Short Communications NEW RECORD of THICK SHELLED RIVER MUSSEL UNIO CRASSUS (UNIONIDAE, BIVALVIA) from PALAKARIA RIVER, BULGARIA Lyubomir Kenderov, Yonko Sashov

Supplement 1 Ecological Engineering and Environment Protection, IX, 2017, p. 96-99

Short communications NEW RECORD OF THICK SHELLED RIVER MUSSEL UNIO CRASSUS (UNIONIDAE, BIVALVIA) FROM PALAKARIA RIVER, BULGARIA Lyubomir Kenderov, Yonko Sashov

Abstract: New data about morphometric parameters and abundance of thick shelled river mussel Unio crassus Philipsson, 1788 from Palakaria River was given. This species is endangered at European level, but in Bulgaria it is widespread in low-flowing waters. Relative high abundance of the local population of U. crassus was recorded. The good status of this population has been noticed and some reasons have been discussed. Possible anthropogenic threats to the species are marked. Keywords: Unio crassus, local population, endangered species, Palakaria River

INTRODUCTION MATERIAL AND METHODS The thick shelled river mussel, U. crassus, is Sampling trip was carried out during 24 widespread European unionid species [14]. This species November 2016 on Palakaria River (left tributary of preferred soft bottom substrate of brooks to lowland rivers major Iskar River) near Rayovo village, municipality with no organic pollution [3, 13, 14, 16, 24, 25]. In recent of Samokov Town. Mussels were collected by hand decades most of populations of U. crassus were and by using hand net from location with decreased dramatically [6, 7, 15, 26]. This is due to high geographical coordinates: N: 42.366270°, E: level of nitrates and whole organic pollution and 23.483367° at 889 m altitude. In this part the river eutrophication of the rivers [4, 9, 12, 17, 26], hydrological was about 5-7 m wide and over 1 m deep. The connectivity and regime inconsistencies [10, 20], predominant bottom substrate is large sand. In the increasing of the water temperature, invasive species shallow shore areas a thick layer of mud pressure [11, 22, 23] and changes of fish hosts [19, 21]. accumulates and also branched bur-reed The species is protected in European (Habitat directive, (Sparganium erectum L. 1753) was growing. All annexes II, IV) and National level (BDA, 2002). Also, U. individuals of U. crassus were collected on shady crassus was included in IUCN Red List of Threatened right river shore, from soft substrate and about 0.25 Species, category “Endangered” [15]. In Bulgaria thick m depth (Fig. 1). shelled river mussel is probably widespread in most The shell morphology of collected individuals was lowland rivers as well as in Danube River [1, 8]. studied by using of three maximal dimensions (length, The aim of this paper is to give new data on height, breadth, ±1mm). The weight of each individual abundance and morphometric parameters of U. was measured in vivo with an accuracy of 1 g. crassus in Palakaria River, Bulgaria.

Fig. 1. Palakaria River upstream Rayovo Village, 24 November 2016. Arrow and white circle: microhabitat of U. crassus, right river shore.

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RESULTS AND DISCUSSION parameters of the sample were following: 43.7 mm average length (± 7.7mm); 25.3 mm mean height (± A total of 56 individuals U. crassus was 3.7 mm); 16.1 mm mean breadth (± 2.7 mm); 11.1 g collected from about 1m2 bottom area. No any mean weight (± 5.1 g) (Table 1). juvenile individual was found. Morphometric

Table 1. Data from measurements of length (l), height (h), breadth (b) and weight (w) of collected individuals U. crassus from Palakaria river near Rayovo village No. l h b w No. l h b w 1 49,5 28,0 16,8 13 29 42,8 24,7 16,3 10 2 49,8 27,4 17,6 14 30 47,6 26,7 16,8 13 3 48,6 27,6 17,7 16 31 44,5 25,0 17,2 12 4 48,5 26,4 16,7 12 32 41,2 25,1 15,6 10 5 56,1 30,1 21,1 21 33 40,5 25,6 16,4 10 6 34,3 22,3 14,9 7 34 45,2 26,7 16,9 12 7 45,6 26,5 17,5 12 35 35,1 22,9 13,7 6 8 45,5 26,7 16,4 13 36 46,5 25,9 16,8 12 9 53,4 30,4 17,8 18 37 47,8 26,8 18,1 15 10 53,8 28,4 20,4 17 38 45,6 25,9 17,7 11 11 47,7 26,1 18,0 14 39 38,8 24,5 16,0 8 12 41,5 25,0 16,4 9 40 47,7 28,0 15,5 12 13 45,5 26,3 15,2 10 41 42,5 24,2 15,3 9 14 52,7 30,7 18,9 18 42 41,7 24,0 14,5 9 15 41,4 24,9 16,2 10 43 50,2 27,7 20,1 17 16 41,6 24,1 16,0 7 44 40,5 24,8 15,2 8 17 49,5 28,2 19,0 16 45 50,2 27,2 18,5 14 18 17,6 10,7 6,2 1 46 35,8 20,8 14,8 7 19 25,0 15,4 9,4 1,5 47 42,4 25,5 15,4 9 20 28,7 18,3 10,3 2 48 45,2 25,9 16,4 13 21 34,4 19,6 11,8 4 49 45,4 25,7 17,0 12 22 37,0 22,6 13,2 6 50 42,8 23,1 16,3 10 23 67,4 36,0 23,0 34 51 43,2 24,7 14,8 10 24 37,9 21,2 12,6 6 52 44,6 25,1 16,0 11 25 44,4 27,1 17,8 14 53 44,4 25,8 16,2 10 26 36,7 23,0 13,3 7 54 37,2 24,7 14,6 7 27 52,2 28,6 17,5 15 55 45,9 27,4 17,3 12 28 37,0 22,3 15,2 6 56 49,4 27,2 15,8 11

In Palakaria River we have found high fish ACKNOWLEDGEMENTS: This work was biodiversity [18] and most of the species are financially supported by the Sofiyska voda (project: preferred host [5, 21, 23] such as: Squalius cephalus Living water - river, dam, biodiversity, life). L. 1758, Phoxinus phoxinus L. 1758 and Chondrostoma nasus L. 1758 ets. This can be an REFERENCES important reason for maintaining of good status of 1. Angelov A., Catalogus faunae bulgaricae. 4. the U. crassus population in Palakaria River. Mollusca: Gastropoda et Bivalvia aquae dulcis, Contrary of good current situation, we assume Pensoft, Sofia, 2000, 57 p. that population of U. crassus is potentially 2. BDA (Biological Diversity Act), threatened due to: urbanization in the area, increased Promulgated, State Gazette, Republic of Bulgaria, agricultural activity, logging and woodworking, National Assembly, Vol. 77, 2002. digging of gravel from the riverbed, municipal 3. Denic M., К. Stoeckl, B. Gum, J. Geist, pollution and also geographic isolation of this Physicochemical assessment of Unio crassus habitat population. Therefore, future research is needed and quality in a small upland stream and implications for clear identification of potential threats is highly conservation, Hydrobiologia, Vol. 735, 2014, 111– recommended. 122.

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НОВИ ДАННИ ЗА ОВАЛНАТА РЕЧНА МИДА UNIO CRASSUS (UNIONIDAE, BIVALVIA) ОТ РЕКА ПАЛАКАРИЯ, БЪЛГАРИЯ Любомир Кендеров, Йонко Сашов

Резюме: Представени са нови данни за морфометричните параметри и обилието на овалната речна мида Unio crassus Philipsson, 1788 от река Палакария. Видът е застрашен на европейско ниво, но в България е широко разпространен в слабо течащите речни участъци. Установена е относително висока численост на локалната популация на U. crassus. Установено е добро състояние на местната популация и възможните причини за това са обсъдени. Забелязани са някои антропогенни заплахи за вида. Ключови думи: Unio crassus, местна популация, застрашен вид, река Палакария

Assistant Professor Lyubomir Kenderov, PhD гл. ас. д-р Любомир Кендеров, Sofia University „St. Kl. Ohridski”, Faculty of Biology, Софийски университет „Св. Климент Охридски”, Department of General and Applied Hydrobiology Биологически факултет, Катедра „Обща и приложна Address: 1164 Sofia, 8, Dragan Tzankov Blvd., room хидробиология” 168 адрес: гр. София (п. код 1164), бул. „Д. Цанков” 8, tel.: 02/8167343 каб. 168 e-mail: [email protected] тел.: 02/8167343 ел. поща: [email protected]

Mr. Yonko Sashov, Bachelor degree student Йонко Сашов – студент, Sofia University „St. Kl. Ohridski”, Faculty of Biology Софийски университет „Св. Климент Охридски”, Address: 1164 Sofia, 8, Dragan Tzankov Blvd., Биологически факултет e-mail: [email protected] адрес: гр. София (п. код 1164), бул. „Д. Цанков” 8

ел. поща: [email protected]