New insights on habitat use by larval Northern Emerald dragonflies (Somatochlora arctica)

Abstract

Odonates are widely considered to be bioindicators of freshwater habitat quality. Somatochlora arctica (Corduliidae) is commonly found across Eurasia, predominantly in North and Central Europe, but in the UK, it has a restricted range and is listed as near threatened despite a large, potential habitat availability. Across their range, larvae are found in Sphagnum-filled bog pools near coniferous woodlands, but detailed data on their habitat requirements are limited and often overlooked in favour of adult surveys which inhibits conservation efforts. This study surveyed three areas across Scotland: Abernethy & Loch Garten National Nature Reserve (NNR), Beinn Eighe NNR and Flanders Moss NNR, to evaluate how different environmental factors per pool (e.g. water depth and chemistry, Sphagnum coverage, woodland distance, etc.) affect the presence of S. arctica larvae. We found a higher occurrence of S. arctica larvae when pools were located close to woodlands (i.e. 0–10 m), and had high coverage of Sphagnum (> 90%). Environmental variables in pools surveyed (i.e. conductivity, water depth, pH and water temperature) had no significant effects on S. arctica presence.Implications for insect conservation: Our results highlight and discuss the importance of nearby woodlands and Sphagnum cover for S. arctica larvae. Future conservation projects should consider the proximity of woodland to current and restored S. arctica sites or promoting expansion of surrounding natural woodland patches to benefit S. arctica and potentially other odonates sharing similar ecological preferences.