European Ocean Biodiversity Information System

This dataset is the main part of a study conducted monthly throughout 2019 at three stations selected due to their combined continental and marine influences. The study aimed to assess the health status of the El Mellah lagoon. The analysis of the spatio-temporal variation of angiosperms reveals significant changes in their distribution within the lagoon, which appear to be linked to fluctuations in the environmental conditions of El Mellah. It is observed that Zostera noltei (Hornemann, 1832) dominates the stations influenced by freshwater, while Ruppia maritima (Linnaeus, 1753) dominates the northern part of the lagoon, where the influence of marine waters is more pronounced. The invasive species Arcuatula senhousia, which was first observed in June 2019 in El Mellah, has been found attached to the leaves and rhizomes of Zostera noltei, and to a lesser extent, on the empty shells of the bivalve Cerastoderma glaucum. Since its introduction, it has dominated the bivalve community in El Mellah with a maximum density of 1321 ± 1167 ind.m-2. This phenomenon can lead to a decline in the biodiversity of the lagoon, particularly affecting the Zostera noltei seagrass and the threatened Cerastoderma glaucum species. It is necessary to conduct comprehensive studies to assess the impact of Arcuatula senhousia in the El Mellah lagoon to implement appropriate conservation and restoration measures to preserve the integrity of the ecosystem."