long time. The mechanism behind this transport is also important, 

 as is the possibility that effects observed in the benthos (and 

 elsewhere) can propagate through the system. It is clear that all 

 aspects of the environment must be considered, with adequate concern 

 for the less visible aspects of the spill. 



Attention cannot arbitrarily be directed toward commercial 

 species, endangered species, or other aspects of the environment 

 that may reflect changeable social values at the time. Social 

 values determine what aspects are of greatest interest and are 

 perhaps a significant focus of the study, but only the investigative 

 team can determine which, sometimes subtle, parameters should be 

 measured. Some examples illustrate this: 



o Often the effects on highly mobile species (however 

 important commercially or aesthetically) are hard to 

 demonstrate because of the difficulty of resampling the 

 same individuals or knowing well enough what they have 

 been exposed to. However, effects may be similar to 

 those observable in sessile or less mobile species. This 

 may have been the case with bottom fish as opposed to 

 herring, 

 o The characteristics of various organisms can make them 



good or poor indicators of various factors. The benthic 

 macrofauna species, Ma coma balthica , are the easiest to 

 sample and analyze, and they are characteristically 

 resistant to damage; this makes them excellent biological 

 indicators of the level of "insult" to the benthic 

 community because they stay alive long enough to repre- 

 sent possibly high concentrations or repeated exposures 

 (Shaw et al., 1976). Their use alone, however, would 

 lead to the erroneous conclusion that effects were slight 

 although concentrations were high. By looking also at 

 the more sensitive meiofauna and the crustacean macrofauna, 

 as was done in the Tsesis study, significant effects 



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