Can Macroinvertebrate Assemblage Changes Be Used as Biological Indicator of Water Quality of the Nokoue Lake (Benin)?

Odountan, Hamed; Abou, Youssouf

doi:10.4236/jep.2015.612122

Cited by 11 publications

(10 citation statements)

References 30 publications

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“…flow regime affects movements, composition, diversity and assemblages of aquatic macroinvertebrates [49]- [51]. Nevertheless, during the same period of high flood, macroinvertebrate assemblage changes can be used as biological indicator of water quality of the Nokoue Lake [52].…”

Section: Macroinvertebratesmentioning

confidence: 99%

Structure and Composition of Macroinvertebrates during Flood Period of the Nokoue Lake, Benin

Odountan¹,

Abou²

2016

OJE

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The Nokoue Lake is the largest lake of Benin Republic and it is also considered as one of the most productive lagoon ecosystems in West Africa. This productivity is decreasing and thus raises productivity issue for a better management and conservation. Macroinvertebrate can be useful for this purpose. A study was conducted to assess the spatial variation of macroinvertebrates during high flood period. A total of 3892 macroinvertebrates of fresh and brackish water were sampled during the survey. Structural analysis of the macroinvertebrate community revealed that it was made up of 16 orders, 48 families and 66 genera dominated by Insecta compared to Mollusca, Crustacea and the Annelida. Insects were dominated by Diptera (Chironomus sp. and Tanytarsus sp.), Coleoptera (Dystiscidae) and accounted for 57.1% of the sampled population. Mollusca, Crustacea, Annelida and Arachnida were the following most abundant and represented 23.9%, 10.7%, 8.1% and 0.2% of the total population, respectively. The Evenness index of Pielou was higher on the Station 8 (0.91-0.97), close to Oueme River. However, no significant difference (p > 0.05) was observed neither between station nor between month on the Shannon-Wiener index (2.06-4.31), Simpson index (0.04-0.40) and the taxa number (10-27). Macroinvertebrate assemblages and composition were primarily due to changes in water quality dependent on hydroclimatic changes and probably to anthropogenic actions. This suggests the need for real investigation of the macroinvertebrate biological capacity when formulating conservation strategies for the Nokoue Lake.

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Section: Macroinvertebratesmentioning

confidence: 99%

Structure and Composition of Macroinvertebrates during Flood Period of the Nokoue Lake, Benin

Odountan¹,

Abou²

2016

OJE

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“…The surface water temperature of Nokoue lake varies between 23°C and 34°C [3], [4]. It is influenced by the air temperature around the lake and presents a difference significant (P <0.001) [1], [24].…”

Section: Physics-chemical Parameters Analyzing 1) Results Of Temperat...mentioning

confidence: 99%

“…During the high-water period, the main source of nitrogen (N) and phosphorus (P) in Lake Nokoue is the Ouémé River, which drains about 90% of the total nitrogen and 60% of the total phosphorus. In low water, the Sô River contributes about 75% of the total nitrogen and 95% of the total phosphorus to the lake [3], [24]. Inorganic Nitrogen (N) and Phosphorus (P) inputs from the two rivers accounted for only 35% of the total nitrogen and total phosphorus loaded into the lake [4], [27].…”

Section: ) Results Of Nutrients (Phosphorus and Nitrogen) Researchmentioning

confidence: 99%

“…This excess biomass leads to an increase in the natural load of the ecosystem in a biodegradable organic matter [32]. The degradation of organic matter present in the water body leads to a decrease in the dissolved oxygen content of the water [23], [24]. As the oxygen stock in the water is very limited, it is rapidly depleted during periods when the respiration of organisms and the decomposition of matter exceeds production by photosynthesis [21].…”

Section: ) Results Of Eutrophication Researchmentioning

confidence: 99%

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Current State of Flooding and Water Quality of Nokoue Lake in Benin (Ouest Africa)

Namwinwelbere

Eugène

Firmin

2022

EJGEO

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A thorough literature review was conducted in order to discover the previous studies that have been done in relation to the problems of flooding and water pollution of Nokoue lake (Benin, West Africa), to identify the limitations of these previous studies, to draw lessons in order to propose how to overcome them. This bibliographic synthesis has shown that previous studies related to the flooding issue have focused on the dynamics of understanding the genesis of flooding. These studies range from the oldest conducted in 1979 to the most recent conducted in 2016. The major results of these studies in relation to floods are hydrodynamic techniques allowing to evaluate in a punctual way the hydrological regime of the Nokoue lake. In other words, they are solutions allowing to reconstitute the floods generated by the river waters. It appeared that these results of flood reconstitution are difficult to generalize because of the complexity of the hydrographic network of Nokoue lake. The hydrodynamics of Nokoue lake is influenced differently by its main water tributaries (the Sô River, the Ouémé River, the Porto Novo Lagoon and the Atlantic Ocean). Therefore, a decision-making issue on planning and flood management must be motivated by a decision support tool. It is moreover recommended in these studies the resumption of the process of hydraulic techniques periodically during the period of high water in order to take advantage of the hydrological behavior of Nokoue lake in terms of overflow which are at the origin of the floods. The need for innovative decision-making solutions on flood planning and management in order to reduce disasters is still a priority for decision-makers. These innovative solutions are undoubtedly the flood forecasting. On the water quality of Nokoue lake, the oldest study conducted dates back to 1987 and the most recent one in 2018. In these studies, water quality is evaluated in two seasons: the low water season (December to mid-May) and the high-water season. It was found that the salinity of the lake increased significantly with an average of 16 ppt during the low water period while during the high-water period, freshwater inflows from the tributaries invaded the lake and prevented water from the Atlantic Ocean from entering. The concentrations of inorganic nutrients in the lake increase from low water to high water. However, the quantification to date of nutrient loads from external sources as well as internal sources to the lake have not been quantified. This implies that further research on the water quality of the lake could be conducted. Prevention actions should consider a predictive monitoring of the water quality index of Nokoue lake.

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“…It is bounded to the west by the Abomey-Calavi plateau, to the east by the Porto-Novo lagoon, to the north by the floodplain of the Ouémé and Sô rivers and to the south by the city of Cotonou. It is directly connected to the Ocean by the Cotonou channel over a length of 4.5 km with a width of about 300 m (Odountan and Abou, 2015). As to Porto Novo Lagoon, it covers a Surface of about 35 km2 at the lowest level and its geographical coordinates are 6°28'North and 2°36' east.…”

Section: Study Areamentioning

confidence: 99%

Mercury content of sarotherodon melanotheron and chrysischthys nigrodigitatus of Lake Nokoue and Porto Novo lagoon in Benin

Degila¹,

Azon²,

Adounkpè³

et al. 2020

Int. J. Bio. Chem. Sci

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Ratification of Minamata Convention by Bénin requires identification of contaminated sites and preservation of health. In this context, the Ministry of Living Environment and Sustainable Development supported the study by making its mercury analyzer DMA80 available. The study aims to identify the level of mercury contamination in two highly valued fish species caught in one of the most productive water bodies where mercury is reported. So, three monthly sample collection campaigns were carried out from April to juin 2018 at nine (09) sites. The back flesh of sarotherodon melanotheron and chrysischthys nigrodigitatus of lake Nokoue and Porto Novo lagoon was analyzed by direct mercury analyzer (DMA 80). it Its operating principle is atomic absorption after thermal decomposition coupled with a gold sensor. The average mercury contents are 20.8 ± 15.5 μg / kg and 6.5 ± 3.8 wet μg / kg weight respectively for Chrysichthys nigrodigitatus and Sarotherodon melanotheron. The highest values obtained at the Porto-Novo bridge for both species remain well below the standard (0.5 mg / kg wet weight). With consumption habits of fish in Benin, the weekly exposure doses seem to be much lower than WHO recommendation. However, deepened studies are needed.Keywords: Fish, mercury, spatial distribution, NoKoué Lake, Porto-Novo Lagoon.

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Can Macroinvertebrate Assemblage Changes Be Used as Biological Indicator of Water Quality of the Nokoue Lake (Benin)?

Cited by 11 publications

References 30 publications

Structure and Composition of Macroinvertebrates during Flood Period of the Nokoue Lake, Benin

Structure and Composition of Macroinvertebrates during Flood Period of the Nokoue Lake, Benin

Current State of Flooding and Water Quality of Nokoue Lake in Benin (Ouest Africa)

Mercury content of sarotherodon melanotheron and chrysischthys nigrodigitatus of Lake Nokoue and Porto Novo lagoon in Benin

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