyr-based herbicide on vasculogenesis in developing Java medaka (Oryzias javanicus) embryo

Vasculogenesis, the process of blood vessel formation by a de novo production of endothelial cells during embryogenesis is an important measure to evaluate developmental toxicity. This study evaluated the effect of Imazapyr, a widely used herbicide in agriculture on vasculogenesis in Java medaka embryo. The fish embryos were exposed to five concentrations of Imazapyr-based herbicide (3.0 ppm, 6.0 ppm, 9.0 ppm, 12.0 ppm) and a control under static renewal condition. Prior to the exposure test, normal pattern of vasculogenesis of the fish embryo was recorded using Motic stereomicroscope with Motic 3.0 attached camera. During the exposure period, we observed and recorded the effect of Imazapyr-based herbicide on the primary vascular development (vasculogenesis) of Java medaka embryo throughout the incubation period. The abnormalities found were formation of abnormal patterns of sinus venosus, common cardinal vein and marginal vein, absence of erythrocytes and blood clotting in the veins. Abnormalities in vasculogenesis started to commence in 6.0 ppm Imazapyr-base herbicide and became more pronounced at higher exposure concentrations. The higher the exposure concentrations the earlier the abnormalities in vasculogenesis appeared. Based on the results, Java medaka embryos are suitable as a model organism for testing vasculogenesis impairments due to environmental pollutants. Furthermore, as other medaka fish, Java medaka has the common pattern for the development of the primary vascular system that can represent other vertebrates

Distribution and localities of Java medaka fish (Oryzias javanicus) in Peninsular Malaysia

The Java medaka (Oryzias javanicus) has recently been highlighted as potential indicator for tropical aquatic ecosystem. However, unlike its Japanese counterpart the Japanese medaka (Oryzias latipes) which has been extensively studied, little information can be obtained on Java medaka population in Malaysia. Despite the growing interest and studies on the fish in the Asian region, its distribution and locality are not well known and this complicates sampling activity in the field as well as obtaining living specimen for laboratory culture purposes. Java medaka population can be easily found in the west coast of Peninsular Malaysia and can withstand wide range of salinity level from estuary and brackish water to freshwater river. However, the fish is not present in the east coast and several factors contributing to their non-distribution are discussed in this paper. The finding provides the first record on the detailed occurrence and distribution of Java medaka fish in Peninsular Malaysia and can also serve as a guide for fish collectors or enthusiast in the country to engage closely with the subject

Effect of glyphosate-based herbicide on early life stages of Java medaka (Oryzias javanicus): a potential tropical test fish

Glyphosate is globally a widely used herbicide, yet there is little information on their toxicity to marine fishes. Java medaka, a small tropical fish native to coastal areas in several Southeast Asian countries, is viewed as a suitable candidate for toxicity test and thus was used for this study. Java medaka adults were cultured in the laboratory and the fertilized eggs of the F2 generation were exposed to different concentrations of glyphosate-based herbicide (100, 200, 300, 400 and 500 ppm) until they hatched. The survival and hatching rates of the embryos, changes in the heart rate and morphological impairments were recorded. Generally, survival and hatching percentage decreased as glyphosate concentration increased. Absence of pectoral fin(s) and cornea, permanently bent tail, irregular shaped abdomen, and cell disruption in the fin, head and abdomen are among the common teratogenic effects observed. Furthermore, risk factor also increased with the increased in glyphosate concentrations

Determination of contamination and bioavailabilities of heavy metals (Cu, Cd, Zn, Pb and Ni) in the Sri Serdang Urban Lake by using guppy fish Poecilia reticulata

The guppy fish, Poecilia reticulata and the lake surface sediments were collected from the Serdang Lake in August 2005. Both the fish and the sediment samples were analyzed for Cu, Cd, Pb, Zn and Ni. The ranges of metal concentrations (μg g-1 dry weight) in the fish were 0.160-11.1 μg g-1 for Cu; 64.6-174 μg g-1 for Zn; 0.400-4.03 μg g-1 for Cd; 3.27-12.1 μg g-1 for Ni and 19.5-50.9 μg g-1 for Pb. In the sediment, the ranges of metal concentrations were 1.97-62.1 μg g-1 for Cu; 31.6-274 μg g-1 for Zn; 1.92-3.17 μg g-1 for Cd; 60.2-94.8 μg g-1 for Ni and 3.23-42.1 μg g-1 for Pb. It was found that the concentrations of Zn was the highest found in both fish and sediment samples, followed by Pb, Cu, Ni and Cd. The similar pattern of heavy metal occurrence was found in the fish and in the sediment, indicated that the fish could be used as a potential biomonitor for metal contamination in the freshwater ecosystem. Since P. reticulata are widely distributed in lakes and in almost all of the urban drainage, this fish species is a very potential biomonitor of heavy metal bioavailabilites in the polluted freshwater ecosystem of Malaysia

Acute toxicity test of copper pyrithione on Javanese medaka and the behavioural stress symptoms

This study was conducted to investigate the median lethal concentration (LC50) of copper pyrithione (CuPT) at 96-hr exposure on adult Javanese medaka (Oryzias javanicus) in revealing toxicological effects of CuPT contamination in the tropical area. Wild stock fishes were acclimatized for 14-days prior analysis. Triplicate of test tanks for seven test concentrations were placed with ten fishes each, this includes two control tanks. The behaviour of the tested fishes was manually observed through a camera. The LC50 of CuPT at 96-h was found to be 16.58 mg/L. Tested fishes swam slowly in vertical movement and swam fast towards food during feeding time as the sign of stress behaviour. Meanwhile, fishes in the two control groups swam actively in a horizontal manner and no excitement during feeding time. No mortality in control groups. Results indicate CuPT to be toxic to Javanese medaka at low concentration and caused behavioural stress

Evaluation of glyphosate levels in sediments of milky stork foraging areas in Kuala Gula Bird Sanctuary, Perak, Malaysia

Glyphosate is the most widely used herbicide in the world since its first introduction in the 1970s. Although its accumulation and direct impact on top predators are unlikely, it has the potential to affect the lower trophic community causing imbalance to the local food web. This paper highlights the background levels of glyphosate in the sediment in a part of the Important Bird and Biodiversity Programme Areas (IBA) in the Matang coast i.e., the Kuala Gula Bird Sanctuary, Perak, Malaysia. Despite housing endangered species like the milky stork and migratory birds, the area is surrounded by massive oil palm plantations that utilize glyphosate-based herbicide. Sediment samples were taken from areas frequently visited by the bird population. The herbicide was analyzed by HPLC-UV detection with previous derivatization using 9-fluorenylmethylchloroformate (FMOC-Cl). In general, the glyphosate levels were between 0.26 and 1.72 ppm. These levels are considered low when compared to other agricultural sites in both local and regional areas. In addition, no significant relationship was established between glyphosate levels in the study sites with the distance from nearby agricultural activity (r = 0.2, n = 18, p > 0.05). This evidence suggests that the pollutant most likely comes from an inter-connected network of water canals and water-bodies that accumulate the plantations’effluent over time. Due to its resistant nature and low concentration in the field, there is little concern over its adverse impact on the aquatic ecosystem in the study area. However, continuous monitoring is still emphasized in this paper

Establishment of java medaka (Oryzias javanicus bleeker) as test organism for ecotoxicological studies in tropical region

The medaka fish is a group of small fish distributed in large areas in Asia. This study attempts to establish Java medaka (Oryzias javanicus) as a test organism for ecotoxicological studies in order to gain knowledge of the changes in biological processes of other organisms when exposed to pollutants. The ecology of Java medaka was investigated to understand their responses to environmental pollutants. The findings covered the distribution and localities of the fish, habitat preference or niche they occupied,relationship with other medaka species, and their spawning ground. Thirty eight localities in the coastal areas in Peninsular Malaysia were surveyed from 2008 to 2013. All localities surveyed in the west and south coast are inhabited by Java medaka in abundance but they do not occur in the east coast. In several localities, Java medaka co-exists with Indian medaka (Oryzias dancena), a phenomenon that has never been reported before. In other localities they inhabit different niche with Indian medaka, preferring areas with higher salinity while Indian medaka choose lower salinity areas. Java medaka can tolerate a wide salinity range (0.2 – 30.0 ppt), making them suitable to represent freshwater and marine environment. To support research activities using Java medaka, the laboratory culture was established. It is carried out in ambient temperature, thus, it can represent almost similar condition with the fish habitat. Their suitability for laboratory cultivation, ease of maintenance, regular spawning, short embryonic period and generation time make Java medaka a convenient test organism. The laboratory culture established in this study further ensures that the test fish is of high quality, free from parasites and diseases. The sensitivity of different life stages of Java medaka to environmental pollutants was tested. All life stages of the fish has been utilised and they have shown particular sensitivity. The embryos were sensitive to low concentrations (0.01 – 0.05 ppm) of heavy metals (Cd, Hg, Pb, Cu and Zn) in terms of developmental impairments. The most significant impairment was embryonic death which was metal dependent where the rank of metal severity is as follows: Cd (47.0- 100%) > Hg (22.0 - 64.0%) > Pb (10.0 - 55.0%) > Zn (6.0 - 40.0%) >Cu (4.0- 38.0%). In exposure to glyphosate-based herbicide, embryonic death was found to be directly proportional to the exposure concentrations. Other developmental endpoints in embryos exposed to the pollutants tested include embryotoxicity and teratogenicity. The developmental stages of Java medaka constitute simple and effective models for evaluating pollutant impact. The induction of micronucleus formation and nuclear abnormalities when the adult fish were exposed to very low levels of Cd and Hg (1.0 and 10.0 ppb) and the induction of only nuclear abnormalities in exposure to higher concentrations of Cu and Zn (10.0 and 100.0 ppb) showed the difference in their genotoxic responses towards different metals. Utilizing Java medaka in testing will closely reflect the impacts of toxic pollutants on the environment particularly for the tropical region. As the fish is new to many local researchers, the findings of this study provide the much needed information. Future researches can utilise the fish in various fields of scientific investigation