IV-355 



including mullet, mackerel, oysters, clams, and mussels 

 (Figure IV. 5. 4). 



Another source of tainting substances directly related to organic 

 waste discharges can develop when some areas the receiving waters 

 reach septlcity, i.e., all of the dissolved oxygen is depleted. 

 Under such anaerobic conditions the decay of the benthic sludge deposits 

 can result in the production of hydrogen sulfide, which has a very 

 strong "rotten egg" odor. This gas, highly soluble in water, causes a 

 black discoloration of bivalve shells and imparts an offensive taste 

 and odor to their flesh when water carrying it moves across shellfish 

 beds. 



HEAVY METALS 



The heavy metal salts are fairly soluble and stable 1n solution. 

 Consequently, they will persist for extended lengths of time. Many 

 of these are highly toxic to the aquatic biota. Since many marine 

 organisms accumulate and concentrate substances within their cell 

 structure, the presence of these metals in small concentrations can 

 have deleterious effects. Table IV. 5.1 lists the more common metals 

 that are of environmental concern (IV-5-1). 



The toxic concentrations listed in the table represent the lowest 

 values for the particular species tested and not absolute minimums. 

 Also, these toxic levels do not consider the synergistic effect that 



