Longevities of Adult Chironomidae (Diptera) from Two Streams in Iceland

Abstract

Mean annual air temperatures are predicted to increase by several degrees in the Arctic. This increase in temperature will likely impact organisms adapted to current conditions. Studies of longevities of winter-active Chironomidae from cold, groundwater-fed streams in Minnesota demonstrate that winter-emerging species are long-lived as adults when incubated at cold or sub-freezing air temperatures post emergence. It is unknown if this holds for species emerging in sub-arctic latitudes during warm months, or if warm air temperatures affect the adults of species emerging from cold and geothermally heated streams. The goal of this study was to determine the effects of exposure to air temperatures predicted by climate change models on the longevities of Chironomidae emerging from both cold and geothermally heated larval environments. Chironomidae were trapped at emergence from two groundwater-fed streams with contrasting (warm and cold) thermal regimes at the Hengladalir valleys in the Hengill alpine geothermal area in southwestern Iceland over 4 days in July 2018. Adults (N=102) were randomly divided into two treatments and incubated at either 20°C or 6°C for 28-32 days to determine influence of source stream and incubation temperature on adult longevity. These temperatures were selected to simulate current and predicted water and air temperatures that adult chironomids are likely to be exposed to with climate change. Adults incubated at 6°C survived longer than adults incubated at 20°C irrespective of source stream. All adults incubated at 20°C died within 1-5 days post-emergence. Longevities of taxa incubated at 6°C ranged from 13 to more than 32 days. Species of Diamesa exhibited the greatest longevities, with 41.7% surviving more than 28-32 days post-emergence at 6°C. We were unable to determine maximum longevity for Diamesa within the 6°C treatment because surviving adults had to be sacrificed at the termination of the experiment on day 32. However, the minimum longevity we report is similar to longevities determined for other Diamesa species and indicates that Diamesa species in Iceland are also long-lived under cold air temperatures. We suggest there may be a difference in longevity between sex, with females living longer than males at cold temperatures. By contrast, we found that both sexes of Diamesa and all other chironomid taxa that we tested are susceptible to warm air temperatures regardless of stream of origin. Therefore, warming climatic temperatures could potentially lead to shortened adult lifespans for these sub-arctic taxa.

First Annoted Checklist of Aquatic Diptera (Insecta) of Two Ramsar Sites (Ahançal and Aït Bouguemaz Rivers) at the Central High Atlas (Morocco): Families Ceratopogonidae, Chironomidae, Tipulidae, Empididae, and Tabanidae

“…Our material (two larvae) collected on March 07, 2020 in the Ahançal spring, Ighboula n'Taghia (A1), extends the presence of this genus to the central High Atlas. Te genus prefers fast mountain streams [139,140], as the case of Ighboula n'Taghia spring, but some species were found in other permanent water bodies [115], including lakes [141].…”

Studying K-12 and post-secondary teachers’ reflections on the value of a citizen science project for fostering learning: The case of a winter stream project

“…Water is an essential resource for life, and with climate change, many freshwater resources will be threatened especially in areas with lower economic development and adaptive strategies for climate warming (Koutroulis et al, 2019). Additionally, studies on winter stream ecology are rare and new investigations indicate a need for broadening research on climate impacts to winter-active and cold-adapted aquatic insects (Anderson et al, 2022;Bodmer et al, 2023;Nyquist et al, 2021). Despite harsh winter conditions, there are insects, which are adapted to complete the adult stage of their life cycle during this season, including a family of aquatic flies called midges, in the chironomidae family (Ferrington Jr & Berg, 2019).…”

Leonard C. Ferrington, Jr. (1948-2021): Chironomid cognoscente and modern-day Renaissance man

“…Len's international collaborations are clearly apparent in the research in which he was involved in (e.g., Norway, France, Germany, Iceland, Italy, Tasmania, Argentina, New Zealand, South Africa, and Mongolia), the meetings and committees he participated in, and the colleagues with whom he published. Due largely to Len's encouragement, support, and vast network of connections, three of Len's most recent Ph.D. students, Corrie Nyquist (Iceland, 2020-2021, Petra Kranzfelder (Norway, 2014(Norway, -2015, and Alyssa Anderson (Norway, 2010-2011 received Fulbright Fellowships that allowed them to complete portions of their dissertation research abroad and build their own collaborative networks. Alyssa Anderson states that had it not been for Len's encouragement and strong support for international experiences, she would not have considered the Fulbright program, let alone working an international experience into her graduate program.…”