Ecological patterns and environmental drivers of terrestrial arthropod metacommunities in tidal marshes and adjacent landscapes of the SW Atlantic

Abstract

Understanding the factors influencing species composition at the metacommunity level is key for assessing landscape biodiversity and conservation. This study investigates terrestrial arthropod assemblages in tidal marshes along the southwest Atlantic coast (Argentina), comparing them to assemblages in adjacent terrestrial environments. The research explores how environmental and ecological factors shape these communities. Arthropods were sampled from 4 tidal marshes and neighboring terrestrial environments within the same marine biogeographic province but spanning 3 terrestrial biogeographic provinces. The study measured abundance, richness, alpha and beta diversity (as turnover and nestedness). Akaike’s information criterion (AIC)-based multiple regression analysis showed that abundance, richness, and alpha diversity of terrestrial arthropods in marshes increased with marsh area, while richness increased with species richness in terrestrial environments, highlighting that marshes provide habitats for many terrestrial species. Abundance declined with temperature range, and richness and alpha diversity increased with salinity. Beta diversity and turnover decreased with rainfall, while beta diversity increased with temperature range. Nestedness showed the opposite pattern, suggesting that physical factors in fluence assemblage structure. Ecological traits of species also influenced marsh–terrestrial community composition: higher beta diversity and turnover were associated with lower proportions of generalists, while turnover declined with more good dispersers in terrestrial environments. This study highlights that although the marsh–terrestrial boundary is not impermeable, it is selective. Higher environmental stress correlates with increased beta diversity, turnover, and reduced nestedness. Spatial structure and species traits suggest deterministic processes dominate, emphasizing the importance of landscape connectivity and the need to integrate metacommunity patterns into coastal conservation strategies.