Record of the invasive Red Sea mussel Brachidontes pharaonis (Bivalvia: Mytilidae) from the lagoon of Boughrara (Southern Tunisia, central Mediterranean sea)

Abstract

Brachidontes pharaonis were recorded in Tunisia water thrice. The first time in August 2007, a living specimen was collected from a freshly loggerhead stranded Zarzis (southern Tunisia). The second time during the project of the 'Protection of the marine and coastal resources of the Gabes Gulf' in 2011, the species was observed aggregated with Mytilaster minimus, in a coastal area of Zarzis. Brachidontes pharaonis was considered rare. In 2013, the mollusca were recorded in the same area (Zarzis) in a very shallow depth in harbour and artificial reef. During an investigation of the lagoon of Boughrara in 2016, a 'Brachidontes bed' were discovred in the north west of the lagoon (Ajim Channel) at depth of 7 m. The salinity and the temperature water were respectively 45 PSU and 26.9 °C. The mollusks density was estimated to 5000 specimens/m2. The biometric measurement was also assessed in the site.