Fig 1.
Images of the Ellesmere Island and Pim Island sites highlighting the differences in microclimate between the four categories.
Col Pond (A) a “warm” site; Plateau Pond 2 (B) a “cool” site with snow persisting in the catchment; Proteus Lake (C) a “cold” site with no catchment vegetation and a pan of ice; and Sverdrup Pond 5 (D) an “oasis” site with considerable catchment vegetation. Photos A-D are taken from July 12th– 18th, 2011. Photo E and F are archival photographs (source John Smol) taken on June 19th, 1983, within one hour of each other. Col Pond (E) is ice free, while a pond on the plateau (F) remains largely ice covered (Plateau Pond 2, located ~0.5 km away and at a similar elevation, was fully ice-covered at the time), illustrating the differences in ice-off times between the “warm” and “cool” sites at the beginning of summer.
Table 1.
Rationale for the group divisions into “warm”, “cool”, “cold”, and “oasis” sites for the ten study sites from Ellesmere Island and Pim Island, Nunavut.
Fig 2.
Location map for Ellesmere Island, Nunavut, Canada (A), with Ellesmere Island in detail highlighting the three study regions: Cape Herschel, Pim Island, and Sverdrup Pass (B), and higher resolution insets of Cape Herschel (C), Pim Island (D), and Sverdrup Pass (E) identifying the 10 lakes and ponds in this study with “warm” sites as red circles, “cool” sites as green circles, “cold” sites as dark blue circles, and “oasis” sites in orange. Major hydrological features are shown in light blue, glaciers in dark grey and 20 m topographic contours as light grey lines. Source: Natural Resources Canada [28].
Table 2.
Coordinates, elevations and estimated maximum depths, and July 2011 water chemistry data for the ten study sites from Ellesmere and Pim Islands (Nunavut, Canada).
Fig 3.
Profiles of 210Pb activities and age-depth models.
The activities in decays per minute g-1 (dpm/g) of unsupported 210Pb (black circles), supported 210Pb (white circles) and 137Cs (grey circles) vs sediment depth (A) and the Constant Rate of Supply 210Pb generated age-depth model (B) for each dated study site: Moraine Pond (I), Paradise Pond (II), Plateau Pond 2 (III), High Lake (IV), Proteus Lake (V), West Lake (VI), SV Pond 5 (VII), and SV Pond 8 (VIII). Error bars represent standard error.
Fig 4.
Relative frequency profiles of dominant diatom taxa sorted according to habitat preference from “warm” sites, along with significant stratigraphic zones.
(A) Col Pond and (B) Elison Lake, on Ellesmere Island, Nunavut, Canada. Habitat preferences are provided and attributed as follows: 1) Douglas et al. [27], 2) Lim et al. [14], 3) Michelutti et al. [55], 4) Kingston [56], and 5) Kociolek and Spaulding [57]. Stratigraphies are plotted against core depth and reference dates are provided from a previous study [4] on the same sites.
Fig 5.
Relative frequency profiles of dominant diatom taxa sorted according to habitat preference from “cool” sites, along with significant stratigraphic zones.
(A) Moraine Pond, (B) Paradise Pond, and (C) Plateau Pond 2, on Ellesmere Island, Nunavut, Canada. Habitat preferences are provided and attributed as follows: 1) Douglas et al. [27], 2) Lim et al. [14], 3) Michelutti et al. [55], 4) Kingston [56], and 5) Kociolek and Spaulding [57]. Stratigraphies are plotted against interpolated 210Pb age.
Fig 6.
Relative frequency profiles of dominant diatom taxa sorted according to habitat preference from “cold” sites, along with significant stratigraphic zones.
(A) High Lake, (B) Proteus Lake, and (C) West Lake, on Pim Island, Nunavut, Canada. Habitat preferences are provided and attributed as follows: 1) Douglas et al. [27], 2) Lim et al. [14], 3) Michelutti et al. [55], 4) Kingston [56], and 5) Kociolek and Spaulding [57]. Stratigraphies are plotted against interpolated 210Pb age.
Fig 7.
Relative frequency profiles of dominant diatom taxa sorted according to habitat preference from Sverdrup Pass “oasis” sites, along with significant stratigraphic zones.
(A) SV Pond 5 and (B) SV Pond 8, Ellesmere Island, Nunavut, Canada. Habitat preferences are provided and attributed as follows: 1) Douglas et al. [27], 2) Lim et al. [14], 3) Michelutti et al. [55], 4) Kingston [56], and 5) Kociolek and Spaulding [57]. Stratigraphies are plotted against core depth and reference dates are provided from 210Pb ages, where suitable (B), and with basal 14C ages.
Fig 8.
Hill’s N2 diversity index values chlorophyll a profiles for all study sites.
Hill’s N2 diversity index values (A, B, C, D) and visible reflectance spectroscopy-inferred chlorophyll a concentrations (E, F, G, H) from lakes and ponds divided into “warm” (A, E), “cool” (B, F), “cold” (C, G), and “oasis” (D, H) groups based upon local elevation and climate gradients on Ellesmere Island and Pim Island, Nunavut, Canada. The diatom zones are indicated on each profile to relate the species changes to the changes in diversity and inferred primary production.