Spatial and temporal variation in the macroinvertebrate fauna of streams of the northern jarrah forest, Western Australia: community structure

Abstract

1. Streams of the northern jarrah forest,, Western Australia, were sampled at twelve sites from December 1981 to December 1982 to examine spatial and temporal changes in the structure of the macroinvertebrate community.2. The climate of this region is quite predictable by Australian standards and each year a hot, dry summer is followed by a mild, wet winter. Highest stream discharge occurs during winter (June-November) reducing to negligible flow over late summer and autumn (January-May). The low flows in summer were associated with warm water, lower dissolved oxygen, increased concentrations of cations and, in many cases, lower pH.3. Temporal changes in abundance, diversity and evenness indicated that the invertebrate fauna became dominated by a few taxa during the summer months. Major spatial and temporal changes in the composition of the fauna were detected by classification and ordination. Summer and winter faunas were identified at most sites and were clearly associated with the seasonal changes in the physical and chemical environment. This seasonaiity is not typical of stream systems previously studied in Australia. Large spatial differences also occurred over small distances among sites in two similar-sized forested catchments.4. Multiple discriminant analysis and stepwise multiple regression analysis showed that velocity and depth were highly associated with the observed temporal changes in the fauna, though other variables, including concentrations of cations and water temperature, were also important. Spatial differences were correlated with concentrations of cations which may simply reflect differences in the geologies of the catchments.

Distribuição espacial e variação temporal da composição de espécies de borrachudos (Diptera: Simuliidae) em uma microbacia situada no norte do Paraná

“…Isso sugere que outros fatores podem estar envolvidos, particularmente os relacionados às condições específi cas dos criadouros, uma vez que a precipitação e temperatura atmosférica atuam indiretamente sobre as comunidades aquáticas por meio de alterações na vazão e na temperatura da água dos cursos d'água (Shipp & Procunier 1986, Pistrang & Burger 1988, Gallardo-Mayenco & Toja 2002, Silk & Ciruna 2005 A investigação de um maior número de variáveis associadas direta e indiretamente às condições sazonais dos criadouros poderia defi nir com maior clareza os fatores que infl uenciam a composição taxonômica das assembléias de simulídeos ao longo do tempo, particularmente nas regiões tropicais. Além do fotoperíodo, da precipitação e da temperatura atmosférica, fatores ligados aos criadouros como vazão, temperatura da água, oxigênio dissolvido, pH e disponibilidade de recursos alimentares também devem ser analisados, uma vez que podem variar ao longo do tempo, infl uenciando a composição da fauna de macroinvertebrados (Thompson & Townsend 1999, Robinson et al 2002, Bunn et al 2006, Richardson et al 2009. Interações biológicas como competição e predação também podem estar envolvidas nas alterações de densidades populacionais de espécies de simulídeos ao longo do tempo (Malmqvist 1994).…”

Climate change and its implications for Australia's freshwater fish

“…As a consequence, the aquatic fauna has evolved under a regime of seasonal inundation of wetlands and annual periods of no-flow in rivers (Bunn et al 1986). However, since 1975, a climatic phase shift has seen significant reductions in rainfall and stream flows (Table 1) (CSIRO 2009a).…”

“…Freshwater environments, and the organisms that inhabit them, are particularly vulnerable because they are isolated and fragmented within a terrestrial landscape (Fausch et al 2002). Furthermore, surface water, which determines the quality and availability of aquatic habitat, depends heavily on rainfall and temperature regimes that will be drastically affected by climate change (Carpenter et al 1992;Hobday and Lough 2011). Relatively few studies have explored the implications of climate change for freshwater biota, with the majority of these focussing on northern hemisphere or high-latitude freshwaters (e.g.…”

“…Relatively few studies have explored the implications of climate change for freshwater biota, with the majority of these focussing on northern hemisphere or high-latitude freshwaters (e.g. Xenopoulos and Lodge 2006;Buisson et al 2008;Graham and Harrod 2009;Heino et al 2009;McCullough et al 2009; but see Carpenter et al 1992, for global perspectives, and Chessman 2009. Projected global warming that surpasses or optimises thermal tolerances and requirements is often emphasised as a major driver of assemblage turnover, range shifts and range expansions in these systems because surface water is seldom limiting (but see Xenopoulos and Lodge 2006, for hydrological example).…”

Spatial distribution of benthic macroinvertebrates in the Erhai basin of southwestern China

“…We defined dominant taxa as those with relative abundances >5% (Bunn et al 1986). These included Baetis sp., Tubificidae, Simulium sp., Eukiefferiella sp., Gammarus sp., and Parakiefferiella sp., and their respective relative abundances were 17.34%, 13.84%, 12.17%, 9.74%, 9.44%, 7.09%, and 6.44%.…”