||Agricultural discharges and human activities affect complex "Nokoué lake, Cotonou and Porto-Novo lagoon ecosystems.
This complex lagoon received effluent, sewage, municipal solid waste coming from neighboring cities. The present study
aims to monitor heavy metals levels contamination in water, sediment and in aquatic species such as fish, oysters and shrimp
during three years in twelve areas along the complex lake and lagoons. An atomic absorption spectrophotometer was used to
measure heavy metals such as lead, cadmium, zinc and mercury. Analyses were done every year during three years. Water,
sediment and aquatic species collected in the complex ecosystem are contaminated by zinc, cadmium, mercury, and lead with
various levels varying according to years. It is important to take appropriate measures to limit the input of pollutants from