Ground-Arthropod Assemblage Response to Groundwater as a Metric of Flooding in the Middle Rio Grande

Riparian zones are dynamic ecosystems, crucial for maintaining biodiversity and ecological balance, particularly in arid environments like the Middle Rio Grande (MRG). Ground arthropods, with their sensitivity to environmental changes, serve as bioindicators for assessing the impacts of water regime changes in the MRG, specifically flooding which was historically the main driver of the MRG ecosystem. This study investigated the responses of ground arthropod communities to fluctuations in groundwater and land management practices within MRG riparian habitats. Using a combination of pitfall trapping and habitat assessments, arthropod abundance was assessed in relation to depth to groundwater (DTG). Findings revealed shifts in arthropod taxa abundance in response to changes in DTG, highlighting groundwater as a driver of the MRG ecosystem and arthropods as bioindicators of DTG. The isopod species Armadillidium vulgare and Porcellio laevis both significantly increased in abundance with a low DTG, with A. vulgare increasing much more at low DTG. Field cricket abundance was also found to increase with a low DTG at a marginal significance level. In addition, the beetle family Carabidae was found to be a good bioindicator of low DTG while the beetle family Tenebrionidae was found to be a good indicator of high DTG. At the genera level, the best bioindicator of a low DTG for Carabidae was Agonum while the best bioindicator of a high DTG for Tenebrionidae was Araeoschizus, and Stenomorpha. These results provide critical insights for conservation efforts and underscore the need for informed water and land management to protect riparian biodiversity in the MRG as flows decrease due to climate change. Some examples where this research could be used to assess conservation efforts include important birding habitat in the Albuquerque area such as the Candelaria Nature Preserve and Valle de Oro National Wildlife Refuge. These areas are undergoing active restoration to increase wetland area and reconnect the bosque floodplain. As these restoration efforts take place, DTG will change and arthropods, due to their quick response to ecosystem changes, would be an ideal tool to assess restoration success.