Effect of Flocks of Anseriform Birds on Seston and Phytoplankton in Lakes of the Taimyr Peninsula

Abstract

The effect of molting anseriform birds on the structure and elemental composition of phytoplankton (seston) has been assessed in 20 Arctic lakes of the Taimyr Peninsula. In lakes (part of the lake) inhabited by ~50–700 birds of six species, the average stoichiometric ratio N : P (mol : mol) was statistically significantly lower than in lakes without anseriforms: 15.8 ± 1.4 and 22.4 ± 2.7, respectively. There was also a tendency of higher average specific electrical conductivity in the lakes with the birds, 113 ± 32 µS/cm, when compared with those without anseriforms, 60 ± 18 µS/cm. The differences could be explained with high probability by the effect of guanotrophication, namely, by a flow in water of metabolites of molting anseriforms. The total biomass of phytoplankton and proportions of algal taxa and cyanobacteria in the total biomass did not differ statistically significantly in lakes with and without molting anseriforms. Therefore, under guanotrophication, the main threat of eutrophication was absent: an increase of biomass of cyanobacteria, causing the nuisance “bloom” of water. Moreover, an opposite tendency occured: in lakes with molting anseriforms, the proportion of cyanobacteria in total biomass of phytoplankton was on average lower than that in lakes without the birds, 16.2 ± 5.3% and 30.8 ± 9.3%, respectively. Thus, a hypothesis was confirmed that artificial guanotrophication should be regarded as a suitable ecotechnology for the increase of productivity of oligotrophic Arctic lakes.