Ali Reza Radkhah, Soheil Eagderi, Hadi Poorbagher, Hashem Nowferesti,
Volume 9, Issue 1 (3-2022)
Abstract
Gambusia holbrooki Girard, 1859 is considered as one of the non-native and invasive species in the inland waters of Iran. This species occurs in most inland basins and aquatic bodies of Iran and has even been found in brackish waters. Extensive adaptations of this species to its different habitats caused numerous changes in its biological characteristics and morphological traits. The present study was performed to investigate the sexual dimorphism of G. holbrooki in the Gamasiab River, Kermanshah Province, Iran. 59 fish specimens were collected from the river in September 2017. After taxonomic confirmation and sex determination, 29 morphological traits were measured in fish samples using a caliper and their meristic traits were recorded. In total, 37 characters (including 8 meristic traits and 29 morphometric traits) were examined. After obtaining morphological data, Principal Component Analysis (PCA) and Discriminant Function Analysis (DFA) were utilized to compare morphological traits between male and female individuals. The results showed that the 59 specimens were comprised of 30 malea and 29 femalea. On the basis of the results, all morphological traits, except the caudal peduncle length, dorsal fin base length and a post-anal length, showed significant sexual dimorphism (p <0.05). The results of DFA and PCA analysis showed that males and females were completely different from each other in terms of morphometric traits. These findings indicate that there is a sexual dimorphism in G. holbrooki of the Gamasiab River. The sexual dimorphism observed in this fish species is due to the sexual selection and increase of reproductive success.
Dr. Atta Mouludi-Saleh, Dr. Soheil Eagderi, Dr. Hadi Poorbagher, Dr. Hamid Reza Esmaeili,
Volume 11, Issue 1 (6-2024)
Abstract
This study was conducted to investigate the ecological niche overlap of two sympatric species, Paracapoeta trutta and Capoeta damascina in the Iranian part of the Sirvan River, Persian Gulf basin. For this purpose, during the winter of 2021, sampling was done from eight stations (each with three repetitions). After identification, samples were released into the same sampling sites. Then some 10 environmental factors including depth, water velocity, river width, pH, temperature, electrical conductivity (EC), total dissolved solids (TDS), Altitude, slope, and dissolved oxygen were measured and recorded. Investigating the habitat suitability indices of P. trutta were recorded as pH 7.5-8, temperature about 10°C, TDS 150mg/liter, EC 400μS/cm, altitude 1150 m, depth 15cm, river width about 9m, velocity 1 m/s, slope 2% and dissolved oxygen 9mg/l and for C. damascina as pH 6-6.5, temperature about 10°C, TDS 180 to 200mg/l, EC 300μS/cm, altitude 1150m, depth 25cm, river width about 6m, velocity 0.5 m/s, the slope is 2% and the dissolved oxygen 8mg. The results of the ecological niche overlap showed that two species based on studied environmental factors had the highest overlap value for dissolved oxygen (0.646) and the value for temperature (0.293). The average ecological niche overlap was 0.432 for the two species.
