Molecular Identification of an Invasive Sarotherodon Species from the Atchakpa Freshwater Reservoir (Ouémé River Basin, Benin) and Comparison within S. melanotheron Using COI Markers

Rodrigue Orobiyi Edéya Pèlèbè,Maarten Van Steenberge,Ibrahim Imorou Toko,Erik Verheyen

doi:10.3390/d13070297

Abstract

The Atchakpa freshwater reservoir (Ouémé Basin, Benin) was found to harbour an unexpected population of a cichlid species that was presumed to be Sarotherodon melanotheron. This species became dominant in the reservoir and became the main fisheries target species. We applied DNA barcoding to identify this population. Besides specimens from the reservoir, we also sequenced S. melanotheron from its native range in Benin at the lower Ouémé and Sô Rivers, and from Lake Nokoué, and Porto-Novo Lagoon. High sequence similarity indicated that all specimens were conspecific. Hence, we cannot exclude that a natural range extension led to the presence of the species in the reservoir. A comparison with sequences from NCBI GenBank confirmed that all samples belonged to the subspecies S. m. melanotheron, which is native to Benin. This comparison also showed that this subspecies was previously introduced in the Philippines. We call for further studies to investigate the socioeconomic, ecological and environmental impacts of the species in the Atchakpa reservoir.

Highlights

The black-chin tilapia, Sarotherodon melanotheron (Rüppell, 1852), is an estuarine species endemic to West and Central Africa [1,2,3] that is well known from the brackish waters of southern Benin
Besides the Atchakpa reservoir, we sampled in two brackish waters: Lake Nokoué and PortoNovo Lagoon, and two freshwaters: Agonlin-Lowé (Ouémé River) and Sô-Ava (Sô River), where S. melanotheron is native
Four specimens per site were fixed in formalin and deposited at the Royal Belgian Institute for Natural Sciences (RBINS) under collection numbers: Atchakpa water reservoir (25907, 25908, 25909, and 25910), Sô-Ava (Sô River) (25923, 25924, 25925, and 25926), Agonlin-Lowé (Ouémé River) (25911, 25912, 25913, and 25914), Porto-Novo Lagoon (25915, 25916, 25917, and 25918) and Lake Nokoué (25919, 25920, 25921, and 25922)

Summary

Introduction

The black-chin tilapia, Sarotherodon melanotheron (Rüppell, 1852), is an estuarine species endemic to West and Central Africa [1,2,3] that is well known from the brackish waters of southern Benin. In the Ouémé River basin, its limit of frequent occurrence is the village of Agonlin-Lowé (Commune of Adjohoun, department of Ouémé) [4] This locality is considered the boundary between the continental and the coastal domains in Benin [4] (Figure 1). A large population of presumed S. melanotheron was discovered prior to 2001 in the Atchakpa freshwater reservoir (SUCOBE dam built in 1982), which is located in central Benin, about 230 km north of Agonlin-Lowé [4,7]. This population, which was only morphologically identified, thrived in the landlocked reservoir.

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Conclusion