Prasert Munsiri, Claude E. Boyd* and Bartholomew W. Green, Department of Fisheries and Allied Aquaculture, Auburn University, Alabama 36849, USA

Ben F. Hajek, Department of Agronomy and Soils, Auburn University, Alabama 36849, USA

15 January 1998 CRSP Research Report 97-116

Abstract Soil cores were taken from ponds at the Central Laboratory for Aquaculture Research, Abbassa, Sharkia, Egypt. Three ponds received little management since construction in the early 1980s. Three other ponds were fertilized heavily in 1993 and 1994 to stimulate tilapia (Oreochromis niloticus) production. Thicknesses of S, M, and T horizons in soil profiles averaged 5, 7.5, and 10 cm, respectively. The S horizon contained more silt than clay, but T and P horizons were 60% clay. Concentrations of total carbon, total nitrogen, total sulphur, phosphorus, calcium, and potassium were greatest in the S horizon and lowest in the P horizon. Intensively managed P-ponds had higher concentrations of phosphorus and lower concentrations of organic matter and sulphur in S and M horizons than B-ponds. Because of high moisture content, low dry bulk density, and greater concentrations of organic matter and nutrients in the S horizon, reactions in this layer probably have a greater influence on pond water quality than those in deeper horizons. For general purposes, soil sampling should be restricted to the S horizon or the upper 5-cm layer where depth of the S horizon is not known. Compared with pond soils from a humid climate in Auburn, Alabama (USA), pond soils at Abbassa had greater concentrations of sulphur, calcium, magnesium, potassium, and sodium, and lower concentrations of iron, manganese, zinc, and copper in S horizons.

*Corresponding author.

This abstract was excerpted from the original paper, which was published in Journal of Aquaculture in the Tropics, 11(1996):319-329.

Water effluent and quality, with special emphasis on
finfish and shrimp aquaculture

George H. Ward, Center for Research in Water Resources, The University of Texas, PRC-119, Austin, TX 78712

15 January 1998 CRSP Research Report 97-117

Abstract Estuaries are coastal watercourses that are subject to both marine and riverine influences. Their principal hydrographic controls are morphology, tides, freshwater inflows, meteorology, and density currents. The propagation of tides and the distribution of salinity are important indicators of circulation in an estuary. Circulation in particular imposes a limit on the ability of an estuary to assimilate wastes without degrading its water quality. This is an important constraint on concentrated aquaculture operations that circulate water, since these produce a large volume of wastewater and also require a supply of uncontaminated water. A general procedure is outlined for determining the "carrying capacity" of the estuary. This requires (1) specification of the water quality parameter(s) that form the basis of water quality evaluation, (2) determining the parameter value(s) of acceptable water quality, (3) development of a water quality model appropriate for the estuary, and (4) establishing the conditions that are critical for water quality.

The water quality model is central to the procedure: it is a combined hydrodynamic and mass balance calculation, designed to reflect the space-time scales controlling the water management problem. Its development requires an extensive base of field data. The model is applied to predicting the water quality regime that would result under a hypothetical distribution and volume of wasteloads. The largest volume of wasteloads that results in water quality equal to the level judged acceptable under critical conditions is the assimilative capacity. It is important to note that assimilative capacity is a function of position in the estuary, and depends upon both local and larger scale hydrography. Single values of "carrying capacity" or "flushing time" applied to an entire estuary are of little use. A case study is presented of shrimp aquaculture in Golfo de Fonseca, Central America. A preliminary analysis of the operations around Estero Pedregal is performed using a one-dimensional model, to illustrate the kinds of analyses that can be carried out and the types of results that can be obtained. These results indicate that shrimp aquaculture in this area is already approaching a level of being self-limited.

This abstract was excerpted from the original paper, which was published in Proceedings of the Twenty-Fourth U.S.-Japan Aquaculture Panel Symposium, Corpus Christi, Texas, October 8-10, 1995, p. 71-84.

A collaborative project to monitor the water quality of estuaries in the shrimp producing regions of Honduras

Bartholomew W. Green and David R. Teichert-Coddington, International Center for Aquaculture and Aquatic Environments, Auburn University, AL, 36849-5419, USA

Marco Polo Micheletti, Secretaría de Agricultura y Ganadería, Tegucigalpa, Honduras

Carlos A. Lara, Asociación Nacional de Acuacultores de Honduras, Choluteca, Honduras

15 January 1998 CRSP Research Report 97-118

Abstract A long-term water quality monitoring project in estuaries of the shrimp producing regions of Honduras was initiated in 1993 as part of the Honduras Pond Dynamics/Aquaculture Collaborative Research Support Program. This project is a collaborative effort of universities, the private sector and the public sector. A technical cooperation agreement that describes specific responsibilities of each participant was signed by all participants. The goal this agreement is to provide a scientific basis for estuarine management and sustainable development of shrimp culture in Honduras. Specific objectives, design and implementation of the project are described. Currently, water quality is monitored every one to two weeks at 19 sites on 12 estuaries. This project has generated the only known long-term data base on the impact of shrimp farming on estuarine water quality. Project results to date indicate no long-term trend in eutrophication in either riverine or embayment estuaries during the period 1993-1997. Nutrient concentrations in riverine estuaries follow a cyclical trend controlled by season; higher nutrient concentrations are observed during the dry season. Factors contributing to project success are discussed.

This abstract was excerpted from Proceedings IV Ecuadorian Aquaculture Conference, 22-27 October 1997.

Douglas H. Ernst, John P. Bolte, Duncan Lowes, and Shree S. Nath, Department of Bioresource Engineering, Oregon State University, Corvallis, OR 97331 USA

15 April 1998 CRSP Research Report 98-119

Abstract The Pond Dynamics/Aquaculture Collaborative Research Support Program (PD/A CRSP) supports applied research and outreach programs for pond-based food-fish production, with funding under the U.S. Agency for International Development (USAID). Since its inception in 1982, the PD/A CRSP has accomplished a wealth of collaborative, multi-national, multi-institutional aquaculture projects, including facilities, investigators, and user-groups in Egypt, Honduras, Indonesia, Kenya, Panama, Peru, Philippines, Rwanda, Thailand, and the USA.

The PD/A CRSP Central Database is a centralized data storage and retrieval system for PD/A CRSP research and for other aquaculture research programs with compatible objectives and standardized methodology. The Database currently contains over 80 aquaculture production studies and represents the world's largest inventory of standardized aquaculture data. The majority of studies currently in the Database are for production of Nile tilapia (Oreochromis niloticus) in sub-tropical and tropical, solar algae ponds, receiving inputs of plant materials, inorganic/organic fertilizers, and/or prepared feeds. Studies of other pond fishes and penaeid shrimp, under monoculture and polyculture management, are also available.

The PD/A CRSP Database can be accessed free of cost by aquaculture researchers, educators, outreach and extension agents, and producers. Data may be searched and extracted according to geographical site, calendar year, fish species, and fish production methods. Weather, water quality, fish performance, and fish culture management regimes may be viewed in raw or summary forms and in graphical or tabular formats. All extracted datasets include references to research investigators, physical descriptions of research facilities, and related publications. An interface to the Database is provided at its Internet Web Site, located at http://biosys.bre.orst.edu/crspDB/. This publication mechanism provides immediate and comprehensive access to the Database worldwide.

The PD/A CRSP Database provides a model for standardized design and reporting of pond-based aquaculture research, and it provides a publication mechanism that leverages the usefulness of such research to the greater aquaculture community. Full reporting of weather, water quality, fish performance, and fish management regimes provides a sound empirical foundation for planning, design, management, and analysis of aquaculture enterprises.

This abstract was excerpted from the original paper, which was published in Tilapia Aquaculture. Proceedings from the Fourth International Symposium on Tilapia in Aquaculture, November 9-12, 1997, Orlando, Florida. NRAES-106: 683-700.

Daniel M. Jamu, Zhimin Lu, and Raul H Piedrahita, Department of Biological and Agricultural Engineering, University of California One Shields Avenue, Davis, CA 95616-5294 USA

15 April 1998 CRSP Research Report 98-120

Abstract The application of Secchi disk visibility measurements (SDV) in modeling phytoplankton productivity and management in aquaculture ponds requires a quantitative treatment of the relationship between SDV measurements and chlorophyll a (chla) concentrations. Almazan and Boyd (1978) produced one such relationship for aquaculture ponds where phytoplankton was the major source of turbidity. However, in aquaculture ponds, organic matter, color of humic substances and inorganic materials like suspended clay may also be significant sources of turbidity. A majority of aquaculture ponds receive high inputs of organic matter in the form of food or organic fertilizers (Edwards, 1987; Schroeder et al., 1991; Chien, 1992). In such systems, non phytoplankton sources of turbidity can be significant and the Almazan and Boyd (1978) relationship may be in- appropriate. Nath (1996) modified the Almazan and Boyd (1978) relationship to allow its applicability in waters with high algal turbidity by including a non algal turbidity parameter. A method for estimating chla from SDV and for partitioning SDV has been proposed for natural freshwater systems (Bannister, 1974; Megard et al., 1980; Lorenzen, 1980). The linear relationship between the overall light extinction coefficient (k_w), the light extinction due to chla (k_c c, where k_c is the light extinction coefficient due to chla and c is the chla concentration) and the light extinction due to non-phytoplankton particulate and dissolved material (k _t) was expressed as (Bannister, 1974; Megard et al., 1980):
k_t = k _w + k_c c (1)
where k_t and k_w have units of m^-1 and k_c has units m^-1(mg.m^-3)^-1. The general applicability of this method to aquaculture has not been evaluated. The aim of this study was to evaluate the applicability of Bannister's approach (1974) to aquaculture ponds by partitioning sources of turbidity and determining the relative importance of phytoplankton and non phytoplankton turbidity.

This abstract was excerpted from the original paper, which was published in Advances in Aquaculture Engineering, Proceedings form the Aquacultural Engineering Society (AES) Technical Sessions at the Fourth International Symposium on Tilapia in Aquaculture, November 9-12, 1997, Orlando, Florida. NRAES-105:159-162.