Physical and chemical limnological characteristics of lakes and ponds across environmental gradients on Melville Island, Nunavut/N. W. T., High Arctic Canada

Abstract

Physical and chemical limnological variables were measured from 40 ponds and 6 lakes across Melville Island, Nunavut/N.W.T., Canadian high Arctic, an environmentally sensitive region where very limited limnological data were available. Mean values of most variables were mid-range when compared to other high Arctic limnological surveys, yet the ranges of most measured variables were amongst the largest yet encountered in Canadian high Arctic regional surveys. The first two axes of a Principal Components Analysis explained 55.2 % of the variation in the environmental data. Variables most strongly associated with axis one were pH, dissolved organic carbon, total dissolved nitrogen, specific conductivity and related variables, while axis two represented gradients of other nutrients and trace metals. High elevation sites near permanent ice caps recorded the lowest specific conductivity and Ca 2+ values yet reported in high Arctic systems. High phosphorus values (>20 μg/L) in some of the Melville Island sites are likely indicative of re-suspended sediments, rather than eutrophic conditions. Total nitrogen to total phosphorus ratios suggest that ∼50 % of the sites are P limited, while 33 % are N limited, supporting previous research which suggests N limitation is more commonly encountered in Arctic than in temperate freshwater ecosystems. Finally, when freshwater sites on Melville Island were grouped according to predefined bioclimatic zones, only the most lushly vegetated zone appeared to affect limnological conditions. with these sites having higher mean total dissolved nitrogen, pH, and specific conductivity.