Arch. Biol. Sci. Belgrade 60 �3� 437�448 2008 DOI:�0.2298/�BS0803437R MACROINVERTEBRATE DIVERSITY IN THE KARST JADRO RIVER (CROATIA) Biljana R�đ� and Sanja Puljas Department of Biology, Science Faculty, University of Split, 2�000 S�lit Croatia Abstract — This �a�er �resents the results of �0 years of investigation of the aquatic macroinvertebrate fauna along the karst Jadro River. The Jadro is a ty�ical karst river. Benthic macroinvertebrates were collected along the river at �5 sites by standard methods of sam�ling in addition to which several �hysicochemical �arameters were also determined. Based on qualitative and quantitative com�osition of the macroinvertebrate fauna corres�ondence analysis divided the river course into three sections: u�stream midcourse and downstream. �orty�three taxa were recorded. Results of sa�robio� logical analysis based on macrozoobenthos indicate that water of the Jadro River belongs to quality classes I and II. Key words: �quatic macroinvertebrates community com�osition Jadro River Dinaric karst Croatia Udc 592(497.5) INTRODUCTION minimum and maximum discharge is from 2 m3/s �July �995� to �00 m3/s �December 2002�. Studies It is well known that benthic macroinvertebrates are have also been carried out on the Jadro�s �hytob� the best studied community of running waters. The enthos �V u k o v i ć �98�� and macrozoobenthos Jadro ��������River��� is �������������������������art of the Dinaric karst ����������which occu� �R a đ a 2002 2006�. �ive sam�ling sites situated �ies almost 50% of Croatia�’s��������������������� territory �����ig. �������. It u�stream in midcourse and downstream were consists of four �aleo�dynamic and �aleo�structural examined. U�stream sites are subject to the direct belts. The area in which Jadro ����������������������River����������������� lies in a region influence of groundwaters es�ecially during the of carbonate landforms and karst �henomena along winter and s�ring seasons. Midcourse sites are �ol� the �driatic Coast. The area includes carbonate land� luted as a result of agriculture and by urban and forms of Mesozoic and later age �K u h t a 2002�. industrial sources of �ollution as are downstream The Jadro was chosen for investigation because it sites. Downstream sites are also under considerable has a ty�ical Mediterranean hydrological regime and is a very im�ortant karst river that has supplied the influence of seawater es�ecially during summer. the city of S�lit with drinking water from Roman The aim of this �a�er is to �resent collected data times to the �resent day. The s�ruce of the Jadro is on the community com�osition and diversity of located at an elevation of 30 meters above sea level. macroinvertebrates as well as differences between Total length of the Jadro is 4.5 km. It discharges into se�arate sectors of the river. Kaštela Bay of the �driatic Sea. The river�s catchment M�TERI�L �ND METHODS area is approximately 260 km2 and is �art of water� shed of the Cetina �����River �����ig. �B�. ���������������hysicochemical Sampling of macroinvertebrates characteristics of the Jadro have been studied by Š t a m b u k � Giljanović ��994 �999 2002 One sam�le of benthic macroinvertebrates was 2005�. The upper �arts have �reserved the river�s taken at each station four times �er year from �994 natural characteristics but the lower �arts are �ol� to 2004 �total of 600���� sam����������������������les������������������)����������������� using����������� a standard ����ond luted by the im�act of human activities such as agri� net �mesh��������� size���� 900 �m�. �������������������������e fauna attached to stone culture and by various wastewaters �Š t a m b u k � surfaces was collected by means of tweezers and G i l j a n o v i ć 2002 2005�. The range between if necessary scra�ed with a fine brush ��lanarians 437 438 BILJ�N� RAĐA and S�NJ� �ULJ�S Fig. 1. �� Sim�lified general tectonic ma� of the Croatian �art of the Dinarides with the distribution of karst; B� e catchment area of the River Jadro. gastro�ods leeches�. e sam�les were �laced in illustrate the distribution of invertebrates along the �lastic bottles and �reserved in 95% ethanol. ey river. Gra�hics were made using �rimer 5.0 software were sorted and identified to the lowest �ossible �C l a r k e and W a r w i c k 200��. Quantitative taxonomic level in the laboratory using a Leica MZ sam�les were considered as the mean �ercentage 7.5 stereozoom microsco�e ��0x�0 and �0x40� and of grou�s in sam�les. Data were calculated by the manuals for identification �B e r n a s c o n i �986 most frequently used clustering strategy namely the �990; B o l e �97�; C a m � a i o l i et al. �994 unweighted �air�grou� method using arithmetic �999; C h i n e r y �984; D a n i e l o � o l and averages �U�GM�� Euclidean distance being taken M a r m o n i e r �994; D i e r l �988; G i r o d as the correlation coefficient �K r e b s �989�. The et al. �980; G i u s t i and � e z z o l i �980; relationshi� between macroinvertebrate taxa and G o u r b a u l t �994; G r a f �974; H a r d e �hysicochemical �arameters on the one hand and �999; K a r a m a n and S k e t �989; R a d o m a n sam�ling sites �er year and season on the other was �973�983; S a n s o n i �998; S c h ü t t �975; analyzed by multivariate techniques such as �rin� S k e t �965 �969 �988 �994�. Oligochaetes were ci�al com�onents analysis ��C��. Gra�hics were identified by �rof. Eva Dumnicka am�hi�ods by made using Statistica 7.� software. The com�lete material is de�osited in the invertebrate collection �rof. Boris Sket and hydrobiid snails by Tonći of the De�artment of Biology of S�lit University�s Rađa. Science �aculty. Estimation of sa�robity was �er� The study included qualitative and quantitative formed by sa�robiological analysis according to analysis of the benthic community. S�ecies diver� � a n t l e and B u c k ��955�. sity was calculated using the number of observed Physicochemical parameters taxa Sim�son's index the Shannon�Weiner index the �ielou index and Margalef's index �K r e b s Several �hysicochemical �arameters �tem�era� �989� and community abundance was analyzed to ture dissolved oxygen dissolved CO2 alkalinity Macrozoobenthos of The Jadro River, CRO�TI� 439 hardness �H and substrates� were measured at each are shown in �ig. 2�. station four times �er year from �994 to 2004 �total of 600 measurements�. Surface water was sam�led in �� 2. Midcourse sites L �oly�ro�ylene sam�ling bottles for determination Thirteen macroinvertebrate grou�s were iden� of some �hysicochemical �arameters. Tem�erature tified from midcourse sam�les �Table ��. �mong dissolved oxygen dissolved CO2 alkalinity and �H them were two grou�s lacking in u�stream sam�les: were measured using a digital meter �Handylab ostracods and worms. These sam�les contained no Schött� with the appro�riate �robes according to stoneflies ��leco�tera�. Gastro�ods were still the ��H� ��995� and hardness in German degrees dominant grou�. �m�hi�ods and insects increased �d°H� was determined as the �roduct of alkalin� in number during s�ring and summer ��ig. 2B�. ity �mg CaCO3/l� times a factor of 2.8. Substrates were estimated at the Institute of Oceanogra�hy 3. Downstream sites and �isheries in S�lit and the �ercentage of �articles Twelve grou�s of macroinvertebrates were iden� was determined using a modified version of the tified from downstream sites �Table ��. The macroin� Wentworth scale according to B o g n e r ��996�. vertebrate community differs from those observed u�stream and midcourse sites. Under considerable RESULTS marine influence there were �olychaetes in sam� Macroinvertebrate community structure �les. Gastro�ods were �resent in smaller number than at u�stream and midcourse sites but they were � total of 43 macroinvertebrate taxa were found numerous in autumn and winter when the influ� during the investigation. The highest taxon richness ence of fresh water is very strong. During s�ring was observed among insects �Insecta), es�ecial� and summer the influence of sea water is dominant ly mayflies �E�hemero�tera� snails �Gastro�oda� and brakish individuals occur �redominantly at sites with eight and seven s�ecies res�ectively. Other near the estuary ��ig. 2C�. invertebrate grou�s were less diverse. The number of taxa observed at each sam�ling site area varied �nalysis of sam�ling sites and taxa obtained between 33 and 43 �Table ��. Seasonal analysis of the using unweighted �airs of grou� ��ig. 2D� shows macroinvertebrate community showed that snails that downstream sam�ling sites exhibit greater dis� have equal abundance from season to season �50 tance than u�stream and midcourse sites the main � 68%�. Differences were determined for am�hi�ods factor for such distance being influence of the sea and insects whose numbers increase during s�ring on downstream sites. There is also greater dis� tance between u�stream and downstream sites than and summer ��2 � 26%� in com�arison with autumn between u�stream and midcourse sites because and winter abundance �6 � �2%� ��ig. 2A-C�. the influence of underground waters in addition 1.