moist but unflooded soils to germinate. 

 The seedlings will survive only if there 

 is a prolonged dry period. Because the 

 timber land is subsiding, it is flooded 

 for increasingly longer periods of time. 

 In 1981 the most prolonged drought since 

 the 1920' s occurred and the survival 

 rate of seedlings that germinated was 

 low. These signs indicate that if the 

 swamp is cut, there may not be another 

 crop without a large replanting effort 

 by the timber companies. 



Natural Renewable Resources Productivity 



There have been a number of studies 

 of aquatic primary production in the 

 Barataria basin and the adjacent Gulf of 

 Mexico (Table 18). Stations in the 

 upper basin (Lac des Allemands, Lake 

 Cataouatche) show high levels of produc- 

 tivity with a pronounced seasonal pulse, 

 are strongly heterotrophic (they produce 

 less organic matter than is consumed) , 

 and they are eutrophic. Waterbodies in 

 the lower basin (Little Lake, Airplane 

 Lake) are less productive, lack any 

 consistent seasonal trends, and are 

 trophically balanced (P=R) to slightly 

 autotrophic. Plankton productivity in 

 the nearshore gulf is strongly increased 

 by the discharge of the Mississippi 

 River. Production studies in the Bara- 

 taria system are summarized in Day et 

 al. (1982). The trends from the upper 

 to the lower basin are: (1) decreasing 

 heterotrophy, (2) decreasing upland 

 runoff, and (3) decreasing wetland to 

 water ratio. This implies that outside 

 sources of organic matter (from upland 

 drainage or wetlands) become less 

 important in terms of community metabo- 

 lism from the headwaters to coastal 

 waters. The upper basin is character- 

 ized by an obvious seasonal pattern; the 

 lower basin lacks this pattern. Chlo- 

 rophyll data taken at 23 stations 

 throughout the basin (Table 18) also 

 support the division of the basin into 

 two parts, in that average chlorophyll 

 levels in the upper basin are 2 to 5 

 times higher than the levels in the 

 lower basin. 



These results indicate that the 

 factors controlling productivity change 



from the upper to the lower basin. In 

 the upper basin, nutrient loading from 

 upland runoff clearly controls both the 

 timing and the magnitude of production. 

 In the lower basin, a combination of 

 water clarity and depth is important. 



Salinity, turbidity, and primary 

 productivity in the nearshore zone of 

 the Barataria basin are directly related 

 to the influx from offshore of Missis- 

 sippi River water (Sklar 1976). This 

 influx comes from westward drifting 

 river water that enters Barataria Bay 

 through the passes. Surface productivity 

 about 11 km (7 mi) offshore from Grand 

 Terre Island peaked in April during 

 maximum river discharge, whereas the 

 minimum occurred in September, when 

 river discharge was low (Figure 51). 

 Surface measurements of annual net pro- 

 ductivity were generally higher in 

 turbid coastal waters off Barataria Bay 

 than in the clearer gulf waters further 

 offshore. Total annual production of 

 266 g C/m 2 (measured from August 1974 to 

 September 1975) was estimated for the 

 nearshore area off of Barataria Bay 

 (Sklar 1976). Happ et al. (1977) mea- 

 sured a mean chlorophyll of 7.6 mg/m 3 in 

 these offshore waters. 



With the tremendous expanse of 

 periodically flooded marsh and swamp in 

 the Barataria basin (304,000 ha, or 

 44.5% of the total basin, Table 13) one 

 might expect these wetlands to play a 

 major role in maintaining or augmenting 

 productivity of the estuarine system. 

 In the past 10 years, considerable data 

 have been collected that quantitatively 

 and qualitatively show the importance of 

 allochthonous inputs of carbon from 

 adjacent wetlands and upstream habitats 

 into water bodies. 



An annual organic carbon budget for 

 Barataria basin was constructed (Day et 

 al. 1982) by a combination of direct and 

 indirect measurements of ecosystem 

 fluxes (Table 19). All aquatic habi- 

 tats are strongly dependent on alloch- 

 thonous organic inputs from adjacent 

 watersheds, and upstream habitats are 

 significant sources of organic matter 

 for downstream habitats. 



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