Table 1.

Environmental variables monitored in the field for determination of possible impact on abundance and composition of freshwater snails in Zambia

Explanatory variables		Response variables
System attribute	Habitat filter	Molluscs
Chemical properties	pH, nutrients (nitrates, phosphates), heavy metals (Cu, Co, Cr, Cd, Pb, Ni)	Species of freshwater molluscs (composition and abundance)
Physical properties	DO, ORP, TDS, EC
	Turbidity, colour, flow
Substrate	Gravel, sandy, muddy, detritus
Ther	Temperature fluctuations
Biological regime	Competitors, predators, macrophytes