Proximate Composition and Determination of Heavy Metal Concentration from Water and in Common Fish Species of Lake Tana
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Date
2014-11
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Addis Ababa University
Abstract
Three main fish species cammanly utilized by cammercial gil/net fishery fi'am Lake Tana are
Labeabarbus species, C.gariepinus and 0. nilaticus. As fish canstitute an important part a/
human diet, it is imperative to. examine the quality and sqrety aspects a/ fish that are a/
particular interest. Fish bady campasitian is affected by exagenaus and endogenaus /actars. A
wide range a/ heavy metals are cantinuausly intraduced in to. the aquatiC environment mainly
due to. anthrapagenic pallutian and hence accumulated in fish tissue. As matter a/ qforementianed/
acts, this study was aimed to. investigate the praximate campasitian a/ often used fish
;pecies, and determined heavy metal (Cr, Cd and Pd) cancentratian a/ the common fish species
and habituated water a/ Lake Tana. Six sites were systematically selected fi'am Lake Tana. The
selectians a/ the sampling sites were based an their proximity to. expected IInthropugenic
emissian saurces. A tatal 0./72 fish specimens were callected alang with six samples (replicated
three time per site) water a/ Lake Tana in FebruCIIY 2014. At the spat aJ sample callectioll,
measurments Jar temperature, pH, electrical candactivity, and tatal dissalved sal ids. Bath jish
and water samples were transparted to. Faad Science and Nutritian labaratary under caal and
aseptic canditians using ice bax. Samples were dried at 60 °C jor 72 hI'S, pulverized in a martaI',
and stored in palyethylene bag until analysis for proximate compasitian and heavy /IIetal
concentratian. Analyses were made based main ~frects: lacatian, sex and ;p ecies. Praxill1i11e
campasitian was determined Jallawing the pracedure a/ AOAC while heavy metals were \IIet
digested and estimated using GFAAS. Data were analyzed using/actarial treatment arrangell1ent
a/ ANOVA. There was significant variatian between sex, lacatian and species with regard to
nutritianal value. Generally, Jemale fish had higher nutritianal value as cal7lpared to their
caunter male. Praximate campasitian significantly varied between different sampling lacations.
0. nilaticus had significantly highest levels aJpratein (18.82%) campared to. bath C. gariepililis
(1 5.2%) and L.intermedius (15.44%) fish species. Hawever, L.intermedius had signijical1flv
highest Jat cantent (2.36%) and grass energy (83.1 Kcal11 00g) relative to. bath L. intermedius and
C. gariepinus. Likewise there was significant variatian an heavy metal accumulatian be/llieen
different sampling lacatian andfish species. The trend aJheavy metals accumulation were in the
order aJ magnitude aJ Cr > Cd> Pd in all sampling lacatian and fish species. The heavy melal
cancentratian and physicachemical variables aJ Lake Tana were within the range 0/ the
recammended limit aJ WHO (2008). Anthrapogenic pol/utian 0/ the lake seems to. pase no. II/reot
oj heavy metal accumulatian regarding the studiedjish species. The heavy metal cantent af /he
studied fish species remained in line 'with /aad safety and quality regulation 0/ WHO (1993)
guidline Jar cansumptian. Hence, it was cancluded that the cansumptian aJ L. intermedius, C.
gariepinus, 0. nilaticus ji-am lake Tana are gaad saurces a/protein and ather nutrients and 1/10P
nat lead to. health hazards induced by heavy metals.
Key words: LakeTana. L.inlermedius, C. gariepinus, 0. nilaticlls · Proximate composition·
Heavy metals· Physico-chemical· Bioaccllmlliatioll. Food safety
Description
Keywords
LakeTana, L.inlermedius, C., gariepinus, 0, nilaticlls, Proximate composition, Heavy metals, Physico-chemica, Bioaccllmlliatioll, Food safety