Sökmen, Teoman Özgür

Small inland lakes support substantial freshwater biodiversity, but independent fish surveys may be constrained by specialised equipment, trained personnel, seasonal replication, and sustained funding. This study evaluated whether repeated observations of routine commercial gillnet catches could characterise the gillnet-catchable fish subcommunity of Çaltıcak (Taşkısığı) Lake, a shallow, approximately 90-ha groundwater-fed lake in Sakarya Province, Türkiye, and support surveillance of the non-indigenous Carassius gibelio. Fish were obtained over 17 sampling nights from 12 February to 3 June 2026 using five separate single-mesh monofilament gillnets (40, 50, 60, 75, and 80 mm mesh-bar length). Total design-based nominal mounted-area effort was 22,451.7086 m2-night, and catch was expressed as area-standardised numerical and biomass catch per unit effort (NPUE and BPUE). A total of 863 individuals from eight species were examined. Blicca bjoerkna, C. gibelio, and Scardinius erythrophthalmus were the most numerically represented species. C. gibelio constituted 26.42% of the examined catch and had a strongly female-biased catch composition (95.2% female). Smaller-bodied cyprinids occurred mainly in 40–50 mm meshes, whereas Cyprinus carpio and Silurus glanis occurred mainly in 80 and 60 mm meshes, respectively; Esox lucius was an exception, occurring mainly in 40–50 mm meshes. The combined catch corresponded to 0.038438 individuals m−2 night−1 and 0.015831 kg m−2 night−1. Approximate overnight soak duration varied seasonally from 9 to 16 h, but exact set and retrieval clock times were not recorded. Deployment coordinates were also not recorded, and sampling was confined to routine commercial fishing zones during February–June. Accordingly, the findings apply only to the gillnet-catchable fish subcommunity and must not be interpreted as a lake-wide fish-community or stock estimate. Repeated monitoring with georeferenced deployment and exact effort records would strengthen this catch-based baseline.

Kırıcı, Muammer; Özdemir, Nurgül Şen; Güneş, Muharrem; Sökmen, Teoman Özgür; Caf, Fatma; Türk, Cebrahil; Demir, Nurullah

Antioxidant defense systems in fish are highly sensitive to environmental variability and provide valuable indicators of physiological stress in aquatic ecosystems. This study evaluated the combined effects of seasonal variation, morphometric parameters (total length, total weight, and condition factor), sex, and species identity on oxidative stress markers and antioxidant defense responses in Capoeta umbla and Capoeta trutta collected from the Karasu River (Türkiye). Fish were seasonally sampled between April 2023 and March 2024, and malondialdehyde (MDA) levels and the activities of key antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR), were analyzed in edible muscle tissues. Length–weight relationships and Fulton’s condition factor were calculated to describe growth patterns and physiological status. The results indicated that seasonal variation was the primary factor influencing oxidative stress responses and antioxidant defense patterns in both species. Higher oxidative stress levels and increased antioxidant enzyme activities were generally observed during the summer period, reflecting physiological responses to elevated environmental temperatures. Morphometric parameters and species identity showed comparatively weaker associations with antioxidant variability. Overall, the findings highlight the dominant role of seasonal environmental dynamics in regulating oxidative balance in freshwater Capoeta species and support the use of antioxidant biomarkers as effective tools for assessing ecosystem health under changing environmental conditions.

Yildiz, Faruk; Aslay, Meral; Kaya, Ozkan

Fritillaria spp., comprising perennial bulbous plants of significant medicinal and ornamental value, face high endangerment in their natural habitats. Despite their importance, the reproductive characteristics and adaptive evolution mechanisms of these species remain incompletely understood. This study focused on the pollination strategies and reproductive biology of Fritillaria imperialis L. The research was conducted at the Erzincan Horticultural Research Institute in Türkiye. Our investigation categorized the flowering process of F. imperialis into nine distinct phases. Through comprehensive assessments of the pollen/ovule ratio, self-incompatibility index (SII), and ex situ pollination experiments, we observed high levels of self-incompatibility and allogamy in F. imperialis. Our findings revealed that pollination of F. imperialis primarily relied on pollen vectors, with Apis mellifera and Bombus terrestris identified as the most effective pollinators. Furthermore, average seed set rate, seed production, and seed viability were quantified at 80.5%, 228 seeds, and 86.3%, respectively. The average numbers of pollen viability and pollen grains were measured at 93% and 702,000, respectively. This comprehensive analysis of the reproductive biology of F. imperialis provides crucial insights for the conservation and genetic management of this highly valuable species. The findings contribute to a deeper understanding of the reproductive strategies employed by Fritillaria spp., which may inform future conservation efforts and breeding programs for these endangered plants.

Aslay, Meral; Yıldız, Faruk; Kaya, Ozkan; Bita-Nicolae, Claudia

Fritillaria is highly endangered in their natural habitats, and these species are perennial bulbous plants with an important medicinal and ornamental value whose reproductive strategies and adaptive evolution mechanisms are still not fully clear. Therefore, the reproductive strategies of endemic species, like Fritillaria michailovskyi Fomin are important to detect the community structure and the diversity patterns of ornamental plants. The current paper on the reproductive strategy of F. michailovskyi, a rare endemic species, was carried out at the Erzincan Horticultural Research Institute, Turkey. Our results indicate that the flowering stages of F. michailovskyi may be divided into eight phases. According to pollination experiments and the pollen/ovule ratio, and the self-incompatibility index (SII) in an ex-situ population, F. michailovskyi indicated high levels of xenogamy and self-incompatibility. It was determined that the pollination of F. michailovskyi mostly depended on pollen vectors, and the effective pollinators of F. michailovskyi were Apis mellifera and Bombus terrestris. In addition, average seed number, seed germination, and average seed viability were found as 144, 46%, and 67%, respectively. The stigma receptivity, pollen grains, and pollen viability were detected as 83%, 252,000, and 95%, respectively. Our study is the first report providing a detailed explanation of the reproductive strategy of this rare endemic species, which could aid in the genetic evolution and conservation of this valuable taxa.

Yıldız, Faruk; Aslay, Meral; Kandemir, Ali; Kaya, Ozkan

Fritillaria aurea, unlike other Fritillaria species, is a narrowly endemic species. It has a brown checkered speckled color on each tepal and also has regular yellow intense colors on the tepals. Its large bell-shaped appearance when the flower is open is one of its most striking ornamental features. However, F. aurea plant numbers are limited in their natural habitats, and their numbers are decreasing day by day; they are even confronted with the risk of extinction owing to the damage resulting from human activities. This detailed investigation of reproductive biology plays a vital role in determining the evolutionary success and survival of F. aurea, largely in determining the effectiveness of their reproductive performance. Our results indicate that the species exhibits a very low partial dichogamy and herkogamy structure, as well as self-incompatible pollination. The flowering period ranges from March to April. Average seed viability, average seed number, and seed germination were determined as 71%, 255, and 45%, respectively. The pollen viability, pollen grains, and stigma receptivity were found as 96%, 392.000, and 85%, respectively. The pollen/ovule ratio (P/O) and self-incompatibility index (SII) in the spontaneous cross-pollination were detected as 1537 and 0, respectively. Flowers of F. aurea were visited by several insect species, mostly honeybees (Apis mellifera); Bombus sp. and Vespa sp. also played a minor role in pollination. To sum up, these results not only lay a solid foundation for further reproductive biology investigations to more broadly reveal the mechanisms of F. aurea endangerment in the future but also provide a reliable theoretical basis for hybridization breeding of parents.