Abdellah Meknachi

Catalase (CAT) is an important enzyme in the antioxidant defense system in marine bivalves. This present work consists first of all in studying the effect, of an acute exposure (bioassays) of the mussels Mytilus galloprovincialis to three types of real effluents [industrial wastewater (IW), desalination station effluent (DSE) and harbor effluents (HE)], on the enzymatic activities CAT. In situ, the transplantation of mussels into natural environments was carried out in the same context. The medium size class of the Mytilus mussel has proven to be the most resistant to contamination by the IW. Notwithstanding, this same size class showed hypersensitivity to contamination by the SDE, thus translating the high toxicity of the latter which led to very high CAT inductions whatever the concentration tested. Furthermore, under controlled laboratory conditions, the HE demonstrated a certain toxicity by inducing the CAT enzyme. On the other hand, the Mytilus mussels transplanted to the khemesti port site are found all dead after ten days of immersion. The deoxygenation of the medium probably had an additional and aggressive effect on our specimens of mussels. This study makes it possible to qualify catalase as a relevant, sensitive, rapid and effective defense biomarker in the evaluation of the health state of the surrounding environment. However, more studies must be made on metabolic activities and energy reserves while adopting the multibiomarker approach.

Physiological response (nitrogen and phosphorus excretion) of the brown mussel (Perna perna) exposed to four sublethal concentrations of cadmium (Cd) and lead (Pb) (50, 100, 150 and 200 µgL -1 ) and three sublethal concentrations of Cu (5, 10 and 15µg.L -1 ), were monitored for 72 hours. The results show a positive correlation between metal exposure and excretory products. Moreover, when compared to the control group, cadmium, lead and copper presented a significant (p < 0.01) alteration of pattern of ammonia-N, nitrate, nitrite and phosphate excretion after 24, 48 and 72 hours. This result suggests that metabolites were affected by heavy metal exposure.

A 62-d trial was conducted to evaluate the effects of different C/N ratios on water quality, growth performance, digestives activity, and antioxidant indicators of tilapia fingerlings in BFT systems. Three biofloc treatments (added molasses) with a C/N ratio of 14 (BFT14), 17 (BFT17), and 20 (BFT20) were tested against control in clear-water, each treatment in triplicate. Four hundred twenty tilapias (24.2±0.1 g) were distributed on 12 tanks of 350 L. The dynamics of water quality parameters showed a shift from a predominantly autotrophic to a predominantly heterotrophic biofloc with an increase in the C/N ratio from 14 to 20. The growth and Feed conversion of tilapia were not significantly different between the control, BFT14, and BFT17 groups. A low weight gain and high FCR were found in the BFT20 treatment (0.61±0.07 and 1.11±0.12 g/d) compared to the control (0.84±0.05 and 1±0.07 g/d). Activities of proteases and alpha-amylase in the liver and digestive tract were similar in all...

An active biomonitoring study was carried out on the bay of Bou-Ismail (Algeria) using mussels (Perna perna) that sampled from the Boumerdes (BM) site and transplanted in net cages during 21 days (between Mars and Aprile 2012) to Bouharoun Harbour (BH) and Khemisti Harbour (KH). After exposure, the cages of mussels were transferred to Mediterranean Aquaculture Elevage (MAE) in Aïn Tagourait (Tipaza) as decontamination cycle (15 days). In parallel, other mussels were transplanted in MAE site, as control animals in all period of contamination/decontamination of mussels transplanted in two harbours. Compared to the MAE control specimens, BH and KH caged mussels presented a significant (p < 0.05) increase of catalase induction (38.43 ± 6.29 U.mg prot-1 , 61.42 ± 10.62 U.mg prot-1 , 72.66 ± 33.86 U.mg prot-1 respectively). In addition, the results of the fecal indicators (total coliforms (TC), fecal coliforms (FC), and Escherichia coli (Ec)), and heavy metals (cadmium and copper), wer...

Brown mussels (Perna perna) were exposed to cadmium (Cd), lead (Pb), and copper (Cu) concentrations under acute exposure and exposure-depuration tests for the estimation of biochemical biomarker catalase (CAT). The acute tests showed accumulated Cd, Pb, and Cu inPerna pernacorrelated linearly with the exposure concentrations (R2=0.794,R2=0.891, andR2=0.985for Cd, Pb, and Cu, resp.). The results of CAT increased significantly in tissues of treatment mussels after 72 h exposure when compared to control. The values of total protein were disturbed in exposed groups when compared with control. These results suggest that metabolites and catalase activity were affected by heavy metal exposures. Analysis using the Spearman rank correlation coefficient showed that the CAT activity appeared to have a significant positive correlativity (Rs=0.921,Rs=0.949, andRs=0.949for Cd, Pb, and Cu, resp.) with the accumulated Cd, Pb, and Cu concentrations, respectively. The result of exposure-depuration te...