Much research in the Delta has focused on foodweb dynamics, stimulated by evidence that low productivity of plankton is linked to declines in several fish species including the endangered delta smelt. Pseudodiaptomus forbesi is the most abundant copepod (small crustaceans) in the Delta in summer. It is an important food source for many fishes and makes up about half of the food of delta smelt. This study focuses on the feeding, reproduction, and growth of copepods as essential foodweb support for fishes. This work investigates four diverse habitats including two open-water channels and two shallow habitats. The researchers will measure copepods´ feeding rates on microscopic plants and animals, and relate feeding to their rates of growth and reproduction. Computer models will be used to estimate their movement and death rates. These results will show the sources of nutrition used for growth and reproduction of these key organisms. Results will inform how food webs respond to large scale changes in the Delta ecosystem, for example, restoration and the Sacramento wastewater treatment plant upgrade.