Abstract
The omnivorous fish species, C. nigrodigitatus feeds mainly on benthic organisms and may therefore consume contaminated food throughout its food web. This can lead to the bioaccumulation of contaminants such as trace elements in their tissues. However, fish consumption is a major pathway of human exposure to contaminants which may cause public health problems. The aim of the present study is to assess trace elements contamination in some species from the food web of C. nigrodigitatus. For this, 10 main food items of the silver catfish were collected at two sites from February to July 2017 and analyzed using an Atomic Absorption Spectrometer coupled with a hydride and cold vapour generator. The concentrations of trace elements varied greatly from one species to another and within each species. These values ranged from 0.007 mg/kg for Hg in C hippos to 354.84 mg/kg for Mn in P. fusca. The most contaminated species by trace elements were benthic organisms: M. perna (Cd, Pb, Hg), Pagurus sp. (Cr, Ni, Cu, Zn), G. paradoxa (As) and P. fusca (Mn). The average concentrations of trace elements found in species were, for the most part, above WHO standards except Hg in M. perna and G. paradoxa. The water-based bioconcentration factors (BCFw) reach 92.58 for Cd, 44.72 for Pb, 382.49 for Hg and 1514.34 for As in M. perna. It is therefore necessary to pay particular attention to this ecosystem and to put in place a better management plan.
Highlights
Most parts of terrestrial and aquatic ecosystems are affected in one way or another by anthropogenic activities such as the rapid industrialization and demographic pressure during the last decades which lead to continental and aquatic ecosystems contamination by trace elements
The average concentrations of trace elements found in species were, for the most part, above WHO standards except Hg in M. perna and G. paradoxa
As for Cu contents, they vary from 0.25 mg/kg in T. zillii to 78.25 mg/kg obtained in F. notialis
Summary
Most parts of terrestrial and aquatic ecosystems are affected in one way or another by anthropogenic activities such as the rapid industrialization and demographic pressure during the last decades which lead to continental and aquatic ecosystems contamination by trace elements. In aquatic environments, significant amounts of trace elements are introduced by industries, mining, fossil fuel combustion, run-off from agricultural lands, house hold sewages, atmospheric deposition and rocks weathering. These metals pose high environmental risks due to their longtime persistence in nature and possible bioaccumulation and biomagnification [1]-[6]. These inputs have greatly altered the biogeochemical cycles of trace metals and enhanced their bioavailability [7] It follows permanent disturbances in aquatic ecosystems leading to environmental and ecological degradation and which constitute a potential risk to a number of flora and fauna species, including human through food web [8] [9]. Trace element contamination of these ecosystems includes that of the fish food web species presenting a serious public health issue because these fish are consumed by humans
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