Özcan Gaygusuz

The bitterling-mussel coevolutionary relationship in areas of recent and ancient sympatry.

Host–parasite relationships are often characterized by the rapid evolution of parasite adaptations to exploit their host, and counteradaptations in the host to avoid the costs imposed by parasitism. Hence, the current coevolutionary state between a parasite and its hosts is predicted to vary according to the history of sympatry and local abundance of interacting species. We compared a unique reciprocal coevolutionary relationship of a fish, the European bitterling (Rhodeus amarus) and freshwater mussels (Unionidae) between areas of recent (Central Europe) and ancient (Turkey) sympatry. Bitterling parasitize freshwater mussels by laying their eggs in the gills of mussel and, in turn, mussel larvae (glochidia) parasitize the fish. We found that all bitterling from both regions avoided one mussel species. Preferences among other mussel species tended to be related to local mussel abundance rather than duration of sympatry. Individual fish were not consistent in their oviposition choices, precluding the evolution of host‐specific lineages. Mussels were demonstrated to have evolved strong defenses to bitterling parasitism in the area of ancient sympatry, but have no such defenses in the large areas of Europe where bitterling are currently invasive. Bitterling avoided glochidia infection irrespective of the duration of sympatry.

Interannual Variability of Fecundity and Egg Size of an Invasive Cyprinid, Carassius gibelio: Effects of Density-Dependent and Density-Independent Factors

ABSTRACT A population of the invasive Prussian carp (Carassius gibelio) was examined over a three-year period in a mesotrophic reservoir to find out interannual variations of fecundity and egg size and the influence of maternal condition (total length, TL, and age class) and environmental factors (water temperature and fish density) on these variables. Prussian carp reproduction was synchronous, with only a single batch, and fecundity ranged from 1,250 to 62,400 eggs per female. Relative fecundities and egg size showed no significant between-year differences. Fecundity increased with age, whereas egg diameter remained unchanged with age and TL. Fecundity was affected positively by TL and negatively by fish density, whereas temperature had no significant effect. Egg size was not affected by fish density or temperature.

Characteristics of a Eurasian cyprinid, Shemaya, Chalcalburnus chalcoides (Güldenstädt, 1772), in a mesotrophic water reservoir

Abstract Age, growth and reproduction of the Shemaya, Chalcalburnus chalcoides, was studied in the Ömerli Reservoir, a large drinking water system located in Istanbul province (Turkey). The von Bertalanffy growth function displayed variation in growth rates between the sexes. Asymptotic lengths calculated for both sexes were high, probably due to the lack of large predatory fishes and lack of fishing in the reservoir. Females dominated all age classes with the exception of the second age, and this phenomenon is characteristic of species from unstable and variable environments. The condition factor and the gonadosomatic index indicated that reproduction occurred around May-June. The estimated mean lengths at first maturity (L T50) were 14.83 cm and 15.98 cm for males and females, which corresponded to 1 and 2 years of age for both sexes. Natural mortality was 0.47/year. Fishing mortality as well as exploitation rate was negligible since fishing activity is prohibited throughout the year.

The role of the European bitterling (Rhodeus amarus, Cyprinidae) in parasite accumulation and transmission in riverine ecosystems

In aquatic ecosystems, fish play a key role in parasite accumulation and transmission to predacious animals. In the present study, realized on seven populations of a small cyprinid fish species, the European bitterling Rhodeus amarus, we investigated (1) the role of the European bitterling as a potential intermediate or paratenic host, (2) the ability of the fish to accumulate parasites with similar final host group, and (3) its significance as a potential source of parasite infection in the ecosystem in respect to habitat characteristics. A total of 36 parasite species were recorded; 31 species (90% of all parasite specimens) were classified as endoparasites. Most of the endoparasites were found in the larval life stage, using bitterling as an intermediate or paratenic host. In particular, parasite community structure showed significantly higher proportions of allogenic parasites in comparison with autogenic. The supposed co-occurrence of parasite species with identical final host groups showed only a weak association. The adjacent reservoir areas were a significant determinant of both the total and infracommunity parasite species richness and for the mean parasite abundance. No relationship between the distance of sampling site from the adjacent reservoir and parasite community characteristics was found. As a small-sized fish with a wide distribution range and high local abundances, the European bitterling can represent a natural prey for a wide range of piscivorous predators. Due to its susceptibility to the number of larval endoparasites, this fish species may therefore fulfill the role as important transmitter of parasites to their final hosts.

Threatened fishes of the world: Salmo platycephalus Behnke, 1968 (Salmonidae)

Common name: Flathead trout (E), Alabalık (Tr) Conservation status: Listed as critically endangered (defined by CR B1ab(v)+2ab(v) criteria) in the IUCN International Red List Identification: D iii 10, A iii 8, P 14, V 9, Ll. scales 109–110, total vertebrae 57–59, pyloric caeca 15–16, gill rakers 23–24. Head broad, snout blunt; fins large with pale margins; preserved colors dusky brown shading darker to lighter from dorsal to ventral (Behnke 1968; Sušnik et al. 2004). Distribution: The flathead trout has a very restricted distribution. It is found in Rivers Karagöz, Soğuksu and Uzunyayla, the tributaries of River Zamantı which belongs to Seyhan Basin emptying into the Mediterranean Sea. Abundance: The population is currently abundant, but restricted. Habitat and ecology: It is adapted to high mountain stream waters. Non-migratory species. Reproduction: Ova up to 2 mm and the spawning period in autumn (Behnke 1968). Maximum lifespan is 10 years (Alp and Kara 2004). Threats: Salmo platycephalus is threatened due to its limited and isolated distribution. A primary continuing threat to this fish is the potential adverse impact of introduced non-native rainbow trout Oncorhynchus mykiss (Walbaum, 1792), which has been commonly cultured and stocked in Turkey. Rainbow trout is a predatory threat to larva of S. platycephalus and direct competitor for food and space. Illegal fishing using nets is a possible threat for population decline in some rivers. Conservation action: The species is officially protected by prohibiting fishing. Conservation recommendations: A detailed study of current population status, and biology and ecology of S. platycephalus is required. It is recommended to avoid releasing cultured O. mykiss. Remarks: Although genetic evidence suggests that S. platycephalus may be conspecific with Salmo trutta, this unique morph warrants protection. Fig. 1 Salmo platycephalus

Threatened fishes of the world: Hemigrammocapoeta kemali Hankó, 1924 (Cyprinidae)

Common name: Cuce Siraz (Tr). Conservation status:Critically endangered CR B1ab (iii) (Crivelli 2006).Identification: DIII7–8, A II 5–6, P I 13, V I 7, Ll.scales 7–11, gill-rakers 13 –16, pharyngeal teeth 3.3.5–5.3.3, total vertebrae 30–31 (Geldiay and Balik 1996;Kucuk and Ikiz 2004). Body moderately deep (3.5–4.5in SL). Length 6–7cm(Balik 1995). Distribution: H.kemali is currently known only from Eregli marsh(southern Anatolia). The total marsh area is less than100 km