INTRODUCTION TO SOUTHERN CALIFORNIA COASTAL MARSHES 



Southern California has a varied and 

 attractive coastline, a warm climate, and 

 a large human population. It is a region 

 where cities have grown rapidly and where 

 the natural landscape has been extensively 

 modified to serve urban development, 

 military uses, shipping and industrial 

 needs, recreation, and tourism. Because 

 of their flat topography and occurrence 

 near waterways, coastal marshes have been 

 prime targets for these modifications. 

 And because disturbance is such a common 

 feature in southern California wetlands, 

 its effects must be considered in 

 developing a profile of the marsh 

 community. Ideally, the profile should 

 summarize the natural characteristics of 

 coastal marshes and discuss how various 

 disturbances have altered them. But 

 disturbance has occurred for so long, has 

 been so pervasive, taken such different 

 forms, and had such different results in 

 each wetland, that sorting out natural and 

 unnatural features is extremely difficult. 



An early investigation provided some 

 information about the numerous coastal 

 marshes prior to the post-war construction 

 boom along the southern California coast 

 (Purer 19^*2). But urban expansion 

 proceeded without regard for or 

 information about the natural resources of 

 coastal wetlands, and no pristine examples 

 are left to reconstruct exactly what was 

 destroyed or altered. Hence, this 

 community profile relies heavily on what 

 ecologists today believe to be more 

 natural versus more disturbed, what is 

 likely to be the normal situation versus 

 what is probably the result of man's 

 intervention, and what experimental 

 studies and long-term observations can 

 tell us about cause-effect relationships. 



Southern California coastal wetlands 

 are small and discrete. They are confined 

 to narrow river valleys, and are separated 

 by coastal hills and mountains (Figures 1, 

 2) . Between the International Border with 



Mexico (32 N) and Point Conception 

 (3'4-1/2°N lat.), there are about 30 

 wetlands. Their total area (less than 

 5000 ha [12,500 ac]) is estimated to be 

 25% of their area prior to the arrival of 

 European man (Speth 1969a, b). 



The marshes within these wetlands are 

 not identical to one another. Some of the 

 differences result from disturbance; 

 others appear to correlate with 

 characteristics of tidal flushing (whether 

 continuous or intermittent). In general, 

 the marshes occur on intertidal slopes or 

 the tops of creek banks which grade rather 

 quickly from mean sea level to extreme 

 high water. A dozen or more halophytes 

 (salt-tolerant plants) are found within 

 this narrow band of habitat. Low-growing 

 succulents (especially the pickleweed, 

 Salicornia virginica ) are abundant 

 throughout most of the intertidal zone, 

 while cordgrass ( Spartina foliosa ) is 

 conspicuous only at the lower elevations 

 in some, but not all, of the marshes. 

 Tidal creeks dissect the marshes, and lead 

 to larger channels or bays. Coastal dunes 

 partially enclose the wetlands, and at 

 times sand bars completely cut off oceanic 

 circulation. 



Because of the great contrast between 

 these general features and the broad 

 coastal plains elsewhere in the United 

 States, the physiographic setting and 

 geological history will be examined first. 

 Then, a summary of the hydrological 

 characteristics and climatic conditions 

 will explain the hypersalinity of southern 

 California marsh soils, which in turn will 

 set the stage for discussing salt marsh 

 vegetation. The role of marshes as 

 habitats for a variety of birds, fish, and 

 other wildlife will then lead to a 

 discussion of management considerations 

 and current attempts to restore and 

 enhance southern California's coastal 

 marshes . 



