FISHERY BULLETIN: VOL, 71, NO, I 



Table 5. — Monthly occurrence and number of individuals of vertebrates and invertebrates collected with otter trawl 

 at Station 3 from August 1970 through August 1971. No individual collected in July and August 1971. 



circulation, accumulation of soft, organically rich 

 sediments, and storm-water runoff from residen- 

 tial and agricultural areas. 



Developers in the Tampa Bay area could re- 

 duce these problems in future projects through 

 better design of canal systems. This would in- 

 volve: (1) elimination of dead-end canals and 

 (2) limiting depths to the euphotic zone approx- 

 imately 1.5 m (5 ft) below mean low water. A 

 flow-through system without deadends would in- 

 sure better tidal exchange and circulation. Also, 

 by limiting depths to approximately 1.5 m below 

 mean low water, the canals probably would not 

 serve as silt traps as readily as deeper canals, 

 and stratification of the water column would be 

 eliminated. In addition, light penetration would 

 occur throughout the water column thereby al- 

 lowing oxygen production through photosyn- 

 thesis by benthic algae and diatoms. 



Elimination of dead-end canals and limiting 

 depths to the photic zone will not necessarily 



insure adequate flushing, however. A major 

 factor that must be taken into account is water 

 exchange through tidal action. Tidal range in 

 most of Florida is very small, varying from 0.3 m 

 to about 1.0 m, and will provide adequate water 

 exchange in canals only short distances from the 

 shoreline. Our data show serious oxygen deple- 

 tion in the deep, dead-end canals only 150 m in- 

 land of the shoreline (Station 6). A safe dis- 

 tance for shallower, flow-through canals can best 

 be determined by an environmental engineer 

 knowledgeable of the tidal range and circulation 

 patterns adjacent to the upland to be developed. 



LITERATURE CITED 



Barada, W., and W. M. Partington. 



1972. Report of investigation of the environmental 

 effects of private waterfront canals. Environ- 

 mental Information Center of the Florida Conser- 

 vation Foundation, Inc., Winter Park, Fla., 63 p., 

 appendices. 



162 



