نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم دریایی، دانشکده علوم و فنون دریایی، واحد تهران شمال، دانشگاه آزاد اسلامی، تهران، ایران
2 گروه مهندسی منابع آب، دانشکده عمران، آب و محیطزیست، دانشگاه شهید بهشتی، تهران، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Introduction: The distribution pattern of simuliids, like other aquatic animals and especially benthic invertebrates, is affected by the surrounding environment and the fluctuations of ecohydraulic variables. These Dipterans are common benthic organisms in running waters, and they show significant reactions in response to variations in the physical habitat and hydraulic variations.
Materials and Methods: In this research, trough PHABSIM simulation system, favorable biological conditions (HSC), and by using HABTAM module, and the percentage of favorable and settleable habitats (WUA) for this group of macrobenthos was analyzed. This research was carried out during 8 surveys (from the beginning of June 2022 to September 2023) in 4 study stations, by measuring 3 hydraulic variables and collecting Simuliid larvae/pupae in Cheshme-Kileh River.
Results and Discussion: A total of 4380 Simuliid larvae and pupae were examined. It is noteworthy that the maximum abundance of Simuliid larvae was recorded at the research center station located upstream (station 1) and the minimum abundance was recorded at the downstream deltaic station (station 4) of Cheshme-Kileh River. The habitat suitability curves (HSC) also showed a significant influence of the larvae of the Simuliid family on the hydromorphological conditions of the habitat in the Cheshme Kileh River, and the optimal habitat ranges for the population of Simulid larvae in the flow velocity of 0.8-1 m/s, depth 0.2 m and the substrate structure index (Channel Index) was evaluated as 50. The pattern obtained in HABTAM clearly shows that Simulid species prefer medium depths of about 0.15 to 0.9 and occupy the most WUA at these depths, at this depth range the maximum WUA% remained constant and the habitat conditions remained favorable for the larvae of this family. On the other hand, the highest value of WUA against dimensionless speed (V/Vmax) was determined to be around 0.4 to 0.5 and the suitable habitat area reached 22%. Also, the percentage of suitable habitat area in the speed ranges of 0.5 to 1.1 m/s remained constant at 18-22%. This suggests that Simuliid larvae prefer moderate flow conditions, which may provide optimal feeding and respiration conditions. In relation with the grain size and bed structure in Cheshme Kileh River, the percentage of suitable/usable habitat (WUA) showed an increase with the increase of D50. Also, in the middle ranges of the bed particles, the area of suitable habitat (WUA) remained in the range of 18-18.5%. And finally, at D50/(D50max ≈ 1), a significant increase up to about 21.5% in the appropriate habitat space was observed for the simulid larvae This trend indicates that the largest relative sizes of substrate materials provide the most suitable habitat conditions for attachment and settlement of simulid larvae. Also, in accordance with the patterns of WUA changes, the abundance distribution of simulid larvae also showed a significant decrease by reaching the river delta and by reducing the size of the bed particles.
Conclusion: Finally, the results of this research exhibited that by simulating and identifying the preferred habitats by macrobenthos, especially the sensitive groups to hydraulic discharge variables, including the larvae of the Simuliidae, it is possible to control the resource exploitation projects and direct the rehabilitation projects in such a way that constraints and advantages of the habitat should be considered and the components of the flow should be controlled in such a way that suitable habitats for simuliids or other macrobenthos and finally fish communities are preserved.
کلیدواژهها [English]
)