more dependent on rainfall. Salinities 

 decreased during winter storms and 

 increased in response to evaporation or, 

 in the case of San Elijo Lagoon, to 

 overflow of storm tides into the lagoon 

 (Figure 7). 



LOWER MARSH: CORDGRASS i SPARTINA FOL/OSA ) 



50 -I 



40 



z 

 < 



5 30 i 



tn 



—I 

 < 



I- 



20 - 



10 



I I I I I 1 I I I I I I I I I I I I I I 



FMAMJJ ASONDJ FMAMJ J ASONDJ FMAMJJ AS 



1979 



1980 



1981 



When water levels of closed lagoons 

 are high enough to flood the marsh, soil 

 salinities can be expected to change in 

 proportion to the length of inundation 

 periods. Long periods of reduced tidal 

 influence at Los Penasquitos Lagoon 

 followed by heavy rainfall in 1978 seem to 

 be responsible for the persistent brackish 

 soils found by Zedler et al. (1980) and 

 Filers (1981). The influence of heavy 

 rainfall on tidal estuaries and non-tidal 

 lagoons is summarized in Figure 8. 



J J 



A S O N 

 1958 



D J F 



M A M J 

 1959 



J A S 



Figure 6. Interstitial soil salinities 

 in the lower marsh (elevation averaging 

 about 7 dm above MSL) at Tijuana 

 Estuary, where Spartina 

 dominant. Asterisks 

 significant differences 

 between sampling dates. 

 Zedler (unpub. ms.b). 



foliosa is 



indicate 



(p < 0.05) 



Data from 



Figure 7. Seasonal changes in water 

 salinity of four lagoons (from Carpelan 

 1969). Los Penasquitos Lagoon became 

 closed to tidal circulation during 

 December 1958 and remained closed for 

 the rest of the study. 



12 



