Haematological and serum enzymes biomarkers of heavy metals in <i>Chrysichthys Nigrodigitatus</i> and <i>Cynoglossus senegalensis</i>

Abstract

Heavy metals are constituents of marine environment that occur as a result of pollution principally due to the  discharge of untreated wastes into water bodies by many industries. Haematological, serum enzymes activity and heavy metal concentrations in feral populations of Chrysichthys nigrodigitatus (Lacepede:1803) and Cynoglossus  senegalensis (Kaup: 1858) from Ebute-Oba section of the Lagos Lagoon, were evaluated from July-September,  2012 in order to determine and establish the relationship between heavy metal levels, serum enzymes activity and haematological parameters in Chrysichthys nigrodigitatus and Cynoglossus senegalensis. Levels of metals in C.  nigrodigitatus and C. senegalensis in mg/l were as follows: (Cr: 0.07 ± 0.001, Cu: 0.027 ± 0.01, Fe: 0.481 ± 0.214, Pb: 0.001 ± 0.001, Zn: 0.316 ± 0.575) and (Cr: 0.010 ± 0.07, Cu: 0.029 ± 0.01, Fe: 0.467 ± 0.217, Pb: 0.021 ± 0.044, Zn: 0.433 ± 0.499) respectively. Serum alanine aminotransferase (ALT), Aspartate  aminotransferase (AST) and Alkalinephosphase (ALP) activities in C. nigrodigitatus and C. senegalensis measured in IU/l were  64.995±44.123, 16.345±166,157.787±34.88 and 73.758±48.768, 29.532±20.100, 45.707±285 respectively. ALP activity between the two species showed a significance difference (P<0.05). Haematological parameters recorded for
C. nigrodigitatus were Hb with 13.325 ± 8.293g/dl, PCV (25.53±11.79%), RBC (2.95±0.73.106mm3),  WBC(124.19±56.41x104mm3), MCHC(32.46±2.18g/l), Neutrophils (41.00±27.91%) and Lymphocyte (64.33±31.94%). While values for C. senegalensis were: Hb (11.33±8.04 g/dl), PCV (34.00±22.83%), RBC (2.70±1.98x106mm3), WBC  (275.20±167.27 104mm-3), MCV (178.94±126fl), MCH (59.63±44.50 Pg), MCHC (33.33±33.28g/l), Neutrophils (39.00±30.33%) and Lymphocytes (80.00±71.77%). Accumulation of heavy metals in both fish species leads to an increased ALT, AST and decreased ALP activities. Conversely, accumulation resulted in reducing Haemoglobin and an increased Red Blood Cells and Lymphocyte counts. Haematological and serum  enzymes activities are predilective biomarkers for the detection and monitoring of aquatic ecosystems pollution. The inclusion of Allium sativum at 1.5g/kg is therefore recommended in the diet of C. gariepinus, for this will boost their growth performance and enhance disease resistance..

Keywords: Biomarkers, Haematological, Serum Enzymes, Heavy Metals, Fish