Aquatic communities of ephemeral stream ecosystems.
TABLE 1--Schedule of sample collection and day of succession (numbers 1-6) for ephemeral stream systems within the study area, 2006.
The biota and succession patterns in ephemeral streams (sensu Armantrout, 1998; Bain and Stevenson, 1999) have not been well studied in the southwestern United States when aquatic habitats are temporarily (e.g., <1 week) created by flow events.
Because these ephemeral streams represent, for aquatic organisms, a small patch of habitat within an otherwise hostile environment, island biogeographic theories (MacArthur and Wilson, 1967) should apply.
Based on previous studies in arid-land streams, the primary species colonizing the small, temporarily wet reaches of ephemeral streams are hypothesized by researchers to be aerial adult colonizers with good powers of dispersal, species with rapid larval development, and those utilizing catastrophic drift from perennial stream reaches upstream (Williams, 2001; Van de Muetter et al., 2007; Lytle and Poff, 2004; Bogan and Boersma, 2012).
We conducted a natural history study to survey the aquatic macroinvertebrates and vertebrates in several ephemeral streams in two regions in Arizona and New Mexico that flowed for short periods of time after monsoon thunderstorms (AWWQRP, 2006).
Regional and Succession Patterns--To analyze regional biogeographic patterns, we identified the number of distinct taxa across all sites and within each watershed, as well as between the "ephemeral reaches of intermittent streams" and the truly "ephemeral streams," as defined above.
Controlling entrenchment of semiarid ephemeral streams is difficult because the extremely variable and dynamic conditions create stream behavior different from that where most hydrological principles and erosion control methods were developed (Bull 1997).
Traditional Zuni erosion-control methods effectively modify channel morphology of entrenched headwater ephemeral streams after small flows and powerful floods in ways that increase the occurrence of overbank flows and the area of alluvial fans flooded by recurrence interval flows of less than or equal to five years.
Discontinuous ephemeral streams. Gepmorphology 19:227-276.
Aquatic habitats include perennial and ephemeral streams, springs, wetland ponds, tinajas (ephemeral rock pools), and alcove pools (permanent rock pools located below large cliff pour offs).
Future studies should focus on identifying and sampling new habitats, especially the numerous wetland-like habitats that occur across the Colorado Plateau, such as hanging gardens and alcove pools, as well as ephemeral streams, because these are poorly sampled and may be first affected by future changes in climate.