Impact of Water Quality Variables on Plankton in the Monterey Bay

Impact of Water Quality Variables on Plankton in the Monterey Bay

Santa Catalina School

Truth Ortiz, Grayce Nichols

The plankton community is the basis of the food web in Monterey Bay, California. Plankton populations vary throughout the year depending on ocean currents, nutrients, seasons, and other ocean conditions such as El Niño. Monitoring the abundance and biodiversity of plankton can be helpful for tracking food web health and ocean conditions (National Centers for Coastal Ocean Science, 2017). In this study, we investigated changes in phytoplankton and zooplankton diversity due to seasonal cycles. We also examined the relationship between plankton diversity and indicators of coastal upwelling (temperature, pH, alkalinity) as well as land runoff (nitrate, fecal coliform). Beginning in August 2018, we collected plankton and water quality data on a weekly basis at the Monterey Wharf II. Using methods developed by the Monterey Bay National Marine Sanctuary Plankton Monitoring Program, we identified the presence or absence of phytoplankton and zooplankton species including harmful algal species (HABS). Phytoplankton diversity shifted from being dinoflagellate dominant in the fall to a balance if diatoms and dinoflagellates in the winter and spring. The number of HABs species varied between 0 and 7 species. Zooplankton were dominated by nauplii, copepods, tintinnids, and polychaetes. Results show a correlation between species diversity and some water quality parameters (Alkalinity, pH, nitrate). We have also observed that diatom diversity correlated with nitrite and as the nitrite decreases, the diversity of diatoms species does as well. Harmful algae and phytoplankton diversity follow similar trends, we suspect that this is also due to upwelling and the nutrients that are brought to the surface. Fecal coliform was found in every sample. As our project progresses, we hope to collect more data on the abundance of populations of certain species of zooplankton in addition to continuing recording presence and absence of species.