Fish assemblage structure in the Tropical Coastal Lagoon of Grand Lahou (Cte DIvoire, West Africa)

Abstract

Fish assemblages and their relationship with hydrological variables were investigated in the coastal lagoon of Grand-Lahou (Côte-d'Ivoire) from November 2013 to October 2014. Samplings were carried out by means of artisanal fisheries, once a month, in three sites. A total of 8571 fish belonging to 47 fish species from 25 families were recorded. The most represented families were Cichlidae and Mugilidae with six species. Each environmental variable, notably, dissolved oxygen (DO), temperature and salinity according to the canonical correspondence analysis (CCA) allowed the distinction of two main sectors in the lagoon, associated with three fish assemblages. Sector 1 including sampling sites 2 and 3, characterized by high salinity fluctuations, functioned as a typical estuary. Two fish assemblages identified in this sector were Lutjanus dentatus, Mugil cephalus, Mugil bananensis, Tilapia guineensis and Tylochromis jentenki in station 2 and Sarotherodon melanotheron, Liza falcipinnis and Pomadasys jubelini in station 3. Sector 2 comprising the sampling site 1, characterized by low salinity fluctuation is associated with 11 fish species, notably, Ethmalosa fimbriata and Elops lacerta. The fish assemblage in this sector depends on season, temperature and DO.

Identification of critical essential habitat for demersal fish in the Gulf of Guinea

“…On this shelf, the fish community is highly diverse, with species of major interest for fisheries and food supply (Le Loeuff, 2001). The land-sea interface hosts a mosaic of habitats: open and closed lagoons (Bakari et al, 2016;Laleye et al, 2007), deltas and estuaries (Okyere et al, 2011), and mangroves (Aheto et al, 2014;Osemwegie et al, 2016). These ECEs face cumulative anthropogenic pressures: mangrove surface loss (Abé and Affian, 1993;Osemwegie et al, 2016), eutrophication (Adingra and Kouassi, 2011), siltation and deoxygenation (Okyere and Nortey, 2018), and xenobiotic loadings (Koffi et al, 2014).…”

“…However, the similarity with conclusions drawn elsewhere for this species led us to validate HSM outputs and related maps. White grouper lives in ECEs such as open lagoons, bays, and estuaries (Bakari et al, 2016;Eugenia et al, 2019;Nunoo et al, 2006;Okyere and Blay 2020;Okyere and Nortey 2018;Sossoukpe et al, 2013b) at the juvenile stage. Out of the estuarine environment, juveniles are dramatically more abundant below 50 m of depth, confirming their high concentration on the coastal fringe of the continental shelf (Vally et al, 2023).…”

“…Many exploited species in the Gulf of Guinea rely on these ECEs for their life cycle (John and Lawson, 1990). In particular, juveniles of many exploited marine species have been observed in and close to coastal lagoons and estuaries (Aheto et al, 2014;Bakari et al, 2016;Eugenia et al, 2019;Nunoo et al, 2006;Okyere et al, 2011;Okyere and Blay, 2020). Thus, the ECEs of the Gulf of Guinea contain nursery habitats (Cosme De Esteban et al, 2023), on which adverse effects of anthropogenic pressures (i.e., drop in area size due to land reclamation, degradation of habitat and water quality linked to eutrophication and pollution; cf.…”

“…White grouper and Cassava croaker are both fish species found in open lagoons and bays on the continental shelf of Gulf of Guinea (Bakari et al, 2016;Eugenia et al, 2019;Nunoo et al, 2006;Okyere and Blay 2020;Sossoukpe et al, 2013b). Red pandora are found in open waters (Kouame et al, 2020;Sylla et al, 2017).…”