A pump sampler is used to sample brine fly larvae and pupae (Ephydra cinerea) from the stromatolites (biostromes) in the Great Salt Lake. In this procedure a SCUBA diver places a bucket over the biostromes and scrubs the surface with a gloved hand, while an assistant in the boat pumps the dislodged organisms to the surface where they are screened and preserved.
Each square meter of substrate can hold several thousand of these organisms. The stromatolites cover approximately 20% of the littoral area of the lake. The larvae graze on the algae (cyanobacteria) growing on the stromatolites, and then pupate and emerge as adults which fly to the shoreline of the lake by the billions. The larvae, pupae and adult flies are an important food for birds that use the lake.
Photo: 2006. The sampling was being done to measure whether selenium bioaccumulates in the cyanobacteria-Ephydra-bird food chain. Little biomagnification was found.