The quality of lake ice is of uppermost importance for ice safety and under-ice ecology, but its ... more The quality of lake ice is of uppermost importance for ice safety and under-ice ecology, but its temporal and spatial variability is largely unknown. Here we conducted a coordinated lake ice quality sampling campaign across the Northern Hemisphere during one of the warmest winters since 1880 and show that lake ice during 2020/2021 commonly consisted of unstable white ice, at times contributing up to 100% to the total ice thickness. We observed that white ice increased over the winter season, becoming thickest and constituting the largest proportion of the ice layer towards the end of the ice cover season when fatal winter drownings occur most often and light limits the growth and reproduction of primary producers. We attribute the dominance of white ice before ice-off to air temperatures varying around the freezing point, a condition which occurs more frequently during warmer winters. Thus, under continued global warming, the prevalence of white ice is likely to substantially increa...
Phytoplankton samples were picked with bottle from among reed stands or from above thick beds of ... more Phytoplankton samples were picked with bottle from among reed stands or from above thick beds of submerged plants from the depth 20-30 cm, were preserved in Lugol’s (acidified iodine) solution and counted under an inverted microscope (Utermöhl, 1958). 3 ml of preserved sample was settled overnight and counted in random fields or transects. Biovolumes of algal cells, colonies and/or filaments were calculated using assigned geometric shapes dimensions, and converted to biomass assuming the specific density of 1 g cm-3 in accordance with Edler (1979). Macroscopic colonies of Gloeotrichia echinulata were enumerated visually in 500 ml measuring cylinder. Counting units are independent (single) algal cells, colonies or filaments/trichomes. One species or taxon may be present in the sample as different counting units and may be counted at different magnifications. References of methods accepted Approved by CEN on 14 July 2006 “Water quality - Guidance standard on the enumeration of phytoplankton using inverted microscopy (Utermöhl technique)” (CEN 15204, 2006) European Standard EN 15204:2006 Utermöhl, H., 1958. Zur Vervollkommnung der quantitativen Phytoplankton-Methodik. Mitteilungen der Internationale Vereinigung für Theoretische und Angewandte Limnologie 9, 1-38. Edler, L. (ed.), 1979. Recommendations on methods for marine biological studies in the Baltic Sea. Phytoplankton and chlorophyll. Baltic Marine Biologists WG 9. (13) Biovolume calculation for pelagic and benthic microalgae | Request PDF. Available from: https://www.researchgate.net/publication/220031275_Biovolume_calculation_for_pelagic_and_benthic_microalgae [accessed Oct 29 2018]. The most commonly used traditional biomass estimate for microalgae is cell biovolume, which is calculated from microscopically measured linear dimensions (Steinman et al. 1991, Snoeijs 1994, Sommer 1994, 1995, Hillebrand and Sommer 1997). Hand-books, most representative Huber-Pestalozzi, G., Komarek, J., Fott, B. 1983. Das Phytoplankton des Süsswassers. 7(1). Chlorophyceae. Chlorococcales. Stuttgart. 1044. S. Komarek, J., Anagnostidis, K. 1999. Süsswasserflora von Mitteleuropa. 19/1. Cyanoprocaryota. 1. Chroococcales. Elsevier Spectrum Academischer Verlag. Heidelberg. Berlin. 548 S. Komarek, J., Anagnostidis, K. 2005. Süsswasserflora von Mitteleuropa. 19/2. Cyanoprocaryota. 2. Oscillatoriales. Elsevier Spectrum Academischer Verlag. 759 S. Komárek, J., 2013. Cyanoprokaryota 3. Teil: Heterocystous Genera. Süsswasserflora von Mitteleuropa. B. 19/3. Springer Spektrum. 1130 S. Krammer, K., Lange-Bertalot, H. 1997-1991. Süsswasserflora von Mitteleuropa. Bacillariophyceae. B. 2, 1-4. Spectrum Academischer Verlag.Heidelberg. Berlin.. Popovský, J., Pfiester, L.A. 20008. Dinophyceae (Dinoflagellida). Süsswasserflora von Mitteleuropa. B. 6. Springer Spektrum. 272 S. Косинская Е.К. 1960. Флора споровых растений СССР. Том 5. Конъюгаты и Сцеплянки. (2). Изд. АН СССР. Москва-Ленинград. 706 стр. In Russian. Korshikov, A.A. (1953). Viznachnik prisnovodnikh vodorosley Ukrainsykoi RSR [Vyp] V. Pidklas Protokokovi (Protococcineae). Bakuol'ni (Vacuolales) ta Protokokovi (Protococcales) [The Freshwater Algae of the Ukrainian SSR. V. Sub-Class Protococcineae. Vacuolales and Protococcales]. pp. 1-439. Kyjv [Kiev]: Akad. NAUK URSR. In Ukrainian. Матвiенко О.М. 1965. Визначник прiсноводных водоростей Украǐнской РСР. 3. Частина 1. Золотисти водорости – Chrysophyta. Изд. Наукова Думка. Киǐв. 367 стр. In Ukrainian. Попова Т.Г. 1955. Определитель пресноводных водорослей. Вып. 7. Эвгленовые водоросли. Изд. Советская Наука, Москва. 282 стр. In Russian
DatasetMethod: Phytoplankton samples were preserved in Lugol’s (acidified iodine) solution and co... more DatasetMethod: Phytoplankton samples were preserved in Lugol’s (acidified iodine) solution and counted under an inverted microscope (Utermöhl, 1958). 3 ml of preserved sample was settled overnight and counted in random fields or transects. Biovolumes of algal cells, colonies and/or filaments were calculated using assigned geometric shapes dimensions, and converted to biomass assuming the specific density of 1 g cm-3 in accordance with Edler (1979). Approved by CEN on 14 July 2006 “Water quality - Guidance standard on the enumeration of phytoplankton using inverted microscopy (Utermöhl technique)” (CEN 15204, 2006) European Standard EN 15204:2006 Utermöhl, H., 1958. Zur Vervollkommnung der quantitativen Phytoplankton-Methodik. Mitteilungen der Internationale Vereinigung für Theoretische und Angewandte Limnologie 9, 1- 38. Edler, L. (ed.), 1979. Recommendations on methods for marine biological studies in the Baltic Sea. Phytoplankton and chlorophyll. Baltic Marine Biologists WG 9
Abstract—In this paper we discuss the problems of the long-term management policy of Lake Peipsi ... more Abstract—In this paper we discuss the problems of the long-term management policy of Lake Peipsi and the roles of natural and anthropogenic factors in the ecological state of the lake. The reduction of the pollution during the last 15 years could not give significant changes of the chemical composition of the water, what implicates the essential role that natural factors have on the ecological state of lake. One of the most important factors having impact on the hydrochemical cycles and ecological state is the hydrological regime which is clearly expressed in L. Peipsi. The absence on clear interrelations of climate cycles and nutrients suggest that complex abiotic and biotic interactions, which take place in the lake ecosystem, plays a significant role in the matter circulation mechanism within lake. Keywords—Lake Peipsi, ecosystem, eutrophication, water
Citizen science projects have a long history in ecological studies. The research usefulness of su... more Citizen science projects have a long history in ecological studies. The research usefulness of such projects is dependent on applying simple and standardized methods. Here, we conducted a citizen science project that involved more than 3500 Swedish high school students to examine the temperature difference between surface water and the overlying air (Tw-Ta) as a proxy for sensible heat flux (QH). If QH is directed upward, corresponding to positive Tw-Ta, it can enhance CO2 and CH4 emissions from inland waters, thereby contributing to increased greenhouse gas concentrations in the atmosphere. The students found mostly negative Tw-Ta across small ponds, lakes, streams/rivers and the sea shore (i.e. downward QH), with Tw-Ta becoming increasingly negative with increasing Ta. Further examination of Tw-Ta using high-frequency temperature data from inland waters across the globe confirmed that Tw-Ta is linearly related to Ta. Using the longest available high-frequency temperature time seri...
Catherine M. O'Reilly, Sapna Sharma, Derek K. Gray, Stephanie E. Hampton, Jordan S. Read, Rex... more Catherine M. O'Reilly, Sapna Sharma, Derek K. Gray, Stephanie E. Hampton, Jordan S. Read, Rex J. Rowley, Philipp Schneider, John D. Lenters, Peter B. McIntyre, Benjamin M. Kraemer, Gesa A. Weyhenmeyer, Dietmar Straile, Bo Dong, Rita Adrian, Mathew G. Allan, Orlane Anneville, Lauri Arvola, Jay Austin, John L. Bailey, Jill S. Baron, Justin D. Brookes, Elvira de Eyto, Martin T. Dokulil, David P. Hamilton, Karl Havens, Amy L. Hetherington, Scott N. Higgins, Simon Hook, Lyubov R. Izmest'eva, Klaus D. Joehnk, Kulli Kangur, Peter Kasprzak, Michio Kumagai, Esko Kuusisto, George Leshkevich, David M. Livingstone, Sally MacIntyre, Linda May, John M. Melack, Doerthe C. Mueller-Navarra, Mikhail Naumenko, Peeter Noges, Tiina Noges, Ryan P. North, Pierre-Denis Plisnier, Anna Rigosi, Alon Rimmer, Michela Rogora, Lars G. Rudstam, James A. Rusak, Nico Salmaso, Nihar R. Samal, Daniel E. Schindler, S. Geoffrey Schladow, Martin Schmid, Silke R. Schmidt, Eugene Silow, M. Evren Soylu, Katrin Teubn...
In this paper we discuss the problems of the long-term management policy of Lake Peipsi and the r... more In this paper we discuss the problems of the long-term management policy of Lake Peipsi and the roles of natural and anthropogenic factors in the ecological state of the lake. The reduction of the pollution during the last 15 years could not give significant changes of the chemical composition of the water, what implicates the essential role that natural factors
Over the last 3-4 decades, Lake Peipsi water (sampling site A, middle part of the lake, and site ... more Over the last 3-4 decades, Lake Peipsi water (sampling site A, middle part of the lake, and site B, northern part) has experienced a statistically significant increase of bicarbonate, pH, chemical oxygen demand, nitrate (and nitrite in site B), due to combination of climate change and eutrophication. By photochemical modelling, we predicted a statistically significant decrease of radicals ·OH and CO3(-·) (site A, by 45% and 35%, respectively) and an increase of triplet states of chromophoric dissolved organic matter ((3)CDOM(∗); site B, by ∼25%). These species are involved in pollutant degradation, but formation of harmful by-products is more likely with (3)CDOM(∗) than with ·OH. Therefore, the photochemical self-cleansing ability of Lake Peipsi probably decreased with time, due to combined effects of climate change and eutrophication. In different environments (e.g. Lake Maggiore, NW Italy), ecosystem restoration policies had the additional advantage of enhancing sunlight-driven detoxification, suggesting that photochemical self-cleansing would be positively correlated with lake water quality.
Fish play a key role in the trophic dynamics of lakes. With climate warming, complex changes in f... more Fish play a key role in the trophic dynamics of lakes. With climate warming, complex changes in fish assemblage structure may be expected owing to direct effects on temperature and indirect effects operating through eutrophication, water level changes, stratification and salinisation. We reviewed published and new long-term fish data series from 24 European lakes. We found profound changes in fish assemblage composition, size and age structure during recent decades and a shift towards higher dominance of eurythermal species. The shift has occurred despite an overall reduction in nutrient loading that should have benefited the fish species typically inhabiting coldwater low-nutrient lakes and larger-sized individuals. The cold-stenothermic Arctic charr has been particularly affected and its abundance has decreased in the majority of the lakes where its presence was recorded. The harvest of cool-stenothermal trout has decreased substantially in two southern lakes. Vendace, whitefish and smelt show a different response depending on lake depth and latitude. Perch was apparently stimulated in the north, with stronger year classes in warm years, but its abundance has declined in the southern Lake Maggiore. Where introduced, roach now seems to take advantage of the higher temperature after years of low populations. Eurythermal species such as common bream, pike-perch and shad are on the increase. The response of fish to the warming in recent decades has been surprisingly strong, making them ideal sentinels for detecting and documenting climate-induced modifications of freshwater ecosystems.
The quality of lake ice is of uppermost importance for ice safety and under-ice ecology, but its ... more The quality of lake ice is of uppermost importance for ice safety and under-ice ecology, but its temporal and spatial variability is largely unknown. Here we conducted a coordinated lake ice quality sampling campaign across the Northern Hemisphere during one of the warmest winters since 1880 and show that lake ice during 2020/2021 commonly consisted of unstable white ice, at times contributing up to 100% to the total ice thickness. We observed that white ice increased over the winter season, becoming thickest and constituting the largest proportion of the ice layer towards the end of the ice cover season when fatal winter drownings occur most often and light limits the growth and reproduction of primary producers. We attribute the dominance of white ice before ice-off to air temperatures varying around the freezing point, a condition which occurs more frequently during warmer winters. Thus, under continued global warming, the prevalence of white ice is likely to substantially increa...
Phytoplankton samples were picked with bottle from among reed stands or from above thick beds of ... more Phytoplankton samples were picked with bottle from among reed stands or from above thick beds of submerged plants from the depth 20-30 cm, were preserved in Lugol’s (acidified iodine) solution and counted under an inverted microscope (Utermöhl, 1958). 3 ml of preserved sample was settled overnight and counted in random fields or transects. Biovolumes of algal cells, colonies and/or filaments were calculated using assigned geometric shapes dimensions, and converted to biomass assuming the specific density of 1 g cm-3 in accordance with Edler (1979). Macroscopic colonies of Gloeotrichia echinulata were enumerated visually in 500 ml measuring cylinder. Counting units are independent (single) algal cells, colonies or filaments/trichomes. One species or taxon may be present in the sample as different counting units and may be counted at different magnifications. References of methods accepted Approved by CEN on 14 July 2006 “Water quality - Guidance standard on the enumeration of phytoplankton using inverted microscopy (Utermöhl technique)” (CEN 15204, 2006) European Standard EN 15204:2006 Utermöhl, H., 1958. Zur Vervollkommnung der quantitativen Phytoplankton-Methodik. Mitteilungen der Internationale Vereinigung für Theoretische und Angewandte Limnologie 9, 1-38. Edler, L. (ed.), 1979. Recommendations on methods for marine biological studies in the Baltic Sea. Phytoplankton and chlorophyll. Baltic Marine Biologists WG 9. (13) Biovolume calculation for pelagic and benthic microalgae | Request PDF. Available from: https://www.researchgate.net/publication/220031275_Biovolume_calculation_for_pelagic_and_benthic_microalgae [accessed Oct 29 2018]. The most commonly used traditional biomass estimate for microalgae is cell biovolume, which is calculated from microscopically measured linear dimensions (Steinman et al. 1991, Snoeijs 1994, Sommer 1994, 1995, Hillebrand and Sommer 1997). Hand-books, most representative Huber-Pestalozzi, G., Komarek, J., Fott, B. 1983. Das Phytoplankton des Süsswassers. 7(1). Chlorophyceae. Chlorococcales. Stuttgart. 1044. S. Komarek, J., Anagnostidis, K. 1999. Süsswasserflora von Mitteleuropa. 19/1. Cyanoprocaryota. 1. Chroococcales. Elsevier Spectrum Academischer Verlag. Heidelberg. Berlin. 548 S. Komarek, J., Anagnostidis, K. 2005. Süsswasserflora von Mitteleuropa. 19/2. Cyanoprocaryota. 2. Oscillatoriales. Elsevier Spectrum Academischer Verlag. 759 S. Komárek, J., 2013. Cyanoprokaryota 3. Teil: Heterocystous Genera. Süsswasserflora von Mitteleuropa. B. 19/3. Springer Spektrum. 1130 S. Krammer, K., Lange-Bertalot, H. 1997-1991. Süsswasserflora von Mitteleuropa. Bacillariophyceae. B. 2, 1-4. Spectrum Academischer Verlag.Heidelberg. Berlin.. Popovský, J., Pfiester, L.A. 20008. Dinophyceae (Dinoflagellida). Süsswasserflora von Mitteleuropa. B. 6. Springer Spektrum. 272 S. Косинская Е.К. 1960. Флора споровых растений СССР. Том 5. Конъюгаты и Сцеплянки. (2). Изд. АН СССР. Москва-Ленинград. 706 стр. In Russian. Korshikov, A.A. (1953). Viznachnik prisnovodnikh vodorosley Ukrainsykoi RSR [Vyp] V. Pidklas Protokokovi (Protococcineae). Bakuol'ni (Vacuolales) ta Protokokovi (Protococcales) [The Freshwater Algae of the Ukrainian SSR. V. Sub-Class Protococcineae. Vacuolales and Protococcales]. pp. 1-439. Kyjv [Kiev]: Akad. NAUK URSR. In Ukrainian. Матвiенко О.М. 1965. Визначник прiсноводных водоростей Украǐнской РСР. 3. Частина 1. Золотисти водорости – Chrysophyta. Изд. Наукова Думка. Киǐв. 367 стр. In Ukrainian. Попова Т.Г. 1955. Определитель пресноводных водорослей. Вып. 7. Эвгленовые водоросли. Изд. Советская Наука, Москва. 282 стр. In Russian
DatasetMethod: Phytoplankton samples were preserved in Lugol’s (acidified iodine) solution and co... more DatasetMethod: Phytoplankton samples were preserved in Lugol’s (acidified iodine) solution and counted under an inverted microscope (Utermöhl, 1958). 3 ml of preserved sample was settled overnight and counted in random fields or transects. Biovolumes of algal cells, colonies and/or filaments were calculated using assigned geometric shapes dimensions, and converted to biomass assuming the specific density of 1 g cm-3 in accordance with Edler (1979). Approved by CEN on 14 July 2006 “Water quality - Guidance standard on the enumeration of phytoplankton using inverted microscopy (Utermöhl technique)” (CEN 15204, 2006) European Standard EN 15204:2006 Utermöhl, H., 1958. Zur Vervollkommnung der quantitativen Phytoplankton-Methodik. Mitteilungen der Internationale Vereinigung für Theoretische und Angewandte Limnologie 9, 1- 38. Edler, L. (ed.), 1979. Recommendations on methods for marine biological studies in the Baltic Sea. Phytoplankton and chlorophyll. Baltic Marine Biologists WG 9
Abstract—In this paper we discuss the problems of the long-term management policy of Lake Peipsi ... more Abstract—In this paper we discuss the problems of the long-term management policy of Lake Peipsi and the roles of natural and anthropogenic factors in the ecological state of the lake. The reduction of the pollution during the last 15 years could not give significant changes of the chemical composition of the water, what implicates the essential role that natural factors have on the ecological state of lake. One of the most important factors having impact on the hydrochemical cycles and ecological state is the hydrological regime which is clearly expressed in L. Peipsi. The absence on clear interrelations of climate cycles and nutrients suggest that complex abiotic and biotic interactions, which take place in the lake ecosystem, plays a significant role in the matter circulation mechanism within lake. Keywords—Lake Peipsi, ecosystem, eutrophication, water
Citizen science projects have a long history in ecological studies. The research usefulness of su... more Citizen science projects have a long history in ecological studies. The research usefulness of such projects is dependent on applying simple and standardized methods. Here, we conducted a citizen science project that involved more than 3500 Swedish high school students to examine the temperature difference between surface water and the overlying air (Tw-Ta) as a proxy for sensible heat flux (QH). If QH is directed upward, corresponding to positive Tw-Ta, it can enhance CO2 and CH4 emissions from inland waters, thereby contributing to increased greenhouse gas concentrations in the atmosphere. The students found mostly negative Tw-Ta across small ponds, lakes, streams/rivers and the sea shore (i.e. downward QH), with Tw-Ta becoming increasingly negative with increasing Ta. Further examination of Tw-Ta using high-frequency temperature data from inland waters across the globe confirmed that Tw-Ta is linearly related to Ta. Using the longest available high-frequency temperature time seri...
Catherine M. O'Reilly, Sapna Sharma, Derek K. Gray, Stephanie E. Hampton, Jordan S. Read, Rex... more Catherine M. O'Reilly, Sapna Sharma, Derek K. Gray, Stephanie E. Hampton, Jordan S. Read, Rex J. Rowley, Philipp Schneider, John D. Lenters, Peter B. McIntyre, Benjamin M. Kraemer, Gesa A. Weyhenmeyer, Dietmar Straile, Bo Dong, Rita Adrian, Mathew G. Allan, Orlane Anneville, Lauri Arvola, Jay Austin, John L. Bailey, Jill S. Baron, Justin D. Brookes, Elvira de Eyto, Martin T. Dokulil, David P. Hamilton, Karl Havens, Amy L. Hetherington, Scott N. Higgins, Simon Hook, Lyubov R. Izmest'eva, Klaus D. Joehnk, Kulli Kangur, Peter Kasprzak, Michio Kumagai, Esko Kuusisto, George Leshkevich, David M. Livingstone, Sally MacIntyre, Linda May, John M. Melack, Doerthe C. Mueller-Navarra, Mikhail Naumenko, Peeter Noges, Tiina Noges, Ryan P. North, Pierre-Denis Plisnier, Anna Rigosi, Alon Rimmer, Michela Rogora, Lars G. Rudstam, James A. Rusak, Nico Salmaso, Nihar R. Samal, Daniel E. Schindler, S. Geoffrey Schladow, Martin Schmid, Silke R. Schmidt, Eugene Silow, M. Evren Soylu, Katrin Teubn...
In this paper we discuss the problems of the long-term management policy of Lake Peipsi and the r... more In this paper we discuss the problems of the long-term management policy of Lake Peipsi and the roles of natural and anthropogenic factors in the ecological state of the lake. The reduction of the pollution during the last 15 years could not give significant changes of the chemical composition of the water, what implicates the essential role that natural factors
Over the last 3-4 decades, Lake Peipsi water (sampling site A, middle part of the lake, and site ... more Over the last 3-4 decades, Lake Peipsi water (sampling site A, middle part of the lake, and site B, northern part) has experienced a statistically significant increase of bicarbonate, pH, chemical oxygen demand, nitrate (and nitrite in site B), due to combination of climate change and eutrophication. By photochemical modelling, we predicted a statistically significant decrease of radicals ·OH and CO3(-·) (site A, by 45% and 35%, respectively) and an increase of triplet states of chromophoric dissolved organic matter ((3)CDOM(∗); site B, by ∼25%). These species are involved in pollutant degradation, but formation of harmful by-products is more likely with (3)CDOM(∗) than with ·OH. Therefore, the photochemical self-cleansing ability of Lake Peipsi probably decreased with time, due to combined effects of climate change and eutrophication. In different environments (e.g. Lake Maggiore, NW Italy), ecosystem restoration policies had the additional advantage of enhancing sunlight-driven detoxification, suggesting that photochemical self-cleansing would be positively correlated with lake water quality.
Fish play a key role in the trophic dynamics of lakes. With climate warming, complex changes in f... more Fish play a key role in the trophic dynamics of lakes. With climate warming, complex changes in fish assemblage structure may be expected owing to direct effects on temperature and indirect effects operating through eutrophication, water level changes, stratification and salinisation. We reviewed published and new long-term fish data series from 24 European lakes. We found profound changes in fish assemblage composition, size and age structure during recent decades and a shift towards higher dominance of eurythermal species. The shift has occurred despite an overall reduction in nutrient loading that should have benefited the fish species typically inhabiting coldwater low-nutrient lakes and larger-sized individuals. The cold-stenothermic Arctic charr has been particularly affected and its abundance has decreased in the majority of the lakes where its presence was recorded. The harvest of cool-stenothermal trout has decreased substantially in two southern lakes. Vendace, whitefish and smelt show a different response depending on lake depth and latitude. Perch was apparently stimulated in the north, with stronger year classes in warm years, but its abundance has declined in the southern Lake Maggiore. Where introduced, roach now seems to take advantage of the higher temperature after years of low populations. Eurythermal species such as common bream, pike-perch and shad are on the increase. The response of fish to the warming in recent decades has been surprisingly strong, making them ideal sentinels for detecting and documenting climate-induced modifications of freshwater ecosystems.
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stimulated in the north, with stronger year classes in warm years, but its abundance has declined in the southern Lake Maggiore. Where introduced, roach now seems to take advantage of the higher temperature after years of low populations. Eurythermal species such as common bream, pike-perch and shad are on the increase. The response of fish to the warming in recent decades has been surprisingly strong,
making them ideal sentinels for detecting and documenting climate-induced modifications of freshwater ecosystems.
stimulated in the north, with stronger year classes in warm years, but its abundance has declined in the southern Lake Maggiore. Where introduced, roach now seems to take advantage of the higher temperature after years of low populations. Eurythermal species such as common bream, pike-perch and shad are on the increase. The response of fish to the warming in recent decades has been surprisingly strong,
making them ideal sentinels for detecting and documenting climate-induced modifications of freshwater ecosystems.