Table 3-4. Quality Control procedures for field sampling, laboratory processing, and data analysis of EMAP-E 

 Louisianian Province benthic data. 



Field Operations 



Sample Collection 



• Sediment should not extrude from the upper face of sampler. 



• Overlying water should be present. 



• Sediment surface should be relatively flat. 



• Entire surface of sample should be included in sampler. 



• Grab must have penetrated sediment to a minimum depth of 7 cm. 



• If these QC guidelines were not met, the sample was rejected. 

 Sample Processing 



• Gentle rinsing of sample through sieve - no forceful jets of water. 



• Preservation of sample with 10% buffered formalin containing Rose Bengal stain. 



Laboratory Operations 



Sample Storage 



• Samples should be stored between 5"C and 30'C to avoid freezing or evaporation. 



• After sorting, organisms should be stored in vials with 70% ethanol. 



• Minimize exposure of samples to direct sunlight. 

 Sorting (i.e., separating organisms from sediment and debris) 



• 10% of all samples are resorted independently by a second, experienced sorter. 



• Re-sorts are randomly chosen (1 out of 10) on a regular basis 



• Sorting efficiency is calculated as: 



# of organisms originally sorted x 100 



# of organisms originally sorted + additional # found in re-sort 



• Actions for unsatisfactory sorting efficiencies: 

 90-95% - Technician should be retrained. 



< 90% - All samples in batch must be resorted and any organisms found 



in re-sort will be added to the original data sheet. 



Species Identification and Enumeration 



• 1 0% of all samples are checked for accuracy by a senior taxonomist. 



• Re-identification samples are randomly chosen (1 out of 10) on a regular basis 



• Accuracy will be calculated as: 



Total # of organisms in QC recount -Total # of errors x 100 

 Total # of organisms in QC recount 

 where errors include: 



Counting error (e.g., counting 11 of a given species instead of 10) 

 Identification error (e.g., misidentifying species X as species Y) 

 Unrecorded taxa errors (e.g., not identifying species X when it is present) 



• Actions for unsatisfactory level of taxonomic accuracy: 



90-95% - Original technician advised, species identifications reviewed, and any changes to species 

 identifications recorded on original data sheet. 



< 90% - Same as for 90-95% but numerical counts should also be corrected on original data sheet. 



• Maintain voucher specimen collection and permanent undegraded collection. 



3-13 



