We examine to what extent the waters of Monterey Bay act independently of those along the central California coast. Sea surface temperatures (SSTs) from 1920 to 2014 from the central California coast and Monterey Bay were analyzed for long-term trends. To estimate the trends, singular spectrum analysis and empirical mode decomposition were employed. Between 1920 and 1940, long-term trends inside and outside Monterey Bay revealed rapidly increasing temperatures. After 1940 trends inside the bay indicate that temperatures increased from ~1950 for the next 40 years, peaking around 1990, and then decreased rapidly through 2013. Offshore, temperatures increased to the early 1960s, after which they decreased until 2014. El Nino episodes, the Pacific decadal oscillation (PDO), and increased coastal upwelling contribute to the long-term trends. Also, the impact of regime shifts associated with the PDO may be sustained for decades. Overall, the differences in the trends inside and outside Monterey Bay are significant only during summer where large-scale processes dominate offshore, and smaller-scale processes are important in and around the bay. Finally, our results suggest that waters inside the bay, although they co-vary with the waters further offshore, often appear to behave independently based on the long-term trends.
Part of the book: Coastal and Marine Environments
Elkhorn Slough was first exposed to the waters of Monterey Bay with the construction of Moss Landing Harbor in 1946. It follows a 10-km path inland from Moss Landing Harbor. Today, it is a habitat and sanctuary for a wide variety of marine mammals, fish, and seabirds. The currents, tides and physical properties of Elkhorn Slough have been observed since 1970. It is an ebb-dominated estuary due to the asymmetric rise and fall of the tides which produces ebb currents that dominate. Tidal distortion increases inland due to frictional effects and extensive mud flats and Salicornia marsh. Tidal distortion also produces overtides and compound tides. Tidal elevations and currents often reveal the characteristics of a standing wave system. The temperature and salinity of lower Elkhorn Slough reflect the influence of Monterey Bay waters, whereas the upper Slough is more sensitive to local processes. Maximum tidal currents in Elkhorn Slough have increased from ∼75 to ∼150 cm/s since 1970. This increase is primarily due to the change in tidal prism which has increased from ∼2.5 to ∼7.6 × 106 m3 between 1956 and 2003. Finally, this increase is due to both man-made changes and continued tidal erosion.
Part of the book: Estuaries and Coastal Zones