LINDALL, FABLE, and COLLINS; CONDITIONS OF UPLAND CANALS 



lively). We were not surprised to find fewer species 

 at Stations 2 and 3, because these stations are 

 farthest from the bayou and were most affected by 

 the critically low oxygen levels. As evidence, 

 catches at the four trawl stations during the sum- 

 mer period of low dissolved oxygen (July- August) 

 are compared in Figure 5. The vast majority of 

 species and individuals occurred nearest the 

 bayou (Stations 1 and 4) during this period of 

 stress. 



2 3 



STATIONS 



Figure 5. — Number of species and individuals caught at each 

 trawl station during the summer period of low dissolved oxygen 

 (June through August 1972). 



CONCLUSIONS 



The upland canal system known as Tanglewood 

 Estates is poorly designed with respect to provid- 

 ing year-round, quality habitat for estuarine 

 species offish and shellfish. Apparently caused by 

 prolonged periods of low dissolved oxygen at the 

 bottom of the canals, the numbers of squid 

 {Lolliguncula breuis) and three species of finfish 



(Eucinostomus argenteus , E. gula, and 

 Leiostomus xanthurus) were drastically reduced 

 in the second year of the system's existence. We 

 believe that the ability of the canal system to pro- 

 vide adequate oxygen for respiration of bottom- 

 dwelling fishes is becoming progressively worse. 

 The main causative factors are: 1) lack of water 

 exchange with the adjacent bayou, 2) water 

 depths greater than the depth of the photic zone, 

 thus preventing photosynthesis by benthic flora, 

 and 3) continuing accumulation of decomposing 

 soft sediments (Hall and Lindall'*). 



The major advantages of upland canal develop- 

 ment, as opposed to bayfill development, are that 

 bay bottom is not adversely altered and water 

 circulation patterns are not altered significantly. 

 In fact, estuarine area is increased. However, as 

 long as land developers continue to design upland 

 canals with dead ends and excessive depths, ox- 

 ygen depletion and the resulting impoverishment 

 of fauna on or near the bottom can be expected to 

 be a recurring problem in summer months. 



LITERATURE CITED 



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



1972. Report of investigation of the environmental effects 

 of private waterfront canals. Environ. Inf. Cent. Fla. 

 Conserv. Found., Winter Park, Fla., 63 p. 



Carr, W. E. S., and C. a. Adams. 



1973. Food habits of juvenile marine fishes occupying 

 seagrass beds in the estuarine zone near Crystal River, 

 Florida. Trans. Am. Fish. Soc. 102:511-540. 



Darnell, R. M. 



1958. Food habits of fishes and larger invertebrates of 

 Lake Pontchartrain, Louisiana, an estuarine community. 

 Publ. Inst. Mar. Sci., Univ. Tex. 5:353-416. 

 LiNDALL, W. N., Jr., J. R. Hall, and C. H. Saloman. 



1973. Fishes, macroinvertebrates, and hydrological condi- 

 tions of upland canals in Tampa Bay, Florida. Fish. Bull., 

 U.S. 71:155-163. 

 McNuLTY, J. K., W. N. Lindall, Jr., and J. E. Sykes. 



1972. Cooperative Gulf of Mexico estuarine inventory and 

 study, Florida: Phase I, area description. U.S. Dep. Com- 

 mer., NOAA Tech. Rep. NMFS CIRC-368, 126 p. 

 Springer, V. G., and K. D. Woodburn. 



1960. An ecological study of the fishes of the Tampa Bay 

 area. Fla. State Board Conserv., Mar. Lab., Prof. Pap. Ser. 

 1, 104 p. 

 Trent, W. L., E. J. Pullen, and D. Moore. 



1972. Waterfront housing developments: their effect on 

 the ecology of a Texas estuarine area. In M. Ruivo (editor). 

 Marine pollution and sea life, p. 411-417. Fishing News 

 (Books) Ltd., Lond. 



■'Hall, J. R., and W. N. Lindall, Jr. Benthic macroinvertebrates 

 and sedimentology of upland canals in Old Tampa Bay, Fla. 

 Unpubl. manuscr., 121 p. Gulf Coastal Fisheries Center, Na- 

 tional Marine Fisheries Service, Panama City, FL 32401. 



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