Lepidurus arcticus

Sampling of Lepidurus arcticus Multiple sampling techniques, such as bottom samplers (Lakka 2020), sieves (Halvorsen 1973), artificial substrates (Fjellheim et al. 2007), benthic littoral kick samples (Fjellheim et al. 2007), traps and density samplers such as ‘peltipelle-sampler’ (Lakka 2013), have been used. Visual observing is also frequently used (Lakka 2020). However, in lakes and ponds with fish, fish stomach analyses proved to be the most effective method, particularly when L. arcticus was present in low numbers or exhibited a patchy distribution (Fjellheim et al. 2007; Qvenild & Hesthagen 2019). The timing of sampling is crucial, as the abundance of L. arcticus varies throughout the season (Qvenild & Hesthagen 2019). Most fish investigations occur from August to October when L. arcticus is more abundant. In cold summers, L. arcticus may appear later and might not be visible until September, if at all. Detecting L. arcticus can be challenging, necessitating repeated investigations. Fish predation greatly diminishes L. arcticus populations, making detection difficult when fish are abundant. Moreover, in Arctic conditions, repeated sampling is essential, as a large portion of the population may be dormant in the egg bank. DISTRIBUTION Lepidurus arcticus has a circumpolar distribution in the northern hemisphere, spanning both North America and Siberia (Rogers 2001; Hessen et al. 2004). The species was first described following a Siberian expedition in 1768, which included Peter Simon Pallas. Lepidurus arcticus is found as far north as 74°N in the eastern Novaya Semlya archipelago (Veckhof 1997) and extends to the Kuril Archipelago (Sayenko & Minakawa 1999). Rasshua Island (47°N) in the middle Kuril Islands is likely the southernmost limit of L. arcticus in Asia. These islands experience frequent summer fog and are snowcovered for much of the year. Lepidurus arcticus is also common in Iceland (Scher et al. 2000; Eiríksson et al. 2021) and Greenland (Sømme 1934; Røen 1962; Jeppesen et al. 2001). Dated sediment remains of L. arcticus show that the species once had a broader range, including Denmark (Økland & Økland 2003), Ireland, Scotland, and the Isle of Man (Mitchell 1957). Distribution in Svalbard The initial record of L. arcticus in the Svalbard archipelago dates back to 1878 in Advent Bay (Richard 1878, cited in Sømme 1934). By the 1930s, it had been documented in at least 16 locations (Sømme 1934). Due to logistical challenges in Svalbard, most records from Spitsbergen come from areas near Longyearbyen and Ny-Ålesund (Figure 2), although some findings are from more remote regions. A few observations are reported from the eastern islands, including a pond in Snaddvika, Murchison Bay on Nordaustlandet (80.0°N, 18.8°E), which might be the northernmost record in Svalbard, albeit lacking an exact date and position (Sømme 1934). There is also an unspecified record from Barentsøya (Richard 1898, cited in Sømme 1934). Bennike & Hedenås (1995) found sediment remains of L. arcticus at four locations in Visdalen on Edgeøya in 1991. Jørgensen & Eie (1993) studied 17 locations on the Mosselhalvøya peninsula in 1977, recording L. arcticus in nine fishless ponds but not in eight lakes hosting Arctic charr (Salvelinus alpinus Linnaeus, 1758). The ponds near Polheim (79.89°N, 16.02°E) are the northernmost properly documented localities for L. arcticus in Spitsbergen, though Sømme (1934) noted a nearby finding in Sorgfjorden (at Treurenberg) at almost the same latitude, which is difficult to pinpoint. In 2010, Lakka (2013) found L. arcticus in one of the four ponds near Polheim. Further northern observations have been made from Reinsdyrflya (79.70°N) (Sømme 1934; Lakka 2013). Recent studies have thoroughly investigated the Lepidurus localities in the vicinity of Ny-Ålesund. In 2010, Lakka (2013) examined nine locations, finding L. arcticus in seven ponds. In 2015, Dimante-Deimantovica et al. (2015) studied eleven locations, with only one record of L. arcticus (information provided by Bjørn Walseng, pers. comm.). Calizza et al. (2022) investigated 18 locations, recording L. arcticus in nine, including three new habitats not previously studied (Dimante-Deimantovica et al. 2015; Lakka 2013). At least four L. arcticus localities (Storvatnet, Solvatnet, Tvillingvatnet, and Trehyrdingene) and two ponds without L. arcticus (Gluudneset and Goose Pond) were studied in all three projects (Calizza et al. 2022; Dimante-Deimantovica et al. 2015; Lakka 2013). Lepidurus arcticus was also detected in Lake Storvatnet in 1980 (Økland & Økland 2003). Lake Solvatnet has been studied on multiple occasions, with Lepidurus eggs collected for laboratory experiments in 2014 and 2015 (Mancinelli & Pasquali 2016; Pasquali et al. 2019). Despite the lack of findings in many locations, L. arcticus appears to be very common in the area, with an early observation near the Conway glacier on Kongsfjorden’s eastern shore (Sømme 1934). Lepidurus arcticus has long been known from the Isfjorden area, with thorough studies by various authors. In Adventdalen, both Sars (1885–91) and Richard (1898) (cited in Sømme 1934) reported L. arcticus from small ponds sampled in 1878 and 1897, respectively. In 1910, Olofsson (1918) found it in a lake (Teich XXI), likely the same location investigated in 1928 by Thor (1930), which he referred to as Isdammane. Lakes and ponds in this area served as drinking water and ice supplies for Longyearbyen, later dammed into the present Isdammen in 1960. In recent years, L. arcticus has been sampled in many localities nearby Isdammen (Lakka 2013; Dimante-Deimantovica et al. 2015). A find was noted six kilometres further into the valley at ‘Engelskhytta’ (Thor 1930). Ponds in Longyeardalen also host L. arcticus (Lakka 2013), though it has not been observed annually in all city ponds since 2010 (Coulson, pers. comm.). On Diabasodden, northeast of Longyearbyen, a pond was positively investigated by both Olofsson (1918) and Dimante-Deimantovica et al. (2015). Expeditions have visited both sides of the Billefjorden area. On Kapp Napier, Olofsson (1918) failed to find the species in six ponds in 1910, but positive findings were made in 1970 and 2014 (Artsdatabanken; Dimante-Deimantovica et al. 2015). In Mimerdalen, three well-defined lakes repeatedly examined as water supplies for Pyramiden’s early settlement also yielded positive findings (Lakka 2013; Dimante-Deimantovica et al. 2015). In Lake Goluboye, two kilometres further into the valley, L. arcticus was found (Dimante-Deimantovica et al. 2015). Two ponds in this area also hosted L. arcticus. Surveys in the outer Isfjorden area include both Ymerbukta in the north and southern banks (Colesbukta, Grønnfjorden, and Kapp Linné). No lakes with Arctic charr have yielded positive findings despite extensive stomach analyses, except for anadromous Arctic charr caught in the outlet rivers of Straumsjøen (Aas 2007; Borgstrøm et al. 2018) and Lake Linné (Ebne 2009). Large, shallow lakes of Flydammane on Erdmans Tundra in Ymerbukta all hosted L. arcticus (Olofsson 1918; Dimante-Deimantovica et al. 2015), as did most ponds in Randvika (Dimante-Deimantovica et al. 2015), Aldegondabreen (Dimante-Deimantovica et al. 2015), Coles Bay (Olofsson 1918), and all at Kapp Linné (Lakka 2013). Thus, L. arcticus seems prevalent in small, fishless water bodies in the Isfjorden area, though year-to-year variation is significant. Further south, only three areas have been investigated. In Sveagruva, van Miejenfjorden, Olofsson (1918) found no records of L. arcticus in five freshwater locations. On the western coast, at Kapp Bruunodden, an old record exists (Sømme 1934). Some activity has occurred at the Polish station in Hornsund, with Janiec (1996) noting L. arcticus in three nearshore ponds in 1989. Genetic studies were conducted in two lakes at Fuglebergsletta by Wojtasik & Brylka-Wolk (2010), with a replicate in Fugledammen by Luoto et al. (2016). Wojtasik & Brylka-Wolk (2010) reported L. arcticus in 13 of 50 water bodies examined in Hornsund, though no further site details are provided. Thus, L. arcticus populations do exist in this area. Lepidurus arcticus is commonly recorded in numerous fishless water bodies in Spitsbergen, ranging from a 6 m 2 pond in Nybyen (Lakka 2013) to the 15 ha Flydammane on Erdmans Tundra (Dimante-Deimantovica et al. 2015). In total, L. arcticus has been documented in at least 81 fishless puddles and ponds in Spitsbergen, plus one locality on Nordaustlandet, one on Barents Island, and four sediment remains sites on Edge Island. Lepidurus arcticus is also noted in two outlet rivers that host anadromous Arctic charr, totalling at least 89 documented localities in Svalbard. Distribution in Bear Island Lepidurus arcticus is frequently found in Bear Island (Klemetsen et al. 1985). In a survey conducted in 1998/1999, Hessen et al. (2004) collected samples of L. arcticus from 29 ponds scattered across the island. Subsequently, in a more extensive survey of 109 ponds on the northeastern plateau, L. arcticus was detected in 71 (65%) of them (Klausen 2012) (coordinates provided by Sigurd Einum, pers. comm.). Lepidurus arcticus is abundant in three rivers – Engelskelva, Jordbruelva, and Lakselva – all of which support populations of resident Arctic charr (Klemetsen et al. 1985). In Bear Island, L. arcticus is also present in lakes where it coexists with Arctic charr. Of the twelve lakes studied, all hosting Arctic charr, L. arcticus was found in eight (Klemetsen et al. 1985; Berg et al. 2010; Evenseth et al. 2005). Overall, L. arcticus is present in 114 locations: 103 fishless ponds, eight lakes, and three rivers with resident Arctic charr populations (Figure 4). Distribution in the Scandes The Scandes represent the southernmost limit of L. arcticus occurrences in Europe (Økland & Økland 2003; Qvenild et al. 2021). The species was first recorded in Norway by G.O. Sars during his mountain tri