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3.2 



DETECTION OF IMPACTS ASSOCIATED WITH 

 LONG-TERM OIL AND GAS ACTIVITY SITES 



Dr. James J. Kendall 



Minerals Management Service 



Gulf of Mexico OCS Region 



Dr. James P. Ray 



Shell Oil Company 



Houston, Texas 77210 



3.2.1 Introduction 



The study(s) to be conducted concerning "Effects of OCS Development and Production Activities, Northwestern 

 Gulf of Mexico," are intended to elucidate the chronic (persistent), low-level (sublethal) stresses and long-term 

 effects thereof associated with developmental drilling and production activities, particularly in an area with a long 

 history of oil and gas development, production, and transportation. In particular, sites in the Western and 

 Central Gulf of Mexico are far enough west to be outside the perpetual influence of the Mississippi River plume. 

 The fiscal year (FY) 1990 effort is conceived as the first of several study years, to be funded in recurring 3-year 

 cycles. The continuation of this study, or suite of related studies, over a multi-year period will allow the Minerals 

 Management Service (MMS) to define these chronic, low-level, long-term stresses of Outer Continental Shelf 

 (OCS) activities. 



This program will build on the findings of past rig and platform monitoring studies conducted in the Gulf of 

 Mexico, Pacific, and Atlantic OCS Regions, as well as other ecosystems studies in the northwestern Gulf previous 

 to, or concurrent with, this effort. This program will complement the companion study concerning "Long-Term 

 Monitoring at Marine Ecosystem Sites", but will differ by focusing on production sites where impacts may have 

 occurred due to offshore oil and gas development activities, as compared to studies of natural variability at sites 

 believed not to have been impacted. 



The importance of this study to the decision making process of the MMS is that the Environmental Studies 

 Program(ESP) has recently shifted its focus to studies of chronic, low-level, long-term environmental stress due 

 to offshore oil and gas activities. Ecosystem processes and functions will also be examined in an attempt to 

 explain the mechanisms at work causing the observed impacts. 



The development of an offshore oil and gas field may have a variety of effects on the marine environment. 

 Effects studies have concentrated on both the usual or unusual agents/activities associated with OCS 

 development. Unusual events/activities would include disastrous events or major unanticipated shifts in program 

 activity. 



While most research shows that the effects resulting from acute, short-term stresses associated with oil and gas 

 structure are localized and ephemeral, there is less certainty regarding the impacts which may result from low- 

 level, sublethal, chronic stresses. As early as 1981, the National Marine Pollution Program Plan (Interagency 

 Committee on Ocean Pollution Research, Development, and Monitoring), concluded that the most significant 

 unanswered questions for the offshore oil and gas industry are those concerning the effects on ecosystems of 

 chronic, low-level exposures resulting from discharges, spills, leaks, and disruptions caused by development 

 activities. 



In keeping with the theme of long-term environmental effects, an attempt was made to focus the discussions here 

 on those effects which were perceived to be long-lasting (possibly longer than two years) and significantly 

 deleterious to either resources (e.g., fisheries) or ecosystem integrity. Finally, it was repeatedly stressed that 

 drilling and production facilities are evolving entities, and that future structures might be expected to have 

 different environmental interactions and effects. 



