IV-418 



of grasses and other vegetation requiring much sunlight. No life 

 was found at locations above the Miami River mouth in areas near 

 sewage outfalls, and there was a zone in mid-bay containing no 

 fixed vegetation. 



The softest sediments were found along the Miami shoreline just 

 north of the Miami River mouth. Soft sediments also occurred in 

 mid-bay with harder sediments along the shores of Miami and Miami 

 Beach where the currents are stronger. 



The oxygen consumption of the sediments was highest in the softest 

 sediments just north of the Miami River mouth, in the northwestern 

 portion of the bay, and in the deep water south of the Miami River 

 mouth. These zones were relatively deep, had poor bottom circula- 

 tion and were zones of major deposition of organic-rich material. 



Both harmful and fertilizing effects were observed in Biscayne 

 Bay. The harmful effects were indicated by the absence of life. 

 These areas were within 200 yearss of sewage outfalls, were greater 

 than average depth and had soft, sticky mud with high amounts of 

 oxidizable organic matter. The fertilizing effects were most 

 pronounced in areas 200 - 600 yards from outfalls in shallow water 

 with good tidal circulation in firm sandy mud. Species associations 

 within definite communities were found to be indicative of both 

 the harmful and fertilizing effects (IV-5-10). 



