Author: Rebecca J Best,  Assistant Professor (Northern Arizona University)

Description:
Aquatic biodiversity is declining globally, and arid regions are particularly at risk due to climate change. As surface water habitats experience higher temperatures and more frequent drying events, it is important to understand which types of systems will provide refugia for aquatic invertebrates. In northern Arizona, natural aquatic systems are infrequent and isolated, whereas anthropogenic stock ponds are abundant across the landscape. Both of these habitats vary in hydroperiod, with some experiencing annual summer drying (ephemeral) and others maintaining aquatic habitat (permanent) in all but the driest years. To better understand community assembly processes in these habitats, and evaluate their relative value as refugia for biodiversity, we sampled aquatic macroinvertebrates and water body characteristics in natural and anthropogenic ponds across three seasons in 2019. We found significant seasonal effects on total abundance, richness, and diversity regardless of habitat type. Natural versus anthropogenic origin had no significant effect on diversity indices. However, hydroperiod had surprising effects on diversity and community composition. In the post-monsoon recovery from summer drying, ponds that were predictably either permanent or ephemeral had higher diversity than ponds that were normally permanent but had experienced extreme drying events in the previous year. Our results suggest that a variety of lentic systems can support aquatic invertebrate diversity, but that extreme events related to climate change can have large and lasting effects.

Category: Scientific Program Abstract > Special Session > SS35 Drying in freshwater systems: merging lotic and lentic perspectives in an era of global change