Artemia selective grazing: survival value and nutritional intake

Grazing experiments were conducted for the zooplankton Artemia franciscana on three of its most common Great Salt Lake (Utah: USA) phytoplankton species (> 80–90% of phytoplankton biovolume: a chlorophyte, Dunaliella viridis; a cyanobacterium, Euhalothece sp., and a bacillariophyte, the pennate diatom Nitzschia epithemioides). For each Artemia developmental stage (nauplii, juveniles and adults), grazing rates (same phytoplankton abundances, temperatures, and salinities) are reported along with grazing preferences for the phytoplankton species in mixes of species pairs and all three species together. Each Artemia developmental stage exhibited different preferences for the phytoplankton species. Preferences measured for each species pair were consistent with preferences when all three species were together and were correlated with the phytoplankton’s survival value for each Artemia developmental stage. Survival values were positively related to the ingestion rate for each phytoplankton species (biovolume/individual/h), likely a function of cell size, and its nutritional quality treated as a function of phytoplankton N:P relative to Artemia developmental stage N:P.