indicating hydrologic flow inhibition, and (5) sites along Pipeline canal (2, 13, 13C, 16) experienced 

 water level changes in the upper ranges of water level changes. 



The range of water level fluctuation at marsh sites was 24 to 36 cm, while canal sites experienced 

 water level changes of 45-67 cm. Since surface response to climatic and tidal factors was on the 

 order of hours to days and we only measured water levels once a month, we could not detect any 

 significant difference between canal and marsh surface water level changes. Swenson and Turner 

 (1987) reported that partially impounded marsh sites in Louisiana were characterized by both longer 

 flooding events and reduced water exchange both aboveground and belowground. 



Degree of Vertical Marsh Movement 



Vertical movement of the marsh revealed several interesting trends: (1) the lakeside station (site 

 5) experienced a range of vertical marsh movement (1.5 cm) that was an order of magnitude less 

 than all other sites, (2) sites with open access to waterways (sites 2, 9, 12, 13, 7, and 1), regardless 

 of exact location within the park, experienced vertical movement ranges clustered at the low end 

 of the range, (3) most of the park experienced slight vertical movement through time (and could 

 thus be called quaking marsh), (4) sites affected by spoil (sites 4, 5, and 10) and several swamp 

 sites experienced the greatest ranges of vertical movement through time, (5) floating marsh (sites 

 10 and 15) and semi-impounded (site 17) and impounded swamps (site 18) were clustered at the 

 high end of the vertical movement range, and (6) the "truest" floating marsh (site 10) experienced 

 significantly more movement than all other sites (see Figure 7). These results suggest that ranges 

 in vertical marsh and swamp movement through time may be a good indicator of vertical marsh 

 stability or lack thereof. 



Salinity 



Seasonally adjusted monthly average salinity means in Bayou Barataria at Lafitte revealed an 

 increase of 1.5 ppt for the record from 1956 to 1981 (Figure 8). Mean salinity increased from 

 about 1.1 ppt to 2.6 ppt. The yearly increase, 0.06 ppt, was highly significant (p>F=0.0001). The 

 model accounted for 13% of the total variation in data. Seasonally adjusted maximum salinity 

 means in Bayou Barataria at Lafitte revealed an increase of 2.95 ppt/30 yr or 0.1 ppt/yr. There 

 were no statistically significant differences between mean surface (1.7± 1.1 ppt) and subsurface 

 park salinities (1.5 ±1.4 ppt). The data suggest that average salinities at Lafitte increased in the 

 early 1960's, possibly because the Barataria waterway enlargement was completed during this period. 



Station Salinities 



Clustering of monthly station salinity results revealed three significant groups (p>F=0.0001): 

 (1) a lakeside quaking marsh group (sites 1, 2, 4, 5, 7, 9, 13) with intermediate salinities which 

 peaked during October or November, (2) floating marsh (sites 10 and 15) and swamp sites (12, 17, 

 and 18) with fresh salinities during the year, and (3) canal sites (13C, 14, 16, 20) which experienced 

 highly variable and erratic yearly salinity patterns (Figures 9 and 10). The extreme variability in 

 salinity at the canal sites emphasized the fact that these areas show quick hydrologic responses to 

 outside environmental factors such as tides and rains. Sites along Segnette Waterway (1,5,7,9, and 

 20) had mean salinities significantly greater than both the floating marsh (10 and 15) and swamp 

 sites (12, 17, and 18). Water salinity at the swamp and floating marsh sites ranged between 0.3 

 and 2.2 ppt (mean = 1.11 ±0.54). These low station salinities appeared to be buffered from the 

 salinity effects of outside environmental factors such as tides. In addition, the salinities of these 

 sites were more heavily influenced by upland runoff than by tidal effects. 



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