Reclamation Information Sharing Environment (RISE)

The Bureau of Reclamation Ecological Research Lab utilizes Imhoff cones to settle water samples specifically collected to analyze for invasive dreissenid mussel larvae. Samples are settled, and the heaviest (bottom) 15 ml are collected and analyzed under a microscope looking for the larvae. Previous research claimed that veligers present in a water sample would settle at the bottom 15 ml. This study examined whether veligers would still settle in the bottom 15 ml through water samples that are thick with different types of suspended solids like zooplankton and algae. This study found that suspended solids, or organic material, and the amount of that material, in water samples does interfere with settlement of veligers in the heaviest 15 ml.