DATA CONCERNING THE FISH COMMUNITIES OF THE BASEU RIVER (ROMANIA)

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1 Analele Ştiinţifice ale Universităţii Al. I. Cuza Iaşi, s. Biologie animală, Tom LIII, 2007 DATA CONCERNING THE FISH COMMUNITIES OF THE BASEU RIVER (ROMANIA) Cătălin Dumitru COSTINIUC 1, Grigore DAVIDEANU 2 and Ana DAVIDEANU 2 1 Al.I.Cuza University, Departament of Biology, Carol I St, 11, Iasi, Iasi County, Romania, RO costiniuc_catalin@yahoo.com; 2 Al.I.Cuza University, Natural History Museum, Independentei Bd., 16, Iasi, Romania, RO grigore@uaic.ro Abstract. The paper presents the results of an ecological study on the Baseu River fish community. Using an electrofisher they were captured, in 7 sample sites, a number of 927 fish specimens belonging to 13 species. They were calculated a series of ecological metrics and indexes in order to assess the fish community structure. Based on this data we were able to conclude that besides the human impact the fish community is still in good state, having a balanced ecological structure. In the Baseu basin they are present at least two protected fish species: Cobitis taenia and Rhodeus sericeus that are protected both at European and national level. Keywords: ihthyofauna, fish communities, Baseu River. Rezumat. Date privind comunităţile piscicole din râul Başeu (România).Lucrarea prezintă rezultatele unui studiu ecologic al comunităţii piscicole din râul Başeu. Cu ajutorul unui electrofisher au fost capturaţi, în 7 staţii, un număr de 927 peşti aparţinând la 13 specii. Au fost calculaţi o serie de indicatori ecologici pentru a evalua structura comunităţii piscicole. Pe baza rezultatelor obţinute se poate concluziona că asociaţia piscicolă este întro stare bună, cu o structură ecologic echilibrată, chiar dacă se manifestă efecte negative ale impactului antropic asupra habitatelor acvatice. În zonă sunt prezente specii de peşti protejate precum Cobitis taenia şi Rhodeus sericeues, care sunt protejate la nivel european sau naţional. Cuvinte cheie: ihtiofauna, comunităţi piscicole, Başeu. Introduction Baseu is a small tributary (on the right side) of the Prut River. Baseu has a total length of 118 km and a basin surface of 961 km 2. Its sources are at an altitude of 300 m on the Ibăneşti-Herţa hill. The river mouth is on the right side of the Prut River at 57 m altitude, only 9 km downstream the Stînca-Costeşti Stanca-Costesti reservoir. The mean slope of the Baseu River is 2.3%o. The river basinhas is placed in the north eastern part of the Moldavian plateau. Land use is mainly agriculture, with few wooded lands. The area is characterized by long drought periods especially during the summer months. They are only relatively small villages in the area, the single urban area being Saveni city (No 9000 inhabitants). Material and Methods The samples were collected by electro fishing during 2005 and 2006 summer, using a FEG 5000 electro fisher (Cowx, 1990). For each sample we fish on a 100 m length covering all the habitat types in the area. In 7 sample sites we collected a total number of 928 specimens, belonging to 2 orders, 4 families and 13 species. The identification was done based on the Banarescu s 2002 identification guidebooks. After identification and measurements the fish were set free, less than 5% of them were retained as voucher specimens for the Natural History Museum. We obtained a series of qualitative and quantitative data concerning the fish populations in the sample sites the fish species list, the absolute numeric abundance for -59-

2 Cătălin Dumitru Costiniuc et al. each species in each of the sites. These data were computed using statistical methods (Angermeier, 1995; Barbault, 1994) in order to calculate a series of ecological metrics and indexes for characterize the fish communities in the studied area. Results and Discussion Table 1 presents the species structure of the fish communities, as number and Table 2 as weight for each of the captured species and in each sample site. From the total of 13 species 11 are indigenous and two are introduced, invasive species Lepomis gibossus and Pseudorasbora parva. The number of species varies in between 3 at Downstream Saveni (the sample site downstream an urban agglomeration) to 9 at site Upstream Negreni. The relatively high number of species here is probably due to the impact of fish farms placed both upstream and downstream the site, which permanently repopulate the river thorough the escaping fish. The quantitative differences (both as number and weights) in between sites are important. They are due to ecological and habitat typology of each site and to the human impact. The numeric abundance of the fish for each site varies in between 218 at site 6 Downstream Hanesti and site 46 at site 5 - Downstream Saveni. The weight abundance varies in between 4274g at site 6 Downstream Hanesti and 472g at site 5 Downstream Saveni. For the entire river length (7 sampling sites) we collected 928 fish specimen, weighting g. Figure 1. List of fish species in the sample points. -60-

3 -61- Table 1. The numeric absolute abundance and weight absolute abundance of fish species for each of the sampling sites, Baseu August SITES / Sampling date Upstrem Hudeşti Downstrem Havârna Upstream Negreni Downstream Stiubieni Downstrem Săveni Downstream Haneşti Stefaneşti Bridge Total indiv / species Total biomass / species Abundance Abundance Abundance Abundance Abundance Abundance Abundance No SPECIES number weight number weight number weight number weight number weight number weight number weight Ord. Cypriniformes / Fam. Cyprinidae 1. Carassius auratus gibelio Bloch, Cyprinus carpio L Scardinius erythrophthalmus L., Alburnus alburnus L., Gobio gobio Val., Rhodeus sericeus Bloch, Pseudorasbora parva Schlegel, Abramis sapa Pallas Fam Cobitidae 9. Cobitis taenia L Ord. Perciformes / Fam. Percidae 10. Perca fluviatilis L Stizostedion lucioperca L., Gymnocephalus cernuus L Fam Centrarchidae 13. Lepomis gibbosus L., Total individuals / site Total biomass / site Total species / site Total sites/ species

4 Cătălin Dumitru Costiniuc et al. From the table 1 and figures 2 and 3 we find that the most important species are Carassius auratus gibelio, Rhodeus sericeus, Gobio gobio and Pseudorasbora parva that represents about half of the total capture, both as individual number and weight. The abundance of Rhodeus sericeus and its presence in most of the sites confirms a good water quality along the river. For the Baseu River of total capture is in between 235 and 46 specimens for each sample (200 m 2 ). The capture consists mainly in small species as Rhodeus sericeus, Gobio gobio, Pseudorasbora parva and Carassius auratus gibelio is the most abundant species as absolute weight covering about 30% of the total fish quantity. The weight of fish capture was usually in between 4274 and 472 g per site. The smaller quantity was Downstream Saveni. Figure 2. The pie chart indicating the relative numeric abundance of the species in the total fish capture for the Baseu River. Figure 3. The pie chart indicating the relative weight abundance of the species in the total fish capture for the Baseu River. Table 2 presents the values of the fish community indexes in the Baseu River. We calculated the constancy, the dominance of the species and ecological significance of different species. The most important or characteristic species is Rhodeus sericeus W = 21.7%, followed by other characteristic species for this community dominance, and ecological significance index W. There were calculated also the constancy and dominance indexes. -62-

5 Analele Ştiinţifice ale Universităţii Al. I. Cuza Iaşi, s. Biologie animală, Tom LIII, 2007 These indexes were used in order to identify the community structure. Based on the values of these indexes, the complementary, species are Pseudorasbora parva, Carassius auratus gibelio and Gobio gobio, with an ecological significance index < 10. All the other species are associate or accidental species. Analysing the index of species similarity graph (Figure 4), we may notice that only 2 sites out of 7 forms a pair with a specific similarity of 70%. The other sites have a relativity small similarity index of 50%. This heterogeneity of the sites may be due to the influence of reservoirs. The specimens escaped from reservoirs induced a bias, since they are not naturally present in the area. The site 5, Downstream Saveni, is isolated from the other because of the poor water quality. This is due to the fact that part of the waste water of the city reaches the river unpurified. The index of cenotic affinity (Figure 5) was calculated in order to appreciate the affinity in between species, which is due to the common preferences for certain habitat characteristics. On the graph, we find that there is one pair grouping the species Gobio and Pseudorasbora with 83.3% cenotic affinity (they can also be considered the most tolerant species of all). The other group contains Carassius, Perca, Scardinius, Gymnocephalus with an affinity of 67%. They are the species that naturally inhabit this area and have a relatively good tolerance to the natural environment factor oscillation (as those caused by the seasonal drought). The species Rodeus sericeus and Cobitis taenia are species that depends on unpolluted water. The first one only spawn in live mussels and the second is a benthic species. Their presence confirms the good water quality in the area. The species Cyprinus carpio, Stizostedion lucioperca are probably escaped from a fish farm. Abramis sapa was found in a single site nearby the confluence with the Prut River. Table 2. The values of the ecological indexes calculated and the index of ecological significance calculated for the Baseu River. Absolute ECOLOGICAL INDEX No. SPECIES Abundence (A) Constancy (C) Dominance (D) Ecological significance (W) % Class % Class % Class 1. Rhodeus sericeus Bloch C D W 5 2. Pseudorasbora parva Schlegel C D W Carassius auratus gibelio C D W 5 Bloch Gobio gobio L C D W 5 5. Perca fluviatilis L C D W 3 6. Cobitis taenia L C D W 3 7. Gymnocephalus cernuus L C D W 3 8. Scardinius erythrophthalmus C D W 2 L.. 9. Alburnus alburnus L C D W Stizostedion lucioperca L C D W Cyprinus carpio L C D W Lepomis gibbosus L C D W Abramis sapa Pallas C D W 1-63-

6 Cătălin Dumitru Costiniuc et al. Figure 4. The graph of the species similarity. Figure 5. The graph of the cenotic affinity index. Table 3. The values of the Shannon-Weaver Diversity and Equitability Index, calculated for the Samples sites on in the Baseu River. SITES Number of individuals Number of species Shannon Weaver Diversity Index Real Diversity H(S) Maximal Diversity H(S)max Equitabilit y Index Upstrea m Hudeşti 1 Downstrea m Havârna 2 Upstrea m Negreni 3 Downstrea n Săveni 4 Downstrea m Săveni 5 Downstrea m Haneşti 6 Ştefăneşt i Bridge

7 Analele Ştiinţifice ale Universităţii Al. I. Cuza Iaşi, s. Biologie animală, Tom LIII, 2007 The Diversity Index Shannon and the Equitability Index, presented in the Table 3 and Figure 6, were calculated in order to find more about the stability and structure of the fish community. From these figures we may conclude that the fish community is relatively diverse and well balance for the entire river length. They are 9 or 8 fish species in three out of seven sample site, seven species in one site and the values of the Equitability Index varies in between and The lowest diversity is at the site placed at the top basin where the water flow is very scarce. Figure 6. The graph of the Shannon Diversity Index and Index of Equitability. From these data we may also appreciate that the conditions along the riverbed are depending of the human impact especially on the presence of reservoirs. These reservoirs has an important impact, they offer conditions for the presence of some species that are not normally present in a relatively small river. The reservoirs maintain also a relatively constant water level during the summer droughts that are characteristic for this region. Conclusions The fish community of the Baseu River consists in 13 species: 11 native and 2 introduced species Pseudorasbora parva and Lepomis gibossus. The dominant species are: Rhodeus sericeus, Pseudorasbora parva, Carassius auratus gibelio and Gobio gobio. The fish community composition is characteristic for small rivers in this hilly region, with river bed consists in sand, clay and moderate flow velocity. The human impact is caused by the hydro technical works, dam construction and fish farm developed in the reservoirs. These works contributed for an artificial increasing of the fish fauna. Both the number and weight abundance of fish are varying in between 218 specimen / 200m 2 to 46 specimen / 200m 2, respectively 3822g / 200m 2 to 19g / 200m 2. Considering the natural low number of species (because of the hydro morphology of the river we need to mention that they are present a series of species protected both at national and international level: Cobitis taenia, Rhodeus sericeus, that are protected by the Habitat Directive of the EEC). References Angermeier, P.L., Smogor, R.A., Estimating number of species and relative abundance in stream-fish communities: effects of sampling effort and discontinuous spatial distributions. Can. J. Fish. Aquat. Sci. 52 pg.,

8 Cătălin Dumitru Costiniuc et al. Barbault, R., Ecologie des peuplements. Structure, Dynamique et Evolution. Masson, Paris, 273 pg. Bănărescu, P., Fauna R.P.R., XIII, Pisces Osteichthyes. Ed. Acad., 958 pg. Bănărescu, P., Class Osteichthyes, în Diversitatea Lumii Vii, Vol. II, Apele Continentale. ed. Bucura Mond, 692 pg. Cowx, I.G., Fishing with electricity. Fishing New Books, British library, 600 pg. Davideanu, Gr., Davideanu, Ana, Popescu, Ir., Contributions a la connaissance de la ichtyofauna actuel de la riviere Jijia. An. St. ale Universitatii "Al. I. Cuza", Iasi, s. Biologie Animală, Tom XLI: Davidenau, Gr., Davidenau, Ana, The ichthyofauna of the Jijia River. în Studii şi Cercetări, Biologie, 5, Universitatea Bacău, pg