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In our deliberations it will be quite helpful if we have a concrete proposal which can be examined and modified. 

 Therefore, I will first explain our purpose and our focus and provide some of the specifics of our task. For the 

 benefit of those who are not as familiar with the shelf, I will provide a brief overview of the northern Gulf shelf 

 environments. Then I will consider problems of sampling including natural variability of the system, sampling 

 locations, and sampling frequency. Types of samples to be taken will be discussed. Finally I will present a 

 concrete proposal in order to facilitate our discussion. I have prepared hand-out sheets including a map, the 

 proposal, and a suggested agenda for our discussions. 



3.3.2 Defining Long-Term Monitoring 



In the introduction the question was asked how long-term monitoring differs from site characterization by simply 

 extending in time. Now that we have imposed some simple limits to our effort, it is possible to suggest a 

 definition of monitoring. Monitoring should be the repeated measurement of variables according to a design 

 which will allow determination of the causes behind any detected changes or apparent equilibria. Successful 

 monitoring is that which leads to greater refinement of the understanding of controlling factors. 



Certainly some of the sampling carried out for monitoring will resemble that carried out for characterization, 

 and to the uninformed critic the two may be confused. However, characterization leads to a picture of stasis. 

 Monitoring appropriate to MMS' mission needs must not be centered around the archiving of data typical of 

 characterization. The analytical and synthesis aspects of monitoring must contain aspects of continuous 

 prediction, testing of predictions, and improvement upon the predictive method. 



3.3.3 Selecting Major Zones of the Northern Gulf Continental Shelf 



A brief overview of the environmental types of the northern Gulf continental shelf is in order to provide 

 background for our deliberations. It is clear that the continental shelf of the northern Gulf of Mexico consists 

 of six major zones, three west of the Mississippi River delta and three east of the Delta (Figure 15). Therefore, 

 a full monitoring effort would seek to study all six zones. 



Considerable discussion was devoted to the relative merits of sample transects versus areal coverage sampling 

 within the six major zones. Since it has been well established that continental shelf fauna is distributed in zones 

 that parallel the continent, cross-shelf transects have been routinely employed to describe patterns over large 

 areas. A long-term monitoring program built around such transects would provide an excellent description of 

 the movement of these faunal zones through time. However, there is no evidence to suggest that long-term 

 impact of oil and gas activities will ever be so pronounced and widespread as to alter these major faunal zones. 

 As scientifically interesting as their long-term patterns may be, such information may be of minimal value in 

 impact detection. 



If cross-shelf transects represent monitoring at an inappropriate spatial scale, what then is the appropriate scale? 

 It was suggested that the scale employed in all previous site specific studies be used. Such studies typically look 

 for faunal change on an area of ocean bottom 2-4 km square. It is the faunal variation within these relatively 

 small areas that has prevented definitive statements about impacts, not cross-shelf faunal zonation changes. 

 However, intensive sampling over an area of a few square kilometers may have major problems. While on the 

 appropriate scale relevant to MMS' mission, only a relatively small area may be studied. And the patterns of 

 variation within such an area may not be generally applicable. 



3.3.4 Determining Replication of Sampling 



The sampling program should take into account three sources of variation: 



• statistical variation due to sampling error; natural variation in the physical and biological phenomena 

 and, imposed variation due to human activities. Sampling error may be reduced by taking an adequate 

 number of samples at each station; 



• natural variability in the ecological systems requires that the sampling sites be representative of the 

 systems under study and that they be repeated with sufficient frequency to provide information 



