Jordi Catalan 1,2* , Sergi Pla-Rabés 2,1 , Alexander P. Wolfe 3 , John P. Smol 4 ,
Kathleen M. Rühland 4 , N. John Anderson 5 , Jiři Kopáček 6 , Evžen Stuchlík 7 , Roland
Schmidt 8 , Karin A. Koinig 9 , Lluís Camarero 2 , Roger J. Flower 10 , Oliver Heiri 11 ,
Christian Kamenik
12
, Atte Korhola
13
, Peter R. Leavitt
14
, Roland Psenner
9
, Ingemar
Renberg 15
1. CREAF, Cerdanyola del Vallès, E-08193, Catalonia, Spain.
2. CSIC-CEAB, Biogeodynamics and Biodiversity group, Accès Cala St
Francesc 14, E-17300 Blanes, Catalonia, Spain.
3. Department of Earth and Atmospheric Sciences, University of Alberta,
Edmonton, AB T6G 2E3, Canada.
4. Paleoecological Environmental Assessment and Research Lab (PEARL),
Department of Biology, Queen’s University, Kingston, ON K7L 3N6, Canada.
5. Department of Geography, Loughborough University, Loughborough LE12
7NQ, UK.
6. Biology Centre ASCR, Institute of Hydrobiology, Na Sádkách 7, CZ-37005
České Budějovice, Czech Republic.
7. Hydrobiological station, Institute for Environmental Studies, Faculty of
Science, Charles University in Prague, CZ-38801 Blatná, Czech Republic.
8. Institute for Limnology, pr. Herzog-Odilo- Straße 101, A-5310 Mondsee,
Austria.
9.
Institute of Ecology, University of Innsbruck, Technikerstrasse 25, 6020
Innsbruck, Austria.
10. Environmental Change Research Centre (ECRC), University College
London, Pearson Building, Gower Street, London WC1E 6BT, UK.
11. Institute of Plant Sciences and Oeschger Centre for Climate Change
Research, Altenbergrain 21, CH-3013 Bern, Switzerland.

12. Institute of Geography and Oeschger Centre for Climate Change Research,
University of Bern, Erlachstrasse 9a, Building 3, CH-3012 Bern, Switzerland.
13. Department of Environmental Sciences, University of Helsinki, P.O. Box 65
(Viikinkari 1), 00014 Helsinki, Finland
14. Limnology Laboratory, Department of Biology, University of Regina,
Regina, SK S4S 0A2, Canada.
15. Department of Ecology and Environmental Science, Umeå University, SE-
901 87 Umeå, Sweden.
*Corresponding author: catalan@ceab.csic.es
* * *
Note: Following extended descriptions of case studies presented in the figures of main text are included. Figure numbers make reference to the main text.
Fig. 1. Early landscape changes at high-mountains, Sägistalsee (Swiss Alps)
Sägistalsee was one of the sites studied within the EU project CHILL-10,000 (ENV4-
CT97-0642) in order to reconstruct climate from remote, high alpine sites across
Europe. However, variability of proxy groups, with the potential for climate reconstruction, namely chironomids, cladocerans, and diatoms (largely dissolved), were masked by strong catchment-lake interactions and discernible human impacts extending to 4000 cal yr BP. At the same time, this lake offered a unique opportunity to disentangle natural (e.g., immigration of Picea abies around 6300 cal yr BP) from human-induced (deforestation, alpine farming since 4000 cal yr BP) changes to the catchment. The first disturbance by humans caused a shift of the whole ecosystem, which resulted in progressively stronger deviations from its original state. In Fig. 1, we summarize the most distinct and informative changes observed in the sediment record.
The depletion in the trees and shrubs around 4000 cal yr BP is consistent with a peak in charcoal in these horizons indicating deforestation using fire. The change in catchment
vegetation (Wick et al. 2003) caused an increase in weathering and destabilized the soil
which in this lake is visible in the quartz to calcite ratio as well as in some other abiotic

and geochemical parameters (Hirt et al. 2003; Koinig et al. 2003; Ohlendorf et al. 2003).
At the same time, pasturing increased the load of organic carbon that ultimately depleted dissolved oxygen in the lake, which in turn resulted in the decline of
chironomids (Heiri and Lotter 2003). Human activity in the catchment was not stable
but depicted three periods with more intense farming, first after 4000 cal yr BP, later with an increase during the Roman period and again since the Medieval with the highest number of pasture indicators. During these periods, depletion in oxygen revealed by chironomids coincides with high organic carbon concentrations. During intervening periods of less severe alpine farming, the lake recovers: oxygen and chironomid abundances increase. However, vegetation never recovers completely.
Under the lead of Andy Lotter, the detailed records of Sägistalsee were published in a special issue of the Journal of Palaeolimnology, Vol 30 No.3 (2003), with
a description of the lake and its catchment characteristics (Lotter and Birks 2003b), the
plant macrofossils and pollen records (Wick et al. 2003), the chironomids (Heiri and
Lotter 2003), the cladocerans (Hofmann 2003), the abiotic changes in the sediment (Hirt et al. 2003; Koinig et al. 2003; Ohlendorf et al. 2003) and summarized by Lotter and
Birks 2003a).
Fig. 2. Acidification and recovery of Starolesnianske lake (Tatra Mountains,
Slovakia)
Starolesnianske pleso is a small acid-sensitive lake in the Tatra Mountains, situated at
2000 m above sea level on granitic bedrock, with sparse and thin soil cover. Deposition of acidifying compounds in this region reached maximum levels in the 1980s and declined sharply during the 1990s as a result of stringent reductions in sulphur and
nitrogen emissions in central Europe (Kopáček et al. 2001). In the 1980s, the lake was a
typical example of strongly acidified Tatra Mountain lakes, with pH <5, elevated concentration of inorganic aluminium (>10 µeq L
–1
), and local extinctions of native
species of crustacean zooplankton (Fott et al. 1994). Despite the high phytoplankton
standing crop, the lake was inhabited by only one species of cladocerans, the ubiquitous
Chydorus sphaericus
(Hořická et al. 2006).
Reconstruction of the acidification history of the lake was conducted using
MAGIC (Model For Acidification of Groundwater In Catchments) (Stuchlík et al.

2002), revealing a slow decrease in lake water pH since the late 19th century, with the
steepest decline, accompanied with an increase in Al concentrations, in the early 1950s, and the culminating acidic stress in the 1980s (Fig. 2). Since the 1990s, the lake water chemistry has been rapidly recovering from acidification due to ~60% and ~40% reductions in deposition of S and N compounds in the region between the late 1980s and
the early 2000s (Kopáček et al. 2006).
Palaeolimnological investigations of lake sediment show that relative abundances of originally dominant species ( Ceriodaphnia quadrangula , Tanytarsus lugens and many others) declined reflecting gradual decreases in pH while acid-tolerant species ( Chydorus sphaericus and Tanytarsus gregarius ) increased after ~1920 (Fig. 2).
Major change in species composition occurred in 1970–1980, when most original species disappeared, corresponding to the pH drop to 4.5-4.9 and parallel increases in
the concentration of ionic (and potentially toxic) aluminium forms. (Fig. 2; Stuchlík et al. 2002). While the chemical recovery of the lake water occurred almost
simultaneously to the decline in acidic deposition, biological recovery has been significantly delayed. Ceriodaphnia quadrangula , the dominant zooplankton species in pre-acidification period, reappeared in the lake in 2000, i.e. ~5 years after the pH had increased >5.0 and Al concentrations declined to values <1 µeq L
–1
(Fig. 2). This species is relatively acid-tolerant, and its historical presence in the lake may demonstrate early (e.g., episodic or seasonal) acidification of Starolesnianske lake that could occur after heavy rains or during snow melt periods, because lake water concentrations of Ca and bicarbonate were extremely low even in the past (based on
MAGIC modelling). The less acid-tolerant calanoid species Mixodiatomus tatricus , which was documented from the lake in the beginning of 20th century and which was absent in the 1980s, has not reappeared yet. Copepods do not leave remains in the lake sediment that are easily recognizable, so detailed historical changes could not be traced.
Fig. 3. Long-range atmospheric pollution. Kangerlussuag lake district (SW
Greenland)
The Kangerlussuaq lake district of SW Greenland is located on crystalline bedrock with dwarf shrub tundra vegetation and encompasses a temperature and precipitation gradient from the ice sheet margin to the coast: an arid interior with warm summers contrasts to

a cooler and more maritime coastal zone (Anderson et al. 2001). Despite being home to some of the longest meteorological records in the Arctic (Box 2002), associated with
whaling stations, and being situated relatively close to the Greenland ice core records, studies in the Kangerlussuaq area illustrate the power of palaeolimnology to “plug the gap” created by remoteness and lack of contemporary monitoring; more than 15 cores have been dated by
210
Pb for analyses of metals, diatoms, pigments and stable isotopes.
There are thousands of lakes, many of which are well buffered while at the coast long-
term oligotrophication is the predominant ecological signal over millennia (Perren et al.
2012). Despite their location, the Kangerlussuaq lakes record unambiguously long-
range atmospheric pollution by Pb, Hg and polycyclic aromatic hydrocarbons (PAHs)
(Bindler et al. 2001b; Bindler et al. 2001a). The local deposition rates of Pb and Hg are
strongly influenced by regional climate with the greater rainfall at the coast enhancing fluxes while Hg concentrations in lakes adjacent to the ice sheet are considerably higher than the regional mean, highlighting the dynamic nature of the land-ice boundary
(Bindler et al. 2001b; Bindler et al. 2001a; Lindeberg et al. 2006). Variability in
effective precipitation undoubtedly exerts a major control on the intermediately located,
inland lakes (McGowan et al. 2003; Anderson and Leng 2004), but other drivers
influence both coastal and ice-marginal lakes (Perren et al. 2012). One of the main local
drivers, which adds complexity to ecological change in the Kangerlussuaq area, is the input of loess, deflated from the sandar draining the ice sheet and which is probably an unquantified source of nutrient inputs to lakes located up to ~70 km from the present ice sheet margin. Southwest Greenland was cooling for much of the mid- to late-20 th century (Fig. 3) but many lakes are dominated by small Cyclotella diatoms and have
been for hundreds of years (Perren et al. 2009; Perren et al. 2012). There is, however,
clear evidence of recent ecological change in the area evidenced by the diatom assemblages (Fig. 3), and shows similar timescales of change to that of changing
atmospheric nitrogen input recorded at the Summit of the Greenland ice sheet (Hastings et al. 2009). Estimates of carbon burial rates over
210
Pb timescales indicate that lake productivity has increased in association with this input of Nr. The timescale of increased NO
3
-
deposition and the corresponding shift in δ
15
N caused by anthropogenically-derived N inputs clearly parallels the timing of changes in Pb and Hg in West Greenland (Fig. 3), again highlighting the extent to which the shadow of atmospheric pollution has permeated the Arctic over the last 150 years.
Palaeolimnological studies in the Kangerlussuaq area demonstrate ecological changes

despite a relatively complacent recent climate history, ultimately suggesting that multiple drivers of limnological change are present, and these may interact in ways difficult to predict.
Fig. 4. The Cyclotella case
It is well established that the biological communities of alpine and Arctic lakes are
particularly responsive to recent warming trends (Catalan et al. 2002; Smol and Douglas
2007). Recent warming, changes in lake ice phenology, and changes in lake-water
properties (e.g., thermal stratification, mixing strength and depth, nutrient distributions, light) have been linked to distinct shifts in diatom assemblage composition favouring
planktonic taxa in many Arctic lakes (Sorvari et al. 2002; Rühland et al. 2003; Smol et
al. 2005; Smol and Douglas 2007), alpine lakes (Catalan et al. 2002; Karst-Riddoch et al. 2005) and non-acidified, non-enriched temperate lakes (Harris et al. 2006)). This
shift in diatoms was often characterized by increases in the relative abundances of small, fast growing planktonic diatoms (centric Cyclotella sensu lato taxa) with concurrent decreases in heavily silicified Aulacoseira species and/or small, benthic
Fragilaria ( sensu lato ) taxa. The striking similarity of this diatom shift recorded in lakes from diverse ecological settings was examined in a synthesis of over 200
palaeolimnological records from the Northern Hemisphere (Rühland et al. 2008).
A key finding of the (Rühland et al. 2008) study was that the median timing of
increasing Cyclotella taxa differed among ecoregions with a significantly earlier onset in Arctic (AD ~1870) compared to temperate (AD ~1970) lakes, and the intermediate timing of change in alpine lakes that was not significantly different from either Arctic or temperate regions (Fig. 4). The alpine trend is more complex likely due to the lower number of representative sites, but also because this category incorporates both Arctic and temperate, high altitude lakes, highlighting the sensitive response of mountain lakes
in temperate latitudes (Battarbee et al. 2002). The highest variability in the timing of
change occurred in the Arctic, likely due to this category incorporating both high and low Arctic lakes. The earlier timing of planktonic increases in Arctic lakes is consistent
with the sensitivity of high latitudes to global warming (Smol et al. 2005; Smol and
Douglas 2007). The largely later timing of this shift in temperate lakes is precisely what
would be predicted with a lag in warming at lower latitudes. Temperate aquatic ecosystems experience longer ice-free periods and growing seasons, and thus take

longer and require a greater temperature increase to reach a tipping point (Fig. 4D) than more sensitive, circum-Arctic (including subarctic) and alpine lakes.
A change in lake ice phenology with warming temperatures (and associated changes in lake water properties) has been invoked as the mechanism for the recent
Cyclotella-Aulacoseira-Fragilaria
shift in Arctic/subarctic and alpine lakes (Lotter and
Bigler 2000; Sorvari et al. 2002; Smol et al. 2005; Smol and Douglas 2007; Rühland et al. 2008). However, examining direct linkages between changes in lake ice cover and
these taxon-specific shifts has not been undertaken in high latitude and altitude regions, primarily because lake ice data from the same lakes studied for diatoms are extremely rare in these remote locations. For this reason, a continuous lake ice record and a highresolution, detailed diatom profile from a dated sediment core (Fig 4D) retrieved from
Whitefish Bay, Lake of the Woods, Ontario, Canada (49.38°N, 94.14°W) provided an excellent opportunity to examine the potential drivers of the Cyclotella Aulacoseira -
Fragilaria trend. Pronounced temperature increases, particularly since the late 1970s, and an increase in the ice-free period by ~28 days in the past 40 years, were strongly correlated to the timing of this taxon-specific shift (Fig. 4D).
Unlike the relatively quiescent climate of the Holocene, there are pre-Holocene examples of abrupt, high magnitude fluctuations in climate that induced pronounced shifts in diatom assemblages that are similar in nature to recent Cyclotella
shifts (Wang
et al. 2008; Wilson et al. 2008; Rudaya et al. 2009; Ampel et al. 2010; Huber et al.
2010; Lami et al. 2010). For example, in France, several abrupt, transitions between
stadials and interstadials during the last glacial period (Dansgaard-Oescher cycles 36.2 to 31.7 thousand years B.P.) were evidenced by strikingly distinct successional shifts between small Cyclotella taxa (interstadials) and small benthic fragilarioid taxa
(stadials) with the re-establishment of remarkably similar species assemblages during
each transition (Ampel et al. 2010). In southeast China, several abrupt shifts between
small Discostella stelligera and heavy Aulacoseira taxa between 17,600 to 6,000 years
B.P. were driven by rapid changes in the intensity of the winter monsoon winds (Wang et al. 2008). During periods of strong monsoons, strong wind-driven turbulence
prevailed, and heavy Aulacoseira taxa dominated. During warmer periods with weak monsoons, lake thermal stability was strong, and small Discostella stelligera taxa dominated.

Fig. 5. Change in seasonality throughout the Holocene as illustrated by lake records from the Pyrenees
Strong seasonal changes driven by weather throughout the year is one of the most prominent features of lake ecosystems, which are amplified when ice cover develops as is typical of remote sites from cold areas. However, these properties have not been exploited when reconstructing seasonality regimes of the past. One possibility is to calibrate the phytoplankton succession locally using sediment traps and chrysophycean
cysts (Pla-Rabes and Catalan 2011), and another is to reconstruct physical or chemical
variables that primarily depend on weather conditions during certain parts of the year. In
Fig. 5, we describe the case of lake water alkalinity and ice cover duration reconstructed
using diatoms (Catalan et al. 2009) and chrysophyte cysts (Pla and Catalan 2005),
respectively, and hypothesize that together they reflect climate oscillations of summer/autumn (snow free) and winter/spring (snow covered) periods. At sites without acid deposition and scarce in-lake alkalinity production, alkalinity is ultimately driven by rock weathering processes sensitive to climate conditions during the snow free period. On the other hand, chrysophyte succession in the water column depends directly on the timing of the ice-free period onset, which relates to spring temperature
(Thompson et al. 2008).
The coring site was Lake Redon (formerly Redó) (42º38’33”N, 0º46’13”E), located in the central Pyrenees at 2240 m a.s.l. It has a surface area of 0.24 km 2 , a maximum depth of 73 m, and a mean depth of 32 m. Average water residence time is over 4 years. The watershed area is a small granodiorite basin (1.55 km 2 ). Land cover consists of poorly developed soil (74%), generally less than 30 cm deep, supporting grasslands. The rest of the area is bare rock. The total length of the core was 56 cm, and dating showed that it covered the last 10,000 years, reflecting the low sedimentation rate in the lake, due to the oligotrophy and a relatively small watershed compared to the lake volume.
Alkalinity changes follow the general temperature trends expected from pollen records in the Pyrenees, with a climatic optimum during the period 6000-8000 years BP and cooling since the Middle Holocene. However, ice-cover duration indicates an opposed tendency for this period, suggesting that winter/spring temperatures increased from the onset of the Holocene up to about 2000 years BP. Therefore, there was a
marked change in continentality, which is in agreement with astronomical forcing (Pla

and Catalan 2005). The Little Ice Age is well recorded by reconstruction of the ice-
cover duration, but is not apparent in the alkalinity-record, indicating that spring conditions could have been particularly harsh during this interval. Despite of the various caveats of using transfer functions based on space for time approximations, these examples show that there is an opportunity for reconstructing changes in seasonality climate using multiple proxies (e.g., microalgal remains, pollen, and geochemistry).
Adequate site selection and an understanding of processed driving statistical relationships are necessary for reliable reconstructions.
Fig. 6. Nitrogen deposition. Pristine Lake (Rocky Mountains, Colorado, USA)
Pristine Lake, in the Rocky Mountains of northern Colorado, U.S.A. (Fig 6), is a seldom-visited lake above local tree line within a cirque immediately west of the
Continental Divide. The lake supports a naturally reproducing population of cutthroat trout ( Oncorhynchus clarki ) and is situated in a federally designated wilderness protection area. However, the region receives considerable Nr deposition sourced primarily from coal-fired power plants in the Yampa Valley, namely at Hayden and
Craig, 50 and 80 km to the west, respectively. Pristine Lake is thus an ideal natural laboratory to examine the consequences of Nr deposition to remote lakes in the Rocky
Mountains. Long-term snowpack chemistry (1993-2010) indicates mean pH of
5.24±0.35, mean [NO
3
] of 0.83±0.14 mg L -1
, mean [NH
4
+ ] of 0.08±0.03 mg L -1
, and mean [SO
4
2] of 0.37±0.09 mg L -1 ( n
=18; (Ingersoll et al. 2011)). Diatom assemblages
in Pristine Lake sediments have undergone pronounced changes in recent decades.
Small benthic fragilarioid and achnanthoid taxa were largely replaced by Asterionella formosa around 1950 AD, followed by marked increases of Fragilaria tenera , F. nanana , and Discostella
spp. after 1985 AD (Fig. 6). According to (Saros et al. 2005),
A. formosa has high Nr requirements and its initial expansion corresponds closely with declining sediment
 15
N values, implying that Pristine Lake became impacted by Nr deposition shortly after 1950 AD. This interval does not appear to be associated with regional climate variability, given relatively stable temperatures between 1930 and 1980
AD at Steamboat Springs, the closest long-term meteorological station (Fig. 6).
However, mean annual and summer temperatures have risen markedly in the last three decades, with an inflection that coincides with the second reorganization of diatom communities in the mid-1980s. At this time, planktonic taxa became even more

prevalent, this time at the expense of several naviculoid genera and presumably as a response to longer ice-free seasons. While the lake remained impacted by Nr deposition, as suggested by the sustained trend of
 15
N depletion, competition for this resource also became intensified, ultimately favouring taxa with lower requirements, such as
Discostella
(Arnett et al. 2012). Increased lake production is evidenced by both the
trends in total diatom concentrations as well as sediment C/N ratios, which reveal an increasingly autochthonous (algal) source of sediment organic matter.
The Pristine Lake stratigraphy thus reflects the combined effects of atmospheric deposition and climate change, as a complex series of interactions that are nonetheless registered faithfully by the sediment record. However, Nr deposition is deemed the primary mechanism driving limnological change at this site. For example, the first axis of Canonical Correspondence Analysis (CCA) constraining diatom assemblages to the primary proxy for Nr deposition,
 15 N, fully explains 62.6% of variance within the biotic response. The stratigraphic profile of sample scores along this axis do not inflect during the interval of inferred climate effects after 1985 AD, suggesting that Nr deposition remained the primary agent of change (Fig. 6). An additional consequence has been the net loss of diatom taxonomic richness in Pristine Lake sediments, from over 60 to ~25 taxa recorded in the profile. Such loss of biodiversity within communities of primary producers is likely to influence resilience towards any future changes while rendering the eventual return to pre-disturbance ecological states highly unlikely.
Are there any encouraging elements of this story? Perhaps. A notable feature of the Pristine Lake diatom stratigraphy is that there is no diatom evidence whatsoever for recent lake acidification, despite the low pH and high acid anion content of regional precipitation, and the absence of carbonate bedrock lithologies. This observation can be
extended to other sectors of the American Rocky Mountains (Wolfe et al. 2003; Saros et al. 2005). In all likelihood, for the time being, sufficient alkalinity is being generated by
in-lake processes to buffer these otherwise acid-sensitive lakes, presumably by the
combined effects of sulphate and nitrate reduction in sediments (Schindler 1986).
As exemplified by the Pristine Lake case study, palaeolimnological reconstructions of Nr deposition effects are complicated but tractable. Moreover, it becomes clear that nitrogen deposition and climate change interact in such ways that it
may prove impossible to disentangle their independent effects fully (Saros et al. 2010).
Indeed, because Nr deposition is mediated by climatic vectors, this outcome is perhaps

not surprising. Future efforts must, therefore, concentrate on the assessment of potential synergism between these two mechanisms of limnological change, and their potential for additional interactions with other stressors.
Fig. 7. Converging lake diatom communities in alpine lakes (Austrian Alps,
Niedere Tauern)
Five mountain lakes of a diatom training set of 41 lakes in the Niedere Tauern (Austria),
which were sampled 1998-99 (Schmidt et al. 2004a), were revisited within the project
DETECTIVE (DEcadal deTECTIon of biodiVErsity in Alpine lakes) of the Austrian
Academy of Sciences and the Institute for Limnology Mondsee. Sediment traps were exposed during 2010-11. Thermistor measurements were used to measure water temperatures and ice-cover duration. Additionally, pH, conductivity, alkalinity, Ca, dissolved organic carbon (DOC), nitrogen (NH
4
-N, NO
3
-N) and dissolved reactive silica (DRSi) were measured. These environmental variables showed year-to-year fluctuations. Planktonic diatoms react faster to short-term environmental variability than the benthic taxa. However, attached benthic forms, which tolerate short-term fluctuations, are suggested to have a competitive advantage against species with a narrower ecological range, hence fostering increased abundance (e.g., the Achnanthes minutissima -complex).
The climatically sensitive Moaralmsee (1825 m a.s.l.) has probably passed a
threshold in recent years (Thompson et al. 2005). Here, marked increases have occurred
in both the length of the growing season (shorter ice-cover) and summer water temperatures. The rise in planktonic diatoms is similar to Oberer Landschitzsee, which is located close to the tree line (2067 m a.s.l.). The diatom plankton in Moaralmsee and
Oberer Landschitzsee, both on predominantly crystalline bedrock (lower pH), is taxonomically poorer and often masked by Fragilaria aff. delicatissima relative to the more alkaline and deeper Twengeralmsee (2118 m a.s.l), where diverse diatom plankton was already present during 1998-99. However, in the warmer lake Oberer Landschitzsee
(Thompson et al. 2005), stability could now be higher than in Twengeralmsee where
environmental fluctuations caused rapid shifts in structure and composition of diatom plankton and a recent reversal has developed (e.g. the shift between Fragilaria aff. delicatissima and F. gracilis
with lower temperature requirement (Schmidt et al.
2004b). The diatom communities of these lakes thus differ in their respective resilience

to environmental change. In the group of less remote and pristine lakes that showed
nearly balanced water to air temperature relations (Thompson et al. 2005), Unterer
Wirpitschsee (1700 m a.s.l.) remained more or less constant (see PCA) whereas in
Unterer Giglachsee (1922 m a.s.l.) lower nutrient (nitrogen) availability may be due for the significant changes observed in diatom assemblage composition (e.g. Cyclotella gordonensis ).
In sum, the investigations indicate lake-specific biological reaction on climate change. The overall tendency between the two surveys was a decline in variability among diatom assemblage composition as shown by the convergence of PCA trajectories (Fig. 7).
ESI References
Ampel L, Wohlfarth B, Risberg J, Veres D, Leng MJ, Tillman PK (2010) Diatom assemblage dynamics during abrupt climate change: the response of lacustrine diatoms to Dansgaard-Oeschger cycles during the last glacial period. J
Paleolimnol 44:397-404
Anderson NJ, Leng MJ (2004) Increased aridity during the early Holocene in West
Greenland inferred from stable isotopes in laminated-lake sediments. Quaternary
Sci Rev 23:841-849
Anderson NJ, Harriman R, Ryves DB, Patrick ST (2001) Dominant factors controlling variability in the ionic composition of West Greenland Lakes. Arct Antarct Alp
Res 33:418-425
Arnett HA, Saros JE, Mast MA (2012) A caveat regarding diatom-inferred nitrogen concentrations in oligotrophic lakes. J Paleolimnol 47:277-291
Battarbee RW, Grytnes JA, Thompson R, Appleby PG, Catalan J, Korhola A, Birks
HJB, Heegaard E, Lami A (2002) Comparing palaeolimnological and instrumental evidence of climate change for remote mountain lakes over the last
200 years. J Paleolimnol 28:161-179
Bindler R, Renberg I, Appleby PG, Anderson NJ, Rose NL (2001a) Mercury accumulation rates and spatial patterns in lake sediments from west Greenland:
A coast to ice margin transect. Environ Sci Technol 35:1736-1741
Bindler R, Renberg I, Anderson NJ, Appleby PG, Emteryd O, Boyle J (2001b) Pb isotope ratios of lake sediments in West Greenland: inferences on pollution sources. Atmos Environ 35:4675-4685
Box JE (2002) Survey of Greenland instrumental temperature records: 1873-2001.
International Journal of Climatology 22:1829-1847
Catalan J, Pla S, Garcia J, Camarero L (2009) Climate and CO
2
saturation in an alpine lake throughout the Holocene. Limnol Oceanogr 54:2542-2552
Catalan J, Pla S, Rieradevall M, Felip M, Ventura M, Buchaca T, Camarero L, Brancelj
A, Appleby PG, Lami A, Grytnes A, Agusti-Panareda A, Thompson R (2002)
Lake Redo ecosystem response to an increasing warming in the Pyrenees during the twentieth century. J Paleolimnol 28:129-145

Fott J, Pražáková M, Stuchlík E, Stuchlíková Z (1994) Acidification of lakes in Šumava
(Bohemia) and in the High Tatra Mountains (Slovakia). Hydrobiologia 274:37-
47
Harris MA, Cumming BF, Smol JP (2006) Assessment of recent environmental changes in New Brunswick (Canada) lakes based on paleolimnological shifts in diatom species assemblages. Canadian Journal of Botany-Revue Canadienne De
Botanique 84:151-163
Hastings MG, Jarvis JC, Steig EJ (2009) Anthropogenic impacts on nitrogen isotopes of ice-core nitrate. Science 324:1288
Heiri O, Lotter AF (2003) 9000 years of chironomid assemblage dynamics in an Alpine lake: long-term trends, sensitivity to disturbance, and resilience of the fauna. J
Paleolimnol 30:273-289
Hirt AM, Lanci L, Koinig K (2003) Mineral magnetic record of Holocene environmental changes in Sagistalsee, Switzerland. J Paleolimnol 30:321-331
Hofmann W (2003) The long-term succession of high-altitude cladoceran assemblages: a 9000-year record from Sagistalsee (Swiss Alps). J Paleolimnol 30:291-296
Hořická Z, Stuchlík E, Hudec I, Černý M, Fott J (2006) Acidification and the structure of crustacean zooplankton in mountain lakes: The Tatra Mountains (Slovakia,
Poland). Biologia 61 121-134.
Huber K, Weckstrom K, Drescher-Schneider R, Knoll J, Schmidt J, Schmidt R (2010)
Climate changes during the last glacial termination inferred from diatom-based temperatures and pollen in a sediment core from Langsee (Austria). J
Paleolimnol 43:131-147
Ingersoll GP, Mast MA, Swank JM, Campbell CD (2011) Rocky Mountain snowpack physical and chemical data for selected sites, 2010, Reston, 12 pp
Karst-Riddoch TL, Pisaric MFJ, Smol JP (2005) Diatom responses to 20th century climate-related environmental changes in high-elevation mountain lakes of the northern Canadian Cordillera. J Paleolimnol 33:265-282
Koinig KA, Shotyk W, Lotter AF, Ohlendorf C, Sturm M (2003) 9000 years of geochemical evolution of lithogenic major and trace elements in the sediment of an alpine lake - the role of climate, vegetation, and land-use history. J
Paleolimnol 30:307-320
Kopáček J, Veselý J, Stuchlík E (2001) Sulphur and nitrogen fluxes and budgets in the
Bohemian Forest and Tatra Mountains during the Industrial Revolution (1850-
2000). Hydrology and Earth System Sciences 5:391-405
Kopáček J, Stuchlík E, Hardekopf D (2006) Chemical composition of the Tatra
Mountain lakes: Recovery from acidification. Biologia, Bratislava 61/Suppl.
18.:S21-S33
Lami A, Marchetto A, Musazzi S, Salerno F, Tartari G, Guilizzoni P, Rogora M, Tartari
GA (2010) Chemical and biological response of two small lakes in the Khumbu
Valley, Himalayas (Nepal) to short-term variability and climatic change as detected by long-term monitoring and paleolimnological methods.
Hydrobiologia 648:189-205
Lindeberg C, Bindler R, Renberg I, Emteryd O, Karlsson E, Anderson NJ (2006)
Natural fluctuations of mercury and lead in Greenland Lake sediments. Environ
Sci Technol 40:90-95
Lotter AF, Bigler C (2000) Do diatoms in the Swiss Alps reflect the length of icecover? Aquatic Sciences 62:125-141
Lotter AF, Birks HJB (2003a) The Holocene palaeolimnology of Sagistalsee and its environmental history - a synthesis. J Paleolimnol 30:333-342

Lotter AF, Birks HJB (2003b) Holocene sediments of Sagistalsee, a small lake at the present-day tree-line in the Swiss Alps. J Paleolimnol 30:253-260
McGowan S, Ryves DB, Anderson NJ (2003) Holocene records of effective precipitation in West Greenland. Holocene 13:239-249
Ohlendorf C, Sturm M, Hausmann S (2003) Natural environmental changes and human impact reflected in sediments of a high alpine lake in Switzerland. J Paleolimnol
30:297-306
Perren BB, Douglas MSV, Anderson NJ (2009) Diatoms reveal complex spatial and temporal patterns of recent limnological change in West Greenland. J
Paleolimnol 42:233-247
Perren BB, Anderson NJ, Douglas M, Fritz SC (2012) The influence of temperature, moisture, and eolian activity on Holocene lake development in West Greenland.
J Paleolimnol in press
Pla-Rabes S, Catalan J (2011) Deciphering chrysophyte responses to climate seasonality. J Paleolimnol 46:139-150
Pla S, Catalan J (2005) Chrysophyte cysts from lake sediments reveal the submillennial winter/spring climate variability in the northwestern Mediterranean region throughout the Holocene. Clim Dynam 24:263-278
Rudaya N, Tarasov P, Dorofeyuk N, Solovieva N, Kalugin I, Andreev A, Daryin A,
Diekmann B, Riedel F, Tserendash N, Wagner M (2009) Holocene environments and climate in the Mongolian Altai reconstructed from the Hoton-
Nur pollen and diatom records: a step towards better understanding climate dynamics in Central Asia. Quaternary Sci Rev 28:540-554
Rühland K, Priesnitz A, Smol JP (2003) Paleolimnological evidence from diatoms for recent environmental changes in 50 lakes across Canadian arctic treeline. Arct
Antarct Alp Res 35:110-123
Rühland K, Paterson AM, Smol JP (2008) Hemispheric-scale patterns of climate-related shifts in planktonic diatoms from North American and European lakes. Global
Change Biol 14:2740-2754
Saros JE, Michel TJ, Interlandi SJ, Wolfe AP (2005) Resource requirements of
Asterionella formosa and Fragilaria crotonensis in oligotrophic alpine lakes: implications for recent phytoplankton community reorganizations. Can J Fish
Aquat Sci 62:1681-1689
Saros JE, Rose KC, Clow DW, Stephens VC, Nurse AB, Arnett HA, Stone JR,
Williamson CE, Wolfe AP (2010) Melting Alpine Glaciers Enrich High-
Elevation Lakes with Reactive Nitrogen. Environ Sci Technol 44:4891-4896
Schindler DW (1986) The significance of in-lake production of alkalinity. , Air, & Soil
Pollution 30:931-944
Schmidt R, Kamenik C, Kaiblinger C, Hetzel M (2004a) Tracking Holocene environmental changes in an alpine lake sediment core: application of regional diatom calibration, geochemistry, and pollen. J Paleolimnol 32:177-196
Schmidt R, Kamenik C, Lange-Bertalot H, Klee R (2004b) Fragilaria and Staurosira
(Bacillariophyceae) from sediment surfaces of 40 lakes in the Austrian Alps in relation to environmental variables, and their potential for palaeoclimatology. . J
Limnol 63:171-189
Smol JP, Douglas MSV (2007) From controversy to consensus: making the case for recent climate using lake sediments. Front Ecol Environ 5:466-474
Smol JP, Wolfe AP, Birks HJB, Douglas MSV, Jones VJ, Korhola A, Pienitz R,
Rühland K, Sorvari S, Antoniades D, Brooks SJ, Fallu MA, Hughes M, Keatley
BE, Laing TE, Michelutti N, Nazarova L, Nyman M, Paterson AM, Perren B,

Quinlan R, Rautio M, Saulnier-Talbot E, Siitonen S, Solovieva N, Weckstrom J
(2005) Climate-driven regime shifts in the biological communities of arctic lakes. Proc Natl Acad Sci U S A 102:4397-4402
Sorvari S, Korhola A, Thompson R (2002) Lake diatom response to recent Arctic warming in Finnish Lapland. Global Change Biol 8:171-181
Stuchlík E, Appleby P, Bitušík P, Curtis C, Fott J, Kopáček J, Pražáková M, Rose N,
Strunecký O, Wright RF (2002) Reconstruction of long-term changes in lake water chemistry, zooplankton and benthos of a small, acidified high-mountain lake: Magic modelling and palaeolimnogical analysis. Wat Air Soil Poll Focus
2:127-138
Thompson R, Kamenik C, Schmidt R (2005) Ultra-sensitive Alpine lakes and climate change. J Limnol 64:139-152
Thompson R, Kamenik C, Schmidt R, Pla S, Rieradevall M, Catalan J (2008) Testing a new multigroup inference approach to reconstructing past environmental conditions. J Limnol 67:155-162
Wang L, Lu HY, Liu JQ, Gu ZY, Mingram J, Chu GQ, Li JJ, Roiual P, Negendank
JFW, Han JT, Liu TS (2008) Diatom-based inference of variations in the strength of Asian winter monsoon winds between 17,500 and 6000 calendar years BP. J Geophys Res - Atmos 113
Wick L, van Leeuwen JFN, van der Knaap WO, Lotter AF (2003) Holocene vegetation development in the catchment of Sagistalsee (1935 m asl), a small lake in the
Swiss Alps. J Paleolimnol 30:261-272
Wilson GP, Reed JM, Lawson IT, Frogley MR, Preece RC, Tzedakis PC (2008) Diatom response to the Last Glacial-Interglacial Transition in the Ioannina basin, northwest Greece: implications for Mediterranean palaeoclimate reconstruction.
Quaternary Sci Rev 27:428-440
Wolfe AP, Van Gorp AC, Baron JS (2003) Recent ecological and biogeochemical changes in alpine lakes of Rocky Mountain National Park (Colorado, USA): a response to anthropogenic nitrogen deposition. Geobiol 1:153-168