International audienc

19In tropical South America, the mudflats of the Amazonian coast are unique because of their 20 large size and unrivaled migration dynamics. On Guiana´s coast, macrofaunal communities 21 are believed to be well-adapted to these dynamic conditions. In this study, the benthic 22 macrofauna was sampled in April 2012 in the Awala-Yalimapo region of western French 23 Guiana and at two sites in Suriname, Warappa Kreek and Bigi Pan, These sites are found 800, 24 920, and 1,140 km from the Amazon delta, respectively. The richness, diversity, and densities 25 of the macrofaunal communities in these mudflats are here described for the first time. Only 26 38 OTU were recorded, among which two species were common and widely distributed: the 27 tanaid crustacean Halmyrapseudes spaansi and the polychaete Sigambra grubii; the former 28 represented 84% of all individuals collected, with densities reaching up to 73,000 individuals. 29 m -2 . Most of the OTU consisted of relatively small individuals (< 10 mm in length). The very 30 low richness and diversity and the small sizes of the organisms are likely linked to the 31instability and softness of the substrate on these mudflats. This study suggests that the 32 differences in macrofaunal community composition among sites could be due to the migration 33 stage of banks rather than the distance from the Amazon Delta and associated effects of river 34 discharge. 35 ManuscriptClick here to view linked References