Dynamic contributions of intermittent and perennial streams to fish beta diversity in dryland rivers

Abstract

Aim To determine the role of flow intermittence and species origin in shaping freshwater fish beta diversity across dryland riverscapes. Location Verde and Little Colorado River basins, United States. Methods Fish beta diversity was investigated in two large rivers with marked differences in basin‐wide flow intermittence. Local site (continually flowing perennial vs. periodically flowing intermittent) and species (native vs. non‐native) contributions to beta diversity were compared within each basin and over multiple decades (1987–2013) in relation to changing hydrologic conditions. Metacommunity dynamics were quantified using changes in alpha‐ (local), beta‐ and gamma‐ (regional) diversity through time. Results Beta‐diversity patterns varied in relation to basin‐wide intermittence. Intermittent sites were most influential to beta diversity where basin‐wide intermittence was lower (Verde River), whereas perennial sites were most influential where basin‐wide intermittence was higher (Little Colorado River). In intermittent sites, native fish species contributions to beta diversity tended to be higher than non‐native species contributions. The relative contributions of perennial and intermittent sites to β‐diversity within each basin were invariant to annual flow regimes, whether atypically lower or higher than average flows, but somewhat related to intra‐annual flow variation. Native species contributions to β‐diversity increased in years with high flow conditions in the Verde River. Over time, beta diversity decreased in the lower intermittence Verde River, indicating taxonomic homogenization, but remained relatively unchanged in the Little Colorado River. Main Conclusions Investigations of beta‐diversity components over time are considered pivotal for conservation prioritization and planning. We found that both intermittent and perennial streams play complementary roles in supporting fish beta diversity, and that their relative contributions increase as basin wide availability of the habitat type decreases. Moreover, contributions of intermittent streams to overall beta diversity were relatively consistent through time and supported native fish diversity. Despite weakening policy protections of intermittent streams, these habitats are critical for supporting local species persistence and regional biodiversity.

Connectivity, habitat, and flow regime influence fish assemblage structure: Implications for environmental water management in a perennial river of the wet–dry tropics of northern Australia

“…M. mogurnda, L. unicolor, and M. australis). Thus, at the landscape level, intermittent streams in this catchment were important in maintaining or contributing to whole-catchment diversitya result supported in other regions of the world (Rogosch & Olden, 2019).…”

Riverine spawning, long distance larval drift, and floodplain recruitment of a pelagophilic fish: A case study of golden perch (Macquaria ambigua) in the arid Darling River, Australia

“…Environmental flows are a primary means of protecting river ecosystems (Arthington, Kennen, Stein, & Webb, ) and under the MDB Plan, an annual total of 2,750 GL of water will be used to restore flow regimes to rivers and their floodplains (Swirepik et al, ). Site‐specific addition of water alone, however, is unlikely to be successful in long‐term population recovery of pelagophilic fish unless tributaries can also be reconnected to main‐stem rivers, where both intermittent and perennial rivers provide complementary roles in sustaining fish populations (Rogosch & Olden, ). A large‐scale, continuously flowing river, hydrologically reconnected to its tributaries, should be a vision for the Darling system.…”

“…This article presents crucial information that emphasizes protection of the integrity of tributary baseflows and connected lotic rivers, and floodplains over very large spatial scales. The Darling River case study highlights the global call for system‐level thinking in maintaining the integrity of large‐river ecosystems, and greater protection of lotic reaches and tributaries for conservation of pelagophilic fishes (Perkin et al, ; Rogosch & Olden, ).…”

Conservation and Management of Isolated Pools in Temporary Rivers

“…All the previously mentioned local and regional factors result in high variability of populations and communities found in IPs even when they are located close in space [22,135] (Figure 6). These Ips, thus, significantly contribute to the higher beta-diversity values reported in temporary rivers in comparison to perennial ones considering both spatial and temporal beta diversity [136,137], and they can harbour complementary sets of species that contribute to gamma (i.e., regional) diversity [138] (Figure 6). This has already been reported for temporary ponds and wetlands, where unique biodiversity adapted to living under harsh environmental conditions can be found [139][140][141].…”