Negative Impacts of the Practices of Acadjas on the Aheme Lake in Benin

Abstract

The objective of this study is to reveal the negative impacts of the practices of acadjas on the Aheme lake in Benin. Various material and methods were used for the measures of the physicochemical parameters such as: colorimetric HACH DR/890, the multiparameter WTW 340i and specific kits for the dosage of minerals. Also, the investigations were made with the resources by persons. It emerges from this study that the practices of acadjas asphyxiate and disturb the lake species. In fact, the concentrations in dissolved oxygen became very weak (1595 mg/L to 3740 mg/L), and the contents of nitrites (2, 25 mg/L to 14, 5 mg/L), suspension materials and turbidity are raised. The consequences both on the aquatic fauna and on the vegetation of the bank are worrying. The waterside populations are also threatened. Some actions in an attempt to regulate the practice of acadjas and promote reforestation of the lagoon bank need to be put in place.

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“…The lake has a surface area of 78 km 2 during the dry season and 100 km 2 during flood season (Dedjiho et al, 2014). The lake is 24 km long and is deeper in its the northern area.…”

Physico-Chemical Characterization of the Surface Water in the Lower Valley of the Oueme in South Benin

“…This is in line with the work of Attingli et al (2017) who have shown that these parameters do not depend on the hydrological cycle but on the fishing zones. According to Djèdjiho (2014), the waters of the Lake Ahémé-Gbézounmè lagoon complex in Benin have very high mineral contents such as nitrite, nitrate and phosphate ions as well as COD and BOD5 concentrations in the water samples analysed. At the level of the Kadicha River in northern Lebanon, the anthropogenic activities carried out (direct discharges of domestic wastewater, leachates and oil mill effluents) pollute surface water (Merhabi et al, 2019).…”

“…According to (Akognonbé, 2014), fishing practices such as the use of hydrocarbon fishing gear and associated mechanical interventions have contributed to the direct pollution of rivers and water bodies. Djèdjiho et al (2014) in their work, pointed out the pollution of Lake Ahémé-Gbézounmè due to strong mineralisation with the corollary appearance and proliferation of macrophytes and phytoplankton. This vulnerability of the surface water to pollution is a reality in the lower Ouémé valley in south-eastern Benin.…”

Dynamic of phytoplankton assemblages, as a response in the change of Water Quality in Lake Ahémé (BENIN)

“…[12]. The strong demographic pressure often reported in this lake leads to eutrophication [13] [14] [15] [4] [11]. These authors also highlighted the problem of the filling up of Lake Ahémé and the change in its hydrological regime.…”

“…In Benin, Lake Ahémé is subject to anthropogenic stress when classified as an area of international interest and part of Ramsar 1017 [11]. Because of its size, productivity, and different uses, it offers extraordinary benefits by providing people with ecosystem goods and services (tourism, fishing, drinking water, etc.).…”