Hyporheic macroinvertebrates in riffle and pool areas of temporary streams in south eastern Australia

Abstract

The hyporheic zone is an important refuge for invertebrates as surface water recedes in temporary streams. In this study, the structure and functional organisation of hyporheic macroinvertebrate assemblages in pool and dry riffle bed habitats of two episodic streams were compared over summer and winter. Multivariate analyses revealed macroinvertebrate assemblages differed significantly between streams, habitats and seasons. While some seasonal differences were expected, the differences between streams were not, given the similarity and proximity of the catchments, and were due to shifts in the abundance of common taxa. Distinct differences between riffle and pool habitats were evident in both the taxonomic and functional feeding group composition of the assemblages. In particular, riffle habitats contained greater numbers of taxa and individuals and a greater proportion of filter-feeding animals compared to pool habitats. Summer samples also had greater numbers of taxa and individuals and greater proportions of collector-scrapers than winter samples. The relative abundance of functional groups was similar between streams in summer but was more variable in winter. Patterns observed in the taxonomic and functional feeding group structure of the macroinvertebrate assemblages were more characteristic of perennial than episodic streams, despite the absence of regular surface flows. This could be attributed to the relatively constant hyporheic flow in these streams. We suggest that classifications of stream flow should consider hyporheic discharge (not just surface flow) as this clearly influences the stream biota. Hydrobiologia (2005) 532: 81-90 Ó Springer 2005

Hyporheic Exchange Under Undular Flows Over a Coarse Granular Bed

“…These findings bear important implications for stream ecology. The higher persistence of hyporheic exchange fluxes in undular flows over coarse granular beds and the presence of both wave-and grain-scale hyporheic exchange fluxes make the patch-scale hydrodynamics over riffles a more favorable environmental setting for riverine habitats, for example, for nutrient cycling and metabolic waste removal (Hose et al, 2005;Jowett & Richardson, 1995), as compared to smooth surface flows over fine-grained beds. We also show that the wave pumping flux is downwelling dominated, driving more of aerated stream water into the bed, while the grain-scale pumping flux exhibits a balanced exchange between upwelling and downwelling.…”

“…Riffles are ubiquitous mesoscale bedforms and important habitats in gravel-bed streams (Hose et al, 2005;Jowett & Richardson, 1995;Newson & Newson, 2000). Under regular low discharges, the surface flows over riffles are characterized by stationary undulations, often called standing waves (see Figure 1a and Movie S1) (Tonina & Buffington, 2007;Trauth et al, 2013).…”

Avaliação dos efeitos dos agrotóxicos Kraft® 36EC e Score® 250EC sobre a comunidade de macroinvertebrados aquáticos: um estudo em modelos ecossistêmicos

“…Em muitos ambientes aquáticos é possível encontrar a comunidade de macroinvertebrados que consiste em várias espécies pertencentes a inúmeros filos que se diferenciam entre os diferentes habitat e estações do ano (ROY et al, 2003;HOSE et al,2005). Os macroinvertebrados possuem muitos táxons, porém os reportados nesse trabalho pertencem à ordem Díptera, Ephemeroptera, Oligochaeta, Odonata, Gastropoda, Tricoptera, Coleoptera, Hemiptera e a Classe Hirudínea, pertencente à Ordem Rhychobidellida (Figura 1).…”