Jellyfish Identification and Quantification in the San Francisco Estuary

As potential predators and competitors of plankton-eating fish, jellyfish have the potential to negatively impact fish populations. Jellyfish were collected weekly with plankton tows from the RombergTiburonCenterpier in Tiburon, CA. Since some jellyfish were too small to identify, one tow was collected and preserved to record abundances, and a second tow was collected to rear jellyfish until distinguishing characteristics were visible enough for identification. Jellyfish in the preserved tows were then identified, measured, and counted, and their abundance (number m-3) was calculated. Jellyfish from the second tows were reared in plastic buckets that were lightly bubbled using aquarium pumps and plastic tubing. Jellyfish were fed plankton (copepods) daily and periodically examined for distinguishing characteristics. Seven species were collected, including Bouginvilla muscus, Coryne eximia, Pleurobrachia bachei, Amphinema sp. (Rees, 2000), Obelia sp., and Turritopsis sp. One species remains unidentified. Species identification is important for monitoring invasions and determining habitat ranges. Abundances ranged from 0 to 33 jellyfish m-3. Data on abundance is important for monitoring potential interactions with fish through predation and competition