Dragonflies: climate canaries for river management

Abstract

Aim Freshwater ecosystems are highly vulnerable to the effects of climate change. Where long‐term datasets are available, shifts in species phenology, species distributions and community structure consistent with a climate change signal have already been observed. Identifying trends across the wider landscape, to guide management in response to this threat, is limited by the resolution of sampling. Standard biomonitoring of macroinvertebrates for water‐quality purposes is currently not well suited to the detection of climate change effects, and there are risks that substantial changes will occur before a management response can be made. This study investigated whether dragonflies, frequently recommended as general indicators of ecological health, are also suitable as indicators of climate change. Location Data were analysed from standard bio‐assessment monitoring at over 850 sites spanning a 9° latitudinal gradient in eastern Australia. Methods Using variation partitioning, we analysed the proportion of assemblage turnover in dragonflies and other macroinvertebrate assemblages that can be explained by climate and other environmental drivers. We also tested whether the utility of dragonflies as indicators improved at higher taxonomic resolution and whether the turnover of dragonfly assemblages was congruent with that of other groups. Results Climate explained three times as much variation in turnover of dragonfly species than dragonfly and other macroinvertebrate assemblages at family level. The dissimilarity of dragonflies and varying turnover in each macroinvertebrate assemblage meant surrogacy amongst groups were low. Main conclusions On the basis of the influence of climate on turnover of macroinvertebrate assemblages, dragonfly species distribution appears highly sensitive to climatic factors, making this taxon a potential useful indicator of climate change responses. However, the low surrogacy amongst assemblages also suggests that a shift in the focus of conservation management from specific taxa to the functional composition of assemblages across a diverse range of habitats is needed.

Climate Warming as an Explanation for the Recent Northward Range Extension of Two Dragonflies, <i>Pachydiplax longipennis</i> and <i>Perithemis tenera</i>, into the Ottawa Valley, Eastern Ontario

“…However, specific decisions to implicate climate warming are often not cautious and may be presented with limited understanding of other potentially contributing factors. Here, criteria are applied to such a decision with regard to dragonflies (Odonata), a group highly sensitive to climatic factors (Bush et al 2013).…”

Freshwater conservation planning under climate change: demonstrating proactive approaches for Australian Odonata

“…An important extension of this study will be to expand the range of taxa assessed because Odonata may not be suitable surrogates for broader freshwater biodiversity (Bush et al . ), and emphasis on a single taxonomic group can lead to biases in conservation planning (Darwall et al . ).…”

“…We chose to focus on Odonata (dragonflies and damselflies) because they are a diverse component of Australian freshwater biodiversity with a high proportion of endemic species (78%) (Theischinger & Endersby ) and they are likely to be highly responsive to climate change (Bush et al . ). Odonata also presents an interesting context for studying how reserves can be clustered to improve connectivity (Hermoso, Kennard & Linke ).…”

Sustaining Freshwater Biodiversity in the Anthropocene

“…Dragonflies as Flagship Species for Water Quality Dragonflies are employed successfully as indicators of ecosystem health in environmental impact assessments and monitoring programs, particularly in Australia (Bush et al 2013) and Europe (Sahlen and Ekestubbe 2001). They can be used as environmental sentinels and as the whistleblowers for freshwater health, providing an easy tool not only for environmental impact assessments, but also for freshwater monitoring, carried out by various stakeholder groups.…”