Techniques for assessment of stratification
and effects of mechanical mixing in tropical fish ponds
James P. Szyper, University of Hawaii, Institute of Marine Biology, P.O.
Box 1346, Kaneohe, Hawaii 96744
C. Kwei Lin, University of Michigan, East Lansing, Michigan 48823
3 May 1991, CRSP Research Reports 91-31
Abstract Density stratification isolates near-surface from bottom pond waters
and prevents exchange of dissolved oxygen (DO) and nutrient elements, potentially
restricting photosynthesis and production. Destratification strategies have
become important for cost-effective intensification of pond aquaculture.
Evaluation of methods and devices has emphasized effects on production,
with little detailed description of effects on physico-chemical components
of pond ecosystems.
This paper describes short-term effects of mechanical mixing on temporal
and spatial distribution of temperature and DO in tropical freshwater fish
ponds. Intensely stratified ponds of 1.5 m depth were monitored at eight
depths for temperature and two depths for DO every 30 min with a modest-cost
automated system of commercially available hardware. Results are presented
as time-series plots, isotherm diagrams of temperature distribution with
time and depth, and a stability index of energy required to mix a pond to
uniform temperature.
Required mixing energy is minuscule compares with electrical energy consumption
of the lowest powered mixing devices discussed in literature. Strategy for
application of mechanical energy to water is critical for efficiency. A
relatively subtle difference between two mixing regimes (daytime mixing
for one 2-h period or two 1-h periods) produced potentially important differences
in temperature and DO distribution.
This abstract was reprinted from the original, which was published in
Aquacultural Engineering 9 (1990) 151-165.
Nitrogen input, primary productivity and
fish yield in fertilized freshwater ponds in Indonesia
Christopher F. Knud-Hansen, Ted R. Batterson, Clarence D. McNabb, Department
of Fisheries and Wildlife, Michigan State University, East Lansing, MI 48824,
USA
Irwan S. Harahat, Komar Sumantadinata and H. Muhammed Eidman, Institut
Pertanian Bogor, Facultas Perikanan, Jalan Raya Pajajaran, Bogor, Indonesia
27 July 1991, CRSP Research Reports 91-32
Abstract Twelve 0.02-ha ponds in West Java were fertilized weekly with four levels
of chicken manure (12.5, 25, 50, and 100 g dry weight/m2/week) during a
149-day growout experiment for Nile tilapia (Oreochromis niloticus)
production. Laboratory leaching experiments for measuring dissolved inorganic
nitrogen (DIN) release form chicken manure showed that nitrogen was released
as ammonia-N, which was rapidly lost from the manure and leveled off at
about 6 mg NH4-N/g dry weight chicken manure after 4-5 days. Allochthonous
DIN input from both chicken manure fertilization and almost daily source-water
additions ranged from 0.055 to 0.142 g N/m2/day. Source water contributed
more nitrogen than manure in all but the highest fertilization treatment.
Pond averages of net primary productivity (NP) ranged from 0.54 to 2.00
g C/m2/day, while gross fish yield at harvest ranged from 4.9 to 15.7 kg
fresh weight/ha/day. Net fish yield (NFY) was linearly correlated to both
the dry weight sum of NP and chicken manure fertilization (r2 = 0.97) and
allochthonous DIN input (r2 = 0.96). Results suggest that Nile tilapia obtained
organic carbon from both primary productivity and manure-derived detritus.
DIN availability limited algal productivity at a chicken manure fertilization
rate of 100 g dry weight/m2/week when microbial decomposition of manure
supplied sufficient CO2. Incorporation of allochthonous DIN input into NFY
increased significantly from 15.0% at the three lower fertilization rates
to 25.4% at the highest loading rate. Using organic fertilizers proportionally
rich in phosphorus and carbon relative to nitrogen may maintain this element's
limitation of algal productivity. Efficient utilization of DIN input also
may minimize total and un-ionized ammonia concentrations. In the absence
of deleterious ammonia effects on survival and growth, fish yields can be
readily predicted from measurements of nitrogen inputs.
This abstract was reprinted from the original, which was published in
Aquaculture, 94 (1991)49-63.
Calibration and validation of TAP, an aquaculture
pond water quality model
Raul H. Piedrahita, Department of Agricultural Engineering, University of California, Davis, California 95616, USA
15 October 1991, CRSP Research Reports 91-33
Abstract A computer model of water quality in aquaculture ponds (The
Aquaculture Pond model, TAP) has been run for data obtained from five research
sites around the world. The procedures followed for data manipulation, and
the assumptions made to complete the data requirements are described. Agreement
between simulated and measured dissolved oxygen values was used as an indicator
of the quality of the simulations. The quality of the simulations varied
between sites and in some cases between pond treatments at a given site.
Possible reasons for the variations in quality of fit are discussed.
This abstract is reprinted from the original, which was published in
Aquacultural Engineering, 9: 75-96(1990).
Modeling water quality in aquaculture ecosystems
Raul H. Piedrahita, Department of Agricultural Engineering, University of
California, Davis, California 95616, USA
15 October 1991, CRSP Research Reports 91-34
Abstract The techniques and uses of computer models, future developments,
and applications of computer modeling in aquaculture are reviewed. The general
characteristics of aquaculture ecosystems are summarized from a computer
modeling point of view. Various types of models of aquaculture systems are
presented, including models that simulate dissolved oxygen concentration,
water temperature, and other water quality variables. The models presented
are reviewed from perspectives of modeling technique, model uses, data requirements,
and predictive ability. Future applications of computer models in aquaculture
research and commercial practice are proposed. These applications include
the development of models integrated with automated data acquisition and
control systems, models that simulate water temperature and water quality
parameters simultaneously, and models for use in stratified ponds.
This abstract was reprinted from the original, which was published in
Aquaculture and Water Quality, 1991. Volume 3 of Advances in World
Aquaculture. Pages 322-362, David E. Brune and Joseph R. Romasso (eds.).
Engineering aspects of warmwater hatchery design
Raul H. Piedrahita, Department of Agricultural Engineering, University of
California Davis, Davis, California 95616, USA
5 October 1991, CRSP Research Reports 91-35
Abstract Engineering considerations for the design of hatchery systems
for warmwater fishes are presented in this paper. The material is presented
as it relates to specific unit operations or activities in a hatchery. Topics
covered include aspects of water quality, water delivery systems, impoundment
types, and water conditioning. The material is generally applicable and
is not specific to a particular level of technological sophistication, or
investment, or to a particular species. Application of the general principles
mentioned to specific situations is dependent on the requirements for a
particular installation.
This abstract was reprinted from the original, which was published in
Aquaculture Systems Engineering, Proceedings of the World Aquaculture
Society and the American Society of Agricultural Engineers, 1991 World Aquaculture Society,
Baton Rouge, LA, USA.
p. 85-100.
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