Dynamics of Zooplankton of Azuabie Creek in the Upper Bonny Estuary of the Niger Delta

Abstract: The dynamics of zooplankton community of Azuabie Creek in the Upper Bonny Estuary of the Niger Delta was studied over a one-year period from April 2006 to March 2007. Ten sites which included locations with sources of human and industrial pollutant inputs and relatively uncontaminated control points along the creek were chosen for the study. Water and plankton samples were collected monthly from each station using standard methods, followed by laboratory analyses. A total of 35 species of zooplankton belonging to eight major taxonomical groups were recorded during the study periods. Out of the total number, 20 species representing 57.14% belonged to the class copepoda; 2 species (5.71%) represented the class euphausiaceae; 1 species (2.86%) represented class spionidae; 2 species (5.71%) belonged to the class protozoa; 4 species (11.43%) belonged to the class cladocera; 3 species (8.57%) belonged to the class insecta, 2 species (5.71%) belonged to cumaceane while 1 species (2.86%) represented the class nematoda. In terms of abundance, the highest number of occurrence found was the class copepoda (88.95%), followed by cumacean (2.76%); cladocera (2.35%), protozoa (1.99%), spionidae (1.63%), insecta (1.28%); nematoda (0.76%) and euphausiid (0.26%). There were significant spatial and monthly (seasonal) differences (p<0.001), as well as interactions in the abundance of major zooplankton taxa. Community indices had significant differences between sampling locations and months, with the wet season months generally having higher species richness, diversity and evenness but lower dominance

Effect of Diazinon on Acid and Alkaline Phosphatase Activities in Plasma and Organs of Clarias gariepinus

Abstract: The aim of this study was to determine the effect of the pesticide, diazinon, on phosphatases in the plasma and organs on Clarias gariepinus. Adult Clarias gariepinus were exposed in four replicates to varying sublethal concentrations diazinon (ranging from 1.00 to 10.0 mg/L) in 30-day semi-static bioassays. Alkaline phoshatase (ALP) and acid phosphate (ACP) were determined in plasma and other organs (gastrointestinal tract -GIT, kidney, muscle, gill and liver) of the fish after the experimental exposures. Dizinon did not cause any statistically significant difference on plasma ALP over the concentrations tested (p>0.05), but ACP showed significantly higher mean value at 10 mg/L compared to the control. ALP and ACP values in all the organs (GIT, intestinal tract, kidney, muscle, gill, liver) decreased with increasing concentration of diazion. This indicates an evidence of inhibition of these enzymes in the organs by the toxicant, and therefore alteration of biochemical processes in C. gariepinus which can be used as bio-indicators of the effects of diazinon in the Niger Delta environment

Spatial and Temporal Variation of Physico-Chemical Parameters of Sediment from Azuabie Creek of the Upper Bonny Estuary, Niger Delta

Abstract: The impacts of human and industrial activities on the physico-chemical quality of sediment of Azuabie Creek in the upper Bonny Estuary of the Niger Delta, Nigeria were studied. Major waste inputs into the creek include run-off from surrounding lands, animal wastes from a major abattoir, human/domestic waste from a high density settlements along the creek and industrial effluents from Trans-Amadi industrial area, hosting a number of manufacturing and oil servicing companies. Sediment samples were collected from ten sampling stations, seven (st. 1, 2, 6, 7, 8, 9 and 10) along the main creek and three (st. 3, 4 and 5) along a creeklet that empties into the main creek. These stations were selected to reflect various points of domestic and industrial waste inputs along the creek. Particle size distribution indicated sediments were generally sandy-mud in nature with higher proportions of clay. Seasonal and spatial variations were observed in mean pH values of sediments while the oxidation-reduction potential of the sediment varied remarkably. TOC in the study area were generally above 1% across all stations during the study while mean values of THC, ranged from 210±0.01 to 10750±0.71.3 mg/kg. NO 3 and PO 4 also varied significantly (p≤0.001). It is concluded that physicochemical variables of sediment from Azuabie Creek are influenced by pollution sources and these would affect the benthic community in the estuarine creek

Tolerance to heavy metals in Littorina saxatilis from a metal contaminated estuary in the Isle of Man

Population differences were measured in the tolerance of Littorina saxatilis from sites around the Isle of Man, to acute exposure to zinc, lead, copper and cadmium. Animals from a site influenced by disused mine run-off in Laxey estuary (high zinc) were compared with animals from less contaminated estuaries (Peel-high lead, but lower zinc), and the relatively uncontaminated Castletown and Ramsey estuaries, plus the open coast near Derbyhaven. Median lethal times (LT50) were estimated for each test concentration (5, 10, 20 mg l?1 Zn; 5, 10 mg l?1 Pb; 0·5, 1·0, 2·0 mg l?1 Cu and Cd) except for those that did not produce sufficient mortalities. Individuals from Laxey estuary showed significantly higher tolerances to zinc (10 mg l?1) and lead (5 mg l?1) than animals from the unpolluted sites. No co-tolerance to copper or cadmium was apparent. Population tolerance to zinc was correlated with reduced accumulation rates. Lead tolerance may result from the ability of the tolerant individuals to sequester the metal and detoxify it in their tissues; the littorinids from Laxey had significantly higher rates of lead accumulation

Reproductive effects of heavy metals on the rough periwinkle <i style="">Littorina saxatilis </i>(Mollusca: Prosobranchia)

218-224The effects of chronic mine-related heavy metal contamination on reproduction of Littorina saxatilis from sites around the Isle of Man were assessed. Size at birth of young, reproductive output (i.e. number of embryos in brood pouch) and frequencies of abnormal embryos in the brood pouch were examined in animals from five sites. Laxey estuary was the most contaminated compared to other sites with less contamination (Peel) and relatively uncontaminated control sites (Castletown, Ramsey estuaries and the open coast near Derbyhaven). The size at birth of young ranged from 0.365-0.876 mm and the lowest mean size at birth (0.517 + 0.048 mm) was found in the animals from Laxey estuary. Those from Derbyhaven had the highest mean size at birth (0.632 + 0.063 mm). ANOVA showed a significant difference in mean size at birth of young, between individuals from the five sites (p<0.0001). However, the individuals from Laxey also had the highest absolute mean count of embryos in their brood pouch implying that there might be some trade-off between reproductive output and size of young as a result of metal contamination. No heavy metal related differences in embryo abnormality were apparent. Rather, a high proportion of abnormal embryos in animals from Derbyhaven suggested that disease conditions, genetic factors or unidentified toxins might account for the differences observed

Interactive Effects of Copper, Cadmium and Lead on Zinc Accumulation in the Gastropod Mollusc Littorina Saxatilis

The effects of copper, cadmium and lead on the bioaccumulation of zinc were studied in populations of the gastropod mollusc Littorina saxatilis from sites in the Isle of Man subjected to varying degrees of mine-related metal contamination. Exposures to 2 mg/L Zn alone and in combinations with 0.01 mg/L, 0.1 mg/L and 1 mg/L of the respective metals were conducted at ?10 ?C in semi-static assays. Copper had a significant antagonistic effect on Zn accumulation at 1 mg/L Cu, but was not antagonistic at 0.01 and 0.1 mg/L Cu. Prior exposure to metals in the field did not appear to affect the interactive effect of copper as all populations showed similar patterns. Combinations of Zn with Cd or Pb at the above concentrations did not show any significant effects on Zn accumulation. On the other hand, Zn had an antagonistic effect on Cd and Pb accumulation but showed inconsistent effects on Cu accumulation. Interactions of Cu and Zn in particular may have repercussions for interpretation of biomonitoring data in L. saxatilis

Heavy metal contamination in sediment and biomonitors from sites around the Isle of Man

The Isle of Man has a long history of mining (Lamplugh, 1903; Garrod et al., 1972) leading to localized heavy metal pollution from abandoned mines. These provide a convenient system for a variety of studies in which closely adjacent contaminated and uncontaminated catchments and estuaries can be compared. This study was a precursor to a detailed examination of tolerance to metal exposure in Littorina saxatilis from contaminated and uncontaminated areas. It was necessary first to characterize the various sites, which also enabled comparisons with previous studies (Southgate et al., 1983) to show if contamination has reduced with time since the closure of the mines (last worked in the 1930s). Both sediments and bioindicators or biomonitors (Mytilus edulis and Fucus serratus) were analysed (see Luoma, 1983; Bryan, G.W., Langston, W.J., Hummerstone, L.G. and Burt, G.R., 1985. A guide to the assessment of heavy metal contamination in estuaries using biological indicators. Occasional Publication of the Marine Biological Association of the United Kingdom 4, p. 91.Bryan et al., 1985; Bryan and Langston, 1992; Phillips and Rainbow, 1993 for discussions of this approach) as they provide distinct measures of time-integrated levels of contamination and bioavailability. The study emphasised estuaries and included a broad coverage of the whole island (cf. Gibb et al., 1996). Five sites were characterized for heavy metals: four estuaries (Castletown, Laxey, Peel and Ramsey) and a coastal site at the Castletown Bay end of Langness near Derbyhaven (see Fig. 1). Laxey and Peel Estuaries drain historical mining regions in the Isle of Man (see Southgate et al., 1983) and the other three were considered relatively uncontaminated control sites