Temporally variable macroinvertebrate–stone relationships in streams

Abstract

Stones were used to sample macroinvertebrates and characterise microhabitats at monthly or bimonthly intervals in six Ecuadorian streams covering a gradient in four different stability measures and other stream characteristics. The physical variables current velocity, water depth, horizontal position, embeddedness and size were measured to characterise stone microhabitats and presumed to be affected by or related to physical impact during hydrological disturbances. My first objective was to analyse how density, the number of families and a richness measure (residuals from a power regression of families vs. individuals) were related to the physical characteristics of individual stone habitats. My second objective was to quantify temporal variability in fauna-stone relationships and to analyse if such variability was related to overall stability of stream reaches. Partial Least Squares (PLS) multiple regression analyses showed high temporal variability between sampling dates in factor loadings of specific stone micro habitat variables. In spite of this, there was a clear negative effect of depth and a positive effect of current on density and number of families. Stone size was consistently negatively related to density and positively related to number of families. Patterns were less clear for richness residuals. Simple linear regressions of fauna vs. stone parameters generally confirmed the results reached by the PLS analysis, although few of the regressions were significant. For all fauna-stone regressions the variability in slopes was much higher among sampling dates within streams (temporal variability) than among streams (spatial variability), and significant slopes were even inverted on different sampling dates. Although the coefficients of variation (CV) of slopes of a given combination of fauna parameter and stone variable from different sampling dates (n ¼ 9-11) were rarely correlated to any of the measures of stream stability, this study has demonstrated high temporal variability in fauna-stone relationships (CV's of regression slopes). Consequently, temporally un-replicated studies of such relationships do not necessarily reveal general patterns.

Invertebrate drift and colonization processes in a tropical Andean stream

“…As a consequence of this, community metrics values were higher for stones located in fast-velocity areas. This has also been reported for stone-fauna experiments in Australia (Downes et al 1995) and in the high Andean streams of Ecuador (Jacobsen 2005). The degree of stone upturn was only important to a few taxa such as Podonominae and Simuliidae.…”

The role of the hydrological cycle on the temporal patterns of macroinvertebrate assemblages in an Andean foothill stream in Colombia

“…According to Flecker and Feifarek (1994) and Jacobsen (2005Jacobsen ( , 2008, the macroinvertebrate assemblages in tropical rivers are conditioned mainly by the flow regime and hydrological disturbance, which affect the stability of the substrate, the drift process and the availability of allochthonous resources, with drift being generally aseasonal (Ramirez and Pringle, 1998;Rodriguez-Barrios et al, 2007). In a Neotropical stream of the Bolivian Andes, Tomanova et al (2006) and Tomanova (2007) concluded that macroinvertebrate communities respond according to the Habitat Templet Theory (Southwood, 1977;Townsend, 1989;Townsend and Hildrew, 1994), establishing a close relationship between environmental conditions of habitat and the biological traits (adaptations) of taxa that live in this habitat.…”

“…In tropical streams, several studies have examined the influence of stream flow on the seasonal variations of invertebrate communities (Hynes, 1975;Dudgeon, 1993;Flecker and Feifarek, 1994;Cressa, 1998;Jacobsen and Encalada, 1998;Ramirez and Pringle 1998), and the importance of hydrological disturbance in tropical mountain streams has been suggested by Jacobsen (2005), Tomanova et al (2006), Tomanova (2007) and Ríos-Touma et al (2011). In Colombia, studies on macroinvertebrate assemblages focus on issues such as the taxonomic diversity and/or their role as indicators of water quality (Roldan, 1988;Álvarez, 2005;Álvarez et al, 2006).…”

Effects of the hydrological cycle on the phycoperiphyton assemblage in an Andean foothill stream in Colombia

“…During the rainy period, water flow may be irregular (Rivera and Donato, 2008) and N o n -c o m m e r c i a l u s e o n l y episodic spates can occur. The intensity of spates during the rainy period is associated with the rainfall frequency and local topography; it may affect streambed stability, turbidity and the mobility of the substrata (Jacobsen, 2005(Jacobsen, , 2008. Such hydrological variability is associated with changes in factors involved with the flow, such as the water speed and depth, and constitutes a disturbance that triggers changes in the phycoperiphyton assemblage and its succession due to their small size, passive dispersal method and generally limited mobility (Connell, 1978;Townsend, 1989;Winemiller et al, 2010, Passy, 2007Algarte et al, 2014).…”