Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 325721
Title The effects of periphyton substrate and fish stocking density on water quality
Author(s) Azim, M.E.; Verdegem, M.C.J.; Singh, M.; Dam, A.A. van; Beveridge, M.C.M.
Source Aquaculture Research 34 (2003)9. - ISSN 1355-557X - p. 685 - 695.
Department(s) Aquaculture and Fisheries
Publication type Refereed Article in a scientific journal
Publication year 2003
Keyword(s) tilapia oreochromis-niloticus - herbivorous fish - nile tilapia - biomass - culture - ponds - reef
Abstract The objectives of this study were to determine how periphyton and phytoplankton biomass vary with grazing pressure by tilapia Oreochromis niloticus, to evaluate the growth performance of fish when substrate is introduced and to calculate the efficiency of nitrogen utilization in substrate and non-substrate systems. Ten circular 1000-L plastic tanks were filled with 15 cm of loamy soil bottom and water. Five different treatments were applied: eight tilapias with substrate (treatment 8T/S), eight tilapias without substrate (treatment 8T), four tilapias with substrate (treatment 4T/S), four tilapias without substrate (treatment 4T) and no tilapia with substrate (treatment OT/S). Each week, 2 g of NaNO3 and 3.5 g of single superphosphate (SSP) were applied to each tank. Sixteen glass slides (1 m x 4 cm x 4 mm) were installed vertically in the tank bottom, one portion extending above the water surface and equally spaced within the water column in all substrate tanks. Periphyton and phytoplankton quantity and quality, water quality, fish growth and proximate fish composition were measured. Because of grazing, phytoplankton and periphyton biomass decreased after the introduction of fish to the tanks. The periphyton biomass was higher in non-fish tanks (treatment OT/S) throughout the experiment than that in tanks with fish (treatments 8T/S and 4T/S). The periphyton biomass was similar in the 4T/S and 8T/S treatments, suggesting that the grazing pressure on periphyton biomass reached threshold levels. Fish ate 25-36% of the total standing biomass every day. Tilapia growth was significantly higher in treatments with substrate. Nitrogen retention was double in substrate ponds compared with in control ponds. There were no significant effects of periphyton substrate or fish density on body composition of fish.
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