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The effects of nitrogen/ phosphorus ratios on the prediction of chlorophyll in phosphorus-limited lakes in Central Ontario

Show simple item record Dillon, P. J. Reid, R. A. Molot, Lewis A.
dc.coverage.spatial Ontario 2019-03-14T17:50:32Z 2019-03-14T17:50:32Z 1991 1991-01
dc.description.abstract The response of mean annual ice-free chlorophyll a in 15 stratified, P-limited oligotrophic and mesotrophic lakes in central Ontario to changes in mean epilimnetic total phosphorus (TP) within a lake was highly variable between years during the period 1976 to 1987. The linear regression coefficient of determination, R2, using all annual means was only 0.36 (n = 172 lake-years) and within-lake regressions revealed mostly random associations between chlorophyll a and TP, suggesting fluctuations about steady state levels. Nevertheless, by using the long-term average of annual means for each lake, a bivariate linear regression model was developed relating the long-term, average response of chlorophyll a to the long-term, average TP concentration in these lakes (R2 = 0.78). Annual variation could not be explained by changes in TN/TP. R2 increased slightly from 0.78 to 0.82 with TN/TP as a second independent variable using long-term averages but remained at 0.78 with 1/TP as a second variable. Re-analysis of published data excluding lakes which were not P-limited showed that TN/TP is of little or no benefit as an independent variable. A minimum of 6 consecutive years of sampling was required to avoid anomalously poor fits (defined as R2 < 0.6) for this set of lakes. Therefore, chlorophyll a/TP regression models should be viewed as steady state models with an inherent inability to predict annual variation.
dc.format pdf
dc.language.iso en
dc.publisher Ontario Ministry of the Environment
dc.rights Queen's Printer for Ontario, Crown Copyright, Non-Commercial Use Permitted
dc.subject chlorophyll a
dc.subject total phosphorus
dc.subject oligotrophic
dc.subject mesotrophic
dc.title The effects of nitrogen/ phosphorus ratios on the prediction of chlorophyll in phosphorus-limited lakes in Central Ontario
dc.type Report
dc.rights.holder Queen's Printer for Ontario
dc.contributor.affiliation Dorset Research Centre, Ontario Ministry of the Environment
dc.contributor.affiliation York University
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