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

ISSN 1995-4255, Contemporary Problems of Ecology, 2023, Vol. 16, No. 6, pp. 679–687. © The Author(s), 2023. This article is an open access publication. Russian Text © The Author(s), 2023, published in Sibirskii Ekologicheskii Zhurnal, 2023, No. 6, pp. 735–746. Effect of Flocks of Anseriform Birds on Seston and Phytoplankton in Lakes of the Taimyr Peninsula M. I. Gladysheva, b, *, S. B. Rosenfeldc, T. N. Anufrievaa, b, G. V. Kirtaevc, E. S. Kravchuka, A. V. Ryabitsevd, A. A. Kolmakovaa, E. A. Ivanovaa, b, and O. V. Anishchenkoa a Institute of Biophysics, Federal Research Center “Krasnoyarsk Science Center,” Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, 660036 Russia b Siberian Federal University, Krasnoyarsk, 660041 Russia c Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow, 119071 Russia d Institute of Plant and Animal Ecology, Ural Branch, Russian Academy of Sciences, Yekaterinburg, 620144 Russia *e-mail: Received February 7, 2023; revised March 12, 2023; accepted March 17, 2023 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. Keywords: guanotrophication, C : N : P stoichiometry, seston, phytoplankton, Taimyr, anseriform birds DOI: 10.1134/S1995425523060082 The anthropogenic eutrophication of natural water bodies—that is, the intensive input of inorganic nutrients, nitrogen, and phosphorus from wastewaters and agricultural land, causing the cyanobacterial and algal bloom, which leads to a sharp deterioration in water quality and a decrease in biodiversity—is a global environmental problem (Downing, 2014; Ibelings et al., 2016; Lurling et al., 2016; McCrackin et al., 2017; Orihel et al., 2017; Paul et al., 2022; Gubelit, 2022). Efforts are being undertaken throughout the world to combat blooming, primarily in lakes and reservoirs, for which a number of special biotechnologies (ecotechnologies) have been developed that reduce the eutrophication effect (Ibelings et al., 2016; Lurling et al., 2016; McCrackin et al., 2017; Paul et al., 2022). However, the artificial eutrophication of Arctic lakes that are naturally oligotrophic can be used to increase fish productivity (Hyatt et al., 2004; Persson et al., 2008). Nevertheless, the artificial eutrophication of lakes that pose a risk of blooming and biodiversity loss can be ambiguously perceived by both the public and specialists taking measures to prevent eutrophication (Ibelings et al., 2016; Lurling et al., 2016; McCrackin et al., 2017; Paul et al., 2022). Meanwhile, along with anthropogenic eutrophication, a natural process occurs that ensures the input of nitrogen and phosphorus into water bodies with the excrements of birds, called guanotrophication (Chaichana et al., 2010; Krylov et al., 2012). The consequences of guanotrophication in aquatic ecosystems may differ from those of anthropogenic eutrophication. If anthropogenic eutrophication most often leads to the toxic cyanobacterial bloom, then microalgae capable of synthesizing omega-3 long-chain polyunsaturated fatty acids (PUFA) with high nutritional value can develop during guanotrophication (Krylov et al., 2011, 2012, 2018). It is possible that bird excrements have a special stoichiometric ratio of elements C : N : P, favorable for the growth of some groups of algae (Krylov et al., 2018). Differences that have occurred at the level of primary producers, phytoplankton, are transformed into 679 680 GLADYSHEV et al. differences at subsequent trophic levels: during guanotrophication, the proportion of copepods (Copepoda) increases in the link of consumers (zooplankton), whereas during anthropogenic eutrophication, cladocerans (Cladocera) predominate in zooplankton (Krylov et al., 2011, 2012, 2013a, 2013b, 2018). Because, as is known, copepods have a higher PUFA content and therefore are more valuable fish food than cladocerans (Gladyshev et al., 2015), it is not surprising that accelerated growth and the development of fish is observed in the zones of guanotrophication (Stolbunov et al., 2017; Krylov et al., 2018). Based on the data on the environmental effects of guanotrophication, we hypothesized that artificial guanotrophication (the input of fertilizers from waste products excreted by birds into the water) may be an acceptable ecotechnology to increase the productivity of oligotrophic Arctic lakes in order to accelerate their rehabilitation from accumulated damage from anthropogenic impact (Gladyshev, 2021). Also, artificial guanotrophication may potentially be considered an environmentally safe method of increasing the fish productivity of Arctic lakes. The aim of this study is to determine the effect of anseriform birds on the structure and elemental composition of phytoplankton (seston) in the Arctic lakes of the Taimyr Peninsula to test the possible effects of guanotrophication by comparing the average numerical values of hydrobiological parameters in two groups of lakes: with and without molting flocks of anseriforms. MATERIALS AND METHODS Selection of the Study Area and Aerial Survey This study was carried out in the lakes of Central Taimyr located in the basins of the Pyasina, Orbita, and Logata rivers, where the largest molting sites of anseriform birds not only in Taimyr, but also in Eurasia, are located. All the tundra lakes under study had similar geomorphological features: shallow, thermokarst, with intense wind mixing. The Taimyr Peninsula is unique, because the birds using three of the four global flyways, African-Eurasian, Central, and Ea (...truncated)