pendently of the other, but the two 

 documents are designed to be comple- 

 mentary. 



USES OF THIS STUDY AND OBJECTIVES 



The primary users of this document 

 include all those interested in the 

 study area, particularly coastal zone 

 managers and other decisionmakers in 

 Louisiana and Mississippi charged with 

 regulating coastal zone activities. Such 

 persons routinely face the difficult 

 task of recommending specific courses 

 of action that will maximize long-term 

 benefits but minimize the adverse envi- 

 ronmental effects that inevitably ac- 

 company most socioeconomic activities in 

 the coastal zone. Environmental impacts 

 vary widely in kind, time, and conse- 

 quences. Many cultural impacts on the 

 coastal zone may go unrecognized because 

 of our incomplete understanding of the 

 functioning of ecosystems. Some activ- 

 ities, like canal dredging in wetlands, 

 have produced cumulative adverse effects 

 that have increased over time. The 

 systems approach used in this report may 

 improve our understanding of this situ- 

 ation. 



Many habitats in the MDPR overlie 

 rich deposits of nonrenewable resources, 

 especially petroleum and natural gas. 

 The immediate economic value of devel- 

 oping these resources has overshadowed 

 long-term ecological values, which have 

 been for the most part unquantif ied . 

 Effective management has been hindered 

 because environmental impacts are not 

 usually stated in units commensurable 

 with economic benefits-. Management 

 priorities, an assessment of the trade- 

 offs between the competing uses of 

 resources, and the evaluation of socio- 

 economic and "natural" processes in 

 common units are all implicit objectives 

 of the specific data collection method- 

 ology presented in the technical report 

 and summarized here. 



MAJOR ISSUES 



During the last two centuries, 

 coastal regions in the United States 



have undergone dramatic changes that 

 include: (1) land clearing and develop- 

 ment; (2) impoundment and draining of 

 wetlands; (3) construction of flood 

 control structures; (4) dredging activi- 

 ties; (5) freshwater diversions; (6) 

 pollution of many kinds, from point and 

 non-point sources; (7) introduction of 

 exotic pests; and (8) harvest pressure 

 on coastal fish and wildlife. We have 

 at present only a rudimentary under- 

 standing of the significance of most of 

 these changes. 



Some representative issues relevant 

 to the MDPR are listed below, divided 

 into groups according to the spatial 

 scale of their impact. 



Regional Level 



1. Wetland loss . The conversion of 

 wetland habitats to open water is ac- 

 celerating in much of the MDPR. ^ The 

 present rate is estimated at 100 kmV yr 

 or 40 mi 2 /yr (Gagliano et al. 1981). 

 This loss is the result of interrelated 

 processes both natural and cultural, 

 including worldwide sea level rise, ero- 

 sion from dredging projects, Mississippi 

 River entrainment, subsidence, saltwater 

 intrusion, and the sediment starvation 

 of marshlands. 



2. River switching . The Atchafa- 

 laya River is currently poised to divert 

 much of the flow of the Mississippi, 

 with potentially major consequences for 

 the economic structure of the region. 



3. Industrial pollution . Water and 

 air quality and chemical waste disposal 

 are major issues in the MDPR, which in- 

 cludes petrochemical and port facilities 

 that are among the most active in the 

 world. 



Hydrologic Unit Level 



1 . Role of wetlands in fishery pro- 

 duction . Fishery production in the MDPR 

 is believed to be dependent on organic 

 matter produced in wetland habitats. 

 Differences in wetland habitat composi- 

 tion among hydrologic units may be 



