Anthropogenic‐driven transformations of dragonfly (Insecta: Odonata) communities of low elevation mountain wetlands during the last century

Abstract

1. Freshwater environments are experiencing high rates of species extinction due to human impacts, with aquatic insects thought to be strongly threatened by these changes; however, long-term research on this topic is scant. Among aquatic insects, dragonflies are considered valuable indicators of human disturbance at multiple scales. 2. This study addresses transformations of odonate communities of low elevation mountain wetlands in the Alps over the last century, comparing historical and present assemblages based on past records derived from scientific collections or literature and present data derived from site resurveys. 3. About 32.6% of species have been extirpated or strongly declined in the area (mostly temporary lentic and lotic water specialists, or cold-adapted species). Conversely, only 12.2% of species were new or considerably increased (mostly permanent lentic specialists and warm-adapted species). Nearly half of historical populations have been lost. The great majority of species which disappeared from all the study sites also disappeared (or strongly declined) at the regional scale. 4. Although gamma species richness was higher in the historical period compared with the present, mean alpha species richness does not significantly differ between the two, likely suggesting homogenisation of communities from historical to the present period. 5. Present communities of dragonflies show a significantly higher community temperature index compared with historical ones. 6. These patterns are putatively explained by the joint effects of land-use change (drainage and reclamation), land-use intensification or abandonment, environmental pollution, and anthropogenic-driven climate warming.

Consistent signals of a warming climate in occupancy changes of three insect taxa over 40 years in central Europe

“…Although commonalities are difficult to derive across different temporal and spatial scales, previous studies suggest a range of possible common drivers of distributional changes of insects that explain similar trends of species in different taxonomic groups. Across taxa, warm‐adapted species show more positive trends under recent climate warming than cold‐adapted species, thus indicating the impact of climate change (Assandri, 2021; Bowler, Haase, et al, 2017; Bowler et al, 2015; Bowler, Hof, et al, 2017; Löffler et al, 2019; Poniatowski et al, 2020; Zeuss et al, 2014). Another important factor shaping insect distributions is loss of habitat due to land‐use change (Fartmann et al, 2021; Wagner et al, 2021; Warren et al, 2001).…”

Cryptic survival and an unexpected recovery of the long-tailed mayflyPalingenia longicauda(Olivier, 1791) (Ephemeroptera: Palingeniidae) in Southeastern Europe

“…River regulations, damming, hydropower plant construction and pollution has drastically altered aquatic habitats of European rivers in the last centuries, leading to a long term process of decline in freshwater insect biodiversity (Assandri, 2021; Jähnig et al ., 2021), especially sensitive groups like Ephemeroptera, Plecoptera and Trichoptera (Graf et al .,2015; Krno et al ., 2018). However, in the recent years water quality of the Danube showed improvement (Liska, 2015; Stoica et al ., 2019) as a result of implementation of the EU Water Framework Directive and of the EU Floods Directive by the International Commission for the Protection of the Danube River (ICPDR), facilitating the return or recovery of some sensitive species.…”

Ecological drivers of Odonata beta diversity in arid and semi‐arid regions of the Central Plateau of Iran

“…This result has important implications for predicting the effect of ongoing climate change and global warming on the composition of Odonata assemblages. In response to climate change, assemblages are predicted to become increasingly composed of warm‐dwelling species and species with high dispersal ability than cold‐dwelling species and species with poor dispersal ability (Termaat et al ., 2015; Assandri, 2020; Bowler et al ., 2020). On the other hand, global warming could increase the frequency and severity of droughts (Dai, 2013), and as the surface water becomes increasingly scarce, species with bivoltine or semi‐voltine life cycles would have a lower chance to complete their larval stages (Hering et al ., 2010), so species assemblages will change in favour of vagrant species that can quickly recolonise habitats.…”

“…Several researchers also have studied Odonata species composition specifically (e.g. Kietzka et al ., 2017; Pires et al ., 2018; Cerini et al ., 2019; Johansson et al ., 2019; Mendes et al ., 2019; Assandri, 2020; Cerini et al ., 2020; Sushko, 2020). However, only a few studies have focused on the freshwater ecosystems located in the arid regions (Epele et al ., 2019; Eslami Barzoki et al ., 2020), notwithstanding in these regions, water bodies are highly vulnerable and information about their biodiversity patterns is vital for designing conservation strategies.…”