碩士 / 國立臺灣海洋大學 / 水產養殖學系 / 98 / Abstract
In order to increase feed intake and avoid cannibalism in the indoor Grouper nursery cultures, cage were placed in the indoor nursery pools. This act caused cut-off of water flow that feces could not be gotten of from bottoms, and more manpower and time was required to change the water and clean the bottoms. Aiming to improve culture techniques, save manpower and time, this experiment attempted to use air lift style feces collectors to solve the problems. On the other hand, according to the nursery procedures we designed and years of experiences in rearing the larvae, this method of frequent and large scale water change contradicted with the principle of the recirculation system theory, in which minimal water change was necessary to stabilize the nitrifying bacteria in the biological filter beds. Therefore, the concentration changes of the water ammonia nitrogen (N), nitrite-N, and nitrate–N were monitored during experiments to know the effects of the biological filter bed on water quality.
The first experiment was designed to and test the apparatus. After 3 improvements, the traction of air flow succeeded in bringing out the feces and residue feed from the bottoms of the feces collectors. As the feces were collected in the boxes, 72 hours experiments were proceeded to compare the feces collection capacity of this apparatus. The results indicated that the feces collecting capacity of this apparatus was better than that of the control set with hanged nets during the first 24 hours with regular removal of collected feces at 2 hour intervals.
The second experiment is to compare the water quality parameter differences between systems with or without feces collecting apparatus. To start with, the base lines of two sets of systems (both without apparatus) were tested for 72 hour fixed amount of feed. The sum of feed in the 1st day was 420g--3% of the total biomass. The feeding was conducted only at the 1st day and water was changed after 72 hours. The results indicated the concentrations of ammonia-N, nitrite-N and nitrate-N in both systems (A & B) were similar and there were obvious decrease in ammonia-N after the stop-feed at the 1st day.
After the base line testing , then the experiments of feces collector effects on water quality were conducted. Three experiments were set for: 24 hour feed to satiation (150g/5 times/day), 48 hour fixed quantity feed (70g/2 times/day) and 72 hour fixed quantity feed (140g/2 times/day). The biomass was 7kg (for 24 hr and 48 hr) and 14kg (for 72 hr) respectively. In the 24 hr experiment, the ammonia-N conc. in B system (without feces collector) was above twice as much as that in the A system (with apparatus). In the 48 hr experiments, the conc. of suspended matter and ammonia-N in B system was higher than in A system, there were no obvious differences in the conc. of nitrite-N and nitrate-N, while the total bacteria count in A system was lower than in B system. In the 72 hr experiments, the ammonia-N conc. in B system was higher than in A system especially in the peak periods of 16 hr, 40 hr and 56 hr., the nitrite-N conc. of B system was higher than in A system during the earlier period from 0 to 32 hr., the nitrate-N conc. of B system was higher than in A system between 16 to 48 hr., the total bacteria count in B system was higher than in A system between 16 to 48 hr., and the conc. of suspended matter in B system was higher than in A system before 48 hr—yet got closer in concentration afterwards.
Throughout the experiments, there were no disease outbreak for the fishling in both A and B system and the water quality in A system (with feces collector) were better than in B system. The results of each water quality parameters indicated that this collecting apparatus could effectively remove feces and residue, and attained the function of helping clarify the water system. However, the collected feces had to be removed frequently during operation so that the clarifying effects would be decreased due to losing the feces by the flush of water in the apparatus. To generalize the concentration changes of ammonia-N, nitrite-N and nitrate-N in both systems, it was founded frequent water change and large-scaled feed would have bad influence on the stability of the micro flora in the biological filter bed, also caused the nitrite-N to accumulate in a short period. Therefore, after proper adjusting the feed (to 2% of the total biomass), the biological filter bed could be stabilized to remove the extra nitrite-N after 4 to 5 days.
| Identifer | oai:union.ndltd.org:TW/098NTOU5086106 |
| Date | January 2010 |
| Creators | Chao-Tse Yanz, 楊兆喆 |
| Contributors | Chyng-Hwa Liou, Yuan-Nan Chu, 劉擎華, 朱元南 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 121 |
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