Hydrological influences on aquatic communities at the mesohabitat scale in high Andean streams of southern Ecuador

Abstract

This study assessed the effects of hydrological events on aquatic communities at the mesohabitat scale (pool, run, and riffle) in the high Andean region. Four headwater sites located in the Zhurucay microcatchment (southern Ecuador), with elevations higher than 3,500 m, were selected and monitored considering in each site a 50‐m‐long reach and within each reach five cross sections. In each of these reaches, 19 sampling campaigns were conducted in the period December 2011–October 2013, collecting macroinvertebrates and physical characteristics. A total of 27 hydrological indices were calculated using the daily flow rate as input. Large peak flow, small peak flow, and low flow (LF) events were defined based on discharge thresholds. Multivariate statistics showed that 14 hydrological indices were significantly related to the aquatic community. Further, the study revealed that (a) peak events produced stronger effects on communities than LF events, (b) the observed effects of LF events were weaker than those encountered in other latitudes, and (c) local benthic communities have more resilience than similar communities studied in other latitudes.

Habitat Suitability Curves for Freshwater Macroinvertebrates of Tropical Andean Rivers

“…Ecuaphlebia genus was present mainly in lower velocity habitats with intermediate substrate size, which contradicts the findings of Vimos-Lojano et al [78] that refers to Ecuaphlebia being present in habitats with faster currents and larger substrate in an Andean subcatchment with elevations higher than 3500 m of elevation. The genus Andesiops, despite having a hydrodynamic form for swimming and tarsal nails for attaching to the substrate [77] do not frequent faster and turbulent flow environments.…”

Habitat simplification changes temporal patterns of invertebrate beta diversity in a high-Andean stream

“…The findings of Jacobsen [6], in particular, suggest that the flow regime primarily drives temporal beta-diversity patterns in Andean communities, since species composition is determined at random after a high-flow event. Subsequent studies revealed mixed shreds of evidence; while some support a random assembly after spate events [12,13], others found no significant differences before and after high-flow events [14,15]. These conflicting results may be explained by differences in habitat heterogeneity or species life histories as well as by methodological differences (e.g., distinct diversity indices).…”

“…In light of this, beta diversity may be higher due to sampling bias (e.g., sampling only one type of substratum), since species occurrence and abundances are tightly coupled with the substratum type in tropical headwaters [12,20]. On the other hand, beta diversity could be higher if the used metric gives more weight to species abundances rather than to species identities since spates tend to affect species abundances rather than their occurrences [11,15]. Therefore, including different metrics is likely to improve our knowledge of the drivers of temporal beta-diversity patterns.…”

Estudio de la diversidad taxonómica y funcional de los macroinvertebrados en un río de montaña Andino

“…Los ecosistemas lóticos de montaña son sistemas complejos en su estructura y funcionamiento; en estos ocurren diferentes procesos que involucran variables físicas, químicas y biológicas, que interactúan de forma sinérgica y hacen que estos sistemas tengan alta heterogeneidad espacio-temporal (Allan & Castillo, 2007;Elosegi & Sabater, 2009). Así, esta variación espacio-temporal contribuye a la dinámica y distribución de las comunidades biológicas (Brooks, Haeusler, Reinfelds, & Williams, 2005;Vimos-Lojano, Martínez-Capel, Hampel, & Vázquez, 2019). Particularmente, los arroyos y ríos de los Andes albergan una alta diversidad biológica que se integra en los procesos ecosistémicos y determina el funcionamiento de éstos.…”

“…Son múltiples los factores que inciden sobre los macroinvertebrados en un río o arroyo de montaña. El ambiente físico es un factor fundamental, donde el sustrato y la dinámica hidráulica modifican la disponibilidad de recursos y la estructura de las poblaciones (Death & Winterbourn, 1995;Rempel, Richardson & Healey, 2000;Brooks et al, 2005;Mesa, 2010;Vimos-Lojano et al, 2019). La materia orgánica según la fuente, su forma y calidad son el otro factor de gran relevancia en la estructura de estos ensamblajes, especialmente en sistemas lóticos andinos (Lujan, Roach, Jacobsen, Winemiller, Vargas, Ching & Maestre, 2013).…”