LINDALL, HALL, and SALOMAN: CONDITIONS OF LTPLAND CANALS 



Table 4. — Monthly occurrence and number of individuals of vertebrates and invertebrates collected with otter trawl 

 at Station 2 from August 1970 through August 1971. No individual collected in August 1970 and in July and 

 August 1971. 



at least 13 of 21 species of fishes collected bj' 

 trawl may be considered bottom feeders. Based 

 ■on these data, it appears that new upland canals 

 provide a better habitat for fishes than do much 

 older bayfill canals in the sense that the former 

 support greater abundance of species and indi- 

 viduals. 



Undoubtedly, the lack of fish in the canals 

 of Tanglewood Estates during the last 2 months 

 of the study was due in part to eflfects of the 

 red tide. Decomposition of the dead fish in- 

 creased oxygen demand on the system during 

 this period, but decline in dissolved oxygen in 

 April and May and corresponding decline in the 

 number of species and individuals indicated the 

 system was deteriorating prior to the red tide 

 outbreak. Our continued study will determine 

 to what degree the system is stressed by low 

 summer oxygen in the absence of red tide. 



Others working in the Tampa Bay system have 

 reported low bottom oxygen in areas of poor 

 water circulation and soft sediment. Dragovich, 

 Kelly, and Finucane (1966) recorded less than 

 2 ml/liter in June and August from a dredged 

 location in central Boca Ciega Bay. In dredged 

 and undredged areas of Hillsborough Bay, re- 

 duced oxygen near the bottom is common during 

 the summer. There, the lack of dissolved oxygen 

 has been attributed to sludge deposited from 

 sewage, as well as high water temperature and 

 poor water circulation (Saloman, Finucane, and 

 Kelly, 1964; U.S. Federal Water Pollution Con- 

 trol Administration, Southeast Region, 1969). 

 A similar condition is shared by older upland 

 canals throughout south Florida (Barada and 

 Partington, 1972) and certain housing develop- 

 ment canals in Texas (see footnote 4). Oxygen 

 depletion in all of these areas is the result of poor 



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