Journl of Agriulturl Siene; Vol. 4, No. 11; 2012 ISSN 1916-9752 E-ISSN 1916-9760 Pulished y Cndin Center of Siene nd Edution Bioumultion of Hevy Metls in Fish (Hydroynus forskhlii, Hyperopisus ee oidentlis nd Clris griepinus) Orgns in Downstrem Ogun Costl Wter, Nigeri Btunde A. Murtl 1, Widi O. Adul 1 & Adeolu A. Akinyemi 1 1 Deprtment of Aquulture nd Fisheries Mngement, Federl University of Agriulture, Aeokut, Nigeri Correspondene: Widi O. Adul, Deprtment of Aquulture nd Fisheries Mngement, Federl University of Agriulture, PMB 2240, Aeokut, Nigeri. Tel: 234-818-342-9107. E-mil: wlxxy@gmil.om Reeived: June 27, 2012 Aepted: July 23, 2012 Online Pulished: Otoer 12, 2012 doi:10.5539/js.v4n11p51 URL: http://dx.doi.org/10.5539/js.v4n11p51 Astrt In this study umultion of some hevy metls Cdmium (Cd), Chromium (Cr), Colt (Co), Nikel (Ni) nd Led (P) in the operulum, gills, hert, kidney, musle nd vertere were determined in some fishes (Hydroynus forskhlii, Hyperopisus ee oidentlis nd Clris griepinus) olleted from fishermen round Ogun estury. The umultion of the metls in different orgns showed signifint differenes (P<0.05) exept led umultion. However, the ioumultion of the hevy metls ws speies-relted s the umultions of the hevy metls nlysed in the smpled fishes were of the following trend: H. forskhlii > H. ee oidentlis > C. griepinus nd the pttern of distriution ws Ni > Cr > Co > Cd > P for ll the fish speies. The levels of Ni nd Cr in this study were higher thn the mximum permissile limits (FAO, UNEP, FEPA nd WHO) for humn onsumption nd tht of Cd, P nd Co were still lower. Sfe disposls of domesti sewge nd industril effluents s well s enforement of lws ented to protet our environment re therefore dvoted. Keywords: hevy metl, ogun estury, Nigeri, ioumultion 1. Introdution Fish umulte toxi hemils suh s hevy metls diretly from wter nd diet, nd ontminnt residues my ultimtely reh onentrtions hundreds or thousnds of times ove those mesured in the wter, sediment nd food (Goodwin et l., 2003; Lonne et l., 2001; Osmn et l., 2007). Hevy metls re norml onstituents of mrine environment tht our s result of pollution, priniplly due to the dishrge of untreted wstes into rivers y mny industries. Bioumultion of hevy metls in tissues of mrine orgnisms hs een identified s n indiret mesure of the undne nd vilility of metls in the mrine environment (Kuuksegin et l., 2006). For this reson, monitoring fish tissue ontmintion serves n importnt funtion s n erly wrning inditor of sediment ontmintion or relted wter qulity prolems (Mnsour & Sidky, 2002; Brk & Mson, 1990) nd enles us to tke pproprite tion to protet puli helth nd the environment. Multiple ftors inluding seson, physil nd hemil properties of wter n ply signifint role in metl umultion in different fish tissues (Hyt et l., 2007; Romeo et l., 1999). Severl studies (Ademoroti, 1996; Cusimno et l., 1986; Heth, 1987; Allen, 1995; Krthikeyn et l., 2007) hve lso indited tht fish re le to umulte nd retin hevy metls from their environment depending upon exposure onentrtion nd durtion s well s slinity, temperture, hrdness nd metolism of the nimls. Adeyeye et l. (1996) lso showed tht the onentrtion of metls ws funtion of fish speies s it umultes more in some fish speies thn others. Fish hve een the most populr hoie s test orgnisms euse they re presumly the est-understood orgnisms in the quti environment (Buikem et l., 1982) nd lso due to their importne to mn s protein soure (Kime et l., 1996). Therefore, this reserh ws to determine the levels of ontmintion nd the ioumultion of Cd, Ni, Cr, Co nd P on some fish speies tht re of ommeril importne (H. forskhlii, H. ee oidentlis nd C. griepinus) in Ogun estury. 51
2. Mterils nd Methods 2.1 Desription of Site The fish were olleted from ommeril fishermen in downstrem Ogun estury situted in Iwopin, Ogun Wterside Lol Government. Its geogrphil oordintes re 6 31' 0" North, 4 10' 0" Est on the mp of Ogun wterside LGA, Ogun Stte, Nigeri. It reeives numer of importnt rivers drining their wters into it nd it orders the forest elt, Omo iospere (Idowu & Ayool, 2008). This estury is n extension of Lekki lgoon whih reeives wter from Ogun River t oordintes 3º25"E nd 6º35"N (Adeisi et l., 1981), nd it is the only re in Ogun Stte with ostline on the Bright of Benin (Oloye et l., 2012). 2.2 Smple Colletion Nine dult fish smples, three eh of H. forskhlii (men weight: 314.2 ± 2.74g nd men length: 33.0 ± 1.15m), H. ee oidentlis (men weight: 463.8 ± 3.76g nd men length: 36.7 ± 0.88m) nd C. griepinus (men weight: 805.0 ± 47.68g nd men length: 39.3 ± 1.45m) were proured from fishermen round the Iwopin, Ogun estury. These fish speies were put in sterile polythene gs nd tken in ieox to the lortory where they were wshed with running tp wter to remove dirt. Fish smples were identified txonomilly using stndrd referene soures (www.fishse.org). All the fish smples were then seprtely stored inside the deep freezer t out -10 0 C nd were llowed to thw; Sles were removed nd wshed with running wter efore disseted with sterile sissors to remove gills, operulum, vertere, hert, musles nd kidney. These were trnsferred into sterile smple ottles, lelled nd kept for digestion nd nlysis of hevy metls. 2.3 Smple Preprtions Prior to digestion smples were seprtely dried in lortory oven t 65 0 C for three dys to otin onstnt dry weight of 0.5g from eh smple. The dried smples were eh ground to powder, using lortory ermi mortr nd pestle, nd sieved with 2mm sieve. 2.4 Digestion of Smple The powdered smples were digested using the proedure desried y Novozmsky et l. (1983) s follows: 0.200g of dry, powdered fish smple ws weighed into 50ml digestion tue nd 2.5ml of Selenium/Sulfuri Aid mixture ws dded to eh tue nd to 5 lnks, used for stndrds. This ws pled in n luminium lok on hotplte, het t pproximtely 200 0 C until the smple fumes. The tues were then removed from the hotpltes nd llowed to ool for 10 minutes. 1ml of 30% H 2 O 2 ws refully dded to the smples nd stndrds. After the retion susided it ws followed with dditionl 2 ml H 2 O 2. Tues were repled on hotpltes nd hevy 15 ml glss vil ws pled on top of eh tue, nd the tues were heted up to 330 0 C. This ws left on the hot pltes until the solutions were ler (usully 2 hours). These smples were llowed to ool nd 0 ml, 0.2 ml, 0.4 ml, 0.6 ml nd 0.8 ml of stok solutions for eh of the hevy metls to e nlysed were dded to the 5 stndrd solutions. The smples nd stndrds were then diluted to the 50 ml mrk. 2.5 Determintion of Hevy Metls Smples were then poured into uto-nlyser ups nd onentrtion of hevy metls (dmium, olt, hromium, nikel nd led) in eh ws determined using Atomi Asorption Spetrophotometer (AAS). The vlues of the hevy metl onentrtions in the tissues were lulted sed on dry weights s this disounted the vriility due to inner prts differenes in the moisture ontent of orgnisms. 2.6 Sttistil Anlysis Results re presented s mens ± SEM, where n equls the numer of fish smples from whih tissues were isolted. Results from ll the speimens were ompred using ANOVA nd P < 0.05 ws onsidered to indite sttistil signifint differene. Mens of signifint differenes were seprted using Dunn s Multiple Rnge Test. 3. Results nd Disussion Cdmium (Cd), Chromium (Cr), Colt (Co), Nikel (Ni) nd Led (P) were nlysed nd the levels of the hevy metls onentrtion were mesured in eh of the fish smples operulum, gills, kidney, hert, musle nd vertere using Atomi Asorption Spetrophotometer. The results of the nlysis re presented in Tle 1 52
nd further illustrted in Figures 1-3. Tle 1. Men onentrtion (ppm) of hevy metls in the tissues of the fish speies in Ogun estury, Ogun Stte, Nigeri. Vlues re presented in mens ± S.E Fish Orgns Cd Ni Cr Co P H. forskhlii Operulum 0.41±0.08 2.74±1.40 0.37±0.20 0.73±0.02 0.07±0.04 Gills Kidney Hert Musle Vertere H. ee oidentlis Operulum Gills Kidney Hert Musle Vertere C. griepinus Operulum Gills Kidney Hert Musle Vertere 0.39±0.08 0.15±0.08 0.26±0.00 0.45±0.23 0.32±0.16 0.25±0.01 0.15±0.08 0.13±0.08 0.13±0.08 0.13±0.08 0.29±0.16 0.41±0.08 0.26±0.15 d 0.28±0.15 3.00±1.44 1.35±0.03 6.33±0.73 5.64±1.85 2.45±0.05 2.47±0.60 2.56±1.44 1.36±0.02 d 1.33±0.05 0.02±0.01 0.79±0.41 5.00±0.00 1.95±0.68 3.66±0.84 4.95±2.15 3.72±0.75 0.68±0.40 d 1.30±0.08 0.02±0.01 0.98±0.17 2.67±0.17 1.76±0.58 1.30±0.70 2.54±0.92 3.43±1.70 2.61±0.15 1.86±0.56 1.73±0.20 1.37±0.66 1.36±0.02 2.44±0.06 1.70±0.60 0.48±0.20 1.17±0.22 0.43±0.23 0.42±0.22 1.66±0.46 1.23±0.67 2.32±0.89 0.37±0.22 1.12±0.24 0.46±0.06 0.06±0.03 0.46±0.23 0.55±0.28 d 1.16±0.20 0.25±0.20 0.03±0.00 0.04±0.02 0.05±0.03 0.02±0.01 0.04±0.02 0.03±0.01 0.02±0.01 0.02±0.01 0.01±0.00 0.01±0.00 0.09±0.01 0.01±0.00 0.03±0.01 0.01±0.00 0.03±0.00 0.02±0.00 WHO (1985)/ FEPA (2003)/ FAO (1983) Limit in fish 0.5-0.6pp 0.15-1.0pp 2.0ppm - 2.0ppm food m m Mens with the sme letters within olumn (ering the sme orgn) re not signifintly different t p < 0.05 Dt on hevy metl onentrtion in the operulum, gill, hert, Kidney, vertere nd musle of H. forskhlii, H. ee oidentlis, nd C. griepinus showed tht hevy metls were umulted in the different orgns s follows: H. forskhlii; Operulum - Co > Cd > Cr > Ni > P, Gills - Ni > Cr > Co > Cd > P, Kidney - Ni > Cr > Co > P > Cd, Hert - Cr > Ni > Cd > P > Co, Musle - Ni > Cr > Co > Cd > P, Vertere - Cr > Cd > Co > P > Ni : H. ee oidentlis; Operulum - Co > Cr > Cd > P > Ni, Gills - Ni > Cr > Co > Cd > P, Kidney - Cr > Ni > P > Cd = Co, Hert - Ni > Co > Cr > Cd > P, Musle - Cr > Co > Cd > P > Ni, Vertere - Co > Cr > Cd > Ni > P : C. griepinus; Operulum - Ni > Cr > Co > Cd > P, Gills - Cr > Ni > Cd > Co > P, Kidney - Ni > Cr > Co > Cd > P, Hert - Ni > Cr > Co > Cd > P, Musle - Cr > Co > Ni > P > Cd, Vertere - Ni > Cr > Co > Cd > P. 53
Figure 1. Distriution of dmium (Cd), nikel (Ni), hromium (Cr), olt (Co) nd led (P) in the operulum, gills, kidney, hert, musle nd vertere of Hydroynus forskhlii from Ogun estury. Vlues re mens ± SE of 3 fish Figure 2. Distriution of dmium(cd), nikel(ni), hromium(cr), olt(co) nd led(p) in the operulum, gills, kidney, hert, musle nd vertere of H. ee oidentlis from Ogun estury. Vlues re mens ± SE of 3 fish Figure 3. Distriution of dmium(cd), nikel(ni), hromium(cr), olt(co) nd led(p) in the operulum, gills, kidney, hert, musle nd vertere of C. griepinus from Ogun estury. Vlues re mens ± SE of 3 fish The distriution of hevy metls in the vrious orgns of the fishes smpled in the Ogun estury is presented in Tle 1 nd further illustrted in Figures 1-3. The onentrtion of dmium vried; in H. forskhlii from 0.00ppm in kidney to 0.45ppm in the vertere, in H. ee oidentlis from 0.00ppm in the kidney to 0.32ppm in the operulum nd in C. griepinus from 0.00ppm in the musle to 0.41ppm in the kidney. Aording to Gosselin et l. (1984), dmium umultes in liver nd kidney, nd more in the kidney thn liver (MCrken, 1987; Venugopl & Lukey, 1978). The dmium onentrtion reported in the kidney nd hert of C. griepinus is in greement with the studies y Ashrf (2005) who reported onentrtion of 0.41ppm in the kidney of Epinephelus mirodon fish from Arin Gulf nd Fromi et l. (2007) who reported onentrtion of 0.69ppm in the kidney nd 0.25ppm in the hert of C. griepinus from Ogun River. Severl studies hve reported higher levels of Cd in different fish smples from some Nigerin rivers. These inlude Odoemeln (2005) who reported 1.50 ppm nd 1.23ppm in Alestes nurse nd Synodontis nigritis respetively from Ogut Lke nd Ishq et l. (2011) reported 0.927ppm nd 0.994ppm in C. griepinus nd T. zillii respetively from River Benue. 54
Okoye (1991) reported onentrtion of 2ppm for dmium nd Oronsye et l. (2010) reported dmium of 0.79-0.98ppm. The levels of Cd (0.00-0.45ppm) reorded in fish smples were lower thn the mximum reommended limits of 2.00ppm (WHO, 1985; FEPA, 2003) in fish food. The onentrtion of nikel vried; in the H. forskhlii from 0.00ppm in the vertere to 6.33ppm in the kidney, in the H. ee oidentlis from 0.00ppm in the musle to 5.00ppm in the gills nd in the C. griepinus from 1.30ppm in the gills to 3.43ppm in the kidney. This is in greement with the findings of Idodo-Umeh (2002) who reported 1.64-3.58ppm from fishes from Olomoro wter odies. However, lower level (0.24 nd 0.36ppm in Mormyops deliiosus nd Mormyrus mrophthlmus) hs een reported y Oronsye et l. (2010) from Ikpo river dm. The result from the present study (0.00-6.33ppm) ws higher ompred with the mximum reommended limits of 0.5-0.6ppm (WHO, 1985; FEPA, 2003) in fish food. The onentrtion of hromium vried; in H. forskhlii from 0.37ppm in the operulum to 5.64ppm in the kidney, in H. ee oidentlis from 0.68ppm in the hert to 4.95ppm in the kidney nd in C. griepinus from 1.36ppm in the musle to 2.67ppm in the operulum. Chromium level of 0.40-5.61ppm ws reported from n investigtion on Prhnn osur from Og River in Benin City y Osohn (2007) nd 29.8-31.6ppm from T. zillii nd 28.1-32.2ppm from C. griepinus from River Benue (Ishq et l., 2011). Also Nwni et l., (2010) reported 1.19ppm in Chyrsihthys nigrodigittus from loti freshwter eosystem t Afikpo nd Odoemeln (2005) reported 1.86ppm in A. nurse from Ogut Lke. The results in this investigtion were lower thn 29.8-31.6ppm in T. zillii nd 28.1-32.2ppm in C. griepinus from River Benue (Ishq et l., 2011). The levels of Cr (0.37-5.64ppm) reorded in fish smples were higher thn the mximum reommended limits of 0.15-1.0ppm (WHO, 1985; FEPA, 2003; FAO, (1983) in fish food. The onentrtion of olt vried; in H. forskhlii from 0.00ppm in the hert to 1.17ppm in the kidney, in H. ee oidentlis from 0.00ppm in the kidney to 2.32ppm in the hert, nd in C. griepinus from 0.00ppm in the musle to 1.16ppm in the vertere. However, the level reported in this study ws in greement with the findings of Erlgere nd Bhdrvthi (2008) where 0.039-1.44ppm were reported in Oreohromis mossmius from Jnnpur Lke in Indi. The distriution of olt in H. forskhlii showed tht the kidney hs out 36% (Figure 1) whih suggests tht the route of exposure of the fish to olt ould e through wter (Coughtrey & Thorne, 1983). This is different with other fish speies suggesting tht the route of uptke of the metl ould e through food. Furthermore, the result showed tht the ottom feeding fish (H. ee oidentlis) hs higher level of olt umultion. This n e s result of the higher exposure of ottom feeding fish due to the high olmine onentrtion in the sediments nd feeding hits. Surfe wter fish in the study (H. forskhlii & C. griepinus) hve higher level of Cd ompred to the demersl fish speies. This ould e ttriuted to the ft tht the ottom sediment onentrtion of dmium is less ville euse of ontinuous relese of eletrons to the environment through miroorgnism respirtion proesses (Kersten & Forstner, 1987), thus mking the exposure to e higher for the pelgi speies. The onentrtion of led vried; in H. forskhlii from 0.02ppm in the vertere to 0.25ppm in the gills, in H. ee oidentlis from 0.01ppm in the musle nd vertere to 0.04ppm in the operulum nd in C. griepinus from 0.01ppm in the gills nd hert to 0.10ppm in the operulum. This result ws lower ompred to the findings 0.395-0.62ppm of Doherty et l. (2010) nd 9ppm Okoye (1991) of led in some fishes from Lgos lgoon. Fromi et l. (2007) lso reported 0.73-4.12ppm in C. griepinus from Ogun River, Osohn et l. (2006) reported 0.10-0.83ppm in some fishes from Og river nd Oronsye et l. (2010) lso gve 3.53ppm nd 2.67ppm in Mormyrops deliisus nd Mormyrus mrophthlmus from Ikpo river dm. The vlues otined for led in this study is in line with tht of Dk et l. (2008) who otined 0.01-0.06ppm in fish speies from Azuie reek in the Bonny estury, Nigeri. Some results reveled high umultion of hevy metls, for exmple, Doherty et l. (2010) reported 0.44ppm nd 0.62ppm of led in C. nigrodigittus nd T. guineensis respetively. The levels of P (0.01-0.25ppm) reorded in fish smples under this investigtion were lower thn the mximum reommended limits of 2.0ppm (WHO, 1985; FEPA, 2003; FAO, 1983) in fish food. The umultion of the metls (Cd, Ni, Cr, Co nd P) ws higher in the gills thn musle of H. forskhlii nd H. ee oidentlis. This is in line with the previous studies of Nwni et l. (2010) nd Edem et l. (2009). This umultion ws, however, signifintly higher (P<0.05) only in H. ee oidentlis. Gill tissues ply n importnt role in interfe with the environment in performing its funtions in gs exhnge, ion regultion, id lne nd wste exretion while musle, on the other hnd, is not n tive tissue in ioumultion (Bj et l., 2005; Filzi et l., 2003; Shukl et l., 2007). It ws noted from this study tht umultion of ll the metls smpled in the kidney of H. forskhlii ws not signifintly higher (P>0.05) thn tht of H. ee oidentlis nd C. griepinus. Also umultion of these 55
metls in the kidney of H. forskhlii ws signifintly higher (P<0.05) thn musle nd vertere ut not signifintly higher in other orgns. The kidney of H. ee oidentlis hd the highest umultion of totl metls.the onentrtions were signifintly higher (P<0.05) thn those in operulum, musle or vertere though not signifintly higher thn the umultions in the gills nd hert. C. griepinus hd the highest umultion of the totl metls in kidney followed y operulum, gills, hert, musle nd vertere ut the differene ws not signifint (P>0.05). In ddition, kidney plyed mjor role in the umultion of the hevy metls y H. forskhlii nd C. griepinus. In the present study, it ws oserved tht the totl onentrtion of nikel in ll the orgns studied ws signifintly higher when ompred with tht of dmium (P < 0.05) ut not signifintly higher thn tht of hromium. Chromium ws signifintly higher thn olt, nd olt ws signifintly higher thn led in totl hevy metls umultion in ll the fish speies smpled under this investigtion. It n e dedued from the ove tht umultion of the hevy metls is more of speies-relted. In ddition to this, it ws noted tht there ws no reltionship etween the umultion ptterns of different metls in the different fishes. Thus, the differenes notied in the levels of umultion in different orgns of fish n e ttriuted to the differenes in their physiologil roles towrd mintining homeostsis, feeding hits, regultory ility nd ehviour of eh fish. This is in ordne with the findings of Cross et l. (1973). However, mjorly musle hd the lest onentrtion of the hevy metls ompred with gills in the fish speies smpled. This is in greement with previous study y Ishq et l. (2011) whih showed tht musle is not n tive orgn in the umultion of hevy metls. Gills, on the other hnd, hs een reported s metolilly tive site nd n umulte hevy metls in higher level. This is evidened y the position tht the gills oupied in the umultion pttern for the hevy metls. The presene of metl inding protein, metlotheonin, hs fvoured the umultion of hevy metls in the kidney s it ws shown to hve the higher level of some of the hevy metls nlysed in this investigtion in the fish speies. Low onentrtion of dmium hs een reported in previous studies (Olif et l., 2004), s oserved in H. ee oidentlis nd H. forskhlii, nd this hs een suggested to e due to low tendeny of dmium towrds the ville tive sites (N nd/or O donor toms) in kidney tissues (Kppus, 1987). In generl, umultion of the hevy metls (totl men) nlysed in the smpled fishes ws of the following trend: H. forskhlii > H. ee oidentlis > C. griepinus nd the pttern of distriution ws Ni > Cr > Co > Cd > P for ll the fish speies. This showed tht the umultion of the hevy metls ws speies-relted s H. forskhlii is predtory nd rnivorous whih might hve fvoured its higher tendeny for metl ioumultion thn others. Also, C. griepinus is generlly omnivorous, hd the lest metls umultion regrdless of its hitt. Therefore, metl umultion ould e relted to fish feeding hits. This onfirms the report of Wiener nd Giesy (1979) s well s Cross et l. (1973). Severl endemi fish speies hve eome thretened (Nwni et l., 2010) leding to the depletion of our fish resoures nd sustntil redution in their nutritive vlues (Srivstv nd Srivstv, 2008). Chemil nlysis of fish, therefore, ensures dietry sfety of the fish from prtiulr ody of wter (NOAA, 1988; Roux et l., 1999). Also in study (Jji et. l., 2007) on the qulity of Ogun River, led nd dmium onentrtions were found to e ove the WHO limit. 4. Conlusion In view of the importne of fish to diet of mn, it is neessry tht iologil monitoring of the wter nd fish ment for onsumption should e done regulrly to ensure ontinuous sfety of the sefood. Sfe disposl of domesti sewge nd industril effluents should e prtied nd where possile, reyled to void these metls nd other ontminnts from going into the environment. Lws ented to protet our environment should e enfored. The tivities t the upper-ourse of the Ogun estury should e kept under strit surveillne s they re ple of inresing the hevy metls dishrge into the river, espeilly s popultion is ound to inrese. The vlues reported in this study ould serve s seline dt to monitor future nthropogeni tivities long the ost, now tht Liquefied Nturl Gs Terminl nd oil refineries re to e loted in the re. The study showed need for ontinuous pollution ssessment study of quti orgnisms in Nigeri. Referenes Adeisi, A. A. (1981). The physio-hemil hydrology of tropil sesonl river-upper Ogun River. Hydroiologi, 79, 157-165. http://dx.doi.org/10.1007/bf00006123 Ademoroti, C. M. A. (1996). Environmentl Chemistry nd Toxiology (pp.171-204). Idn, Foludex Press Ltd.. Adeyeye, E. I., Akinyugh, R. J., Feosi, M. E., & Tene, V. O. (1996). Determintion of some metls in 56
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