Appendix E: Field Scientist Report 



until ready to be moved to a new sampling site or transported back to Costa Rica. If previously 

 arranged contacts with local scientists cannot be made, the Field Scientist should travel with a 

 companion for assistance and personal security in remote areas. 

 Variety of species 



Because of the large area covered by this study, it was not possible to sample the same 

 species of bivalves at every location. As a result, a number of different species had to be sampled. 

 In those locations where no species was obviously the dominant one, a sample of every species 

 encountered in the site was collected. This will allow for a inter-comparison among the different 

 bivalves and will provide valuable information when comparing different locations where only one 

 of the species is present. 



Sampling Summary 



Six sampling missions operated out of Costa Rica and one sampling mission operated out 

 of College Station, Texas. Following is a brief description of the sampling missions (sampling 

 date in parenthesis), location characteristics and possible sources of contaminants as observed by 

 the Field Scientist. The order of the following descriptions is chronological, following the actual 

 schedule of the sampler. Samples collected were numbered sequentially with a unique 4-digit 

 identification code as they were collected. A summary of the EMW sample collection is found in 

 Appendix A. 



In general, duplicate samples were collected from 3 different stations within each site. 

 Distances between stations varied from 500 to 1000 meters. Total wet weight tissue per station 

 was between 200 and 300 grams in 2 replicate samples and total wet weight of tissue per site is 

 approximately 600 to 900 grams. When conditions did not allow for the sampling of 3 different 

 stations within each site, duplicate samples from only 1 or 2 stations were collected. In instances 

 where more than one species was present, all of them were sampled in order to allow for species 

 inter comparisons that might assist in comparing areas where only one of these species is present. 

 Photographs of the locations/stations were taken to document the area for further sampling efforts. 

 Shell samples from each location were kept for a later confirmation/identification of the species. 

 Frozen samples were transferred to San Josd, Costa Rica. 

 1st IMW Sampling Mission: Argentina and Uruguay 



Bivalve samples from 9 pre-selected sites in Argentina and 2 in Uruguay were collected 

 between November 13 and December 5, 1991. 

 ARGENTINA 



Hudson (11/17/91). Hudson is located about 45 km to the southeast of Buenos Aires city. 

 Approximate travel time was 1:15 h. At this site 3 duplicate samples (Corbiculafluminea) were 

 collected. 



