If we compare the apparent sea-level rise data with the sedimentation rate data it 

 becomes clear that since 1954 streamside marshes have kept pace with apparent sea- 

 level rise and, therefore, are maintaining their relative elevaton within the tidal range, 

 but inland marshes are not. Thus, through time flooding of inland marshes (representing 

 75% to 80% of the salt marsh area) increases and at some point the plants can no longer 

 survive (Mendelssohn et al. 1981). Once the inland marshes begin forming into ponds and 

 the ponds enlarge and coalesce, the streamside marshes are subject to wave attack and 

 they begin to erode laterally. 



Examining the seasonality of sedimentation (Figure 4) with the use of the artificial 

 marker technique provides additional insights on why the marshes are not maintaining 

 their elevation. From 1975-78 most of the aggradation occurred during the winter, but 

 when the 1979 dataware added sedimentation appears to be equally important during 

 winter and summer. 



3.0 



STREAMSIDE 

 INLAND 



SU SP,FA 



SU SP.FA 



SEASONS 

 (1975-1978) 



SEASONS 

 (1975-1979) 



Fiqure 4. Seasonality of sedimentation in the Barataria saline marsh, 

 1975-1978 and 1975-1979. Spring and fall values have been combined. 

 Values represent accumulated totals for the time period indicated. 



