Spatiotemporal assemblages of soil arthropods communities in a tropical palustrine-estuarine urban coastal wetland

Abstract

Caribbean coastal wetlands have undergone significant anthropogenic changes since colonial times, leading to a diverse range bio-physicochemical environments and varied vegetation. These changes have fostered complex ecosystems that support varied ecological niches for soil arthropod communities, essential to wetland food webs and biogeochemical processes. The sensitivity of soil arthropods to environmental changes makes them key bioindicators of ecological shifts.<br /> <br /> This research aims to assess soil arthropods distribution and interactions in response to spatiotemporal bio-physicochemical dynamics within Las Cucharillas Natural Reserve, a tropical palustrine-estuarine, urban coastal wetland in Puerto Rico. We conducted sampling across two sets of 10 m² plots-one with autochthonous organic substrate and the other with allochthonous mineral soil-over a year, covering different hydroperiod conditions. In each plot, soil samples were collected from under three randomly selected plant functional types and processed using lighted Tulgren-Berlese funnels for soil arthropods extraction. Phreatic level, pH, salinity, and litter quality (C%, N% and C:N ratio) and quantity (dry weight) were measured.<br /> <br /> Results indicated significant effects of hydroperiod conditions on soil arthropod assemblages. Optimal conditions during wet periods led to enhanced community metrics and complex assemblages. Moderate dry and moist periods resulted in decreased arthropod density, richness, and diversity, suggesting these conditions may surpass many taxa's resilience. Whereas flood periods significantly reduced arthropod richness and shifted the community composition toward water-tolerant taxa.<br /> <br /> Vegetation type and hydroperiods influenced habitat and resource availability, impacting arthropod trophic structures and community dynamics. Soil arthropod trophic guild densities peaked in both equilibrium (C:N ratio between 20:1 and 30:1) and immobilization (C:N ratio >30:1) phases of decomposition. Fluctuations in litter mass carbon and nitrogen concentration, driven by hydroperiods and plant types, were crucial for determining soil arthropod richness and abundance.<br /> <br /> This research highlights the combined effects of plant-hydroperiod interactions on substrate habitat and resource availability, and their influence on soil arthropod assemblages and trophic structures. It offers valuable insights for ecosystem management and conservation strategies aimed at preserving biodiversity and ecosystem functionality in wetland environments.These strategies are crucial tools for addressing global and regional climate change, sea level rise, and increased anthropogenic use of the region.