Limnol. Rev. (2019) 19, 3: 137–145 DOI 10.2478/limre-2019-0012 Te lethal efect of hydrotechnical concrete on freshwater Bivalvia Barbara Wojtasik 1,2 , Małgorzata Zbawicka 3* , Lucyna Grabarczyk 4 , Marzena Kurpińska 4 1 Department of Genetics and Biosystematics, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland; 0000-0001-5389-1810 2 HydroBiolLab, Research and Development Company, Hydrobiological Laboratory, Żeliwna 23a, 81-159 Gdynia, Poland, e-mail: hydrobiollab@wp.pl 3 Institute of Oceanology, Polish Academy of Sciences, Department of Genetics and Marine Biotechnology, Powstańców Warszawy 55, 81-712 Sopot, Poland, e-mail: mzbawicka@iopan.gda.pl (*corresponding author); 0000-0001-5156-6184 4 Department of Mechanics of Materials and Structures, Gdańsk University of Technology, Gabriela Narutowicza 11/12, 80-233 Gdańsk, Poland Abstract: Most hydrotechnical buildings under construction demand the concrete mixture to be set directly under water. Te main reason for such a procedure is to limit the washing away of the the concrete binding mixture and to increase the efciency of organisation of work so as to ensure continuity in concreting. Te impact on the aquatic environment of recent developments in concrete technology and the use of new components has not yet been established . Natural pebble aggregate containing portland cement and fugacious siliceous ash as a binder was used to prepare BP concrete samples, while concrete marked LB was composed with lightweight aggregate and portland cement as a binder. Te aim of this paper was to answer to the question whether hydrotechnical concrete of diferent compositions (BP and LB) and the technology of setting in a water habitat have any infuence on the life condition of commonly occurring Dreissena polymorpha (Mollusca, Bivalvia). Te lethal efect of two types of freshly hardening concrete was observed. In the case of LB concrete the lethal outcome for D. polymorpha could be the efect of a considerable increase of electrolytic conduction in the test cultivation. In the case of BP the parameters of electrolytic conductivity and pH did not exceed the values appearing in lakes. Te possibility of the occurrence of toxic compounds of D. polymorpha, arising from the reaction of the aquatic / lake environment or the elution of some components should be taken into account. D. polymorpha serves as an indicator of toxicity in the aquatic environment and therefore can be used as a model organism in the analysis of the infuence concrete on the natural environment. Te results obtained in this study indicate the signifcant impact of modern chemical composition of concrete on the aquatic environment and the living organisms that cover it. Tey underline the need for research based on the hydrobiont reaction to the substances used in the natural environment. Key words: hydrotechnical buildings, concrete admixtures, freshwater reservoirs, Dreissena polymorpha, toxic Introduction Over recent years there has been intensive develop- ment in technologies for the construction of concrete buildings in water. Most hydrotechnical buildings un- der construction demand the concrete mixture to be set directly under water (underwater concrete, UWC). Te main reason for concreting under water is to limit the washing away of the binder of the concrete mixture and to increase the efcient organisation of work, thus ensuring continuity of concreting. In the case of un- derwater concretes, 375 kg of cement and additives are needed for one cubic metre of concrete. Tis is justifed by the possible loss of binder from washing away (JSCE 1991; Neville 2011). Irrespective of the underwater concreting cements, special chemical additives and ad- mixtures adequate for outside conditions and the size of the concreted element should be used (Horszczaruk et al. 2014; Horszczaruk and Brzozowski 2014). Underwa- ter concreting requires pebbles and broken aggregates. Te characteristic feature of the set of modern mixtures used for underwater concretes is the necessity of apply- ing an anti-washout admixture (AWA). Te anti-wash- out admixture (AWA), used in a quantity of less than 5% of cement mass, is designed to prevent the rinsing of frm materials from the concrete mixture and at the same time retain water in the mixture and prevent any occurrence of bleeding (Assaad et al. 2011; Heniegal 2012). Te US Army Corps of Engineers Standard (US- ACE 2006), is a tested method for determining the re- Barbara Wojtasik et al.