ABSTRACT
Sequential alterations of body weights as well as total lipids, triglycerides, cholesterol and ketone body levels in the blood of Protopterus annectens during twelve month duration of aestivation were investigated. The results revealed that after the first trimester of dormancy, there was significant body weight reduction (p<0.05) coupled with significant hypolipodaemia, hypotriacylgly-cerolaemia and hypocholesterolaemia respectively (p<0.05) but without significant ketonaemia (p<0.05). The total lipid, triglyceride, cholesterol and body weight reductions continued through the second, third and fourth trimesters of aestivation respectively (p<0.05) but with serum ketone body levels remaining unaltered (p<0.05). Thus, the utilization of lipids as a source of energy during aestivation of P. annectens does not lead to ketone body accumulation.
ABSTRACT
A study was conducted between March 2006 and February 2007 to assess the concentration of Fe, Zn, Cu, Mn, Pb, and Cr in the gills and muscles of six fish species (Chrysichthys nigrodigitatus, Clarias anguillaris, Tillapia zillii, Mormyrus rume rume, Mormyrus macrophthalmus and Mormyrus tapirus) from lotic freshwater ecosystem at Afikpo South- East Nigeria using Atomic Absorption Spectrophotometer. In all the fish species studied the concentration of metals in the gills was significantly higher than that of the muscles (p<0.05). While the highest concentration (mg l-1) of Fe (702.20±0.04), Zn (34.40±0.02), Cu (2.10±0.01), Mn (4.91±0.08) Pb (0.50±0.02) and Cr (1.12±0.07) were recorded in the gills of C. nigrodigitatus, that in the muscles were recorded in T. zillii (443.20±0.08, 23.30±0.06, 1.33±0.06, 3.09±0.02, 0.31±0.01 and 0.66±0.04 for Fe, Zn, Cu, Mn, Pb and Cr respectively). The lowest concentration of all the heavy metals in the gills was recorded in M. tapirus (309.00±0.07, 16.45±0.03, 0.92±0.04, 2.15±0.04, 0.21±0.01 and 0.50±0.06 mg l-1 for Fe, Zn, Cu Mn, Pb and Cr respectively) while the lowest in the muscles was recorded in C. anguillaris [Fe (186.00±0.07), Zn (14.20±0.08), Cu (0.56±0.03), Mn (1.30±0.02), Pb (0.10±0.01) and Cr (0.28±0.04)]. The order of heavy metals concentrations in both the gills and muscles was Fe>Zn>Mn>Cu>Cr>Pb. While the concentration of Zn, Cu and Pb both in the muscles and gills of all the six fish species studied were within the WHO and FEPA prescribed limits, that of Fe(except in the muscles), Mn and Cr were above the prescribed limits thus indicating contamination of the fish species by these metals. Fe has the highest bio-concentration factor (BCF) in both tissues while the least was Cu. Periodic monitoring of these metals in both fishes and river to ensure safety is advocated.