Appendix E: Field Scientist Report 



destination in Costa Rica and then College Station, Texas, samples were stored frozen in Texas 

 until analysis. 



In a few countries or locations where there were no local contacts, the access to the pre- 

 selected sampling locations was either by rented car or public transportation and sampling was 

 completed with the assistance of local fishermen. In these cases, the samples were processed on 

 combusted aluminum foil in the hotel and kept in the freezer of the hotel restaurant or a local store 

 with freezer until ready to move them to a new sampling location or transported back to Costa 

 Rica. 



During this initial phase, no geographic location data was recorded. In the future, the IMW 

 Field Scientist should be supplied with hand-held GPS instrumentation to systematically record the 

 location of each site. 



Sample Collection 



Bivalves were collected by hand, with tongs or using a small hand-held dredge. Inter tidal 

 and shallow subtidal sites were collected by hand. Because of the large area covered in this study, 

 bivalves were found to be attached to rocks, attached to the roots of mangroves, buried in the mud 

 or in the sand or simply lying on hard to medium-soft bottom. At deeper subtidal sites, bivalves 

 were collected with the help of local divers. In a few cases were the direct access to the sampling 

 area was not possible, the sample was obtained from commercial oyster fishermen. Clumps of 

 bivalves were separated in individual organisms before cleaning. Bivalves were separated from 

 attached debris and/or mud and washed "in situ" before shucking them in the laboratory. In 

 locations where more than one species of bivalves were present, i.e. none of the bivalves was 

 obviously dominant, samples of the different species were collected. This allowed not only for a 

 species inter comparison at a given site but also to compare sites where only one of the species is 

 present. 



Sample Processing 



In general, samples were processed the same day they were collected. As samples were 

 collected, they were cleaned, labeled according to site, station and replicate and kept in ice chests 

 until ready to be processed in the laboratory later in the day. An effort was made to collect pooled 

 organisms within the same size range. This was done with the intention to assure that pooled 

 organisms were of similar age. Since the decision was to collect sufficient sample from each site, 

 e.g. 200 to 300 grams of wet tissue per station (up to 900 grams of wet tissue per site), to allow 

 for re-analyses of a sample if necessary, the number of pooled organisms in each sample varied 

 with organism size. In all but one site, the number of pooled organisms per sample was 10 or 



