Abstract
Causes of the disappearance of the aquatic plant <i>Egeria densa</i> and black-necked swans in a Ramsar sanctuary: comment on Mulsow & Grandjean (2006)
Highlights
In an attempt to demonstrate the ultimate causes of the massive mortality and emigration of blacknecked swans at the Ramsar site Carlos Anwandter Nature Sanctuary, Mulsow & Grandjean (2006, available at: www.int-res.com/articles/esep/2006/E66.pdf) used field data, microcosm experiments and basic chemical theory, to postulate that calcium bicarbonate is removed from water, due to the increase in sulphate by the effluent of the pulp mill of CELCO, Valdivia, Chile
Using data from Mulsow & Grandjean (2006), we ran a correlation analysis which indicated a negative relationship between SO42– and HCO3, but the regression analysis showed that only 48.6% of the variation in HCO3– may be explained by variation in SO42– (r2 = 48.6, p = 0.017, n = 11; and r2 = 47.2, p = 0.001, n = 18, including all the averaged subsamples in the analysis)
We conclude that the incorrect analyses of Mulsow & Grandjean (2006) and their confusing report of their field evidence weakly support the hypothesis being tested in their laboratory experiment: the effect of SO42– on Egeria densa
Summary
Causes of the disappearance of the aquatic plant Egeria densa and black-necked swans in a Ramsar sanctuary: comment on Mulsow & Grandjean (2006). In an attempt to demonstrate the ultimate causes of the massive mortality and emigration of blacknecked swans at the Ramsar site Carlos Anwandter Nature Sanctuary, Mulsow & Grandjean (2006, available at: www.int-res.com/articles/esep/2006/E66.pdf) used field data, microcosm experiments and basic chemical theory, to postulate that calcium bicarbonate is removed from water, due to the increase in sulphate by the effluent of the pulp mill of CELCO, Valdivia, Chile This process is deemed to affect the photosynthetic rate of the plant Egeria densa, the main food of the black-necked swans, which in turn provokes the known mortality and emigration of these birds from this site.
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