Paleoenvironmental Reconstruction of the Hachichina Wetland (Gulf of Gabes, Tunisia) Based on Multiproxy Records Over the Last 3000 Years

As part of a research project established between Sfax and Lisbon University, a multiproxy approach to infer the environmental evolution and coastal dynamics was conducted on sediment core with the aim to decipher forcing factors shaping the Hachichina wetland over the last 3000 years. The core was sub-sampled at each 2 cm and samples were used for sedimentological and micropaleontological study. These proxies afford us the means to discern distinct phases of marine transgression. Firstly, there are two notable phases: TR1, occurring roughly 3000 years before present, and TR2. During these phases, we observe elevated levels of CaCO3 alongside the prevalence of lagoonal ostracods taxa, notably Xestoleberis aurantia and Leptocythere pellucida, constituting approximately 60% of the assemblage. This is complemented by brackish (25%), marine (10%), and coastal (5%) species. Secondly, a regressive period around 1300 years before present is apparent, characterized by environmental restriction. This era is marked by a decline in coarse fraction and CaCO3, coupled with an increase in organic matter (OM), magnetic susceptibility (MS), and a predominance of brackish ostracod association, accounting for about 65% of the assemblage. Notably, this association includes euryhaline and eurythermic species such as Cyprideis torosa and Loxoconcha elliptica.