C.F. Knud-Hansen, T.R. Batterson, and C.D. McNabb, Department of Fisheries and Wildlife, Michigan State University, East Lansing, Michigan, USA
1 October 1993, CRSP Research Report 93-56
Abstract Two grow-out experiments were conducted to evaluate the functional role of chicken manure for Nile tilapia, Oreochromis niloticus (L.), production in central Thailand. Experiment 1 examined the relationship between chicken manure input and net fish yield (NFY). Experiment 2 determined the value of chicken manure in providing tilapia particulate organic carbon, and/or dissolved inorganic carbon (DIC) for stimulating algal productivity. In both experiments supplemental urea and triple superphosphate (TSP) gave all treatments total nitrogen (N) and phosphorus (P) inputs of 28.0 kg/ha/week and 7.0 kg/ha/week, respectively.
Addition of chicken manure to inorganic fertilization did not enhance production of Nile tilapia. NFY in experiment 1 increased with decreasing manure loading, which corresponded to increasing TSP input. Regression analysis suggested that chicken manure-P was about 10% effective as TSP-P at increasing NFY. NFY was linearly correlated to net primary productivity (r2 = 0.62, P<0.001), which was linearly correlated to total alkalinity (r2 = 0.77, P<0.001). Treatment differences in alkalinity, community respiration or dissolved oxygen concentrations at dawn were not related to manure input. Simple economic comparisons discourage the purchase of chicken manure as a source of soluble N and P for increasing algal productivity in Thailand.
This abstract was excerpted from the original paper, which was published in Aquaculture and Fisheries Management 24:483-493, 1993.
Claude E. Boyd and David Teichert-Coddington, Department of Fisheries and Allied Aquacultures, Auburn University, Alabama 36849, USA
1 October 1993, CRSP Research Report 93-57
Abstract Two 1000 m2 ponds at the El Carao National Aquculture Center at Comayagua, Honduras were deoxygenated by treatment with sodium sulfite and cobalt chloride, and biological activity was suppressed by formalin and copper sulfate application. Wind speed and the change in dissolved oxygen concentration were monitored with a data logger system during reaeration period. Standard oxygen transfer coefficients were related to wind speed measured at 3-m height by the equation: KLa20 = 0.017X - 0.014; r2 = 0.882 where KLa20 = standard oxygen transfer coefficient at 20°C (h-1) and X = wind speed (m s-1). A method for computing pond reaeration rate from the standard oxygen transfer coefficient is presented.
This abstract was excerpted from the original paper, which was published in Aquacultural Engineering 11:121-131, 1992.
David R. Teichert-Coddington and Bartholomew W. Green, Department of Fisheries and Allied Aquacultures, and Alabama Agricultural Experiment Station, Auburn University, AL 36849-5419, USA
1 October 1993, CRSP Research Report 93-58
Abstract Water column respiration (WCR) was measured in dark BOD bottles for 2, 4 and 8 h intervals during 22 h periods in two 1000 m2 ponds stocked with Oreochromis niloticus at 1 m-2, and fertilized weekly with chicken litter at 750 kg total solids ha-1. Mean WCR ranged from a low of 0.39 mg l-1 for 8 h nocturnal intervals to a high of 0.62 mg l-1 for 2-h diurnal intervals. WCR was significantly influenced by daylight and time into the diurnal or nocturnal period when it was determined. Mean WCR was significantly greater during the day than during the night (P<0.01). During the day, 2 h incubation intervals resulted in significantly higher WCR than 4 h or 8 h intervals (P<0.01); length of incubation interval did not significantly influence nocturnal WCR (P>0.05). Higher WCR during the day and during short diurnal incubation intervals was attributed to greater availability of photosynthetic respiration substrate. Diurnal, diel, or nocturnal WCR could be best estimated by a single 2, 4 or 8 h incubation interval, respectively, beginning at 0800 h.
This abstract was excerpted from the original paper, which was published in Hydrobiologia 250:159-165, 1993.
Christopher F. Knud-Hansen, Ambutong K. Pautong Asian Institute of Technology, Agriculture & Food Eng. Division, G. P. O. Box 2754, Bangkok 10501, Thailand
1 October 1993, CRSP Research Report 93-59
Abstract Two experiments were conducted to better understand the role
of urea in pond fertilization. In Experiment 1, urea dissolved in pond water
and incubated in aquaria at approximately 30°C disappeared at a rate
of 303 µg urea-N l-1 day-1 under natural sunlight
conditions, and 102 µg urea-N l-1 day-1 under dark
conditions. Total alkalinity decreased in dark aquaria and increased in
sun-exposed aquaria, consistent with stoichiometric expectations. Urea hydrolysis
was negligible in distilled water exposed to light.
This abstract was excerpted from the original paper, which was published in Aquaculture 114:273-283, 1993.
Increasing attached microorganism biomass as a management strategy for Nile tilapia (Oreochromis niloticus) production
Madhav K. Shrestha, Asian Institute of Technology, Agriculture and Food Engineering Division, GPO Box 2754, Bangkok, 10501, Thailand
11 May 1994 , CRSP Research Report 93-60
Abstract Feeding of attached microorganisms and detrital biomass (AMDB) by Nile tilapia (Oreochromis niloticus) was examined in two 8-week experiments conducted in outdoor concrete tanks. Although the addition of vertically placed plastic baffles and bamboo poles did not significantly increase net fish yield, differences in AMDB in tanks with and without fish clearly demonstrated AMDB was ingested by tilapia. Tilapia feeding behavior and gut analyses supported this conclusion. Because of similarities between fish and algal productivities in tanks with and without additional substrates, however, the added financial and labor costs do not warrent (sic) the use of plastic baffles or bamboo poles in static water tilapia culture systems.
This abstract was excerpted from the original paper, which was published in Aquacultural Engineering 13:101-108, 1994.
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