estuarine science. This facility was originally 

 located on 70 acres of abandoned agricultural 

 land at the southern edge of Tijuana Estuary 

 (Figure 6.1). It was moved near the Visitor 

 Center in 1990 to gain greater security and 

 improve facilities. Its main purpose is to 

 support experimentation in outdoor 

 mesocosms (moderate-size artificial wetlands 

 in replicate). The disturbances to Tijuana 

 Estuary are what catalyzed a shift toward 

 manipulative experimentation. Controlled 

 field experiments became impossible when 

 background conditions (e.g., tidal flushing) 

 could not be assured. The NOAA Sanctuary 

 Programs Division and California State 

 Resources Agency sponsored the development 

 of the outdoor laboratory, which is operated 

 by San Diego State University. 



nterstate 

 Hwy 5 



San Diego 

 1 



National City 



Chula Vista 



Tijuana 

 E3tuary 



Coronado 

 Avenue 



Hollister Rd. 



Tijuana 



Visitor Center 



PERL mesocosm facility 



Original PERL site 

 1 800 Monument Road 



Figure 6.1. Location of the Visitor Center for 

 Tijuana River National Estuarine Research 

 Reserve at 301 Caspian Way (accessible from 

 3rd or 4th Streets, which intersect Coronado 

 Ave. /Imperial Beach Blvd.). Symbols mark 

 two research facilities developed by PERL. 



The types of mesocosms that were built 

 and used for thesis research by SDSL) graduate 

 students included coastal scrub vegetation (A. 

 Corbet, SDSU, unpubl.), fish ponds (White 

 1986), dunes (Wood 1987, Vourlitis 1991), 

 lower- and middle-elevation salt marshes 

 (Griswold 1988), and lagoon waters 

 populated by phytoplankton, macroalgae, and 

 epibenthic algal mats (Fong 1991). 



6.2.1 Habitat Construction 



In addition to providing mesocosm 

 facilities for research, the PERL site was used 

 to construct large wetland habitats and to 

 establish native plant nurseries for local 

 restoration projects. The State Resources 

 Agency (Environmental License Plate Fund) 

 and the State Coastal Conservancy sponsored 

 the habitat construction project in the late 

 1980's. Fresh, brackish, and saline 

 impoundments of several sizes were 

 constructed by Chris Nordby and Barry 

 Dubinski to determine whether such habitats 

 would subsidize areas used by estuarine 

 species. The wetlands extended over about 30 

 acres of the original PERL site and provided 

 essential refuges during times of whole- 

 ecosystem perturbation. They attracted 

 wildlife and helped to determine how salinity 

 and vegetation influence animal use. 



6.2.2 Native Plant Nurseries 



A native plant nursery was developed and 

 used to propagate coastal plants for 

 transplantation to regional restoration 

 projects. At the request of the California 

 Department of Parks and Recreation, native 

 dune plants were grown by Brian Fink for 

 dune restoration projects at Border Field 

 State Park and Silver Strand State Beach. 

 These restoration projects were a direct 

 outgrowth of Fink's earlier M.S. thesis 

 research (Fink 1987). 



The PERL nursery was also used by Brian 

 Fink to propagate native halophytes for the 

 salt marsh restoration at San Diego Bay 

 (Sweetwater Marsh National Wildlife Refuge). 



1 24 



