The aquatic ecosystem is the most diverse ecosystem on the planet, from which life first emerged (Tideman, 2000). Aquatic organisms rely on water for their life processes, as it serves as both an external and internal medium. Therefore, water is essential for the survival of all living beings. Human activities, such as domestic waste disposal and agricultural runoff, can significantly disrupt the ecosystem of Iwo Reservoir. The impacts of these effluents on water quality, aquatic organisms, and the safety of humans who are environmentally or occupationally exposed to these disturbances are critical ecological concerns. Monitoring water quality through various methods is vital for managing fisheries, monitoring pollution, regulating water supplies, treating sewage, and overseeing freshwater reservoirs (Valentyne, 1957). This process involves assessing water quality, which indicates the pollution levels of the water body. Any changes in water quality have direct implications for the biotic community structure, where the most vulnerable organisms may perish while sensitive species survive, acting as indicators of pollution.
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Plankton
Plankton—both phytoplankton and zooplankton—are particularly relevant in this context, as their populations reflect changes in physical and chemical parameters caused by effluent discharge. Utilizing biological indicators to assess the effects of pollution incorporates both short- and long-term impacts on living resources and ecological systems. Iwo Reservoir is subject to various human activities, including domestic and agricultural practices. For this reason, it is essential to consider its physical, chemical, and biological characteristics. As such, both the ecology and management of these ecosystems require significant attention, alongside regular limnological studies. Sample of zooplankton e.g Copepod and dinoflagellates e.t.c
Zooplankton serve as a primary food source for pelagic fish, especially their larvae (Olaniyan, 2011; Quasim, 2012), while these fish consume phytoplankton. Phytoplankton e.g
cyanobacteria, silica-encased diatoms.e.t.c
This interdependence highlights the importance of plankton within aquatic ecosystems, with their abundance and diversity closely tied to water quality (Quasim, 2012). Numerous studies have investigated plankton populations in various Nigerian water bodies, including the River Sokoto (Green, 1960) and River Benue (Agouru and Audu, 2012), as well as in Ikere Gorge Reservoir (Kehinde and Ayoade, 2012), Ojofu Lake (Omowaye et al., 2011), and Nkisa and Orashi Rivers in Rivers State (Yakubu et al., 2000). Research on Nigerian planktonic organisms includes works by Adeniyi (1978), Jeje and Fernando (2000), Kadiri (1988), and Opute (2000).
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Iwo Reservoir is influenced by human activities, which include domestic and agricultural practices. It primarily functions as a source of municipal water supply and supports local fishing activities. However, shallow reservoirs like Iwo are particularly vulnerable to pressures from human activities, including pollution from anthropogenic sources, eutrophication, and excessive water extraction. Such pressures pose significant threats to both the primary purposes of the reservoir and the additional benefits it may provide. Approximately 200,000 people rely on this reservoir for domestic and industrial water supply, fisheries, and recreational activities. Given its importance, there is a need for comprehensive studies to understand the dynamics of the reservoir. Despite the pressures from the surrounding population, there have been no limnological or fisheries studies conducted on the reservoir, which has likely led to changes in its water quality and quantity.
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This study aims to evaluate the water quality parameters in relation to plankton production and to propose management solutions for the reservoir's water usage. The goals of this research focus on the utilization of Iwo Reservoir, the challenges of effective management, and ensuring good water quality and sustainable fisheries exploitation.
Researchers and surveyor:OLATUNBOSUN IBRAHIM