- Dispersion, either active or passive, plays an important role in community assembly during colonization of newly available habitats such as the arid riverbed of intermittent rivers. These unstable environments are often exposed to the ongoing colonization process from adjacent river bank habitats, a local biodiversity hotspot. We sought to identify diversity, origin, and colonization pathways of terrestrial invertebrates in the arid beds of intermittent Mediterranean rivers.
- Crossvanes window traps and pitfall traps were used to sample aviation and underground invertebrates during arid riverbed colonization. Invertebrate communities were sampled in three habitat types of the intermittent karst Kurcic River in Croatia: arid riverbed, riverbanks and highland habitats. For aerial invertebrates, we distinguished between daytime and nocturne settlers and horizontal and vertical settlers. All invertebrates were identified for species-to-species levels, carabidae, Araneae, and orthopra orders. Environmental parameters were measured in each habitat.
- Colonization of the dry riverbeds was mainly during the day. Aerial invertebrates established vertically and horizontally from their adjacent riverbank habitats and along the riverbed. Invertebrate catches are positively correlated with wind speed and direction, indicating the importance of passive dispersion by aviation plankton. Underground invertebrate communities exhibit rapid arid riverbed colonization, with riparian habitats supporting the highest diversity and unique taxa. Taxonomic indicators showed different patterns of subterranean invertebrates and taxa studied respectively.
- The observed patterns suggest that the ground-inhae family and carabidae family have been established in arid riverbeds, primarily due to ripples from riverbank habitats. In contrast, ortopra probably colonized from its highland habitat to arid riverbeds. Simultaneous sampling of airborne and ground-dwelling settlers characterized responses that could not be detected using a single method.
- Our study shows that multiple dispersive modes and source habitats are involved in the colonization of arid riverbeds. Our results highlight the importance of conserving river banks and highland areas along intermittent rivers as sources of aridity. Given the increased intermittent rivers due to climate change, conservation and restoration of appropriate river landscapes could be more broadly relevant in the future.
Rujanović, L., Rebrina, F., Vilenica, M., Medak, K., Entling, M., & Brigić, A. (2025). Terrestrial invertebrates fight back: aerial and ground-based colonization of arid riverbeds. Freshwater Biology, 70(2), E14379. https://doi.org/10.1111/fwb.14379
