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Historical Data 



Historical results can be examined for two purposes. First, we can seek examples of process studies dealing 

 with impacts. Second, we can seek out existing information which will help design the study in the TEXLA 

 region. In the first case, we find little of immediate utility. None of the previous MMS "Ecosystem Studies" (see 

 Avent, section 2.1.5) were process oriented. Even the most recent large MMS studies on Georges' Bank and 

 the Santa Maria Basin were based upon time-series monitoring with little attention to the processes behind the 

 measured parameters. The Department of Energy has supported major coastal ecosystem studies, but none of 

 these were designed to produce information similar to MMS' practical management needs. 



While no major ecosystem studies have been conducted in the TEXLA region, several important programs have 

 contributed markedly to our ability to design and execute successful ecosystem studies in this region (see Rabalais 

 and Turner, section 2.2.11; Darnell and Rowe, section 2.2.12; and Rabalais, section 2.2.15). Most notably, these 

 include ongoing research on the Mississippi River plume, regional hypoxia, and the dynamics of ring-shelf 

 interactions. 



3.1.3 Recommended Goals & Objectives 



The general goals of this proposed study should be to (without any implied order of importance): 



• begin the study with the construction of a heuristic ecosystem model to serve as a design guide, to be 

 used during the study for heuristic and experimental probing, and to test hypotheses using the data 

 collected during the study and simulation; 



• link processes and species populations, the model should include explicit representation of stocks and 

 processes to be measured to understand structure and function of benthic and pelagic communities. This 

 would include: (a) quantified standing stocks, with identification of the dominant (10 most abundant) 

 species of phytoplankton, zooplankton, epifaunal fish, megafauna, infaunal macrofauna, and meiofauna 

 and, as appropriate, bacteria, and (b) quantified roles of each functional assemblage, its production, and 

 consumption of organic matter; 



linkages between system components and geographic regions should focus upon quantification of the 

 sources and fates of organic matter, including riverine, upwelling, eddy, and shelf regions from the 

 Mississippi River delta to Brownsville, Texas; 



physical studies should seek to determine transport mechanisms and forcing functions of biological 

 processes; 



• the regional importance of the Mississippi/Atchafalaya River plumes will be determined, especially of 

 nutrients of presumed importance to phytoplankton; 



• the regional importance of hypoxia will be examined to understand (quantitatively) what natural 

 phenomena contribute to hypoxia and understand hypoxia sufficiently well to separate its effects from 

 other natural and man-made influences, especially those activities regulated by the MMS; 



• all components shall be designed to characterize and determine the effects of variability on ecosystem 

 processes (biogeochemical), including the effects of eddies, river, winds, water level, insolation, and 

 riverine derived nutrients and sediments that have varied significantly this century. 



It is necessary to draw some limits upon the scope of inquiry so as to keep the project within reasonable limits. 

 It was the consensus of the participants that regions within the span of the barrier islands could be safely omitted 

 so long as major fluxes to OCS waters were estimated and included in models. Special habitats such as 

 seagrasses warrant independent study, and commercial species such as fishes also warrant separate study. 



