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Effluents and Pollution Research
PD/A CRSP Nineteenth Annual Administrative Report

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Research Projects
Effluents and Pollution Research

Subcontract No. RD010A-19

Staff
Auburn University, Alabama

Claude E. Boyd US Principal Investigator
Oscar ZelayaGraduate Assistant (Honduras; CRSP funded)

Cooperators
Auburn University, Alabama

Bartholomew Green
David Teichert-Coddington

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 was then 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. 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

The following Ninth Work Plan investigation continued into the current reporting period:

Note: 9ER4 was funded after publication of the Ninth Work Plan. The 9ER4 work plan appears in the Addendum to the Ninth Work Plan. The deliverable under this project was a thesis; however, for reporting purposes, a modification of the thesis was submitted.

Publication

Zelaya, O., 2001. Effects of water recycling on water quality and bottom soils in shrimp ponds. M.S. thesis, Auburn University, Alabama.

Presentation

Zelaya, O., C.E. Boyd, D. R. Teichert-Coddington, and D.B.Rouse. Effects of water circulation on water quality and bottom soil in shrimp ponds. Presented to Aquaculture America 2001 at Orlando, Florida, 21–25 January 2001.

Effects of Water Recycling on Water Quality and Bottom Soils in Shrimp Ponds

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

This study evaluated changes in chemical characteristics of production pond water, soils, and shrimp yields in response to water recycling through an oxidation pond. Nine 0.1-ha ponds were stocked with Litopenaeus vannamei post-larvae. Three ponds were stocked with a high density of shrimp (50 m-2), three were stocked with a low density of shrimp (25 m-2), and three others were stocked with a high density of shrimp while pond water was recycled through an adjacent pond of equal volume not stocked with shrimp. The density of shrimp in low-density and high-density-with-recycling treatments was equal when based on the total water area of production and recycling ponds. Mean shrimp yields for low-density (LD), high-density (HD), and high-density-recycling ponds (HDR) were 1,706 kg ha-1, 4,648 kg ha-1, and 4,534 kg ha-1, respectively. There was no significant difference (P > 0.05) in yields between HD and HDR treatments or between LD and HDR treatments when based on total water surface area. Mean harvest weights of individual shrimp ranged from 22 to 25 g and were not different (P > 0.05) among treatments. Recycling water from HDR ponds through an oxidation pond resulted in significant reductions in the mean mass weight of total nitrogen (TN) and total ammonia nitrogen (TAN) compared with HD ponds because HDR ponds used twice the water volume. The sum of the mean mass weight (kg) for water quality variables found in HDR ponds and oxidation ponds was significantly greater than the mean mass weight in HD ponds, except for nitrate-nitrogen (NO3-N), nitrite-nitrogen (NO2-N), and TAN. No differences were noted for water quality in HDR and LD ponds. No differences were observed among treatments for soil pH; concentrations of carbon, sulfur, and nitrogen; soil respiration; and phosphorus absorption capacity. We concluded that recycling water from a production pond through an oxidation pond of equal volume had minimum to no effect on water quality and shrimp yields. The major operational disadvantages of recycling water were that pond space was put into nonproductive use as oxidation ponds, and 3.3 times more energy was used for aeration and water circulation. It would be better to stock two ponds at half the rate instead of doubling the volume of water per pond by recycling through an oxidation pond.


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