Climate-driven regime shifts in the biological communities of arctic lakes

Abstract

Fifty-five paleolimnological records from lakes in the circumpolar Arctic reveal widespread species changes and ecological reorganizations in algae and invertebrate communities since approximately anno Domini 1850. The remoteness of these sites, coupled with the ecological characteristics of taxa involved, indicate that changes are primarily driven by climate warming through lengthening of the summer growing season and related limnological changes. The widespread distribution and similar character of these changes indicate that the opportunity to study arctic ecosystems unaffected by human influences may have disappeared.climate change ͉ paleolimnology ͉ Anthropocene ͉ warming ͉ indicators P olar amplification of anthropogenic warming is consistently predicted by general circulation models, largely because of positive feedback mechanisms involving cryospheric processes (1). This heightened climatic sensitivity is supported by recent accelerations of glacier retreat (2), sea-ice thinning (3), and permafrost degradation (4). Although the instrumental record of temperature across the Arctic is incomplete and generally of short duration, warming appears to be concentrated in the decades between approximately anno Domini 1915-1940 and approximately anno Domini 1965. However, proxy data indicate that much of the Arctic began to warm considerably earlier, in the mid-19th century (6). Such generalized trends, however, are neither spatially nor temporally uniform (7), because of regional differences in continentality, ocean heat transport, glacier and sea ice distribution, topography, and vegetation. For example, whereas much of Beringia and central Siberia have warmed Ͼ0.5°C in the last 50 years, there has been little change or even cooling (7) in parts of the North Atlantic sector. Nonetheless, all subregions of the Arctic are considered highly ecologically sensitive, implying that anthropogenic warming will test ecosystem resilience and potentially induce dramatic shifts in community composition.In the absence of long-term climatic and environmental monitoring data, proxy data from the sediments of lakes and ponds, which are ubiquitous features of most arctic landscapes, can be used to provide a long-term perspective of environmental change (8, 9). Siliceous algal remains, specifically the valves of diatoms (Bacillariophyceae) and the stomatocysts and scales of chrysophytes (Chrysophyceae and Synurophyceae), as well as chitinous invertebrate remains (Chironomidae, Diptera and Cladocera, Crustacea), are the primary paleoindicators in lake sediments that provide reliable records of changes in water quality, habitat, and catchment processes (10). Here, we synthesize a large number of paleolimnological records from arctic lakes and ponds, providing a circumpolar assessment of recent ecological changes. These data show that striking and often unprecedented ecological changes have occurred within the last Ϸ150 years, following several millennia of relatively stable communities.High-latitude lakes are extremely responsive t...

A combined paleolimnological/genetic analysis of diatoms reveals divergent evolutionary lineages of Staurosira and Staurosirella (Bacillariophyta) in Siberian lake sediments along a latitudinal transect

“…Although diatoms in Arctic freshwater habitats show a wide range of environmental tolerances, individual species often require very specific hydrochemical conditions (Laing et al 1999). Increases in air temperature can reduce the duration of seasonal ice cover in a lake, affecting light exposure, growth rates, exchanges of gases and nutrients, and thermal stratification and mixing in the lake (Smol et al 2005), such that diatom species shifts can be attributed to a variety of temperature-related environmental factors.…”

Holocene climate conditions in central Yakutia (Eastern Siberia) inferred from sediment composition and fossil chironomids of Lake Temje

“…At the present state of knowledge, biological indicators from aquatic (chironomids, diatoms, ostracods, cladocera) and terrestrial environments (pollen, plant macrofossils) are the most reliable proxies, because they react sensitively to climate change and define different aspects of environments, which should be assessed together for reliable reconstructions (Smol et al, 2005;Solovieva et al, 2005Solovieva et al, , 2008Kienast et al, 2011;Self et al, 2011;Palagushkina et al, 2012;Pestryakova et al, 2012). The basis, however, of all quantitative reconstruction approaches are regional calibration datasets from which the empirical reconstruction models (i.e.…”

Combining limnology and palaeolimnology to investigate recent regime shifts in a shallow, eutrophic lake

“…sudden and large events that lead to rapid ecosystem reconfiguration from one alternative state to another (Lees et al 2006;Andersen et al 2009). Regime shifts occur in multiple ecosystem types (Scheffer et al 2001), including marine environments (Collie et al 2004;Spencer et al 2011), Arctic lakes (Smol et al 2005), brackish lagoons ), terrestrial systems (Dearing 2008) and coastal areas Duarte et al 2009). These shifts are, however, especially well-documented in shallow lakes, and are often associated with anthropogenic eutrophication (McGowan et al 2005;Hargeby et al 2007;Scheffer and Jeppesen 2007;Scheffer and van Nes 2007;Zimmer et al 2009;Hobbs et al 2012).…”