descriptions of these assemblages in the gulf by Chittenden and 

 McEachran (1976). Such evidence suggests that the cumulative impacts 

 from man's activities may have been minimal, at least to date. 



However ecological systems are seldom characterized by gradual 

 declines but, in contrast, change very rapidly when thresholds 

 separating regions of no effect from effect are reached. Once a new 

 condition or state is reached, a system often does not return to the 

 original condition even when the disturbance is removed. The 

 information which is most needed for the Texas-Louisiana shelf ecosystem 

 is some estimate of its assimilative capacity (i.e. the amount of a 

 given material that can be contained in a waterbody without producing an 

 unacceptable impact on living organisms or non-living resources). Given 

 the magnitude of organic and inorganic loadings to the shelf system from 

 all sources, it is conceivable that the assimilative capacity of the 

 shelf ecosystem can, and may soon, be reached. Conventional methods of 

 impact assessment (assessment via baseline studies of system components) 

 need to be replaced with studies of system processes because results of 

 man's activities usually assert themselves as impacts through alteration 

 of support processes, rather than through direct obliteration of 

 components (populations). A characterization of process rates and 

 mechanisms, rather than a compilation of baseline data about components, 

 would enable scientists to project more effectively how oil and gas 

 development may alter the system components. 



The characteristics of processes are temporally and spatially more 

 conservative than are characteristics of components. As a result of 

 this relative constancy, process information is more broadly applicable 

 than are conventional baseline data. Thus, information obtained for the 

 Texas-Louisiana shelf system might consequently be more freely 

 extrapolated to answer questions about development impacts in other 

 areas (e.g. the eastern Gulf of Mexico). 



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