Rainfall Influences the Patterns of Diversity and Species Distribution in Sandy Beaches of the Amazon Coast

The Amazon region is one of the Earth’s hotspots biodiversity and has a pivotal role in climate regulation. Yet, little known about its coastal biodiversity. Here, we performed first assessment macrobenthic diversity ecological patterns sandy beaches north River delta, world’s largest freshwater input into oceans. By assessing spatial temporal changes soft-bottom environmental variables three (Goiabal, Nazaré, Sumaúma) northernmost stretch Brazilian coast, found low richness (14 taxa, overall; Goiabal: 3.27 ± 1.78; Nazaré: 2.34 1.29; Sumaúma: 2 0.67) (Goiabal: 0.72 0.52; 0.62 0.46; 0.55 0.39) across 2949 individuals with great dominance estuarine species (notably Nephthys fluviatis Sphaeromopsis mourei). Abundance was higher during rainy periods, same pattern observed for comparison to transitional at least on Nazaré Beach. Environmental heterogeneity reduced resulting abundance dominant lower beta diversity. Most presented aggregated distribution upper intertidal zone, assemblages were linked variations rainfall organic matter content sediment. Given uniqueness severe erosional process affecting northern coast region, our results provide essential baseline knowledge better understand processes influencing understudied We advocate that further studies expand findings support conservation this region.