1 3 ABUNDANCE 2 Unvegetated Microplastic retention in the sediment of small-bodied tropical seagrass meadows This study presents the first assessments of MP contamination in seagrass meadows of the Southwestern Tropical Atlantic bioregion. Our results showed that the MPs are ubiquitous even in a Marine Protected Area. There was no difference in the abundance of MPs between vegetated and unvegetated areas. Seasonal influence was not relevant in the MP abundance in the three studied seagrass species. Identifying the drivers leading to MP accumulation in seagrass meadows may include a wider assessment of seagrass species with different plant traits and meadow complexities, as well as the local environmental factors is necessary. 66% Fiber 21% Film 4% Fragment First study to investigate MP in Halodule wrightii, Halophila decipiens and H. baillonii Now 25% of the 72 seagrass species have been investigated. Brazil Halodule wrightii Halophila decipiens Halophila baillonii MICROPLASTIC IN TROPICAL ESTUARINE SEAGRASS MEADOWS: DOES SEAGRASS SIZE MATTER? 1 Department of Biology, Federal Rural University of Pernambuco (DB/UFRPE), central campus, Recife, Brazil. 2 Department of Fisheries and Aquaculture, Federal Rural University of Pernambuco (DEPAQ/UFRPE), central campus, Recife, Brazil. 3 Centro de Ciências do Mar do Algarve (CCMAR), University of Algarve, Gambelas campus, Faro, Portugal. * Corresponding author: viegasmao@gmail.com DOI: 10.5281/zenodo.12709067 Published: July, 10, 2024 ACKNOWLEDGMENTS Study area INTRODUCTION OBJECTIVE RESULTS Ana M.C. Souza , Guilherme V.B. Ferreira , Carmen B. de los Santos , Flávia L. Frédou , Karine M. Magalhães 2 1 * 3 2 1 METHODS Seagrass meadows have been appointed as efficient microplastic (MP) trapping hotspots. MPs accumulation in the seagrass sediments from the Tropical Atlantic bioregion, such as those found i n South America, have not been investigated yet. Also, small-bodied segrass species are much less studied than large ones onther capacity to retain s MPs. Research sedimentary MP retention in areas vegetated by small-bodied seagrass species Halodule wrighti i (HW), Halophila decipiens (HD), and H. baillonii (HB) a nd an adjace nt unvegetat ed (U N) ar ea in a tropi cal estuary in the Brazilian coast, according to seasonality. Sampling was carried out in a multispecific seagrass meadow and an adjacent unvegetated area durin g the dry and rainy seasons. Biomass, shoot density and canopy height did not variation between seasons. Sediment between sand and fine sand CHARACTERIZATION Sediment samples (N = 80) A total of 227 MP particles Microplasctic Meadow and Sediment Analysis 1. Characterization Seagrass meadow Sediment 2. Microplastic Extraction (NaCl / NaOH) Visual identification 3. Literature review All types of documents Web of Science Environmental Protection Area (APA) of Santa Cruz MPs abundance (particles Kg dw) Unvegetated Vegetated p > 0.05 MPS VARIATION Species/season No significant variation among species and the adjacent unvegetated area, neither for seasonality was detected. However, we found a positive correlation betwee n MPs abundance and sediment grain size. South Atlantic Ocean CONCLUSION Fibers (73%) Blue (51%) < 1 mm (80%) Areas/season Unvegetated = 125 ± 117 (Itens/kg dw) = Vegetated = 144 ± 143 (Itens/kg dw) -1 -1 Total = 142 ± 140 (Itens/kg dw) -1 MEADOW CHARACTERIZATION -1 MPs abundance (particles Kg dw) -1