Received date: 10.09.2013 Accepted date: 01.04.2014 Published date: 27.08.2014
Five freshwater fishes, Carassius gibelio (Bloch, 1782), Gobio bulgaricus Drensky, 1926, Leucaspius delineatus (Heckel, 1843) Phoxinus strandjae Drensky, 1926 and Rutilus rutilus (Linnaeus, 1758) were recorded for the first time for Istranca Stream which is emptying to Lake Durusu in ?stanbul. With the result of present study, the number of the fish species living in the basin has increased to 33.
Istranca stream, Fish fauna, Cyprinidae
Turkey has a substantial biodiversity in re-spect to its geographical location. While totally 236 freshwater fish species inhabit in the inland waters of Turkey (Kuru, 2004), this number is increasing with some new studies (Freyhof and Özuluğ, 2006; Turan et al., 2006a; Turan et al., 2006b; Özuluğ and Freyhof, 2007a; Özuluğ and Freyhof, 2007b; Özuluğ and Freyhof, 2008; Tu-ran et al., 2008a; Turan et al., 2008b; Turan et al., 2008c; Freyhof and Özuluğ, 2009a; Freyhof and Özuluğ, 2009b; Küçük et al., 2009; Turan et al., 2009a; Turan et al., 2009b; Schöter et al., 2009; Freyhof and Özuluğ, 2010; Turan et al., 2011; Özuluğ and Freyhof, 2011; Turan et al., 2012a; Turan et al., 2012b; Turan et al., 2013).
Lake Durusu is located on the northwestern of Istanbul near the coasts of the Black Sea and is 70 km away from the city center. The lake was a lagoon until 1883 and the connection with the Black Sea was supplied by a canal named Dar-boğaz. The lagoon was blocked by a regulator constructed for drinking water resource. Because of Lake Durusu is rich in terms of streams and all of the surface waters and streams flow to the lake, it became freshwater lake in due time (Baylan and Karadeniz 2006; Özuluğ, 2008). One of the main water supply of the lake is Istranca stream which has 443 km2 basin (Figure 1).
Devedjian (1926), Battalgil (1941), Kosswig and Battalgil (1943), Ladiges (1960), Balık (1985), Geldiay and Balık (1996) had mentioned totally 20 freshwater fish species present in the lake. But the most detalied research about the fish species of the Lake Durusu Basin and the Is-tranca Stream was studied by Özuluğ (2008) and a total of 27 fish species belonging to 10 families were identified. According to Turan et al., (2013), this number has increased to 28 with oc-currence of Alburnoides tzanevi Chichkoff, 1933 in Lake Durusu.
There is no detailed study about the fishes of Istranca Stream that is the most important stream feeding the Lake Durusu. The aim of the study is to present the fish fauna of the Istranca Stream with new records.
The present study was carried out in Is-tranca Stream between March 2012 and June 2013. The fish specimens were collected by electroshocker. For morphological examina-tion, some specimens from every species were preserved in 5% formaldehyde solution and stored as museum material in Istanbul University Science Faculty Hydrobiology Museum-IUSHM. The other specimens were studied to determine their biological charac-teristics. During the analysis of the fish, the taxonomic order suggested by Nelson (2006) was used, and the names of species were at-tributed following Eschmeyer (2013).
During the surveys, totally 19 fish species were captured from the Istranca Stream. These specimens are Alburnoides tzanevi (Bloch, 1782), Alburnus istanbulensis Battalgil, 1941, Barbus cyclolepis Heckel, 1837, Carassius gibelio (Bloch, 1782), Gobio bulgaricus Drensky, 1926, Leucaspius delineatus (Heckel, 1843), Petroleu-ciscus borysthenicus (Kessler, 1859), Phoxinus strandjae Drensky, 1926, Rhodeus amarus (Bloch, 1782), Rutilus frisii (Nordmann,1840), Rutilus rutilus (Linnaeus, 1758), Squalius cepha-lus (Linnaeus, 1758), Vimba vimba (Linnaeus, 1758), Cobitis pontica Vasil’eva & Vasil’eva 2006, Esox lucius Linnaeus, 1758, Knipowitschia caucasica (Berg, 1916), Neogobius cf. euryceph-alus (Kessler, 1874), Neogobius gymnotrachelus (Kessler, 1857), Neogobius melanostomus (Pal-las, 1814), Proterorhinus semilunaris (Heckel, 1839), respectively. Five fish species, C. gibelio (Bloch, 1782), G. bulgaricus Drensky, 1926, L. delineatus (Heckel, 1843) P. strandjae Drensky, 1926 and R. rutilus (Linnaeus, 1758) were rec-orded for the first time for Durusu Lake Basin.
The species, C. gibelio (Figure 2), G. bulgari-cus (Figure 3), L. delienatus (Figure 4), P. strandjae (Figure 5) and R. rutilus (Figure 6) were captured from 5 different stations in Is-tranca Stream. The station coordinates and indi-vidual numbers for each species were given in Table 1.
Carassius gibelio (Bloch, 1782)
Material examined: 1 specimen, total length 7.8 cm, Station 2- 41º18'50.94''N 28º14'56.15''E, 6 April 2012; 2 specimens, total length 6.0-7.6 cm, Station 1 - 41º19'47.10''N; 28º15'47.59''E, 6 April 2012; 1 specimen, total length 9.4 cm, Sta-tion 3 - 41º23'56.44''N; 28º11'37.18''E, 15 June 2012; 1 specimen, total length 13.1 cm, Station 3 - 41º23'56.44''N; 28º11'37.18''E, 20 June 2013.
Gobio bulgaricus Drensky, 1926
Material examined: 4 specimens, total length 8.7-9.7 cm, Station 4 - 41º25'3.00''N; 28º8'18.42''E, 4 April 2012; 7 specimens, total length 5.5-7.2 cm, Station 2 - 41º18'50.94''N; 28º14'56.15''E, 16 May 2012,
Leucaspius delineatus (Heckel, 1843)
Material examined: 9 specimens, total length 2.4-3.3 cm, Station 5 - 41º22'45.12''N; 28º17'45.96''E, 12 March 2012; 10 specimens, total length 2.7-3.9 m, Station 5 -41º22'45.12''N; 28º17'45.96''E, 17 January 2013; 3 specimens, total length 3.2-4.5 cm, Station 5 - 41º22'45.12''N; 28º17'45.96''E, 19 February 2013.
Phoxinus strandjae Drensky, 1926
Material examined: 11 specimens, total length 4.3-7.1 cm, Station 2 - 41º18'50.94''N; 28º14'56.15''E, 5 May 2012.
Rutilus rutilus (Linnaeus, 1758)
Material examined: 1 specimen, total length 13.0 cm, Station 5 - 41º23'56.44''N; 28º11'37.18''E, 18 April 2013.
C. gibelio described as an invasive fish spe-cies for Turkish inland waters (Özuluğ et al., 2004) was recorded for the first time from Gala Lake in Turkey (Baran and Ongan, 1988) and in-troduced the other drainage systems in Thrace shortly (Özuluğ et al., 2004; Özuluğ, 1999), how-ever it has not reported from Lake Durusu by Özuluğ (2008). Only 5 individuals of C. gibelio were captured during the research in Istranca Stream. There is no data about the situation of the species in Lake Durusu but it can be easily adapted and become one important fish species for the lake because of its successful spawning strategy and high ability at colonization for new environments. Due to this reason, the monitoring study should be carried out for Lake Durusu as soon as possible.
P. strandjae was firstly described from Is-tranca range in Bulgaria by Drensky at 1926, but he did not state on which slope the species had been obtained. At 1951, he stated that the speci-mens had been collected from the Veleka and Rezve drainages, draining from Istranca to Black Sea in Bulgaria and Turkey (Kottelat, 2007). The species was only known from these two drainage systems and with this study the distribution area of the species has widen.
Two Gobio species, G. kovatschevi and G. bulgaricus were identified from Thrace region (Kottelat and Freyhof, 2007; Turan et al. 2012a). The natural distribution area of the G. ko-vatschevi is only known from the River Prova-diskaya in Bulgaria and the other Gobio species G. bulgaricus is known from Bulgaria, Greece, Macedonia and Turkey (Kottelat and Freyhof, 2007). Turan et al. (2012a) has identified Gobio specimens lived in Istranca Stream (D. Turan has confirmed that, this stream is not in the Durusu basin and draining to the Black Sea at Kırklareli (pers. comm.)) as G. kovatschevi and, in Meriç and Ergene rivers as G. bulgaricus.
L. delienatus is a small cyprinid species diag-nosed with incomplete lateral line with about 2-12 pored scales (Berg, 1949). It can be easily confused by little chubs at first sight with body form and having large silvery scales. L. deline-atus is native to Thrace and Anatolian coast of Sea of Marmara in Turkey (Kottelat and Freyhof, 2007, Gaygusuz et al. 2013), however it has rec-orded from Kura and Aras drainages (Kuru, 1980), too.
R. rutilus widely distributed in Europe, the Black Sea and Azov Sea basin occurs Büyükçekmece, Apolyont, Manyas and Sapanca lakes, Seyhan Dam Lake and streams in Samsun city (Geldiay and Balık, 1996; Ergüden et al., 2008). The monitoring study should be carried out for the population structure of this species in Lake Durusu because of it prefers lentic systems mostly.
In conclusion, the Lake Durusu Basin is rich as a regard to fish fauna. Until today, although some reports have been given on the fauna of the Lake Durusu, new fish species still appear from the streams feeding the lake. It could be said that detailed field survey is very important for the systematic faunal studies.