Document Type

Master's Thesis

Degree Name

Master of Science (M.S.)


Moss Landing Marine Laboratories


Nitrate transport from Elkhorn Slough (ES) to the nearshore surface waters of Monterey Bay is examined using two years of time-series data from the Land-Ocean Biogeochemical Observatory (LOBO). Hourly nitrate, temperature and salinity measurements from nearshore moorings 2.5 km north (summer, 2008) and 2.5 km south (summer– fall, 2009, winter 2010) of the Moss Landing Harbor entrance at 20-m depth were monitored with the objective of observing high nitrate events associated with terrestrial-sourced waters. Nearshore nitrate supply from ES was quantified in comparison to upwelling and internal waves based on estimates of volume transport and average nitrate concentration observed at LOBO moorings. One distinct runoff event, October 13-14, 2009, was observed during the two-year study period. Data from the LOBO mooring array was used to assess the impact of this winter-type event in comparison to the longer time-series of summer conditions. Despite intensive agricultural-based nitrate loading within Old Salinas River, the summer contribution to the nearshore nitrate budget from the Elkhorn Slough system was over an order of magnitude less than upwelling and 4 to 13-fold less than internal waves. While rates of nitrate transport vary seasonally, assessment of nitrate transport mechanisms to coastal Monterey Bay in the summer to early fall is essential to understanding the dynamics of extreme algal blooms that typically occur during these months.


Thesis (M.S.) Division of Science and Environmental Policy. Moss Landing Marine Laboratories