Research Projects
Effluents and Pollution Research

Subcontract No. RD010A-07

Note: Additional project information on Staff, Networking, Educational Outreach, Publications, Presentations, Conferences, and Awards appears in the Pond Dynamics Research Section, p. 29.

Staff

Auburn University, Alabama

Claude E. Boyd	US Principal Investigator, Project Leader
Oscar Zelaya	Graduate Assistant (Honduras; CRSP funded)

Background

Oscar Zelaya, a student from Honduras, was selected to receive CRSP funding for graduate studies under 8HCD1B, an Eighth Work Plan activity originally overseen by the CRSPs Education Development Component. Responsibility for overseeing this activity has since been transferred to Claude Boyd, Zelaya's major professor. Zelaya's thesis research is described in work plan study 9ER4, "Effects of water recirculation on bottom soils and water quality in aquaculture ponds."

Development of alternative production and harvest technologies to reduce the environmental impact of nutrient loading in receiving waters by aquacultural effluents was identified as a key objective in the Continuation Plan 1996–2001. A series of research projects examining the impacts of shrimp culture effluents in Honduras identified the presence of nutrients and dissolved oxygen beyond the carrying capacity of the local estuarine system. Current research examines the use of recirculating water systems as an alternative to effluent release and examines the effect of varying stocking densities and recirculation rates on pond production.

Work Plan Research

This subcontract was awarded funding to conduct the following Ninth Work Plan investigation (see Pond Dynamics Research (p. 29) for information on another funded investigation under this subcontract):

• Effects of water recirculation on water quality and bottom soil in aquaculture/9ER4. The report submitted for this investigation was a progress report.

Note: 9ER4 was funded after publication of the Ninth Work Plan. The 9ER4 work plan will appear in the Addendum to the Ninth Work Plan.

Effects of Water Recirculation on Water Quality and Bottom Soil in Aquaculture Ponds

Ninth Work Plan, Effluents and Pollution Research 4 (9ER4)
Progress Report

Oscar Zelaya, Claude E. Boyd, David R. Teichert-Coddington, and Bartholomew W. Green
Department of Fisheries and Allied Aquacultures
Auburn University, Alabama, USA

Abstract

There is considerable interest in reducing negative environmental impacts of shrimp and fish farming. One of the most promising methods for reducing the environmental effects of pond aquaculture is to use water-recirculating systems to minimize effluents. However, few studies have been performed to evaluate the effect of recirculation upon soil and water quality in ponds. This study evaluates changes in physical and chemical characteristics of pond water and soils in response to varying density of production and in the presence or absence of water recirculation. Ponds were stocked with Litopenaeus vannamei and arranged in three treatments: 1) high-density stocking (50 post-larvae m^-2) (HDR) with water recirculation into another pond of equal volume without shrimp (R); 2) high-density stocking (50 post-larvae m^-2) without recirculation (HD); and 3) low-density stocking (25 post-larvae m^-2) without water recirculation (LD). Water quality variables determined weekly included soluble reactive phosphorus, total phosphorus, total nitrogen, nitrites, nitrates, and total suspended solids. Every two weeks determinations were done for 5-d biochemical oxygen demand, and chlorophyll a. Soil variables determined at the beginning and end of the study included total nitrogen, soil respiration, pH, carbon, and sulfur. Analysis of variance techniques were used to determine if significant differences existed among treatments with respect to soil and water quality variables.