Resistance to drying: The role of seedbanks and hyporheic refuges in invertebrate communities

Abstract

Abstract Aquatic refuges are essential for invertebrate communities to cope with flow intermittence in intermittent rivers and ephemeral streams (IRES), but their contribution to recovery after drying remains unclear, although they may be essential to safeguard IRES biodiversity. Here, we explored the role of hyporheic zones (HZs) and dry sediments (seedbanks) as aquatic refuges in six Mediterranean intermittent streams during drying and their contribution to community recovery at the local scale. We analysed the taxonomic and functional composition and diversity in the refuges and benthos under connected flow conditions by combining field and laboratory conditions. We explored the relationship between these metrics and the drying duration, expecting a reduction in diversity and an increase in resistance trait abundances in the refuges. The seedbank and HZ contributed 16 and 40% of the benthic taxa, respectively, and up to 60% of the functional richness found in the benthos. Conversely, we only found a negative relationship of drying duration with the relative abundance of resilience traits, not with resistance traits as initially predicted. The expected increase in drought severity due to climate change will compromise the water needed to maintain the HZ and the moisture in streambed sediments. Therefore, the protection of the integrity of biodiversity recovery mechanisms in IRES is a priority.