Biharean Biologist (2009) Vol. 3, No.2, Pp.: 139-141 P-ISSN: 1843-5637, E-ISSN: 2065-1155 Article No.: 031120
The status of the Freshwater Gobiid, Knipowitschia mermere Ahnelt, 1995: distribution ecology and threats
Gülnaz ÖZCAN
Mustafa Kemal University Fisheries Faculty, Iskenderun, Hatay, Turkey, E-mail: [email protected]
Abstract. Twelve specimens of Knipowitschia mermere Ahnelt, 1995 were caught in Lake Marmara between March 2007 and September 2007. K. mermere, a freshwater gobiid endemic to Turkey is threatened by extinction. It is found in one lake in western Anatolia. Gobiid populations have not been studied much, but the available data are summarised in this short review. Adult fish attain a size of 14-24 mm (total length) and fecundity is low (100-800 eggs per female).
Key words: Knipowitschia mermere, distribution ecology, threats, conservation, Turkey
Introduction Kovačić & Šanda, 2007 (Montenegro) Knipowitschia radovici Kovacic, 2005 (Endemic to Croatia); Freshwater fish species face severe threats in many parts Knipowitschia mrakovcici Miller, 1991 (Endemic to of the world. The threats leading to declines and Croatia); Knipowitschia milleri (Ahnelt & Bianco, 1990) extinction are multiple and often act in synergy by (Endemic to Greece)] of the genus Knipowitschia drought, excessive water abstraction, habitat loss or worldwide (Whitehead et al. 1984, Ahnelt 1995, Miller degradation (pollution, eutrophication, cannalisation 2004, Kovačić 2005, IUCN 2007). and waterworks) are among the main ones (Kottelat & Presently, the well-known Knipowitchia members are Freyhof 2007). Also, introduction of alien species to an Knipowitschia caucasica, Knipowitschia ephesi, ecosystem is one of the major causes of declined Knipowitschia longecaudata, Knipowitschia mermere in biodiversity. Turkey (Meriç 1986, Ahnelt et al. 1995, Ahnelt 1995, Knipowitschia, a “sand-goby” genus of Ponto- Neer et al. 1999, Turan et al. 2005). Among these Caspian origin comprised of fifteen described eurytopic Knipowitschia ephesi and Knipowitschia mermere are or freshwater species mostly endemic and of limited endemic species for Turkey. distribution in habit the Black and Caspian Sea, and Knipowitschia mermere is a fish species from the drainages of the Aegean, Ionian, Adriatic Sea and Gobiidae family. Today, this endemic species is Anatolia (Miller 2004, Kovačić 2005). restricted to Lake Marmara in western Anatolia. It lives There are approximately 15 species in this genus: in the shallow lake of Marmara (3,400 ha). Natural Knipowitschia mermere Ahnelt, 1995, is one of the fifteen habitat is freshwater lakes and drainages. The species is species [Knipowitschia cameliae Nalbant & Otel, 1995) threatened by habitat loss, water extraction, irrigation, (Romania); Knipowitschia caucasica (Berg, 1916) (Turkey, drought and pollution. Critically Endangered CR Greece, Romania, Armenia and Georgia); Knipowitschia B1ab(iii) ver 3.1 (2001) (Crivelli 2007). croatica Mrakovic, Kerovec, Misetic & Schneider, 1996 The specimens, including the photographed, are (Endemic to Croatia); Knipowitschia ephesi Ahnelt, 1995] preserved in 4% formaldehyde and deposited in the (Endemic to Turkey) Knipowitschia goerneri Ahnelt, 1991 Museum of the Faculty of Fisheries, Mustafa Kemal (Endemic to Greece); Knipowitschia iljini Berg, 1931 University, Iskenderun-Hatay (Collection numbers: (Former USSR and Asia: central part of the Caspian MSM-FISH/2007-1). The examined specimens are in Sea); Knipowitschia longecaudata (Kessler, 1877) (Coastal accordance with the original description of Knipowitschia and brackish water of the Black Sea, the Caspian Sea mermere by Ahnelt (1995). and the Sea of Azov); Knipowitschia mermere Ahnelt, 1995 (Endemic to Turkey); Knipowitschia panizzae (Verga, 1841) (Albania, Bosna and Herzegovina, Greece and Material and Methods Italy); Knipowitschia punctatissimus (Canestrini, 1864) (Italy and Croatia); Knipowitschia thessala (Vinciguerra, Lake Marmara is located in the western part of Anatolia, 1921) (Endemic to Greece) Knipowitschia montenegrina Turkey (38º 37' N 28º 00' E) (fig.1). Its surface area is 45 km2
©Biharean Biologist, Oradea, Romania, 2009 Biharean Biol. 3, 2009 http://biologie-oradea.xhost.ro/BihBiol/index.html Oradea, Romania 140 Özcan, G. with a depth of 4 or 6 m. Annual temperature varies between only the western Anatolian Lake Marmara (Mermere), 17.0 and 29.0 0C at the surface. Dissolved oxygen varies which lies about 100 km inland, cut off from the River -1 between 9.2 and 15.2 mg.l (Balik et al. 1991). While the lake Gediz by embankments (Ahnelt 1995). Apart from K. was originally a natural one, the Turkish State Water Supply mermere, native fish species such as Anguilla anguilla, Administration (DSI) transformed it into a reservoir by dam Chalcalburnus chalcoides, Rhodeus sericeus amarus, Silurus construction in the year 1953. Marmara Lake provides an environment supporting a rich aquatic bird fauna. It has an glanis, Barbus pectoralis and introduced species such as eutrophic character (Balik et al. 1991). The lake water is used Carassius carassius, Ctenopharyngodon idella, Cyprinus for irrigation by Salihli and Golmarmara plains. carpio and Sander lucioperca live in the Marmara Lake The specimens examined in this study were taken from (Balik et al. 1991). various areas in Marmara Lake (380 37' N and 280 00' E) Lake-shores are rich in aquatic vegetation (Chara sp. between March 2007 and September 2007. The specimens were (Characeae); Ruppia cirrhosa (Ruppiaceae) and Vallisneria collected with a fine-mesh hand-net and fixed in 4% formalin spiralis over soft silty bottom. Specimens were collected solution in the field and preserved in 70% ethanol in from the aquatic vegetation. Some of the physical- laboratory. All material is deposited in the Museum of the Faculty of Fisheries, Mustafa Kemal University, Iskenderun- chemical parameters that were measured are: water Hatay. temperature: 31.1 0C, pH: 7.79, dissolved oxygen 5.3 mg l−1; salinity 0.09 ppt; conductivity 324.0 μS25 0C; alkalinity, 4.6 meq l−1. According to the data given above, the species prefers small and permanent waters. Another clue for the ecological requirements of Knipowitschia mermere is that it apparently prefers low oxygenated freshwaters with very low salinity values. The aquatic vegetation in the habitat probably acts as a food supply depot and provides shelter against predators such as pike and other (cyprinid) fishes that inhabit its distribution area. The specimens for the study were caught at 0.5 m depth, 33 0C among algal vegetation. Among the specimens were egg-bearing individuals within piles of vegetation near the shore nearly died due to water abstraction for irrigation during the reproductive period
of these individuals. Twelve K. mermere specimens were Figure 1. Map of study area. caught in the lake. The total length for males was 14.0- 23 and for females 16.5-24 mm. Fecundity rate is very
low (100-800 eggs per female). Fecundity was estimated gravimetrically. To determine the It was observed in the study that this species coexists number of eggs, they were weighed and counted under a stereomicroscope. Egg diameters were measured under a with the other Knipowitschia species (Knipowitschia stereomicroscope with an ocular micrometer. Some of the caucasica) in the lake. The major threats to this endemic physical-chemical parameters were measured in the field with species are as follows: 1. S. lucioperca, which inhabits the a WTWpH330 model pH-meter, a YSI 30 model SCT-meter lake after having been introduced to Demirkopru Dam, (Salinity-Conductivity- Temperature meter), and a WTW which supplies water to the lake. 2. During the Oxi330 model dissolved oxygen-meter. reproductive period, this species spawns among pails of vegetation near the shore, however, due to the decline in water level, reproduction area for this species has Result and Discussions been damaged. Today, K. mermere (western Anatolia) is restricted to Freshwater Lake Marmara is a shallow 3400 ha expanse small freshwater habitats. K. mermere has already been of water and has rich vegetation (wet meadows, significantly impacted by these factors and consequently reedbeds) (Ahnelt 1995). Ranunculus sphaerospermus and it has presented a decline in Lake Marmara. As a Phragmites australis are widespread in the lake, also precaution against the extinction of this species, in the Myriophyllum spp and Carex otrubae were found in the first place, irrigation in summer time which coincides lake. Kum stream, which flows into the lake, provides with their reproductive phase should be taken under nutrients for phytoplankton and aquatic source. In control or accomplished without causing any change in addition, Lake Marmara is nourished by Gediz River water level. Besides, S. Lucioperca, a predator of K. (Yildiz & Ozdemir 2005). Knipowitschia mermere inhabits mermere, should also be taken under control.
Biharean Biol. 3, 2009 The status of the Freshwater Gobiid, Knipowitschia mermere Ahnelt, 1995: distribution ecology and threats 141
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