DOI: 10.5061/dryad.g7h7n
title: Data from: Ice-cover is the principal driver of ecological change in High Arctic lakes and ponds

description: Recent climate change has been especially pronounced in the High Arctic,
 however, the responses of aquatic biota, such as diatoms, can be modified
 by site-specific environmental characteristics. To assess if
 climate-mediated ice cover changes affect the diatom response to climate,
 we used paleolimnological techniques to examine shifts in diatom
 assemblages from ten High Arctic lakes and ponds from Ellesmere Island and
 nearby Pim Island (Nunavut, Canada). The sites were divided a priori into
 four groups (“warm”, “cool”, “cold”, and “oasis”) based on local elevation
 and microclimatic differences that result in differing lengths of the
 ice-free season, as well as about three decades of personal observations.
 We characterized the species changes as a shift from Condition 1 (i.e. a
 generally low diversity, predominantly epipelic and epilithic diatom
 assemblage) to Condition 2 (i.e. a typically more diverse and ecologically
 complex assemblage with an increasing proportion of epiphytic species).
 This shift from Condition 1 to Condition 2 was a consistent pattern
 recorded across the sites that experienced a change in ice cover with
 warming. The “warm” sites are amongst the first to lose their ice covers
 in summer and recorded the earliest and highest magnitude changes. The
 “cool” sites also exhibited a shift from Condition 1 to Condition 2, but,
 as predicted, the timing of the response lagged the “warm” sites.
 Meanwhile some of the “cold” sites, which until recently still retained an
 ice raft in summer, only exhibited this shift in the upper-most sediments.
 The warmer “oasis” ponds likely supported aquatic vegetation throughout
 their records. Consequently, the diatoms of the “oasis” sites were
 characterized as high-diversity, Condition 2 assemblages throughout the
 record. Our results support the hypothesis that the length of the ice-free
 season is the principal driver of diatom assemblage responses to climate
 in the High Arctic, largely driven by the establishment of new aquatic
 habitats, resulting in increased diversity and the emergence of novel
 growth forms and epiphytic species.
description: Col Broken
 stickCol Pond plot of broken
 stick model resultsCol
 ConissCol Pond plot of CONISS
 model resultsCol N2Col Pond Hill's N2
 and chlorophyll a outputCol
 PondCol Pond diatom raw
 count data and relative abundances including basionyms and modern
 taxonomic designationsElison broken
 stickElison Lake plot of
 broken stick model resultsHigh broken
 stickHigh Lake plot of broken
 stick model resultsMoraine broken
 stickMoraine Pond plot of
 broken stick model resultsParadise Broken
 stickParadise Pond plot of
 broken stick model resultsPlateau Pond 2 broken
 stickPlateau Pond 2 plot of
 broken stick model resultsProteus broken
 stickProteus Lake plot of
 broken stick model resultsSV5 broken
 stickSV Pond 5 plot of broken
 stick model resultsSV8 broken
 stickSV Pond 8 plot of broken
 stick model resultsWest broken
 stickWest Lake plot of broken
 stick model resultsElison
 conissElison Lake plot of
 CONISS model resultsHigh
 conissHigh Lake plot of CONISS
 model resultsMoraine
 ConissMoraine Pond plot of
 CONISS model resultsParadise
 ConissParadise Pond plot of
 CONISS model resultsPlateau pond 2
 conissPlateau Pond 2 plot of
 CONISS model resultsProteus
 conissProteus Lake plot of
 CONISS model resultsSV5
 conissSV Pond 5 plot of CONISS
 model resultsSV8
 conissSV Pond 8 plot of CONISS
 model resultsWest
 conissWest Lake plot of CONISS
 model resultsElison
 N2Elison Lake Hill's
 N2 and Chlorophyll a valuesHigh
 N2High Lake Hill's N2
 and Chlorophyll a valuesMoraine
 N2Moraine Pond Hill's
 N2 and Chlorophyll a valuesParadise
 N2Paradise Pond
 Hill's N2 and Chlorophyll a valuesPP2 N2Plateau Pond 2
 Hill's N2 and Chlorophyll a valuesProteus
 N2Proteus Lake Hill's
 N2 and Chlorophyll a valuesSV5 N2SV Pond 5 Hill's N2
 and Chlorophyll a valuesSV8 N2SV Pond 8 Hill's N2
 and Chlorophyll a valuesWest
 N2West Lake Hill's N2
 and Chlorophyll a valuesElison
 LakeElison Lake diatom raw
 count data and relative abundances including basionyms and modern
 taxonomic designationsHigh
 LakeHigh Lake diatom raw
 count data and relative abundances including basionyms and modern
 taxonomic designationsMoraine
 PondMoraine Pond diatom raw
 count data and relative abundances including basionyms and modern
 taxonomic designationsParadise
 PondParadise Pond diatom raw
 count data and relative abundances including basionyms and modern
 taxonomic designationsPlateau Pond
 2Plateau Pond 2 diatom
 raw count data and relative abundances including basionyms and modern
 taxonomic designationsProteus
 lakeProteus Lake diatom raw
 count data and relative abundances including basionyms and modern
 taxonomic designationsSverdrup Pass
 PondsSverdrup Pond 5 and 8
 diatom raw count data and relative abundances including basionyms and
 modern taxonomic designationsWest
 LakeWest Lake diatom raw
 count data and relative abundances including basionyms and modern
 taxonomic designationsElison_Lake_July_17_2007-July 16 2011 thermistorElison Lake thermistor data from July 17 2007 to July 16 2011Grouping rationaleAdditional summary of field notes providing support for grouping rationale.High Lake activityHigh Lake 210Pb activity from gamma-datingMoraine activityMoraine Pond 210Pb activity from gamma-datingParadise activityParadise Pond 210Pb activity from gamma-datingPlateau Pond2 activityPlateau Pond 2 210Pb activity from gamma-datingProteus activityProtease Lake 210Pb activity from gamma-datingSV Pond 5 activitySV Pond 5 210Pb activity from gamma-datingSV Pond 8 activitySV Pond 8 210Pb activity from gamma-datingWater chem additional parameters all sitesAdditional water chemistry parameters for all sitesWest activityWest Lake 210Pb activity from gamma-datingHigh Lake datesHigh Lake 210Pb dates using CRS dating methodMoraine Pond DatesMoraine Pond 210Pb dates using CRS dating methodMoraine datesParadise datesParadise Pond 210Pb dates using CRS dating methodPlateau Pond2 datesPlateau Pond 2 210Pb dates using CRS dating methodProteus datesProteus Lake 210Pb dates using CRS dating methodSV Pond 5 datesSV Pond 5 210Pb dates using CRS dating methodSV Pond 8 datesSV Pond 8 210Pb dates using CRS dating methodWest Lake datesWest Lake 210Pb dates using CRS dating methodSV Ponds 14C datingSV Pond 5 and 8 14C dates and types of microfossils datedHills N2 scriptHill's N2 R script used to calculate Hill's N2 and rarify species count data (using pre-made packages)