Heavy metal profile of water, sediment and freshwater cat fish, Chrysichthys nigrodigitatus (Siluriformes: Bagridae), of Cross River, Nigeria
Ezekiel Olatunji Ayotunde1*, Benedict Obeten Offem1 & Fidelis Bekeh Ada1
*Dirección para correspondencia
Abstract Cross River serves as a major source of drinking water, transportation, agricultural activities and fishing in Cross River State, Nigeria. Since there is no formal control of effluents discharged into the river, it is important to monitor the levels of metals contaminants in it, thus assessing its suitability for domestic and agricultural use. In order to determine ]]>
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Key words: Cross River, maximum limit, fish, water, sediment, heavy metals. Resumen Cross River funciona ]]>
Palabras clave: río Cross, límite máximo, peces, agua, sedimentos, metales pesados.
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Water pollution has become a global problem. Water is essential to all living organisms and in all aspects of human life. Unfortunately, the availability and quality of water have been impacted upon by both natural and anthropogenic sources, leading to poor water quality and productivity of aquatic ecosystems (FAO 1992). Heavy metals are chemical elements with a specific gravity that is at least five times the specific gravity of water. The specific gravity of water is 1 at 4°C (39°F). Simply stated, specific gravity is a measure of density of a given ]]>
et al. 2008). High concentration exposure is not necessary to produce a state of toxicity in the body ]]>
et al. 1978). Heavy metals belong to the group of elements whose hydro-geochemistry cycles have been greatly accelerated by man. The rapid industrialization, coupled with technological advances in agriculture, has introduced various pollutants (synthetic and organic) into the aquatic ecosystems, which serves as the ultimate sink for most metals (Ogbeibu & Ezeunara 2002). Harvey & Lee (1982) and Bradley & Morris, (1986) have also reported the significance of increased metal loadings in aquatic ecosystems ]]>
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Waste water streams containing heavy metals are produced by many manufacturing processes and find their way into the environment (Soon et al. 1980, Higgings & Dasher 1986, Oguzie 1996, Ogbeibu & Ezeunara 2002). Metals persist in the environment and become bioconcentrated and bioamplified along the food chain. This may be responsible for high concentrations of these metals in predators such as sharks and eagles (Broda 1972, Martins ]]>
et al. 2004). Bio-accumulation in fish has been reported by many researchers (Jernelov & Lann 1971, Goldwater 1971, Mathis & Cummings 1973, Chernof & Dooley 1979, Bull et al. 1981, Biney et al. 1991, Law & Singh 1991). The ]]>
Diffusion facilitated transport or absorption in gills and surface mucus are the mechanisms of uptake from water (Oguzie 1996). The concentrations of heavy metals in fish have been reported to depend upon the rate of uptake ]]>
et al. 1981). Fish production is an important industry in Nigeria where riverine settlements are established (Ako & Salihu 2004). Fish is a valuable and cheap food item and source of protein to man. Concern about heavy-metal contamination of fish has been motivated largely by adverse effects on humans, given that consumption of fish is the primary route of heavy metal exposure (Nsikak et al. 2007). In order to effectively control and manage water pollution due to heavy metals, it is ]]>
et al. 2008). Sediments can be sensitive indicators when monitoring contaminants in aquatic environments. The sediments were polluted with various kinds of hazardous and toxic substances, including heavy metals. These accumulate in sediments via ]]>
et al. 2005, Lopez & Lluch 2000, Mohamed 2005). Many researchers have used sediment cores to study the behavior of metals (Bellucci et al. 2003, Bertolotto et al. 2003, Borretzen & Salbu 2002, Lee & Cundy 2001, Weis et al. 2001). Cross River serves ]]>
Chryshchythys nigrodigitatus) in Cross River State, and compare the results ]]>
Materials and methods
Study area: The study site is the Cross River, a floodplain river located at the South Eastern part of Nigeria (Fig. 1) on Latitude 4o25´ - 7o.00´ N, Longitude 7o15´ - 9o30´ E. It is bounded in the South by the Atlantic Ocean, East by the Republic of Cameroun, the Nigerian states of Benue in the North, Ebonyi and Abia in the West and Akwa Ibom in the South West. Climate of the study area is defined by dry season and wet season. The wet season (April-October) is characterized by high precipitation (3050±230mm), while the dry season ]]>
Sample collection: Three sample stations designated stations Ikom (Station I), Obubra (Station II), ]]>
C. nigrodigitatus) were collected from each of the three sampling stations every three months. A water sample was collected at 30cm below the surface and bottom using one liter polythene bottles with screw caps. Sediment samples was collected using Eckman grab into plastic bags previously cleaned with detergent and treated with 10% ]]>
Chryshchythys nigrodigitatus (29.4-39.5cm SL, 310-510g) were caught from each sampling station using three inch beach seine nets, set gill nets, baited hooks various sizes, and traps set overnight prior to collection. The specimens were taken in polythene bags and stored in a deep freezer at -10°C in the laboratory prior to treatment and analysis where skin, gills and liver were evaluated (Obasohan et al. 2007). ]]>
Samples treatment and analysis: Sediment samples were oven dried to constant weight at 105oC. The samples were grounded using mortar and pestle and sieved through 2mm mesh size to remove coarse materials. The fish samples were allowed to defrost and then dried to constant weight in an oven at 105oC. Water samples were not subjected to any further treatment and were sent directly for analysis using a ]]>
The data obtained ]]>
et al. 2004, APHA 1998). Results ]]>
The result of the accumulation of heavy metals in Catfish Chrysichthys nigrodigitatus is presented in table 2, the highest concentration of copper (0.279±0.022 μg/g) was observed in the gill at Ikom (Station I) (p<0.05). However, there was a non significant difference (0.034±0.017 and 0.031±0.024 μg/g) between ]]>
Table 1). The highest concentration of Lead (0.008±0.008 μg/g) was observed in the liver at Ikom (Station I) (p<0.05), there was a significant difference (0.005±0.009 and 0.003±0.002 μg/g) between gill and skin at Obubra (Station II) and Calabar (Station III), respectively. The minimum concentration of Lead (0.001±0.001μg/g) was found in the liver at Obubra (Station II). ]]>
The highest concentration of Cadmium (0.011±0.007μg/g) was observed in the liver at Ikom (Station I) and Gill at Calabar (Station III) (p<0.05), there was a significant difference (0.004±0.004 and 0.003±0.005 μg/g) between gill and skin at Obubra (Station II) and Calabar (Station III), respectively. The minimum concentration of Cadmium (0.000±0.000μg/g) was found in the liver and skin at Obubra (Station II). The highest concentration of Zinc (0.009±0.001μg/g) was observed in the liver at Calabar (Station III) (p<0.05), there was a significant difference (0.004±0.004 and 0.003±0.002μg/g) between gill and skin at Ikom (Station I) and Obubra (Station II), respectively. The minimum concentration of Zinc (0.002±0.002μg/g and 0.002±0.002μg/g) was found in the gill and skin at Obubra (Station II). Chromium and Cobalt were not detected in all the stations during the experiment (Table 2). The result of the accumulation of heavy metals in water is presented in table 2 and the mean concentrations for Cu, Fe, Pb, Cr, Co, Ca and Zn in surface and bottom water observed different concentrations among the studied stations, but higher concentration values were observed in bottom water samples in all stations, when compared to surface samples. Chromium and Cobalt observed the lowest values for both surface and bottom water, while Iron resulted with the highest concentration value (0.053±0.04μg/g and 0.044±0.05μg/g) in bottom water samples from Ikom Beach (Station I) and Obubra Ogada Beach (Station II), respectively. These Stations resulted also with the highest heavy metal concentration values for bottom water samples (0.0782μg/g and 0.0787μg/g) when compared to Calabar Station with 0.059μg/g. Copper concentrations were highest (0.037±0.03 μg/g) in Calabar Beach bottom samples. Besides, Copper and Iron were the most common heavy metals for both surface and bottom water, but also in sediment samples from the evaluated stations. The results of the accumulation of heavy metals in sediments is presented in table 2, the mean concentrations of Cu, Fe, Pb, Cr, Co, Ca and Zn observed in different concentrations among the studied stations, but the highest value were observed at Calabar (Station III) and Ikom (Station I) (p<0.05). Copper and Cadmium observed the highest values at Calabar (Station III) and Ikom (Station I) (0.037±0.03μg/g and 0.099±0.004μg/g, respectively), while Cobalt and Cadmium observed the lowest (0.0001±0.00μg/g and 0.0000±0.000μg/g) at Obubra (Station II) and Calabar (Station III). Chromium was not detected in all the stations. Discussion
Knowledge of heavy metal concentrations in fish is important with respect to nature of management and human consumption of fish. Generally, heavy metal concentrations in the tissue of freshwater fish vary considerably among different studies (Javed & Hayat 1998, Chattopadhyay
et al. 2002, Papagiannis et al. 2004), possibly due to differences in metal concentrations and chemical characteristics of water from which fish were sampled, ecological needs, metabolism and feeding patterns of fish, and also the season in which studies were carried out. In the river, fish are often at the top of the food chain and have the tendency to concentrate heavy metals from water (Mansour & Sidky 2002). Therefore, bioaccumulation of metals in fish can be considered as an index of metal pollution in the aquatic bodies (Javed & ]]>
et al. 2007, Anim et al. 2011). In the present study, the result of the accumulation of heavy metals in Catfish
Chrysichthys nigrodigitatus showed that the highest concentration of copper (0.297±0.022 μg/g) was observed in the gill at Ikom (Station I) (p<0.05). However, there was a non significant difference (0.034±0.017 and 0.031±0.024μg/g) between liver and skin at Obubra (Station II) and Calabar (Station III), respectively. The minimum concentration of Copper (0.001±0.001μg/g) was found in the gills ]]>
et al. 1981, Biney et al. 1991, Law & Singh 1991). The uptake of heavy metals in fish was found to occur through absorption across the gill surface or through the gut wall tract (Mathis & Cummings 1973). Diffusion facilitated transport or absorption in gills and surface mucus are the mechanisms ]]>
The concentrations of heavy metals in fish have been reported to depend upon the rate of uptake through the gut from food and the rate of excretion (Bull et al. 1981). The accumulation of copper in the gills may be due to adsorption to the gill surfaces and dependent on the availability ]]>
Clarias batrachus. Huges & Floss (1978) also found the low accumulation of zinc in gills of the rainbow trout. ]]>
The highest concentration of copper (0.65±0.11μg/g) was detected in the liver tissue of O. niloticus, while the lowest detected limit (0.01±0.01μg/g) was found in the bone tissue of O. niloticus. Liver concentrates higher levels of copper in all the six species of fishes than the other organs. Akan et al. (2009) ]]>
et al. 1994). Copper can combine with other contaminants such as ammonia, mercury, and zinc to produce an additive toxic effect on fish (Herbert
et al. 1964, Rompala
et al. 1984).
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The higher levels of trace elements such as lead and chromium in liver relative to other tissues may be attributed to the affinity or strong coordination of metallothionein protein with these elements (Ikem et al. 2003). According to Allen-Gill & Martynov (1995), low levels of copper and zinc in fish muscles appear to be due to low levels of binding proteins in the muscles. Canli & Kalay (1998) determined the concentrations of cadmium and chromium in the gills, liver and muscles of
Cyprinus carpio, Barbus capito and Chondrostoma regium caught at five stations on the Seyhan river system. Liver and gill tissues showed higher metal concentrations than muscles tissue. Thus, heavy metals when discharged into the river enter the food chain and accumulate in the fish body as determined during this investigation. Similar work was carried out by Wegwu et al. (2006), they worked on the assessment of Heavy-Metal Profile of the New Calabar River and its ]]>
Clarias gariepinus and find out that the results indicate that trace metals (except for Zn), even at very low concentrations, negatively affect fish hatch and fry rearing, implying that aquatic milieus contaminated by trace metals are not suitable as nursery grounds for fish cultures.
The highest concentration of iron (0.371±0.489μg/g) was observed in ]]>
Table 1). Fish liver exhibited highest tendency to accumulate both the metals. The accumulation of both cadmium and chromium were the minimum in fish gills. Dural et al. (2007) and Ploetz ]]>
et al. (2007) reported highest levels of cadmium, lead, copper, zinc and iron in the liver and gills of fish species viz. Sparus aurata, Dicentrachus labrax, Mugil cephalus and Scomberomorus cavalla. Yilmaz et al. (2007) reported that in Leuciscus cephalus ]]>
Lepornis gibbosus, cadmium, cobalt and copper accumulations in the liver and gills were maximum, while these accumulations were least in the fish muscle. Accumulation in the liver can be the result of detoxicating mechanisms and may originate from metal in the food (Karadede & Unlu 1998, Shoham-Frider et al. 2002). However, the liver is the preferred organ for metal accumulation as could be deduced from the present study. ]]>
The highest concentration of Lead (0.008±0.008μg/g) was observed in the liver at Ikom (Station I) (p<0.05), there was a significant difference (0.005±0.009 and 0.003±0.002μg/g) between gill and skin at Obubra (Station II) and Calabar (Station III), respectively. The minimum concentration of Lead (0.001±0.001μg/g) was found in the liver at Obubra (Station I). Lead accumulates significantly in the bone, liver, stomach, gills and ]]>
T. zilli, C. anguillaris, Protoptenus, O. niloticus, E. niloticus and S. budgetti. The highest levels of lead (0.32±0.12μg /g) were observed in the liver tissue of T. zilli, while the lowest limit (0.01±0.0.01Mg/g) was detected in the bones of C. anguillaris and S. budgetti. The concentrations of lead ]]>
et al. (1977). Those highest concentrations were in gills, kidney and spleen in rainbow trout. (Oladimeji & Offem 1989), noticed in O. niloticus, that the gills consistently accumulated ]]>
et al. 1984). The biological effects of sublethal concentrations of lead include delayed embryonic development, suppressed reproduction, and inhibition of growth, increased mucous formation, neurological problems, enzyme inhalation and kidney dysfunction (Rompala et al. 1984, Leland & Kuwabara 1985). The levels of lead in liver, gills, stomach, kidney and bone tissue of T. zilli,
C. anguillaris, Protoptenus, O. niloticus, E. niloticus and S. budgetti were below the 0.5μg g-1 limits (Walsh et al. 1977). The highest concentration of Cadmium (0.011±0.007μg/g) was observed in the liver at Ikom (Station I) (p<0.05), there was a significant difference ]]>
et al. 1991). The highest concentrations of (0.03±0.01- 0.22±0.01μg/g) in liver tissues of the above species were below the 0.5μg/g threshold considered harmful to fish and predators (Walsh ]]>
et al. 1977). The cadmium-related contamination of the aquatic habitat has greatly increased in the last decades, resulting in an increase of cadmium deposits in tissues of aquatic organisms in all food chain systems (Giles 1988). It is important to note that cadmium is a highly toxic element for all mammals and fish. Cadmium levels have constantly been increasing, and consequently, the research on cadmium has become quite topical and urgent. ]]>
The highest concentration of Zinc (0.009±0.001μg/g) was observed in the liver at Calabar (Station III) (p<0.05), there was a significant difference (0.004±0.004 and 0.003±0.002μg/g) between gill and skin at Ikom (Station I) and Obubra (Station II), respectively. The minimum concentration of Zinc (0.002±0.002μg/g and 0.002±0.002μg/g) was found in the gill and skin at Obubra (Station II). Zinc was detected in all the fish samples, and the ]]>
et al. 1991).
Prasathp & Khanth (2008) reported the impact of Tsunami on the Heavy Metal accumulation in water, sediments and fish at Poompuhar Coast, Southeast Coast of ]]>
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In sediment, metal levels differed significantly (p<0.05) and were highest at Station I, except Cu which level was highest at Stations II, III. The highest metal levels in sediment at Station I, is similar to the situation in water and could also be due to the nearness of Station I to the drainage discharge point from WEMCO Company. Sediment metal levels recorded in this study were low, when compared to the levels for unpolluted inland water sediment (GESAMP 1982). Sediments were considered an important indicator for ]]>
et al. 1996). Sediments have frequently been analyzed to identify sources of trace metal in the aquatic environment because of the high accumulation rates exhibited (Forstner
et al. 1981). Sediment analysis allows contaminants that are adsorbed by particulate matter, which escape detection by water analysis, to be identified. The nonresidual fraction of the sediment is considered to ]]>
et al. (2004) showed that the bioavailability of even a minute fraction of the total sediment metal assumes considerable importance. This is especially true to burrowing and filter feeding organisms.
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Fish absorb metals through ingestion of water or contaminated food. Heavy metals have been shown to undergo bioaccumulation in the tissue of aquatic organisms. On consumption of fish and other aquatic organisms these metals become transferred to man. However, it is not yet known whether the fishes in the River have been severely affected by heavy metals, based on the results obtained from this study. Although the results do not explicitly indicate a manifestation of ]]>
Acknowledgments
Funds and facilities used for these studies were provided by Cross River University of Technology 2010 Senate Research Grant Award, under the auspices of the Education Trust Fund (ETF), Abuja, Nigeria. This support is acknowledged with gratitude. Sincere thanks go to Emmanuel Effiom, the laboratory scientists in the Department of Chemistry, University of Calabar for laboratory assistance.
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*Correspondencia:
Ezekiel Olatunji Ayotunde: Department of Fisheries and Aquatic Sciences, Faculty of Agriculture and Forestry. Cross River University of Technology Calabar, PMB 102 Obubra Campus, Obubra Cross River State, Nigeria. eoayotunde@yahoo.co.uk. Benedict Obeten Offem: Department of Fisheries and Aquatic Sciences, Faculty of Agriculture and Forestry. Cross River University of Technology Calabar, PMB 102 Obubra Campus, Obubra Cross River State, Nigeria. benbeff06@yahoo.com. Fidelis Bekeh Ada: Department of Fisheries and Aquatic Sciences, Faculty of Agriculture and Forestry. Cross River University of Technology Calabar, PMB 102 Obubra Campus, Obubra Cross River State, Nigeria. fbekeh@yahoo.com.
1.Department of Fisheries and Aquatic Sciences, Faculty of Agriculture and Forestry. Cross River University of Technology Calabar, PMB 102 Obubra Campus, Obubra Cross River State, Nigeria; eoayotunde@yahoo.co.uk, benbeff06@yahoo.com, fbekeh@yahoo.com
Received 06-VI-2011. Corrected 27-II-2012. Accepted 23-III-20
