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 SCUBA diver places a bucket over the biostromes and scrubs the surface with a gloved hand, while the assistant in the boat pumps the dislodged organisms into buckets. 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: 18 July 2008. The sampling was being done to measure mercury biomagnification in the cyanobacteria-Ephydra-bird food chain.