The distribution of dinoflagellate cyst assemblages in recent sediments of the Oualidia Lagoon, Morocco, with a focus on toxic species

Harmful algal blooms (HABs) are becoming widely distributed and more frequent, threatening socioecosystems human health. We determined species composition, abundance spatial distribution of dinoflagellate cysts in the upper sediment Oualidia Lagoon located on Atlantic coast Morocco. Sediment samples were collected 2017 at 51 stations, environmental parameters measured together with microphytoplankton abundance. characteristics including water percentage, organic matter content grain size determined. Fourteen cyst morphotypes identified, Lingulodinium polyedrum (50%) Gonyaulax spinifera (22%) dominating assemblages. Total densities ranged from 0 to 293 g−1 dry sediment. Cyst positively correlated increased decreasing size. revealed presence three neurotoxic species: Alexandrium minutum, tamarense complex, Gymnodinium catenatum. Numerous had accumulated sediment, and, because they likely responsible for initiation HABs Lagoon, should be monitored.