___

• U. pictorum 17 32 43 52 58 65 70 74 78 81 84 87 90 13 90 97 Present study U. pictorum 38 53 64 72 72 78 80 81 9 81 Kara (2004)
• U. pictorum 16 Yalçın (2006)
• U. pictorum 13 75 Negus (1966) U. pictorum 66 Kiss (1994)
• U. crassus 20 34 47 58 66 70 74 7 74 47 Present study U. crassus 19 29 42 52 53 58 61 7 61 Akyurt and Erdoğan (1993) U. crassus 82 Kiss (1994)
• A. cygnea 150 87 Present study A. cygnea 145 89 Başçınar (2003)
• Turkey (Akyurt and Erdoğan, 1993; Kara, 2004) recorded contrasting growth rates (both slower and faster) with shorter lifespans (Table 4). The fact that these studies made estimates of age based on counting external growth bands on the shells, which has been considered an unreliable method for ageing due to underestimation of older specimens (Neves and Moyer, 1988), may explain some of these growth variations among studies. Notwithstanding the limitations of this method, it would appear that the growth and lifespan of Unio species are variable in Turkey, perhaps related to variation in temperature and water quality. Although Anodonta species were not aged in the present study because of their thin shells, our estimates of b for A. cygnea corresponded closely with those of Lake
• Çıldır in eastern Turkey (Başçınar 2003), though there were differences in maximum shell length (Table 4). The occurrence of A. woodiana in the Lake Sapanca basin represents the first record for Turkish waters. This species may grow to a large size and is native to east and Southeast Asia (Watters, 1997). The rapid dispersal of this species has recently been recognized, with reports of its occurrence in Serbia (Paunovic et al., 2006), Poland
• (Kraszewski, 2007), the Czech Republic (Vrtílek and Reichard, 2012), and Romania (Popa et al., 2007) in the Danube basin. The initial introduction and spread of
• A. woodiana is thought to have occurred via the export of fish species such as Carassius auratus, C. gibelio, Ctenopharyngodon idella, and Hypophthalmichthys molitrix from eastern Asia for ornamental or biological control purposes (Watters, 1997). Carassius species in particular have spread extensively in Turkish waters (Tarkan et al., 2012) and C. gibelio is known to occur in Lake Sapanca
• (A.S. Tarkan, unpublished data), and is also distributed throughout the country, raising the possibility that A. woodiana may be more widespread in the region than this single case might suggest. A recent study on the invasion success of A. woodiana demonstrated that it is a successful invasive species tolerant of a wide range of environmental conditions (Douda et al., 2012). Monitoring of freshwaters in the vicinity of Lake Sapanca and elsewhere in western Turkey is warranted to measure the potential spread of this species.
• In conclusion, the present study provides baseline data for future work on some ecologically important and common freshwater bivalves, some of which have not been previously studied in this respect in Turkey. These data facilitate more effective conservation measures for native mussel species, which are under threat of pollution, habitat degradation, and nonnative species introductions. All of these threats were apparent in the present study of Lake Sapanca and it is likely that bivalve populations face similar challenges elsewhere in Turkey, as well as in other areas of the Black Sea region in which these mussels are native. Further comprehensive studies focusing particularly on the ecology and habitat requirements of native and nonnative mussel species are warranted to better understand the conservation status of native mussels, not only in the Lake Sapanca basin, but also elsewhere in Turkey. Acknowledgments We thank Matej Polačik, Meriç Albay, Latife Köker, and Adnan Sümer for their invaluable help in sampling and water quality analyses. This study was financially supported by CSF 13-05872S. We thank the Sapanca Inland Fish Aquaculture and Research Application Station of the Fisheries Faculty of İstanbul University and the Republic of Turkey Ministry of Food, Agriculture, and Livestock for facilities and permits necessary to conduct the study. In addition, we thank the 2 anonymous reviewers for their useful comments to improve the paper. References
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