Effect of Air Temperature Increase on Changes in Thermal Regime of the Oder and Neman Rivers Flowing into the Baltic Sea

Gintaras Valiuškevičius,Adam Choiński,Alexander Volchak,Mariusz Ptak,Sergey Parfomuk,Ivan Kirvel,Svetlana Sidak,Pavel Kirvel

doi:10.3390/atmos12040498

Abstract

The paper presents long-term changes in water temperature in two rivers, Oder and Neman, with catchments showing different climatic conditions (with dominance of marine climate in the case of the Oder and continental climate in the case of the Neman River). A statistically significant increase in mean annual water temperature was recorded for four observation stations, ranging from 0.17 to 0.39 °C dec−1. At the seasonal scale, for the winter half-year, water temperature increase varied from 0.17 to 0.26 °C dec−1, and for the summer half-year from 0.17 to 0.50 °C dec−1. In three cases (Odra-Brzeg, Odra-Słubice, Niemen-Grodno), the recorded changes referred to the scale of changes in air temperature. For the fourth station on Neman (Smalininkai), an increase in water temperature in the river was considerably slower than air temperature increase. It should be associated with the substantial role of local conditions (non-climatic) affecting the thermal regime in that profile. Short-term forecast of changes in water temperature showed its further successive increase, a situation unfavorable for the functioning of these ecosystems.

Highlights

IntroductionWater temperature in rivers is one of the basic properties determining a number of processes occurring in these ecosystems, shaping their environmental and economic potential
Results presented in the paper, referring to the properties of the thermal regime of the Oder and Neman Rivers, based on the analysis of mean annual and monthly water temperatures pointed to the variability between them
In terms of the rate and scale of changes in water temperature, they were at a similar level, whereas it should be emphasized that in one of the cases a considerably lower rate of temperature increase was observed

Summary

Introduction

Water temperature in rivers is one of the basic properties determining a number of processes occurring in these ecosystems, shaping their environmental and economic potential. This statement refers to water quality, biodiversity, etc. One of the basic indicators of water quality is the content of dissolved oxygen, dependent on water temperature. According to Morrill et al [1], in places with currently low dissolved oxygen content, an increase in water temperature in summer may cause its decrease to a critically low level, endangering many water species. Water temperature affects spawning periods and indicators of growth and mortality of organisms inhabiting rivers for which life processes occur in a particular thermal range [2]. One of the directions leading in recent years is the issue concerning the effect of climate warming on the thermal regime of flowing waters

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