Changes in diatom assemblages in Lake C2 (Ellesmere Island, Arctic Canada): response to basin isolation from the sea and to other environmental changes

Abstract

Diatoms preserved in the sediments of Lake C2 (82~ ' N, 76o00 ' W), a high arctic meromictic lake, track changes in the lake's salinity which have occurred as the basin was isolated from the sea. An assemblage dominated by marine taxa, such as Chaetoceros species, Nitzschia cylindrus and Diploneis spp., was replaced by a Cyclotella kuetzingiana var. planetophora dominated freshwater fora. A brief brackish period separates the two assemblages.Relatively little floristic change occurred within either the marine or freshwater periods, indicating rather stable environmental conditions, except that rheophilous diatoms fluctuated in relative abundance during the lacustrine phase, perhaps tracking past changes in discharge from inflowing streams. These may reflect periods of warmer, wetter environmental conditions.

Recent sedimentation in a high arctic lake, northern Ellesmere Island, Canada

“…Longer sediment cores were obtained with a Reasoner percussion corer (Reasoner, 1993) during the summer of 1992 recovering a complete lacustrine sediment sequence down to marine sediment and basal till (cf. Douglas et aL, 1996). For this study surface cores were obtained from the ice by subsampling an Ekman dredge.…”

Lake-Sediment Records of Recent Environmental Change on Svalbard: Results of Diatom Analysis

“…venter, and F. pseudoconstruens together with Nitzschia species such as N. frustulum and N. alpina, and Cymbella reinhardtii (Figure 2). Fragilaria-dominated assemblages are common in physically disturbed, unstable environments often characteristic of the early Holocene and recently deglaciated sites (Haworth 1975;Denys 1990;Bradshaw et al 2000) and in basins isolated from the sea (Stabell 1985;Douglas et al 1996). Fragilaria species may also be most competitive on sand or silty habitats (Kingston 1984) such as those found in these strandflat lakes on Svalbard where aquatic macrophytes are rare.…”

“…Because they are deeper and larger than the strandflat lakes there are more habitats available for diatom colonisation and growth and consequently the assemblages are more diverse, and include centric, presumably planktonic forms. Planktonic diatoms are found in Holocene sequences elsewhere in the Arctic (Lemmen et al 1988;Douglas et al 1996;Wolfe 1996). These two lakes have much more 'dynamic' diatom assemblages than the first group, exhibiting very dramatic changes through time.…”

The Taconite Inlet Lakes Project: a systems approach to paleoclimatic reconstruction

“…-the environmental records preserved in the sediments (Lamoureux & Bradley, 1996;Douglas et al, 1996). …”

“…These studies provided insight into the recent paleoenvironmental record represented by the diatom flora in the sediments and further discussion of this aspect of the study is given in Ludlam et al (t 996). The diatom record in a core which extends back to the time when lake C2 was part of Taconite Inlet is given in Douglas et al, 1996. Collectively, these studies provide a comprehensive evaluation of the modern environment in the Taconite Inlet area in general, and the Lake C2 watershed, in particular. By taking a systems approach, we have tried to assess the role of different factors which determine the inter-annual variations of sediment accumulation in the lake.…”