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Primary Processes 



Primary Production 

 Carbon Flux to Bottom 

 Nutrient Cycling (Nitrogen) 

 Transport Phenomena 



• Studies Based Upon Faunal Groups 



Food Web Analysis - Stable isotope analysis and experimental benthic studies with 

 exclosure/inclosures, ship board experimentation, and various new microbial studies (e.g., dilution 

 experiments, chemical inhibitors, isotope tracers, etc.). 



Benthic Process Studies - Descriptive and experimental studies focused on control sites, 

 measurements of changes in food supply (sediment traps, phytoplankton productivity), mapping (time 

 series) of growth rates of important benthic animals, experiments on the effect of disturbance from 

 trawls, storms and drilling muds/effluents, and on predation, especially from shrimp and other 

 abundant epibenthos. Separate studies are needed on the effects of resuspension and nepheloid 

 layers. Previous studies indicate that abundant or ubiquitous benthic organisms should be used as 

 indicators in these studies. 



Phytoplankton Components - Phytoplankton productivity must be of adequate resolution in time and 

 space to distinguish gradients as well as describe mean fields; mesoscale physical features evolve 

 through time, on a scale of days to weeks, so that plumes and/or eddies must be mapped 

 synoptically; the largest horizontal environmental gradients are at the mesoscale physical features 

 and these should be mapped at time-space scales of days and kilometers. 



Studies Based Upon Chemical Aspects 



Oxygen - Construct an oxygen budget. Determine the vertical exchange coefficient across water 

 column layers of different degrees of stratification; of particular interest is hypoxia. 



Carbon - Complete a total carbon budget. Primary production measurements, sediment trapping, 

 respiration rate measurements (water column and benthos) should be conducted concurrently. This 

 should be a seasonal study for one year at one location (transect) near the Mississippi River, and 

 then expanded to shelf-wide cruises in subsequent years during critical periods of hypoxic water mass 

 formation, during the summer when strongest, and during breakup. 



Contaminants - Trace the fate of petroleum products in foodchains using standard fingerprinting 

 techniques, including stable isotope analyses. Synthesize target compounds with 14C label and 

 conduct uptake experiments at platform sites. 



• Field Designs Employed 



Regional Coverage - Based upon major physical regimes with sampling grids laid out to capture the 

 events of these systems 



Mississippi/Atchafalaya plume 

 coastal boundary currents westward 

 outer shelf and gyres, mid-shelf westward 



Frequency and Duration of Sampling - Approximately 10 regional cruises will be required per year 

 for approximately five years. 



