USE OF SILVER CARP (HYPOPHTHALMICHTHYS MOLOTRIX) AND BIGHEAD CARP (ARISTICHTHYS-NOBILIS) FOR ALGAE CONTROL IN A SMALL POND - CHANGES IN WATER-QUALITY

One thousand silver carp (Hypophthalmichthys molitrix) and 500 bighead carp (Aristichthys nobilis) were introduced into a small shallow pond in Arvada, Colorado during March 1992. The pond had nuisance algal pr oblems and was matted with Rhizoclonium spp. During the three-year stu dy period (1992-1994), turbidity increased from 9 NTU to 15 NTU (p<0.0 5), mean chl alpha concentrations increased from 42.60 mu g/L to 78.79 mu g/L (p<0.05), total phytoplankton concentrations decreased from 19 2,000 #/mL to 105,000 #/mL (p<0.05), total zooplankton densities decre ased from 3100 #/L to 555 #/mL (p<0.05), total phosphorus increased fr om 0.090 to 0.143 mg/L (p<0.05), and total inorganic nitrogen increase d from 0.220 to 1.125 mg/L (p<0.05).