The International Mussel Watch 



1. Collection Methods 



1.1 Sampling Sites 



Samples will be obtained from pristine areas away from any obvious sources of local 

 contamination, from agricultural region, and from the outer estuaries of major river systems which 

 may drain regions receiving inputs from both agriculture and industry. Sampling from estuarine 

 areas undergoing major salinity variations will be avoided. 



1.2 Seasonality 



It is recognized that seasonal changes in bivalve physiology can lead to variations in 

 chlorinated hydrocarbon content and concentration. However, in cases where these effects have 

 been studied (Phillips, 1980), chlorinated hydrocarbon concentration rarely varies more than a 

 factor of 2 to 5. Since order of magnitude differences in chlorinated hydrocarbon concentrations 

 are sought for, the spatial trend analysis, seasonality effects are considered to be of minor 

 importance. Therefore, we do not feel it necessary to sample during any particular season, 

 particularly in the tropical and subtropical regions where trickle spawning is common. 



1.3 Depth 



At bivalve sites, depth to bottom will be estimated. 



1.4 Position on shoreline 



Bivalve samples should be collected as low on the tidal horizon as possible. Time of 

 collection, time of high or low water for the day, and the tidal reference location are recorded on 

 the Bivalve Sampling Position or Bivalve Observations Logs. 



The tidal horizon is estimated most accurately at the time of low water for that day. 



1.5 Temperature 



Bottom water temperature will be measured to 0.1 degree at each bivalve sampling site. 

 Temperature may be measured with a portable digital thermometer or calibrated glass mercury 

 thermometers. 



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