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Accueil du site → Master → Pays Bas → 2013 → Changes in water quality parameters in mariculture ponds and implication on fish growth

UNESCO-IHE Institute for Water Education, Delft (2013)

Changes in water quality parameters in mariculture ponds and implication on fish growth

Mzee, S.T.

Titre : Changes in water quality parameters in mariculture ponds and implication on fish growth

Auteur : Mzee, S.T.

Université de soutenance : UNESCO-IHE Institute for Water Education, Delft

Grade : Master of Science (MS) 2013

Water quality is among the most important factors that control fish production. The parameters of water quality also impact either directly or indirectly on other production indices. A study was conducted in mariculture ponds along the Kenyan coast to evaluate the suitability water quality and the accompanying changes for suitability for culture of milkfish (Chanos chanos). During the study changes in water quality during neap and spring tide periods was monitored in mariculture fish ponds. Among the parameters included in the study were physico-chemical (Temperature, Dissolved Oxygen, DO, pH, salinity, NH4+, NO3-, SRP (PO43-), and biotic (phytoplankton). Tidal influence on these variables was investigated for a period of 4 months. The study involved regular as well as diel sampling. Diel data of water quality parameter demonstrated significantly (P < 0.05) variation between neap and spring periods. Mean temperature,DO, pH and salinity values during spring and neap tide periods were 30.4 ± 0.14 oC and 31.34 ± 0.10 oC ; 5.99 ± 0.10 mg/l and 5.63 ± 0.04 mg/l ; 6.87 ± 0.03 and 6.71 ± 0.02 ; and 31.95 ± 0.06 ppt and 32.34 ± 0.12 ppt, respectively. Among the measured nutrients SRP and NH4+-N varied significantly (P < 0.05) between spring and neap periods. NO3-N did not vary statistically (P > 0.05) between the two periods. Pond water mixing and stratification was more controlled by salinity than temperature and temperature was in most cases higher at the bottom than surface stratum in the afternoon Principal component indicated that most of the pond processes involved redox-reactions with temperature, pH and DO loadings. Other pond processes involved photosynthetic process involving DO and temperature while the third was dominated by evaporative concentration with temperature and salinity as loading parameters. Chlorophyll aconcentration was significantly (P < 0.05) different between neap and spring period with higher values in neap period. The change of water quality variables in mariculture was highly influenced by the change in tidal regimes. Spring tide diluted pond water and elevated pH while salinity was elevated and pH declined during neap tide

Sujets  : Water quality ponds fishes nutrients Kenya

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