The San Francisco Bay Estuary is home to many species of marine and wildlife that create a delicate ecological balance. Invasive jellyfish introduced to the bay though cargo shipping are believed to be competing with the endangered delta smelt for the same food source of copepods. Samples of zooplankton were taken from high and low salinity zones in the San Francisco Bay over three years in months June through February to correlate with the peak of the jellyfish lifecycle. The preserved samples are looked through and jellyfish are removed and recorded. The species of jellyfish is determined using features such as mouth shape, tentacle formation, radial and centripetal canal prominence, velum width, and presence of statoscyts and ocelli. There are major species being studied include the cnidairia Blackfordia virginica, Maeotias marginata, and Moerisia lyonsi as well as the ctenophore Pleurobrachia bachei. Other species have been identified but are not as abundant. An image of each jellyfish is recorded and the bell height and diameter is measured using a pixel measurement ratio overlaid on an image taken of the jellyfish. Given that the jellyfish are zooplankton, they are most commonly sized at ± 1mm but can be found as large as 15mm. The purpose of this study is to track the abundance of jellyfish in the bay to provide data to compare with other studies to determine if the jellyfish are affecting the ecology of the bay as a threat to the delta smelt.


Marine Biology | Population Biology | Terrestrial and Aquatic Ecology


Lindsay J Sullivan

Lab site

Romberg Tiburon Center for Environmental Studies (RTC)

Funding Acknowledgement

This material is based upon work supported by the S.D. Bechtel, Jr. Foundation and by the National Science Foundation under Grant No. 0952013. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the S.D. Bechtel, Jr. Foundation or the National Science Foundation. This project has also been made possible with support of the National Marine Sanctuary Foundation. The STAR program is administered by the Cal Poly Center for Excellence in Science and Mathematics Education (CESaME) on behalf of the California State University (CSU).



URL: https://digitalcommons.calpoly.edu/star/246


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