Examination of the alpine chironomid stratigraphy of Eğrigöl (Antalya)

In this thesis study, the chironomid stratigraphy of Eğrigöl (Antalya) was examined in a 50 cm core at 1 cm sequence intervals. Breaks in chironomid communities along the depth axis were identified using numerical methods and interpreted ecologically. Raw counts were converted to percentages based on the total number of head capsules per sample, rare taxa were filtered out according to low contribution thresholds, and a Hellinger transformation was applied. Principal Component Analysis (PCA) was used for ordination of the taxa. The PC1 axis was interpreted together with the species ordination and the PC1–depth profile. Constrained clustering approaches were applied for zonation, and a total of six zones (Z1–Z6) were defined using CONISS and one-dimensional dynamic programming–based segmentation on PC1 (with BIC evaluation). Diversity indices including Shannon–Wiener (H), species richness (S), and Pielou's evenness (J) were calculated and compared across zones. The results showed that PC1 represents the trophic status/oxygenation gradient. The negative side of the PC1 axis corresponded to the dominance of surface-near, eutrophic/warming-tolerant taxa (e.g., Chironomus plumosus type, Endochironomus type, Glyptotendipes type, Polypedilum type), whereas the positive side of PC1 corresponded to taxa adapted to oligotrophic, cooler, and well-oxygenated conditions in the lower part (e.g., Tanytarsus type, Paratanytarsus type, Cladotanytarsus type, Cricotopus type, Zavreliella type). Major zonal breaks were evident at ~8–10 cm, ~20–22 cm, and ~35–40 cm depths. H and J values peaked in Z3–Z4, indicating a balanced composition, while in Z1 evenness decreased due to the dominance of a few species, and in Z6 low richness together with an oligotrophic structure was observed.