- Email: [email protected]
Effects of inflow water quality on living conditions in cyprinid fish ponds
394
Abstracts /Aquaculture I29 (1995) 391-395
each 1 m diam. and 2 m high, were suspended in a pond (27 X 6 X 1.5 m deep) with their bases embedded in the sediment, inside a double-skin UVI polyethylene greenhouse located in Central Scotland ( WN) . Two isonitrogenous doses - a high level (H) of 14 and a low level (L) of 7 kg N/ha/week - of matured chicken and cow manure (coded P and C, respectively) were tested in a triplicated randomised experimental design. The organic matter, total nitrogen and phosphorus contents (% dry wt.) of the cow manure were 75.4,2.6 and 2.8%, respectively, with corresponding values for the chicken manure of 84.0, 2.2 and 3.8%. Each mesocosm was stocked after 1 week with 5 ca. 21 g Cyprinus carpio, each individually tagged with alcian blue. During a 6-week trial in SeptemberOctober 1991, water temperature dropped from 24 to 12”C, pH range was 6.0-7.3 and D.O. rose from 1.8 to 4.7 mg/l (22 to 47% saturation). All forms of inorganic N and P were significantly higher (P I 0.05) in treatment PH, followed by CH and PL, with lowest nutrient levels in CL. Chlorophylla responded similarly, with significantly different means of 19.8,17.1,10.6 and 8.4 ,ug/l in treatments PH, CL, PL and CL, respectively. Phytoplankton was dominated by Chlorophyceae and Cyanophyceae, with significantly higher total abundance at high N doses (10.6$0.80 SEX lo’/1 compared with 6.0 k 44 X lo’/1 at low doses; P < 0.001). High N doses produced significantly more crustacean zooplankton (4070 f 730 and 3330 +630/l of Daphnia, Bosmina and Cyclops spp. with PH and CH, respectively-different at P I 0.01) than at low N doses (2390 + 500/l). Fish weight specific growth rate responded similarly to N dose, being significantly higher in PH and CH (0.82 f 0.11 and 0.57 kO.O83%/day) than in PL and CL (0.41OkO.035 and 0.25 +O.O4l%/day, respectively; P< 0.001). Daily fish production was equivalent to 9.6,8.4,5.4 and 3.2 kg/ha in treatments PH, CH, PL and CL, respectively. Thus nitrogen input is the main determinant of primary, secondary and fish production, although chicken is more effective than cow manure on an isonitrogenous basis. These results illustrate the value of mesocosms as a low-cost method for factorially designed trials of pond inputs.
Effects of inflow water quality on living conditions in cyprinid fish ponds V.V. TutundW, L.B. VidmaniC, V.D. PoleksiC Department
of Animal Breeding, Faculty of Agriculture, Nemanjina 6, 11080 Zemun-Belgrade, Yugoslavia
In order to study the cause of decrease in fish yield per unit area in spite of increased food consumption, physical, chemical and biological parameters of four cyprinid fish ponds, receiving moderately to heavily polluted inflow waters were investigated. It was found that although for most chemical parameters pond water was still within the range suitable for fish production, quite often organic matter, ammonia and inorganic phosphorus content were higher, while nitrate content was low. COD content was 25.45-88.45 ppm, PO, 0.07-0.586 ppm and NO3 O-1.54 ppm. In bottom sediments, negative values of redox potential predominate, which indicates anaerobic conditions and the possibility of water pollution from the pond bottom. During the study period, primary production of phytoplankton was high, but secondary production of both zooplankton and bottom fauna was low. Values for total zooplankton biomass in all ponds except one varied from 0.006 to 14.564 mg/l due to dominance of small forms. Bottom fauna was mainly represented by Oligochaeta, and in the second half of the rearing season, its abundance and biomass drastically decreased. It can be concluded that plankton composition and the decrease in bottom fauna diversity and abundance correspond to the
Abstracts/Aquaculture
129 (1995) 391-395
395
degree of water and bottom sediment quality degradation. Deterikation of a water chemical regime leads to morphological changes and parasitic invasion of fish respiratory organs. Examination of gill morphology has shown that besides normal structure, changes were present.
Abstracts /Aquaculture I29 (1995) 391-395
each 1 m diam. and 2 m high, were suspended in a pond (27 X 6 X 1.5 m deep) with their bases embedded in the sediment, inside a double-skin UVI polyethylene greenhouse located in Central Scotland ( WN) . Two isonitrogenous doses - a high level (H) of 14 and a low level (L) of 7 kg N/ha/week - of matured chicken and cow manure (coded P and C, respectively) were tested in a triplicated randomised experimental design. The organic matter, total nitrogen and phosphorus contents (% dry wt.) of the cow manure were 75.4,2.6 and 2.8%, respectively, with corresponding values for the chicken manure of 84.0, 2.2 and 3.8%. Each mesocosm was stocked after 1 week with 5 ca. 21 g Cyprinus carpio, each individually tagged with alcian blue. During a 6-week trial in SeptemberOctober 1991, water temperature dropped from 24 to 12”C, pH range was 6.0-7.3 and D.O. rose from 1.8 to 4.7 mg/l (22 to 47% saturation). All forms of inorganic N and P were significantly higher (P I 0.05) in treatment PH, followed by CH and PL, with lowest nutrient levels in CL. Chlorophylla responded similarly, with significantly different means of 19.8,17.1,10.6 and 8.4 ,ug/l in treatments PH, CL, PL and CL, respectively. Phytoplankton was dominated by Chlorophyceae and Cyanophyceae, with significantly higher total abundance at high N doses (10.6$0.80 SEX lo’/1 compared with 6.0 k 44 X lo’/1 at low doses; P < 0.001). High N doses produced significantly more crustacean zooplankton (4070 f 730 and 3330 +630/l of Daphnia, Bosmina and Cyclops spp. with PH and CH, respectively-different at P I 0.01) than at low N doses (2390 + 500/l). Fish weight specific growth rate responded similarly to N dose, being significantly higher in PH and CH (0.82 f 0.11 and 0.57 kO.O83%/day) than in PL and CL (0.41OkO.035 and 0.25 +O.O4l%/day, respectively; P< 0.001). Daily fish production was equivalent to 9.6,8.4,5.4 and 3.2 kg/ha in treatments PH, CH, PL and CL, respectively. Thus nitrogen input is the main determinant of primary, secondary and fish production, although chicken is more effective than cow manure on an isonitrogenous basis. These results illustrate the value of mesocosms as a low-cost method for factorially designed trials of pond inputs.
Effects of inflow water quality on living conditions in cyprinid fish ponds V.V. TutundW, L.B. VidmaniC, V.D. PoleksiC Department
of Animal Breeding, Faculty of Agriculture, Nemanjina 6, 11080 Zemun-Belgrade, Yugoslavia
In order to study the cause of decrease in fish yield per unit area in spite of increased food consumption, physical, chemical and biological parameters of four cyprinid fish ponds, receiving moderately to heavily polluted inflow waters were investigated. It was found that although for most chemical parameters pond water was still within the range suitable for fish production, quite often organic matter, ammonia and inorganic phosphorus content were higher, while nitrate content was low. COD content was 25.45-88.45 ppm, PO, 0.07-0.586 ppm and NO3 O-1.54 ppm. In bottom sediments, negative values of redox potential predominate, which indicates anaerobic conditions and the possibility of water pollution from the pond bottom. During the study period, primary production of phytoplankton was high, but secondary production of both zooplankton and bottom fauna was low. Values for total zooplankton biomass in all ponds except one varied from 0.006 to 14.564 mg/l due to dominance of small forms. Bottom fauna was mainly represented by Oligochaeta, and in the second half of the rearing season, its abundance and biomass drastically decreased. It can be concluded that plankton composition and the decrease in bottom fauna diversity and abundance correspond to the
Abstracts/Aquaculture
129 (1995) 391-395
395
degree of water and bottom sediment quality degradation. Deterikation of a water chemical regime leads to morphological changes and parasitic invasion of fish respiratory organs. Examination of gill morphology has shown that besides normal structure, changes were present.