Pore Water Nitrite+ Nitrate 



Pore water NO," + NO3 concentrations were typically 



higher than open water values (Table 6-4). At the 



Reference Station, values ranged from 0.5 to 



38.2 (jmoles, and at Stations II and III, concentrations 



ranged from 0.1 to 49.8 |jinoles and 0.4 to 11.9 ^xmoles, 



respectively. 



large-scale whole transect analyses: 

 Individual Species Responses to Events 



There was considerable variability in the percent cover 

 of each species within and between stations before and 

 after composite hydrographic events (Figures 6-7 

 through 6-9). At the Reference Station and Station III, 

 vegetation changes appear to be predominantly 

 precipitation-mediated rather than flow generated, 

 while changes at Station II occurred as a result of both 

 flow through the channels and direct precipitation. 



Reference Starion 



Batis maritima - At the Reference Station, total 

 transect percent cover of Batis maritima cycled 

 seasonally with peaks generally occurring in the 

 summer and declines in the late fall/early winter 

 (Figure 6-7a). The greatest increase in cover (3.5% to 

 23%) occurred between February and August 1997. 

 Between February and June, the study area received 

 52.1 cm (20.7 inches) of rain, or 57% of the total yearly 

 rainfall. At the Reference Station, B. maritima exhibited 

 a decrease in cover in June 1998. From April to June 

 1998, there was litde precipitation (< 0.91 cm, or 

 0.36 inches), unlike other springs during the study 

 period when several inches of rain fell during the same 

 period. 



Borrichia frutescens - Percent cover of Borrichia 

 frutescens at the Reference Station exhibited an inverse 

 correlation with Batis maritima cover (r^=0.61) 

 (Figure 6-7b). Generally, peaks in B. frutescens occurred 

 when B. maritima cover was relatively low. 



Distichlis spicata - At the Reference Station, cover of 

 Disticblis spicata exhibited an overall decrease from 



10% in February 1996 to < 1% in June 1997 



(Figure 6-7c). Cover remained < 1% for the remaining 



study period. 



Monanthodoe littoralis - At the Reference Station, 

 Monanthocloe littoralis cover remained relatively constant 

 throughout the study period (29 to 42%), exclusive of a 

 23% decline in cover (from 37 to 14%) between 

 January and September 1999 (Figure 6-7d). The initial 

 decline in cover occurred followed six months with 

 about 45 cm (18 inches) rain. The lowest cover 

 measured coincided with the passing of Hurricane Bret 

 (August 1999). The storm released over 15 cm 

 (6 inches) of rain in one day. The transect was also 

 flooded by a tidal surge. M. littoralis cover increased 

 20% (14 to 34%) in the two months following the 

 hurricane, a period with litde to no rainfall. Similar, 

 but smaller-scale declines in cover were seen following 

 two or more consecutive months with several inches of 

 rainfall (August to September 1996 and February to 

 June 1997). The decreases in cover were always quickly 

 followed by an increase in growth. 



Salicornia bigelovii - At the Reference Station, 

 Salicomia bigelovii cover exhibited spring peaks greater 

 than 10% cover occurring in 1996, 1997 and 1998 

 (Figure 6-7e). The largest peak (30%) in June 1999 was 

 about 20% higher than the other two peaks and 

 occurred following a winter and spring with consistent 

 rainfall (11 out of 14 months received over 5 cm 

 (2 inches) of rain). 



Bare Area — On occasion, decreases in bare area 

 corresponded with increases in Salicomia bigelovii cover. 

 For example, S. bigelovii cover was about 29% in the 

 summer 1999, and bare area cover decreased by about 

 20% (Figures 6-7e and 6-7f). However, there was no 

 strong correlation between the two parameters 

 (r = 0.27 for S. bigelovii cover > 2%). The greatest 

 bare area cover at the Reference Station (69%) 

 occurred in September 1999 following the composite 

 hydrographic event in September 1999, which included 

 the landfall of Hurricane Bret. 



Chapter Six V 6-15 



