INTRODUCTION 



OVERVIEW 



The Mississippi Deltaic Plain Re- 

 gion (MDPR) of southeastern Louisiana 

 and Mississippi includes the 3,400,000 

 ha (8,398,000 acres) result of 7,000 

 years of sediment accretion on the 

 northern Gulf of Mexico Continental 

 Shelf between about Longitude 88 and 92 

 degrees W. 



This report is a descriptive nar- 

 rative aimed at characterizing the 

 region's ecology and its environmental 

 problems. A companion technical report 

 (Costanza et al. 1983) was also prepared 

 that includes more detailed quantitative 

 descriptions of the major ecological 

 habitats of the region. The data col- 

 lected in the technical report are 

 intended to serve as a data base for 

 addressing specific environmental man- 

 agement questions. This narrative 

 report summarizes: (1) the major classes 

 of environmental problems, their complex 

 origins and interdependencies ; (2) the 

 natural systems of the region, their 

 histories, structure, and function; 

 (3) the recommendations that have been 

 proposed to deal with the environmental 

 problems of the region; and (4) how the 

 data base assembled in the technical 

 report might help in dealing with these 

 problems more rationally. 



Much of the descriptive summary on 

 the MDPR presented in this narrative 

 report will be familiar to some readers, 

 but it was included so that readers with 

 diverse backgrounds could obtain the 

 framework necessary to understand the 

 region and its problems. 



BACKGROUND AND ORGANIZATION 



The National Coastal Ecosystems 

 Team of the U.S. Fish and Wildlife Ser- 

 vice (Department of the Interior) has 

 completed the ecological characteriza- 

 tion and syntheses of several coastal 

 regions (e.g., Gosselink et al. 1979; 

 Procter et al. 1980). This report is a 

 part of a similar effort for the Mis- 



sissippi Deltaic Plain Region (MDPR). 

 Characterization studies review all 

 relevant existing information about 

 particular coastal regions and synthe- 

 size this information to provide a basis 

 for informed management. The technical 

 report (Costanza et al . 1983) is orga- 

 nized around a series of quantitative, 

 hierarchically nested descriptive models 

 at three levels of resolution: (1) the 

 overall region, (2) the seven hydrologic 

 units of which the region is composed, 

 and (3) 20 habitats that have been 

 identified as important in the various 

 hydrologic units (Figure 1) . The models 

 illustrate (and quantify to the extent 

 possible) the major physical and bio- 

 logical processes and interactions that 

 occur at each level of resolution. 



To facilitate cross-referencing 

 between the technical and narrative 

 reports, both documents are similarly 

 organized, incorporating three levels of 

 geographic resolution: region, hydro- 

 logic unit, and habitat. The habitat 

 level is the most detailed, and each 

 habitat is described as a system of 

 interconnected physical components and 

 organisms. The hydrologic unit level is 

 intermediate, with each unit presented 

 as a system of habitats interconnected 

 by flows of water, dissolved and sus- 

 pended inorganic and organic matter, and 

 organisms. Each hydrologic unit is 

 driven by physical and socioeconomic 

 inputs. The broadest level of resolu- 

 tion is the entire MDPR. At this level, 

 interactions among hydrologic units are 

 examined, with socioeconomic and geo- 

 logical forces of paramount interest. 



As a complement to the models, this 

 report describes the MDPR, its habitats, 

 and its hydrologic units. The narrative 

 also provides additional information 

 that is not included in the technical 

 report. The descriptions are intended 

 to interpret and summarize the data in 

 the technical report. The narrative 

 report also contains generalized man- 

 agement recommendations based on infor- 

 mation developed in both documents. 

 Analysis of the data base and applica- 

 tions to specific management questions 

 have yet to be completed, however. Each 

 report is intended to be useful inde- 



