Biomarker Approach of Freshwater Mussels Nitia teretiuscula and Spathopsis rubens (Bivalvia: Unionidae, Mutelidae) as Invertebrate Bioindicators in Monitoring Aquatic Environmental Quality

Bivalves are abundant in many types of freshwater environments and are relatively easy to collect and identify also they have been used frequently as bioindicator organisms. At metal concentrations that are within ranges common to natural waters, mussel species are generally effective bioaccumulators. Pollution of water and sediment of River Nile is a threat on survival and existence of bivalves. Concentrations of six heavy metals were analyzed in the soft parts (foot, mantle, gills and digestive tissue) of the investigated mussel species Nitia teretiuscula Philippi, 1818 and Spathopsis rubens Lamarck, 1819, as well as the Nile water and sediment samples collected from Tura (Helwan Governerate) and El-Kanater (Qalyuobia Governerate). Fe and Mn showed the highest level of metals accumulated in different soft parts of both species (g/Kg/ dry wt) collected from two localities and were ranged between 303.26-669.45, 424.8-788.7 for Fe and 156.5-592.4, 115.4-649 for Mn in soft parts of N. teretiuscula and S. rubens, respectively, collected from Tura region and 144.49-481.6, 152.47-911.69 for Fe and 263-475.3, 306-628.9 for Mn in soft parts of N. teretiuscula and S. rubens, respectively, collected from El-Kanater region. Other metals analyzed are fluctuated in their levels of accumulation. However, all metals measured in the collected tissues exceeded the permissible levels. Also, bioconcentration factor (BCF) and transfer factor (TF) were calculated. The highest BCF observed for Mn and the lowest recorded for Co measured in the digestive tissue of N. teretiuscula collected from Tura region (13381.5 g/Kg/dry wt), (4.2 g/Kg/dry wt), respectively. In addition, the TF of the sediments to tissues (g/Kg/dry wt) was greater than that of water (mg/ L) to tissues 0.2-5.7, 0.0001-0.2 in Tura and 0.2-3.4, 0.0001-0.08 in El-Kanater regions, respectively.