ABSTRACT: Diatom ecology and paleolimnology of high arctic ponds

CGRG Bibliography of Canadian Geomorphology
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Abstract

Epiphytic, epilithic, and surface sediment diatom assemblages were identified and enumerated from a suite of 35 study ponds from Cape Herschel (78 37 N, 74 42 W), east-central Ellesmere Island. Physical and chemical limnological data indicate that all sites are shallow (maximum depth, Zmax <2 m), clear, oligotrophic and freshwater. The ponds are completely frozen for 10 months of the year; however, during the short summers, water temperatures warm substantially (to a recorded maximum of 17 C) and fluctuate diurnally. With the exception of one pond (Paradise Pond, pH=6.5), the ponds are alkaline (pH range of 7.4 to 8.60), reflecting local geology (e.g., calcareous tills). Major ions in water are relatively similar amongst the 35 sites, although environmental gradients exist. Over 130 taxa from 28 genera were identified in the periphyton samples. Although some of the recorded taxa were common to all three habitats, many of the diatom taxa exhibited varying degrees of microhabitat specificity. Marked difference in species composition are evident amongst the ponds. Weighted averaging and calibration were used to develop a transfer function to infer pondwater alkalinity. Optima derived from rock and sediment assemblages were more reliable than those derived from moss assemblages. Paleolimnological analyses from seven ponds showed that sediment cores from these shallow sites do appear to faithfully record a useful stratigraphic record of environmental change. Striking successional changes were noted in diatom assemblages during the ponds' recent (ca. last 200 year) histories. Although the causes of these diatom assemblage shifts cannot be determined at this time, regional environmental changes likely related to anthropogenic activity may be responsible.

Bibliography of Canadian Geomorphology