Assessing Riparian Quality Using Two Complementary Sets of Bioindicators

Abstract

Biological indicators are being increasingly used to rapidly monitor changing river quality. Among these bioindicators are macroinvertebrates. A shortcoming of macroinvertebrate rapid assessments is that they use higher taxa, and therefore lack taxonomic resolution and species-specific responses. One subset of invertebrate taxa is the Odonata, which as adults, are sensitive indicators of both riparian and river conditions. Yet adult Odonata are not necessarily an umbrella taxon for all other taxa. Therefore, we investigated whether the two metrics of aquatic macroinvertebrate higher taxa and adult odonate species might complement each other, and whether together they provide better clarity on river health and integrity than one subset alone. Results indicated that both metrics provide a similar portrait of large-scale, overall river conditions. At the smaller spatial scale of parts of rivers, Odonata were highly sensitive to riparian vegetation, and much more so than macroinvertebrate higher taxa. Odonate species were more sensitive to vegetation structure than they were to vegetation composition. Landscape context is also important, with the odonate assemblages at point localities being affected by the neighbouring dominant habitat type. Overall, benthic macroinvertebrates and adult Odonata species provide a highly complementary pair of metrics which together provide large spatial scale (river system) and small spatial scale (point localities) information on the impact of stressors such as riparian invasive alien trees. As adult Odonata are easy to sample and are sensitive to disturbance at both small and large spatial scales, they are valuable indicators for rapid assessment of river condition and riparian quality.

Influence of invasive palms on terrestrial arthropod assemblages in desert spring habitat

“…Coarse structural differences can drive apparent invasive-native differences via habitat 23 selection by arthropods, and a more depauperate odonate assemblage, relative to lower plant 1 structure, has been found among both invasive and native trees (Smith et al, 2007). Our one 2 site that was dominated by native trees, however, had arthropod assemblage metrics that 3 varied from average (for native habitat) to near the high end of the range.…”

Aquatic insects indicate terrestrial habitat degradation: changes in taxonomical structure and functional diversity of dragonflies in tropical rainforest of East Kalimantan

“…mayflies, caddisflies or stoneflies, but also dragonflies) are used as indicators of pollution in streams or lakes, whereas terrestrial insects (beetles, ants or butterflies) are widely used as ecological indicators of terrestrial habitats (da Rocha et al 2010). The Odonata, as a group of freshwater invertebrates closely linked to specific freshwater habitat conditions, are widely used as ecological indicators of habitat quality and the integrity of freshwater ecosystems (Hardersen 2000;Sahlén and Ekestubbe 2001;Smith et al 2007;Silva et al 2010;Arimoro et al 2011;Simaika and Samways 2011;Dolný and Harabiš 2012). Some studies (e.g.…”

An easy-to-use index of ecological integrity for prioritizing freshwater sites and for assessing habitat quality

“…Ideally, it should also operate at the species, rather than higher, taxonomic level, so as to be sensitive to the various subtle characteristics of, and changes in, the habitats (Smith et al 2007). Many biodiversity measurements have fallen short of the ideal because they have consisted of simple counts of the numbers of species (species richness), an observation voiced by many (Jennings 2008;Price et al 1999).…”

“…Previous work has shown a strong correlation between adult dragonfly scores and macroinvertebrate scores (Smith et al 2007). This suggests that the DBI, as a measure of ecological integrity, could be used alongside macroinvertebrate scores (Dickens and Graham 2002) for freshwater health assessments.…”

“…The DBI is based on the widely recognized potential of Odonata as indicator species (Chovanec 2000), although to date the index has been used only for measuring habitat recovery (Samways and Taylor 2004). This is an extension of the fact that odonates can be used as indicators of freshwater health (Oertli 2008), ecological integrity (Smith et al 2007;Chovanec and Waringer 2001), and global climate change (Ott 2008).…”