An Experimental Test of the Crayfish (Orconectes immunis) as a Control Mechanism for Submersed Aquatic Macrophytes

ABSTRACT

The ability of the crayfish Orconectes immunis to graze submersed aquatic macrophytes was evaluated experimentally. Crayfish at a biomass greater than 140–150 g m⁻² (fresh weight) significantly decreased macrophyte biomass in all experiments. The rate of crayfish grazing in cages where significant decreases in macrophyte biomass occurred averaged 0.012 g m⁻² day⁻¹ crayfish⁻¹ (ash-free dry weight) of macrophytes.

Key Words:

• crayfish
• macrophytes
• weeds
• grazing
• biological control