Phytoplankton high in an essential fatty acid may be a major factor in supporting thriving fish populations and clear water in lake ecosystems, say researchers from UC Davis and the University of Washington. A new study points to the quality, rather than the quantity, of the phytoplankton, which are tiny plants at the bottom of the food chain, in nourishing robust communities of zooplankton, the tiny animals that provide food for greater fish production and keep algae biomass in lakes under control. The finding, which could have important implications for fisheries managers and water quality, including in Lake Tahoe, was published today in the journal Nature. The critical link in freshwater and marine food chains is often the one between the tiny plants and animals, according to UC Davis research associate Dorthe Muller-Navarra and limnology Professor Charles Goldman, and Michael Brett, assistant civil and environmental engineering professor at the University of Washington. Anne Liston, a UC Davis research technician, also participated in the study. "Phytoplankton that are more nutritious can have a major impact on the overall food web," Brett said. "What the study shows is that the rate at which zooplankton convert phytoplankton biomass to zooplankton biomass depends on the supply of this class of essential fatty acids. This gives us important insights into what may determine how energy moves through aquatic food webs." Those insights could help scientists predict biomass and energy flow rates in aquatic ecosystems, providing possible tools for fisheries managers, Muller-Navarra added. "It may even be useful to enhance the success of lake restoration efforts."