Spfi 



Figure 67. The life cycle of the brown shrimp (Gosselink 1980), 



larger, deeper water bodies which they 

 appear to use as "staging areas" for 

 emigration. These anigrations occur 

 primarily at night and are keyed to the 

 phase of the lunar tidal cycle, with 

 greatest movement during periods of high- 

 est tides (Blackmon 1974). 



In the Mississippi Delta there appear 

 to be no fish species that spawn in fresh 

 water and move to the ocean as they 

 mature. But in other locations these 

 species make extensive use of the marshes 

 through which they pass on these migra- 

 tions. 



A different kind of migratory use of 

 marshes is that of numerous bird species 

 which move daily in and out of the marshes 

 to feed. Wading birds, for example, may 

 nest in adjacent upland areas and along 

 beach rims but feed along the marsh edges 

 and in marsh ponds during the day. Their 

 daily travels may cover many miles. One 

 manber of this group, the white ibis, has 

 been reported to travel as much as 80 km 

 from its nesting site to feed (Lowery 

 1960). In a similar vein,Tamasier (1976) 

 found wintering green-winged teal and 

 pintail resting during the day on large. 



shallow ponds. The birds then spread out 

 to forage elsewhere at night. Deer and 

 other mammals may also venture out into 

 marshes to forage from upland resting 

 areas (Schitoskey and Linder 1979). 



Intercontinental Couplings 



The most dramatic inter-ecosystem 

 couplings are those of the migratory birds 

 that link Canadian and Alaskan pothole 

 wetlands to gulf coast marshes. The 

 Mississippi delta wetlands are at the 

 southern extreme of the major duck and 

 goose migration corridors (Figure 68). 

 Many songbird species winter further south 

 and are found moving through the delta 

 marshes only during fall and spring migra- 

 tions. As mentioned earlier, we have wery 

 poor information about the importance of 

 winter-habitat quality of birds that nest 

 in the far north, but all indications are 

 that it is extremely important for nesting 

 success. 



TEMPORAL USE OF MARSHES 



It is interesting to observe how 

 different migrating species use coastal 

 wetlands at different times. (Figure 69). 



81 



