ADDITIONAL STUDIES OF THE FISHES, 



MACROINVERTEBRATES, AND HYDROLOGICAL CONDITIONS OF 



UPLAND CANALS IN TAMPA BAY, FLORIDA 



William N. Lindall, Jr./ William A. Fable, Jr.,^ and L. Alan Collins^ 



ABSTRACT 



Hydrological and biological data from a concluding study of upland canals in Tampa Bay, Fla., are 

 presented and compared with those collected the previous year. Critically low levels of dissolved 

 oxygen occurred more frequently and over a longer pyeriod of time in the second year. Most affected were 

 the inland portions of the canal system where the number of species declined markedly over the 

 previous year. Impoverishment of fauna on or near the bottom is expected to recur during summer 

 months because of oxygen depletion resulting from a combination of continuing accumulation of 

 decomposing organic sediment, warm water, and little circulation in the dead-end canals. 



In order to create waterfront property while not 

 violating legislation that curtails dredging and 

 filling of wetlands below the mean high-water 

 line, land developers in Florida and elsewhere are 

 digging access canals that lead from open water to 

 upland acreage (Barada and Partington 1972). 

 Florida's shoreline has already been extensively 

 altered by such practice (McNulty et al. 1972), 

 and further alteration can be expected because of 

 ever-increasing demand for waterfront property. 

 If the coastal zone is to be managed wisely, infor- 

 mation on the suitability of these man-made 

 waterways as habitat for aquatic organisms is 

 urgently needed. 



In June 1970 a small, upland canal system in 

 Old Tampa Bay, Fla., was completed (Figure 1). 

 This offered a unique opportunity to study the 

 development of and changes in ecological condi- 

 tions in upland canals. The fishes, macroinverte- 

 brates, and hydrological conditions occurring in 

 the canals during the first year following 

 completion of the system were described by 

 Lindall et al. (1973). In that study, however, the 

 unusual occurrence of red tide (caused by 

 Gymnodinium breve) and drought produced 

 conditions that were atypical for the area. 

 Conditions during our second year were more 

 typical. Further studies by us are unlikely owing 

 to closure of the laboratory at St. Petersburg 



'Environmental Assessment Division, National Marine 

 Fisheries Service, NOAA, St. Petersburg, PL 33702. 



^Gulf Coastal Fisheries Center, National Marine Fisheries 

 Service, NOAA, Port Aransas, TX 78373. 



^Gulf Coastal Fisheries Center, National Marine Fisheries 

 Service, NOAA, Panama City, FL 32401. 



Manuscript accepted February 1974. 

 FISHERY BULLETIN: VOL. 73, NO. 1, 1975. 



Beach and relocation of personnel. Thus, we pre- 

 sent the results from our follow-up study in this 

 paper. We discuss the hydrological conditions 

 and biota found in the canals during the second 

 year and make comparisons with those found in 

 the first year. 



STUDY AREA AND METHODS 



The study area, known as Tanglewood Estates, 

 is located on the southwest shore of Old Tampa 

 Bay in northeast St. Petersburg, Fla. (Figure 1). 

 Development of the canal system, sampling 

 procedures, sampling gear, and station descrip- 

 tions were reported previously (Lindall et al. 

 1973). Briefly, sampling consisted of trawling at 

 each station in the canals with concomitant 

 measurements of temperature, salinity, and 

 oxygen. Sampling was conducted monthly from 

 October 1971 through September 1972. 



TEMPERATURE 



Water temperatures at the control and canal 

 stations are shown in Figure 2. At the control 

 station (Station 1) surface and bottom tempera- 

 tures ranged from 20.0° to 29.3°C and were nearly 

 identical in any one sampling period. The greatest 

 difference was in December when the bottom was 

 1.1°C higher than the surface. Canal stations 

 showed greater temperature ranges than the con- 

 trol station. They ranged from 20.0° to 30.6°C at 

 the surface and 17.8° to 29.7°C at the bottom. With 

 few exceptions, water temperature at the bottom 



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