Abstract
Water temperature is an important ecological variable that affects the functioning of lakes. Unfortunately, for many lakes there are no long-term observations enabling the assessment of changes in water temperatures. This makes it difficult to include this aspect in research into the biology, ecology and chemistry of such lakes. This paper presents a literature review related to changes of surface water temperatures in lakes and in particular describing the response of water temperatures and stratification to changing climate in Polish lakes. On this basis, a model based on the available data on water temperature in 931 Polish lakes in the years 1951–1968 was proposed, which allows to estimate the baseline water temperature on any day of the year. This model is calculated using the complementary error peak function on the 0–3 m water temperature dataset, which provides the best reduction of diurnal temperature fluctuations. It can be an alternative to the average temperature of surface waters, which are calculated on the basis of systematically collected data. Based on the average water temperature data obtained from 56 thermal profiles in 10 lakes in 2010–2019, the equation was analogically calculated. The average monthly water temperatures in June, July, August and September and the change in water temperature (0.24–0.30 °C decade−1) in the period 1951–1968/2010–2019 were estimated then. Similar regional or single lake trends have been found in studies by other authors covering a similar or longer period of time. The proposed method, which is suitable for simulating temperatures, especially in summer, enables the determination of the value of changes in surface water temperature in Polish lakes when only thermal profiles data from different dates are available, which can be especially helpful when analyzing hydrobiological results.
Highlights
Direct and indirect relationships of water temperature and limnological phenomena are numerous and fundamental to the course of biological and chemical processes, as well as to the hydrological cycle [1]
This would make it possible to consider the aspect of climate change in hydrobiological studies, e.g., by comparing the water temperature recorded during these studies with the averaged data from this baseline, which illustrates the annual cycle of water temperature in Polish lakes before strong climate change during the second half of the 20th century
The study results presented in this paper show that it is possible to calculate the equation describing the trend of surface water temperature changes in lakes during the calendar year on the basis of non-systematically collected data over the long-term (1951–1968)
Summary
Direct and indirect relationships of water temperature and limnological phenomena are numerous and fundamental to the course of biological and chemical processes, as well as to the hydrological cycle [1]. The aims of this review paper are: (1) to provide an overview of the current research (2) to establish a curve describing the changes in water temperature in lakes located in a specific geographical region, which can be used as a reference point in the assessment of thermal conditions in lakes for which there are no systematic collected data This would make it possible to consider the aspect of climate change in hydrobiological studies, e.g., by comparing the water temperature recorded during these studies (in thermal profiles) with the averaged data from this baseline, which illustrates the annual cycle of water temperature in Polish lakes before strong climate change during the second half of the 20th century
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