La lagune Aghien est une lagune périurbaine sujette à plusieurs types de pressions anthropiques. Ces pressions pourraient avoir des répercussions sur les communautés biologiques qui peuvent être des indicateurs de l’état de qualité écologique de cette lagune. Parmi ces communautés biologiques, il y a les mollusques qui sont potentiellement capables de coloniser la zone profonde des systèmes lagunaires et lacustres. L’objectif de cette étude était d’évaluer l’état biologique du sédiment de la lagune Aghien à partir de l’Indice Malacologique de qualité des systèmes Lacustres (IMOL). Sur chaque station, l’échantillonnage du sédiment, a été réalisé en raison de trois échantillons de sédiments prélevés avec la benne Van Veen. Au total 10 taxons appartenant à 7 genres de mollusques ont été collectés dans le sédiment des différentes stations de la lagune Aghien. Selon l’IMOL, cinq stations sur les onze indiquent un état biologique moyen. L’état biologique du sédiment est connu et présente un état biologique globalement moyen. L’IMOL peut être utilisé pour évaluer les eaux lentiques ayant 10 mètres de profondeur maximale English title: Biological state of the sediment of the Aghien lagoon from the Malacological Quality Index of Lacustrine Systems (IMOL) (South-east, Ivory Coast) The Aghien lagoon is a peri-urban lagoon subject to several types of anthropogenic pressures. These pressures could have effects on biological communities which may be ecological quality status indicators. Among these biological communities, mollusc’s which are likely to colonize the deep zone of lagoon and lake systems. This study was carried out to assess the biological state of Aghien lagoon sediment from the malacological index of lake systems (IMOL). At each station, sediment sampling was performed due to three sediment samples taken with the Van Veen grab. A total of 10 taxa belonging to 7 kinds of molluscs were collected in the sediment of the various stations. According to IMOL, five of the eleven stations, had an average biological state. The biological state of the sediment was known and had an average biological state.  IMOL can be used to assess lentic waters up to 10 meters deep.

Port activities such as ship traffic and dredging of port basin's sediment can impact biological communities such as the benthos, the composition of which remains unknown. Moreover, the knowledge of the ivorian’s port basin benthic fauna is of concern to both scientists and port authorities in the development of their activities. This study carried out in July and December 2021, aimed to provide the first data on the composition of San-Pédro’s port basin benthic macroinvertebrates communities. For this purpose, four (4) sampling points were defined near the new wharf and in the central channel of this port. The measurements of the physical-chemical parameters of the darsine waters (temperature, salinity, turbidity, dissolved oxygen and lead content) were carried out in situ between 6 a.m. and 8 a.m. using a multiparameter. Benthic macroinvertebrates were collected with a Van Veen bucket with the help of two divers. The physical-chemical parameters indicated that the waters were oxygenated and turbid in the construction area of the new wharf. They were salty, warm, and rich in lead in the central channel. 39 species classified in 34 families, 25 orders, 07 classes, and 05 phyla. The phylum of mollusks (with 29 species) was the most preponderant. The distribution of macroinvertebrates was influenced by lead, turbidity, dissolved oxygen, salinity, and temperature. The benthos populations of port basin were lowly diversified and with a fairly balanced organization.

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The needs induced by the galloping demography and urbanization in the north-central part of Côte d'Ivoire have provoked strong anthropic pressures on the Bandama River, particularly its section located in the Haut-Bandama Wildlife reserve. This is reflected in the increased invasion of this watercourse by aquatic plants and algae, its enrichment in suspended matter and chemicals of all kinds. This state of the river could have repercussions on the development of biological organisms such as fish. Thus, the study aimed to determine the size structures and length-weight relationships of Brycinus imberi, Labeo coubie and Oreochromis niloticus from the Bandama River located in the Haut-Bandama wildlife Reserve. It was carried out along the longitudinal gradient (upstream-downstream) of the Bandama River, on 06 stations and during 08 sampling campaigns between January 2018 and February 2019. Fish specimens’ lengths measurements were made with an ichthyometer, and with an electronic scale, for the weights. The analysis focused on the size structure and length-weight relationships. Length-weight Relationship (LWR) was described by the equation: W = aLb. Brycinus imberi specimens’ sizes varied from 5.3 to 13.5 cm SL. At Labeo coubie, the specimens have sizes that oscillate between 7.6 and 51.2 cm SL. As for Oreochromis niloticus, the sizes were between 8.7 and 17 cm SL. Growth appeared allometric negative with b values of 2.70 for Brycinus imberi, 1.08 for Labeo coubie, and 2.51 for Oreochromis niloticus.

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