FISHERY BULLETIN: VOL. 80, NO. 2 



ment District (SFWMD) (unpubl. data). Tem- 

 perature and dissolved oxygen measurements 

 were taken at 0.3 m and 1.0 m depths. The aver- 

 age of two or three readings represent one mea- 

 surement. The average number of measurements 

 was two to three per month at each station. Data 

 of hydrogen ion concentration expressed as pH 

 were obtained from the Dade County Depart- 

 ment of Environmental Resources Management 

 (DERM) and USGS (unpubl. data). 



DERM and USGS obtained routine monthly 

 water quality data for Black Creek, Mowry, and 

 Moody Canals downstream from salinity struc- 

 tures and made them available for this study. 

 The DERM laboratory also made water quality 

 analyses of eight southeast Biscayne Bay water 

 samples collected at intervals of 2 mo. The sam- 

 ples, taken from slick-free water (see Discussion 

 section), were kept in plastic bottles which con- 

 tained a few milliliters of hydrosulfuric acid for 

 preservation, and were refrigerated until arrival 

 in the laboratory. Chemical analyses were made 

 for total ammonia nitrogen, nitrite, nitrate, phos- 

 phate, and total organic carbon. DERM and 

 USGS furnished data on heavy metals in Black 

 Creek and Mowry Canals and pesticides in Black 

 Creek Canal. 



Fish were kept alive in an aerated plastic con- 

 tainer until arrival and dissection at the labora- 

 tory. Body surface, fins, gills, gill covers, and 

 mouth were searched for parasites; the gill 

 arches and single parasites fixed and preserved; 

 and the parasites identified and counted. When 

 parasites were too numerous for total counts, 

 estimations of numbers per gill arch were made 

 from counts per gill filament. Formalin, 2 AFA 

 (alcohol-formol-acetic acid) fixative, and Bouin's 

 solution were used to fix whole gill arches and 

 trematodes. They were preserved in 70%ethanol. 

 For the purpose of identification whole mounts 

 were made of Trematoda using Harris hema- 

 toxylin and Permount. Whenever possible, origi- 

 nal descriptions of parasites were used for identi- 

 fication together with Yamaguti's (1963, 1971) 

 keys for identification of trematode genera. His- 

 tological sections of 12 entire gill arches from 12 

 fish were examined. Arches were decalcified 

 prior to embedding and cut at 8 /xm. Sections 

 were mounted, stained with hematoxylin and 

 eosin (H&E) and Periodic Acid Schiff (PAS). 

 Histological techniques were after the method 



described by Humason (1972). Statistical evalua- 

 tion of all station salinity data consisted of calcu- 

 lations of standard deviation (Snedecor and 

 Cochran 1967). 



RESULTS 



Water Quality 



Variations in salinity occur in Biscayne Bay 

 from year to year because of climatic conditions. 

 The salinity readings of all stations were similar 

 during the dry season of 1976, mainly January to 

 June (Table 2). Maximum salinities in both the 

 bay and canal entrances were 40-417.. at this 

 time. More freshwater discharge into the canals 

 and Biscayne Bay during the rainy season in the 

 fall accounted for a slight drop in salinity and 

 some fluctuation mainly in the canals at that 

 time. The lowest salinity reading from surface 

 water samples from the entrance of Moody Canal 

 in September indicated that freshwater dis- 

 charge was more noticeable in this narrow canal 

 than in the others. Some salinity measurements 

 were taken immediately after freshwater dis- 

 charge (see Table 2, footnotes). A typical reading 

 showed that the fresh water flowed as a shallow 

 surface layer about 30 cm deep out of the canals. 

 During freshwater discharge, salinity at the sur- 

 face varied from 57.. to 157..; at a depth of 30 cm it 

 rose by 15-207.., and at a depth of 1 m it was close 

 to the reading before the discharge, indicating 

 that there was little vertical mixing. 



The statistical analysis of monthly averages of 

 salinity data of all stations of 1.0 m depth showed 

 that two-thirds of the values fell within one stan- 

 dard deviation of 1.85 on each side of the mean of 

 36.87... Temperatures reflected seasonal changes 

 at all stations and were similar, with most values 

 between 20° and 30°C (Table 2). Differences may 

 reflect the time of day when readings were 

 taken. Dissolved oxygen concentration fluctuated 

 mainly at canal entrances. Values ranged from 4 

 ppm to above 8 ppm (Table 2). Values below 6.8 

 ppm did not occur in southeast Biscayne Bay. 



Phosphates, ammonia, nitrites, and nitrates 

 present at the collection sites from May 1975 to 

 August 1976 are listed in Table 3. The southeast 

 Biscayne Bay water quality data were similar to 

 those of de Sylva 3 and Bader and Roessler 4 . In 

 general, southeast bay values were low in all 



2 Reference to trade names does not imply endorsement by 

 the National Marine Fisheries Service, NOAA. 



3 de Sylva, D. P. 1970. Ecology and distribution of post- 

 larval fishes in southern Biscayne Bay, Florida. Univ. Miami 



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