Boreal lake study

Even within the subset of boreal lakes there is probably a direct relationship between external inputs of organic matter and their importance to zooplankton (Meili, M. Fry, B. Kling, G. W. unpublished data). In the case of Lake N2 and other upland arctic lakes, thermokarst processes and active erosion of shoreline peat banks are much less important than they are in coastal plain lakes (62, 75, 103). In addition, DOC made up less of the total organic carbon in Lake N2 than it did in the humic lake studied by Hessen (72) the ratio of DIC DOC.POC in Lake N2 was 25 8 1 (Table II), whereas in the humic lake the ratio was 1.6 21 1. The lower loading rates of particulate carbon and the smaller relative amounts of DOM in Lake N2 may explain the observation that pelagic productivity depended mainly on new algal production. 

Climate changes may also have significant effects on lake DOC concentrations. In a 20-year study of boreal lakes in the Experimental Lakes Area of northwestern Ontario, Schindler et al. (1997) reported that lake DOC concentrations declined by 15-25% as mean annual temperatures increased by 1.6°C, precipitation declined by 40%, and runoff declined by 70% due to increased evaporation and decreased precipitation. The primary reason for the decline in lake DOC was reduced inputs of DOC from terrestrial catchments, although in-lake removal of DOC also increased slightly via either increased acidification, UV light penetration, or microbial degradation. 

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