Freshwater ostracods from ice-wedge polygon ponds in Adventdalen, Svalbard

Freshwater ostracods (Crustacea, Ostracoda) are of interest in modern biological studies, while fossil records of ostracod valves enable us to reconstruct past lacustrine environments. The about 1mm long crustaceans carry a calcite carapace that is biomineralized from dissolved components in the ambient water, and completely envelopes their body. Ostracods inhabit almost all aquatic environments, even shallow freshwater ponds in the vast circumartic permafrost areas. In high-latitude areas, ostracod species diversity, their modern ecological demands, and instrumental records of environmental parameters are only scarcely documented. Such reference information is the key to quantitatively reconstruct past environments from fossil ostracod assemblages. This gap in ostracod data limits their use as biological indicators in the Arctic, where the effects of future climate warming are expected to be strongest. The objective of the study presented here was to extend the data set on arctic freshwater ostracods and environmental records by characterizing presentday habitat conditions, abundance and diversity of ostracod assemblages in periglacial freshwaters on Svalbard. The aims of this project were 1. to conduct an inventory of the abundance, diversity and ecological ranges of the freshwater ostracods living in polygon ponds in Adventdalen near Longyearbyen (78°11’11”N, 15°55’20”E), 2. to determine the present-day hydrochemical and sedimentary characteristics of ostracod habitats, and 3. to witness temporal variability in a polygon pond during the Arctic summer season 2013. The study site was located near the University Centre on Svalbard (UNIS)-run monitoring site for thermal contraction cracking in ice-wedge polygons on a river terrace in outer Adventdalen (Christiansen 2005). Permafrost on Svalbard is estimated to be of late Holocene age with temperatures of -5.2 to -5.6 °C in boreholes in the Adventdalen area (Christiansen et al. 2010). Ice-wedge polygons form in cold-climate environments under permafrost conditions and are the most common periglacial patterned ground features in the Arctic (Minke et al. 2007). Since the permafrost table efficiently blocks drainage pathways, surface depressions hold ponding water during summer, and freeze solid in winter. Those shallow periglacial surface freshwaters, called polygon ponds, are hotspots of biological activity in the otherwise hostile tundra. They provide diverse habitats to aquatic communities including freshwater ostracods. For this study, we choose an area with polygon ponds that are known to persist during the summer season. Our sampling scheme of 13 ponds in total comprised collecting freshwater ostracod individuals, pond water and sediment samples. One species, Tonnacypris glacialis (SARS, 1890), was found in only one of the sampled sites, the pond AD-01 (Fig. 1). Continuous water temperature records directly below the water surface in AD-01, and at the sediment surface in about 25cm water depth were collected between July 20 and September 25, 2013. We measured water and thaw depth in the pond centre and the thaw depth of the surrounding polygon rim. The last record at September 25, 2013 completed the observation season with the presence of 2-3cm lake ice. Preliminary results suggest the pond water is welloxygenated and dilute with slightly acidic pH. The hydrochemical fingerprint and sedimentary characteristics of inter- and intrapolygon ponds may allow a differentiation between the two subtypes for the first time, and are subject of ongoing work. Active-layer thickness was around 40-100 cmin polygon rims, we measured about 50-80 cm thaw depth under pond centres. A considerable increase in water surface area extend occurred in the monitored pond after a rain period. The records obtained from this and similar studies in the Siberian Arctic demonstrate that small and shallow periglacial surface waters are sensitive to local permafrost and climate variations. References Christiansen HH. 2005. Thermal regime of icewedge cracking in Adventdalen, Svalbard. Permafrost and Periglacial Processes 16: 87-98. Christiansen HH, Etzelmüller B, Isaksen K, Juliussen H, Farbrot H, Humlum O, Johansson M, Ingeman-Nielsen T, Kristensen L, Hjort J, Holmlund P, Sannel ABK, Sigsgaard C, Åkerman HJ, Foged N, Blikra LH, Pernosky MA, Ødegård RS. 2010. The thermal state of permafrost in the Nordic Area during the International Polar Year 2007–2009. Permafrost and Periglacial Processes 21: 156–181. Minke M, Donner N, Karpov N, de Klerk P, Joosten H. 2007. Distribution, diversity, development and dynamics of polygon mires: examples from Northeast Yakutia (NE Siberia). Peatlands International 1: 36-40

Fennoscandian permafrost peatland dynamics and climate feedbacks in the future

Non peer reviewe

Overlooked organic vapor emissions from thawing Arctic permafrost

Volatile organic compounds (VOCs) play an essential role in climate change and air pollution by modulating tropospheric oxidation capacity and providing precursors for ozone and aerosol formation. Arctic permafrost buries large quantities of frozen soil carbon, which could be released as VOCs with permafrost thawing or collapsing as a consequence of global warming. However, due to the lack of reported studies in this field and the limited capability of the conventional measurement techniques, it is poorly understood how much VOCs could be emitted from thawing permafrost and the chemical speciation of the released VOCs. Here we apply a Vocus proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF) in laboratory incubations for the first time to examine the release of VOCs from thawing permafrost peatland soils sampled from Finnish Lapland. The warming-induced rapid VOC emissions from the thawing soils were mainly attributed to the direct release of old, trapped gases from the permafrost. The average VOC fluxes from thawing permafrost were four times as high as those from the active layer (the top layer of soil in permafrost terrain). The emissions of less volatile compounds, i.e. sesquiterpenes and diterpenes, increased substantially with rising temperatures. Results in this study demonstrate the potential for substantive VOC releases from thawing permafrost. We anticipate that future global warming could stimulate VOC emissions from the Arctic permafrost, which may significantly influence the Arctic atmospheric chemistry and climate change.Peer reviewe

Consistent centennial-scale change in European sub-Arctic peatland vegetation towards Sphagnum dominance – implications for carbon sink capacity

Abstract Climate warming is leading to permafrost thaw in northern peatlands, and current predictions suggest that thawing will drive greater surface wetness and an increase in methane emissions. Hydrology largely drives peatland vegetation composition, which is a key element in peatland functioning and thus in carbon dynamics. These processes are expected to change. Peatland carbon accumulation is determined by the balance between plant production and peat decomposition. But both processes are expected to accelerate in northern peatlands due to warming, leading to uncertainty in future peatland carbon budgets. Here, we compile a dataset of vegetation changes and apparent carbon accumulation data reconstructed from 33 peat cores collected from 16 sub-arctic peatlands in Fennoscandia and European Russia. The data cover the past two millennia that has undergone prominent changes in climate and a notable increase in annual temperatures towards present times. We show a pattern where European sub-Arctic peatland microhabitats have undergone a habitat change where currently drier habitats dominated by Sphagnum mosses replaced wetter sedge-dominated vegetation and these new habitats have remained relatively stable over the recent decades. Our results suggest an alternative future pathway where sub-arctic peatlands may at least partly sustain dry vegetation and enhance the carbon sink capacity of northern peatlands.Peer reviewe

PeRL:A circum-Arctic Permafrost Region Pond and Lake database

Ponds and lakes are abundant in Arctic permafrost lowlands. They play an important role in Arctic wetland ecosystems by regulating carbon, water, and energy fluxes and providing freshwater habitats. However, ponds, i.e., waterbodies with surface areas smaller than 1. 0 × 104ĝ€m2, have not been inventoried on global and regional scales. The Permafrost Region Pond and Lake (PeRL) database presents the results of a circum-Arctic effort to map ponds and lakes from modern (2002-2013) high-resolution aerial and satellite imagery with a resolution of 5ĝ€m or better. The database also includes historical imagery from 1948 to 1965 with a resolution of 6ĝ€m or better. PeRL includes 69 maps covering a wide range of environmental conditions from tundra to boreal regions and from continuous to discontinuous permafrost zones. Waterbody maps are linked to regional permafrost landscape maps which provide information on permafrost extent, ground ice volume, geology, and lithology. This paper describes waterbody classification and accuracy, and presents statistics of waterbody distribution for each site. Maps of permafrost landscapes in Alaska, Canada, and Russia are used to extrapolate waterbody statistics from the site level to regional landscape units. PeRL presents pond and lake estimates for a total area of 1. 4 × 106ĝ€km2 across the Arctic, about 17ĝ€% of the Arctic lowland ( < ĝ€300ĝ€mĝ€a.s.l.) land surface area. PeRL waterbodies with sizes of 1. 0 × 106ĝ€m2 down to 1. 0 × 102ĝ€m2 contributed up to 21ĝ€% to the total water fraction. Waterbody density ranged from 1. 0 × 10 to 9. 4 × 101ĝ€kmĝ'2. Ponds are the dominant waterbody type by number in all landscapes representing 45-99ĝ€% of the total waterbody number. The implementation of PeRL size distributions in land surface models will greatly improve the investigation and projection of surface inundation and carbon fluxes in permafrost lowlands. Waterbody maps, study area boundaries, and maps of regional permafrost landscapes including detailed metadata are available at https://doi.pangaea.de/10.1594/PANGAEA.868349

Data for wetlandscapes and their changes around the world

Geography and associated hydrological, hydroclimate and land-use conditions and their changes determine the states and dynamics of wetlands and their ecosystem services. The influences of these controls are not limited to just the local scale of each individual wetland but extend over larger landscape areas that integrate multiple wetlands and their total hydrological catchment – the wetlandscape. However, the data and knowledge of conditions and changes over entire wetlandscapes are still scarce, limiting the capacity to accurately understand and manage critical wetland ecosystems and their services under global change. We present a new Wetlandscape Change Information Database (WetCID), consisting of geographic, hydrological, hydroclimate and land-use information and data for 27 wetlandscapes around the world. This combines survey-based local information with geographic shapefiles and gridded datasets of large-scale hydroclimate and land-use conditions and their changes over whole wetlandscapes. Temporally, WetCID contains 30-year time series of data for mean monthly precipitation and temperature and annual land-use conditions. The survey-based site information includes local knowledge on the wetlands, hydrology, hydroclimate and land uses within each wetlandscape and on the availability and accessibility of associated local data. This novel database (available through PANGAEA https://doi.org/10.1594/PANGAEA.907398; Ghajarnia et al., 2019) can support site assessments; cross-regional comparisons; and scenario analyses of the roles and impacts of land use, hydroclimatic and wetland conditions, and changes in whole-wetlandscape functions and ecosystem services

Buried Peats: Past Peatland Distribution as an Indicator of Hydroclimate and Temperature

Peatlands, wetlands with > 30 cm of organic sediment, cover more than 3 x 106 km2 of the earth surface and have been accumulating carbon and sediments throughout the Holocene. The location of peatland formation and accumulation has been dynamic over time, as peat formation in areas like Alaska and the West Siberian Lowlands preceded peat formation in Fennoscandia and Eastern North America due to more favorable climate for peat formation. Using the geographic distribution of peatlands in the past can indicate general climatic conditions, including hydroclimate, given that the underlying geology is well understood. Peatlands form under a variety of climatic conditions and landscape positions but do not persist under arid conditions, instead requiring either humid conditions or cold temperatures. However, peatlands may have existed in the past in areas not currently suitable for peatland formation and persistence, but where peats can be found at depth within the sediment column. Here we map the locations of histic paleosols, relict peat, and buried peats since the Last Glacial Maximum using a compilation of sites from previous studies. We compare these records of past peatland distribution to present-day peatland distribution. We evaluate regional differences in timing of peatland development in these buried peatlands to the development of extant peatlands. Finally, we compare the timing of past peatland extent to the to modeled paleoclimate during the Quaternary. In addition to implications for paleoclimate, these past peatlands are not well accounted for in present-day soil carbon stocks but could be an important component of deep soil carbon pools

Permafrost is warming at a global scale

Permafrost warming has the potential to amplify global climate change, because when frozen sediments thaw it unlocks soil organic carbon. Yet to date, no globally consistent assessment of permafrost temperature change has been compiled. Here we use a global data set of permafrost temperature time series from the Global Terrestrial Network for Permafrost to evaluate temperature change across permafrost regions for the period since the International Polar Year (2007-2009). During the reference decade between 2007 and 2016, ground temperature near the depth of zero annual amplitude in the continuous permafrost zone increased by 0.39 ± 0.15 °C. Over the same period, discontinuous permafrost warmed by 0.20 ± 0.10 °C. Permafrost in mountains warmed by 0.19 ± 0.05 °C and in Antarctica by 0.37 ± 0.10 °C. Globally, permafrost temperature increased by 0.29 ± 0.12 °C. The observed trend follows the Arctic amplification of air temperature increase in the Northern Hemisphere. In the discontinuous zone, however, ground warming occurred due to increased snow thickness while air temperature remained statistically unchanged

Priorities and interactions of Sustainable Development Goals (SDGs) with focus on wetlands

Wetlands are often vital physical and social components of a country's natural capital, as well as providers of ecosystem services to local and national communities. We performed a network analysis to prioritize Sustainable Development Goal (SDG) targets for sustainable development in iconic wetlands and wetlandscapes around the world. The analysis was based on the information and perceptions on 45 wetlandscapes worldwide by 49 wetland researchers of the GlobalWetland Ecohydrological Network (GWEN). We identified three 2030 Agenda targets of high priority across the wetlandscapes needed to achieve sustainable development: Target 6.3-'Improve water quality'; 2.4-'Sustainable food production'; and 12.2-'Sustainable management of resources'. Moreover, we found specific feedback mechanisms and synergies between SDG targets in the context of wetlands. The most consistent reinforcing interactions were the influence of Target 12.2 on 8.4-'Efficient resource consumption'; and that of Target 6.3 on 12.2. The wetlandscapes could be differentiated in four bundles of distinctive priority SDG-targets: 'Basic human needs', 'Sustainable tourism', 'Environmental impact in urban wetlands', and 'Improving and conserving environment'. In general, we find that the SDG groups, targets, and interactions stress that maintaining good water quality and a 'wise use' of wetlandscapes are vital to attaining sustainable development within these sensitive ecosystems. © 2019 by the authors