| A long-term survey of two mussel populations from two natural mussel beds, Bordj El Kiffan and Boudouaou, was carried out from the end of 1984 to the beginning of 1991. Samples had been also collected from 1978-1979 then from 1992-1993, but only from the first of these. Maximal densities were higher than 10,000 ind. m(-2), due to the spring and summer heavy spatfall. At Bordj El Kiffan, densities of M. galloprovincialis were 50 times more important than those of P. perna. At Boudouaou, the abundance of P. perna was 1.7 times higher than that of M. galloprovincialis. From 1986 to 1988, the mean annual biomass in dry weight of tissue including ash was higher for P. perna at Boudouaou (0.886 kg. m(-2)) than at Bordj El Kiffan (0.486 kg. m(-2)). For M.... |
