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Understanding the invasion success of alien species includes developing knowledge on how the biological traits of their populations respond to spatial differences in environmental conditions. For invasive fishes, while the influence of latitudinal and climatic gradients on their biological traits over large spatial scales is well established, there is less certainty in how these vary over smaller scales. Here, we tested the influence of a climatic and geographic gradient on the reproductive traits and body sizes of the invasive mosquitofish Gambusia holbrooki across five climatic regions in Turkey. The results revealed that the environmental conditions across eight sites provided two gradients: a latitudinal gradient (where northern sites were cooler with less rainfall) and a coastal–inland gradient (where changes were apparent from coastal areas and into inland areas). These gradients had marked effects on the traits of both sexes. In sites in coastal and southern areas, males had significantly larger gonopodia and females had greater fecundity than in inland and warmer areas, and with both sexes having body sizes that were smaller. The spatial differences in the male traits were suggested as being driven by differences in selection pressures at the sites that related to differences in their population abundances. The results revealed that environmental conditions across a relatively small spatial scale had some strong influences on the expression of specific biological traits of these mosquitofish populations, but with further work needed to test how these influences affect their invasion success. [ABSTRACT FROM AUTHOR]

In the scope of this study, fish fauna of Küçük Menderes River and its tributaries, updated with the comparison of the recent ichthyofaunal studies, as well as the length-weight relations (LWR) and condition factors (CF) were estimated for 7 freshwater fish species belonging to six families from the river basin: endemic Oxynoemacheilus eliasi, Cobitis fahireae; invasive, Carassius gibelio, Atherina boyeri, transloce Perca fluviatilis and the native Squalius fellowesii, Cyprinus carpio. The fish samples were collected with various fishnets and DC electro-fishing devices from six stations in 2018 and 2019. The LWR of the fishes was studied based on 379 specimens. The estimated values of parameter b ranged from 2.884 (A. boyeri) to 3.176 (C. fahireae). The coefficient of determination (R2) was changed between 0.792 to 0.980 for all sampling localities. In the study, Fulton's condition factor ranged between 0.391 (S. fellowesii) to 3.080 (S. fellowesii); the relative condition factor ranged between 0.346 (O. eliasi) to 2.746 (S. fellowesii), respectively. This research is anticipated to contribute valuable insights for the conservation of the species, while also furnishing essential data to inform future fisheries management studies in the region. [ABSTRACT FROM AUTHOR]

This paper, the Oligochaeta fauna of some lakes located at the West Black Sea Region of Turkey, was reported using results obtained. Having no previous faunistic studies, some physico-chemical features and Oligochaeta fauna of the lakes were determined for the first time in this research. Consequently, 30 species were determined, 13 species from Tubificidae family and 17 species from Naididae family. The average density of total Oligochaetes in the benthos of the lakes was 417 individuals m-2. The dominant species Tubifex tubifex accounted for 170 individuals m-2 and represented 40.7 % of total Oligochaeta community in the lakes studied. With regard to the rational distribution of species by station, Station 9 (Lake Yeniçağa) was the richest with 19.75% and Station 7 (Lake Abant) was the poorest with 3.23%. There are no data on the Oligochaeta fauna of this region so far. The determined taxa from is region. [ABSTRACT FROM AUTHOR]