Klimato kaitos ir antropogeninės veiklos įtaka vandens telkiniams

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Changes in river water temperature between 1980 and 2012 in Yongan watershed, eastern China: Magnitude, drivers and models

Climate warming is expected to have major impacts on river water quality, water column/hyporheic zone biogeochemistry and aquatic ecosystems. A quantitative understanding of spatio-temporal air (Ta) and water (Tw) temperature dynamics is required to guide river management and to facilitate adaptations to climate change. This study determined the magnitude, drivers and models for increasing Tw in three river segments of the Yongan watershed in eastern China. Over the 1980-2012 period, Tw in the watershed increased by 0.029-0.046°Cyr-1 due to a ~0.050°Cyr-1 increase of Ta and changes in local human activities (e.g., increasing developed land and population density and decreasing forest area). A standardized multiple regression model was developed for predicting annual Tw (R2=0.88-0.91) and identifying/partitioning the impact of the principal drivers on increasing Tw:Ta (76±1%), local human activities (14±2%), and water discharge (10±1%). After normalizing water discharge, climate warming and local human activities were estimated to contribute 81-95% and 5-19% of the observed rising Tw, respectively. Models forecast a 0.32-1.76°C increase in Tw by 2050 compared with the 2000-2012 baseline condition based on four future scenarios. Heterogeneity of warming rates existed across seasons and river segments, with the lower flow river and dry season demonstrating a more pronounced response to climate warming and human activities. Rising Tw due to changes in climate, local human activities and hydrology has a considerable potential to aggravate river water quality degradation and coastal water eutrophication in summer. Thus it should be carefully considered in developing watershed management strategies in response to climate change

Development of Lithuania after 1990: visions, facts and memories. About the international scientific conference dedicated to the 90th anniversary of Vytautas Landsbergis, the first head of state of the restored independent Lithuania

Komunistinių režimų žlugimas bei demokratijos įsigalėjimas buvusiose sovietinėse Vidurio ir Rytų Europos šalyse yra vienas svarbiausių XX a. pabaigos pasaulio įvykių, lėmusių tolimesnį pasaulio tvarkos pasikeitimą. Nuo šio istorinio lūžio praėję metai Vidurio ir Rytų Europos šalyse (taip pat ir Lietuvoje) vadinami transformacijų laiku, per kurį pasikeitė valdžia, institucijos, visuomenė. Šis Naujausiųjų laikų Lietuvos valstybės laikotarpis ir buvo reflektuojamas 2022 m. spalio 25 d. Lietuvos nacionalinės Martyno Mažvydo bibliotekos organizuotoje tarptautinėje mokslinėje konferencijoje „Lietuvos kūrimasis po 1990 m.: vizijos, realijos, atmintys“. Konferenciją inspiravo ir Lietuvos Aukščiausiosios Tarybos-Atkuriamojo Seimo pirmininko, pirmojo atkurtos nepriklausomos Lietuvos vadovo Vytauto Landsbergio, kurio indėlis į šio laikotarpio procesus neabejotinai reikšmingas, 90 metų jubiliejus. Konferencijos tema – Lietuvos valstybingumo raida nuo nepriklausomybės atgavimo iki nūdienos – analizuota šiais aspektais: Lietuva iš jos vadovų perspektyvos; Lietuva ir jos politinės ateities vizijos išeivijos svarstymuose; skirtingi posovietinės transformacijos bruožai; kelias į pilietinę visuomenę; atminties ir atminties institucijų transformacijos. Perskaityti pranešimai padėjo geriau suvokti, kaip Lietuvos piliečiai ir jiems atstovaujantys politikai supranta valstybingumą, valstybės kūrimo procesą, galiausiai, kokia Lietuva matoma šiuolaikiniame globaliame pasaulyje. Reikšminiai žodžiai: Lietuvos valstybingumas po 1990 m., pokomunistinė transformacija, pilietinė visuomenė, Vytautas Landsbergis.The collapse of communist regimes and the emergence of democracy in the former Soviet countries of Central and Eastern Europe have been one of the most consequential world events of the late 20th century that led to further changes in the world order. The years that have passed since this historic turning point are known in the countries of Central and Eastern Europe (including Lithuania) as a time of transformation, during which governments, institutions and societies have changed. This period in the history of the Lithuanian state was reflected at the conference 'The Development of Lithuania after 1990: Visions, Facts and Memories,' organized by the Martynas Mažvydas National Library of Lithuania on October 25, 2022. The conference was dedicated to the 90th anniversary of Vytautas Landsbergis, the Chairman of the Supreme Council-Reconstituent Seimas of the Republic of Lithuania and the first leader of the restored independent Lithuania, whose contribution to the processes of that period has been significant. The theme of the conference, the development of Lithuanian statehood from the restoration of independence to the present day, was discussed from the following perspectives: Lithuania from the perspective of its leaders; Lithuania and visions of its political future in the discussion by expatriates; various aspects of the post-Soviet transformation; on the road to civil society; and the transformations of memory and memory institutions. The presentations showed how Lithuanian citizens and the politicians representing them understand statehood and the process of state building, also, how Lithuania is seen in today’s global world. Keywords: Lithuanian statehood after 1990, post-communist transformation, civil society, Vytautas Landsbergis

Multicomponent assessment of the impact of hydropower cascade on fish metrics

The water sector is one of the priority areas of the European Union; therefore, legislation encourages the development of methods to protect the river ecosystem. The key to this is the characterization of the river's physical features with respect to ecological quality. Rivers are a complex system in which geomorphic conditions, hydrological regime, and ecological indicators interact. The group of hydropower plants (HPPs) that forms a hydropower cascade disturbs the natural continuity of river system components. Analysis of the spatial and temporal alterations in the river environment is important for understanding the potential impact of the hydropower cascade on ecological indicators. In a current study, the multicomponent assessment was used to evaluate the impact of the hydropower cascade of five HPPs on fish metrics as ecological indicators in the case study Varduva River. The research involved field surveys to collect hydrological data in highly affected ungauged river to estimate indicators of hydrologic alterations under HPPs operation, use of Unmanned Aerial Vehicles and digital photogrammetry to map geomorphic units, fish sampling to estimate composition of fish species and guilds, and fish habitat availability modelling based on the collected data and the conditional habitat suitability criteria using the MesoHABSIM modelling approach. Results revealed that the technical characteristics of HPPs determined their individual operation mode, which had a crucial impact on the hydrologic alterations of the river and, together with the distance between the dams, on the variation of fish metrics in the hydropower cascade. The intensive operation of the hydropower cascade created adverse effects for intolerant fish but was advantageous for tolerant fish species. The proposed HPP multimetric correlated with the fish metrics and showed similar tendencies between HPPs as habitat integrity index (IH), derived from MesoHABSIM modelling

Fish assemblages under climate change in Lithuanian rivers

Scopus IG 2-s2.0-85060223547Alterations of abiotic factors (e.g., river water temperature and discharge) will definitely affect the fundamental processes of aquatic ecosystems. The purpose of this study was to examine the impact of climate change on the structure of fish assemblages in fast-flowing rivers belonging to the catchment of the major Eastern European river, the Nemunas. Five catchments of semi-natural riverswere selected for the study. Projections of abiotic factorswere developed for the near (2016–2035) and far future (2081–2100) periods, according to four RCP scenarios and three climate models using the HBV hydrologicalmodelling tool. Fishmetric projectionswere developed based on a multiple regression using spatial data. No significant changes in projections of abiotic and biotic variables are generally expected in the near future. In the far future period, the abiotic factors are projected to change significantly, i.e., river water temperature is going to increase by 4.0–5.1 °C, and river discharge is projected to decrease by 16.7–40.6%, according to RCP8.5. By the end of century, the relative abundance of stenothermal fish is projected to decline from24 to 51% in the reference period to 0–20% under RCP8.5. Eurythermal fish should benefit from climate change, and their abundance is likely to increase from 16 to 38% in the reference period to 38–65% under RCP8.5. Future alterations of riverwater temperaturewill have significantly more influence on the abundance of the analysed fish assemblages than river dischargeGamtos tyrimų centrasLietuvos energetikos institutasVilniaus universitetasVytauto Didžiojo universitetasŽemės ūkio akademij