Hodkinson, I.D., A. Babenko, V. Behan-Pelletier, J. Bocher, G. Boxshall, F. Brodo, S. J. Coulson, W. De Smet, K. Dózsa-Farkas, S. Elias, A. Fjellberg, R. Fochetti, R. Foottit, D. Hessen, A. Hobaek, M. Holmsstrup, S. Koponen, A. Liston, O. Makarova, Y. M. Marusik, V. Michelsen, K. Mikkola, A. Pont, A. Renaud, L.M. Rueda, J. Savage, H. Smith, L. Samchyshyna, G. Velle, F. Viehberg, D. H. Wall, L. J. Weider, S. Wetterich, Q. Yu, and A. Zinovjev. 2013. Chapter 7, Terrestial and Freshwater Invertebrates. Pp. 195-223. In: Meltofte, H. (ed.), Arctic Biodiversity Assessment, Reykjavik, The Arctic Council, Conservation of Arctic Flora and Fauna, Akureyri, Iceland. 195 Chapter 7 Terrestrial and Freshwater Invertebrates Lead Author Ian D. Hodkinson Contributing Authors Anatoly Babenko, Valerie Behan-Pelletier, Jens Böcher, Geoffrey Boxshall, Fenja Brodo, Stephen J. Coulson, Willem De Smet, Klára Dózsa-Farkas, Scott Elias, Arne Fjellberg, Romolo Fochetti, Robert Foottit, Dag Hessen, Anders Hobaek, Martin Holmstrup, Seppo Koponen, Andrew Liston, Olga Makarova, Yuri M. Marusik, Verner Michelsen, Kauri Mikkola, Tero Mustonen, Adrian Pont, Anais Renaud, Leopoldo M. Rueda, Jade Savage, Humphrey Smith, Larysa Samchyshyna, Gaute Velle, Finn Viehberg,Veli Vikberg, Diana H. Wall, Lawrence J. Weider, Sebastian Wetterich, Qing Yu and Alexy Zinovjev Consulting Authors Richard Bellerby, Howard Browman, Tore Furevik, Jacqueline M.Grebmeier, Eystein Jansen, Steingrimur Jónsson, Lis Lindal Jørgensen, Svend-Aage Malmberg, Svein Østerhus, Geir Ottersen and Koji Shimada Contents Summary ..............................................................196 Big new insects have appeared, beetles that fl y. 7.1. Introduction .......................................................196 » [American buring beetle] 7.2. Status of knowledge ..............................................198 Jolene Nanouk Katchatag an Inupiaq from Unalakleet, Alaska; 7.2.1. Terrestrial Arctic invertebrate bio diversity ....................198 Mustonen & Mustonen 2009. 7.2.1.1. An invertebrate biodiversity profi le for a high Arctic region, Svalbard ..........................198 7.2.1.2. A biodiversity profi le for a selected group, Arctic insects within the Nearctic region ..............199 7.2.1.3. Biodiversity of Arctic invertebrates, the best collective estimates .........................202 7.2.1.4. Variation within species ..............................203 Now the black fl ies appear before the mosquitoes, 7.2.2. Historical overview ..........................................206 » this is something new. 7.2.3. Regional considerations .....................................207 7.2.3.1. Habitat specifi city and its implications for biodiversity 207 Komi Irina Kaneva from the Krasnochelye wilderness village 7.2.3.2. Biodiversity changes along latitudinal gradients ......209 on the Kola Peninsula; 7.2.3.3. Geographical and regional variations in biodiversity . 210 Mustonen 2011. 7.2.3.4. Endemic species .....................................213 7.3. Status and trends .................................................213 7.3.1. Species richness and distribution ............................213 7.3.1.1. The importance of species interactions ...............215 7.3.2. Population sizes and densities ...............................216 7.4. Conclusions and recommendations ...............................216 Judging by the last year there are almost no mosquitoes 7.4.1. Sensitive areas and hotspots .................................216 » left in Lovozero [Luujavre]. It can be real evidence that 7.4.2. Key knowledge gaps and recommendations .................217 climate is changing. Even some species of southern 7.4.3. Recommended conservation actions ........................218 bugs and spiders appeared in tundra. 7.4.4. Other key messages .........................................218 Vladimir Galkin, a member of the Sámi community Piras .................................................... Acknowledgements 218 on Lovozero Lake in the Murmansk region of Russia; References .............................................................218 Mustonen & Zavalko 2004. 196 Arctic Biodiversity Assessment SUMMARY species that can provide a focus for raising the profile of invertebrates as a whole. The known terrestrial and freshwater invertebrate faunas of the Arctic comprise several thousand described species, representing over 16 major phyla. Many other 7.1. INTRODUCTION species remain to be discovered and/or described. Arctic endemic species occur in many invertebrate groups. A The observations by indigenous peoples given on the title significant proportion of Arctic species have circumpolar page of this chapter, often made in association with tra- distributions. By comparison with better known groups ditional activities such as reindeer herding, hunting and such as vertebrates and plants, the invertebrates exhibit fishing, clearly suggest that profound changes are oc- much higher biodiversity at all taxonomic levels and curring in the invertebrate faunas of the Arctic regions. attain greater population densities in favorable habitats. This chapter attempts to set a baseline for invertebrate Springtail (Collembola) numbers, for example, some- biodiversity within the Arctic, to document the scien- times exceed 0.5 × 106/m2 and eelworm (Nematoda) tific evidence for such change and to provide a prognosis populations reach over 7.0 × 106/m2 in areas of Taimyr. and recommendations for the future. Little is know about the detailed distribution and biology Even within the scientific community, the biodiversity of most species, and good long-term population data of invertebrates inside the Arctic is poorly understood on individual species, sufficient to indicate population by non-specialists and is thus frequently underplayed or trends, are almost entirely lacking. Predictions of how sometimes ignored. The CAFF Habitat Conservation Arctic invertebrate communities may respond to climate Report No.4 (Principles and Guidelines), for example, change are, of necessity, based on extrapolations from states that “invertebrate fauna in the Arctic is scarce” experimental and/or distributional studies based on a (CAFF 1996), a statement far removed from reality. few selected species or species groups in a restricted Collectively, the number of Arctic invertebrate species range of habitats. greatly exceeds that of all other non-microbial eukaryot- ic species groups combined, including the plants and the This chapter brings together, and highlights for the first vertebrates. Furthermore, invertebrates are often found time, baseline information on the biodiversity of all Arc- at densities of several hundred thousand, and occasional- tic terrestrial and freshwater invertebrates. It evaluates ly several million, per square meter. Arctic invertebrate the importance of habitat diversity, climatic severity and faunas are thus far from simple, but their complexity is biogeography, particularly historic patterns of glacia- less overwhelming than for many tropical ecosystems, tions, as determinants of invertebrate biodiversity. The and their diversity is perhaps more readily understand- significance of the Beringia refugium for biodiversity in able (Danks 1990, Vernon et al. 1998). several groups is stressed. Invertebrates are key play- ers in a range of ecosystem services within the Arctic, The mistaken idea of an overly ‘simple’ Arctic inver- including herbivory, decomposition, nutrient cycling, tebrate food web almost certainly owes its origin to a pollination, parasitism and predation. summarizing diagram of the nutrient flow pathways through the ecological community of Bjornøya, Sval- Changes in invertebrate communities, perhaps involving bard, published by Charles Elton in 1923 (Hodkinson & new invasive species, may have important impacts on Coulson 2004). This diagram, erroneously interpreted several of these processes, particularly through interac- as a ‘simple’ food web, still holds sway in several modern tions with other groups of organisms. The key environ- ecology textbooks. In such diagrams, it is assumed that mental factors (drivers) determining species success in individual species within related invertebrate groups an era of climate warming are likely to be mean summer are ecologically interchangeable, performing similar and winter temperatures, soil-moisture availability, ecological functions or responding in similar ways to length of growing season and the frequency of freeze/ environmental change. They are in consequence usu- thaw events that may disrupt preparation for and emer- ally consigned together, for example to a ‘box’ labeled gence from the overwintering state. ‘ciliates’ or ‘Collembola’. This assumption of species equivalence is mistaken, and important components of Several recommendations for future action are listed. biodiversity become hidden when species are aggregated Highest priority should be given to establishing an and compartmentalized in this way. Take for example the inventory of Arctic invertebrate species, including their unicellular ciliates, a group whose biodiversity is poorly distribution, habitat preference and ecological function. known within much of the Arctic. Despite their relatively This list should be used to identify true Arctic endemic simple body form, the freshwater ciliates of Svalbard fall taxa, classify species according to IUCN Red Book into eight different trophic groups, each feeding on dif- criteria and identify the vulnerability of species and their ferent microscopic prey