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<p>Although periphyton-based aquaculture is gaining traction, key drivers affecting periphyton dynamics in aquaculture production systems are not well documented. The study investigated the effect of different substrates, seasonality and grazing by <i>Oreochromis mossambicus</i> on periphyton composition in aqua dams. Three experiments were conducted. In the first experiment, net, stone, and plastic were deployed in triplicates in aqua dams. The periphyton (mainly attached algae) biomass was high on the plastic (155.40 no./ml) and net (150.63 no./ml) substrate. The net substrate was subsequently used in the second experiment to determine the seasonal variation of periphyton in aqua dams. Periphyton was most abundant in summer and winter. The dominant phylum in winter was Bacillariophyta and in summer it was Chlorophyta (mainly <i>Scenedesmus</i> sp.). The network analysis produced a weak connection since a few genera dominated the periphyton biomass across seasons. Periphyton abundance in summer was influenced by DO, EC, temperature, nitrogen, salinity, and transparency, while in winter it was influenced by nitrate. The third experiment was conducted in fibreglass tanks to determine the effect of <i>O. mossambicus</i> grazing on periphyton. Stomach and faecal analysis showed that <i>O. mossambicus</i> were grazing mostly on <i>Scenedesmus</i> across different size groups. However, the Chesson selectivity index showed no evidence of food selection. Multivariate analysis showed that season and substrates are the main factors affecting periphyton dynamics in aqua dams. Deployment of net and plastic substrate in aqua dams is recommended in order to reduce feed costs. </p>

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Periphyton dynamics in aqua dams stocked with Oreochromis mossambicus in Limpopo Province, South Africa

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年6月26日

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  • Khathutshelo C. Hlongwane,
  • Ngonidzashe A. G. Moyo,
  • Mmaditshaba M. Rapatsa-Malatji

摘要

Although periphyton-based aquaculture is gaining traction, key drivers affecting periphyton dynamics in aquaculture production systems are not well documented. The study investigated the effect of different substrates, seasonality and grazing by Oreochromis mossambicus on periphyton composition in aqua dams. Three experiments were conducted. In the first experiment, net, stone, and plastic were deployed in triplicates in aqua dams. The periphyton (mainly attached algae) biomass was high on the plastic (155.40 no./ml) and net (150.63 no./ml) substrate. The net substrate was subsequently used in the second experiment to determine the seasonal variation of periphyton in aqua dams. Periphyton was most abundant in summer and winter. The dominant phylum in winter was Bacillariophyta and in summer it was Chlorophyta (mainly Scenedesmus sp.). The network analysis produced a weak connection since a few genera dominated the periphyton biomass across seasons. Periphyton abundance in summer was influenced by DO, EC, temperature, nitrogen, salinity, and transparency, while in winter it was influenced by nitrate. The third experiment was conducted in fibreglass tanks to determine the effect of O. mossambicus grazing on periphyton. Stomach and faecal analysis showed that O. mossambicus were grazing mostly on Scenedesmus across different size groups. However, the Chesson selectivity index showed no evidence of food selection. Multivariate analysis showed that season and substrates are the main factors affecting periphyton dynamics in aqua dams. Deployment of net and plastic substrate in aqua dams is recommended in order to reduce feed costs.