** l **w 



***tiB^Kj 



^ B fl te- "' r rtdrteffi' 1 *™* 



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Figure 1.2. The northern arm of Tijuana Estuary, looking east (photo by D. Fink). 



describe in Chapter 3, Tijuana Estuary is 

 sometimes river dominated, sometimes 

 partially mixed, and usually vertically 

 homogeneous, although with marine rather 

 than brackish water. Its vertical salinity 

 profile can become positive or negative, 

 depending on weather and tidal flushing 

 conditions. 



Because most of the estuary has shallow- 

 water habitat, the wetland classification of 

 Cowardin et al. (1979) is also applicable. 

 The intertidal portion of the system fits 

 within the California Province, estuarine 

 system, intertidal subsystem, emergent 

 wetland class, persistent subclass, dominated 

 by common pickleweed (Salicornia virginica) 

 and Pacific cordgrass (Spariina foliosa). 



Tijuana Estuary is a highly variable 

 system that may best be termed an 

 "intermittent estuary." During the winter 

 wet season, its waters are diluted by rainfall 



and streamflow; during the rest of the year, it 

 is an extension of the ocean. As sireamflow 

 and wetland soil salinities suggest (Chapter 

 3), it may be one of the nation's most variable 

 estuaries. 



1 .3 THE ESTUARINE HABITATS 



Tijuana Estuary is a wetland-dominated 

 estuary (Figures 1.2-1.3). There is no 

 major embayment, but rather a series of 

 channels and a relatively narrow ocean 

 connection. In most years, the mouth has been 

 open, and tidal flushing has prevailed. The 

 intertidal area supports mostly salt marsh 

 vegetation, while mudflats and sandflats 

 occupy only a small fraction of the site. 

 Inland, the upper salt marsh grades into 

 transitional vegetation, which in turn grades 

 into coastal scrub and chaparral. 



