Contribution to the Knowledge of Zooplankton in the Mellacore Estuary, Republic of Guinea

Abstract

This study aims to inventory the zooplankton stand in the Mellacorée River estuary, as well as its composition, abundance, and structure during the dry season. This river is located in Forécariah Prefecture, the southwestern Republic of Guinea. It is located about 30 kilomètres from the border with Sierra Leone. Sampling work at the stations was carried out monthly from December 2019 to May 2020 using the plankton net “Djedi”, 55 µm mesh vacuum. For a total of 10 stations sampled, 21 species belonging to 12 families (Calanidae, Paracalanidae, Eucalanidae, Calocalanidae, Oithonidae, Medusae, Phaenidae, Mysidacae, Sagittidae, Cladocère, and Euphausiacae) were identified. The density is dominated by the species Paracalanus parvus (41866.31 ind/m 3 ) followed by Calanus helgolandicus (19277.49 ind/m 3 ) and then Eucalanus elongatus (13221.98 ind/m 3 ), Lucifer sp (66.65 ind/m 3 ) and other organisms: nauplii larva (111.1 ind/m 3 ). Analysis of the samples shows a high zooplankton diversity with the following relative frequencies: Calanidae (36.06%); Paracalanidae (34.66%); Eucalanidae (17.83%); Calocalanidae (0.84%); Oithonidae (1.17%); Medusae (0.23%); Temoridae (0.12%); and other larva organisms, nauplii (1.09%). Biomass ranged from 170.2758 mg/m 3 to 48.6824 mg/m 3 . However, the highest biomass was obtained in February and the lowest in March. Conclusion and application: The results of our investigation suggest that the zooplankton community of the Mellacore River estuary exhibits significant richness and diversity. This research can be a valuable biomonitoring tool to assess the ecological integrity of this aquatic system. Further study on the phytoplankton of the Mellacore River is essential to improve knowledge of the different plankton species.