disturbances have altered marshes is 

 difficult and requires a combination of 

 comparisons between more- and 

 less-disturbed wetlands, experimental 

 manipulations, and observations before and 

 after disturbance events. 



Urban Development 



Because of their location near the 

 ocean and natural harbors, salt marshes 

 have been prime sites for urban 

 development. As stated in the California 

 Coastal Plan (Calfiornia Coastal Zone 

 Conservation Commission 1975) : 



"In southern California, 75 percent 

 of the coastal estuaries and wetlands 

 have been destroyed or severely 

 altered by man since 1900. 

 Two-thirds of 28 sizeable estuaries 

 existing in southern California at 

 the turn of the century have been 

 dredged or filled." 



Great losses have occurred in the vicinity 

 of Los Angeles and San Diego. Comparison 

 of historical maps with current wetland 

 configurations emphasizes this point 

 (Figure 49). In the case of Anaheim Bay, 

 wetland habitat has largely been lost to 

 marina development and Navy uses (Speth et 

 al. 1976). Just north of Anaheim Bay, an 

 850 ha (2,100 ac) wetland has been reduced 

 to about 209 ha (517 ac) now known as the 

 Ballona Wetland. Of this acreage, about a 

 fifth is a functioning wetland, about half 

 could be easily restored by breaching 

 dikes which prevent tidal circulation, and 

 the remaining acreage could be restored 

 with some difficulty (Clark 1979). In San 

 Diego Bay, about 240 ha (600 ac) out of 

 800 to 1,200 ha (2,000 to 3000 ac) of 

 intertidal sand and mudflats remain, and 

 10 to 15% of the original 970 ha (2,400 

 ac) of salt marsh are left (Browning and 

 Speth 1973). 



These major losses of wetland habitat 

 have certainly had impacts beyond the 

 immediate areas destroyed. Southern 

 California's coastal wetlands were well 

 known for their migratory waterfowl , as 



evidenced by the numbers of gun clubs that 

 became established in the late 1800 's and 

 early 1900's (Speth et al. 1976). Just 

 how much bird usage and populations 

 have declined is immeasurable. Alternative 

 stopping places for migratory waterfowl 

 are rare in the region's arid landscape, 

 and reduced coastal wetland acreage means 

 fewer water-dependent birds. 



Locally, urbanization near marshes 

 changes water circulation and water 

 quality, increases noise levels, and 

 alters skylines as tall buildings replace 

 low horizons. Marshes which were once 

 contiguous have become dissected and 

 interrupted by barriers to both animal 

 movements and plant dispersal. We are 

 just beginning to discover the importance 

 of species movements from one wetland to 

 another. It seems particularly important 

 for birds to have alternative resting and 

 feeding sites near tidal wetlands; when 

 tides inundate their mud and sandflat 

 habitats, shorebirds move upstream or to 

 ponds or to drier roosting areas (Boland 

 1981). 



If wildlife protection were the only 

 consideration, a program of major wetland 

 expansion and restoration would be 

 implemented. But, recognizing the 

 impediments to such ideological solutions 

 and accepting the likelihood that even 

 further elimination of wetland habitats 

 will occur, it is important to develop 

 recommendations which will insure the 

 least detrimental changes. Onuf (1980) 

 recommended that protection of natural 

 resources be the highest priority in the 

 management of coastal wetlands. The best 

 available methods of protecting wildlife 

 should be applied. 



Discussions among wetland scientists 

 and coastal planners, including a workshop 

 specifically designed to produce 

 guidelines for the protection of wetland 

 resources (Onuf 1979), have led to the 

 development of a number of recommendations 

 for dealing with development around the 

 periphery of wetlands. These are 

 summarized in the following suggestions. 



87 



