somayyeh kheiri

The Kashkan River, situated in western Iran, is a significant waterway, primarily utilized for drinking water supply and agricultural purposes. Consequently, rigorous monitoring of the river’s water quality is imperative. Diatom’s teratological forms, and ecological stress indicators, play a crucial role in water quality assessment programs. Understanding the correlation between environmental factors and these teratological forms is crucial for accurate water quality indices. The primary objective of this study was to investigate the diatom teratological communities in the Kashkan River and explore their correlation with heavy metals, aiming to elucidate water quality dynamics. In spring 2019, 48 epipelic and epilithic samples were collected along the Kashkan River, considering the impact of anthropogenic activities on the river. Three distinct teratological forms were identified comprising type 1) deformities in valve outlines, type 2) deformities in striations, and type 3) mixed deformities. Notably, valve deformities in Achnanthidium minutissimum and Diatoma moniliformis were the most prevalent. Furthermore, the concentrations of Cd, Fe, and Cr in the sediments emerged as significant environmental variables associated with elevated heavy metal levels in the Kashkan River. Principal component analysis (PCA) highlighted that sedimentary Fe, Cu, and Cr concentrations were key factors influencing the composition of diatom teratological forms. Consequently, implementing a water quality management program is vital to enhance the overall water quality in the Kashkan River.

Diatoms are a key group of organisms of the periphyton and have a significant contribution to primary production in rivers. Despite their importance, little information exists about the taxonomy and distribution of periphytic diatoms in Iran. Central Alborz is one of the hotspots known globally for its fauna and flora and the Damavand River is one of the permanent rivers flowing in the region. Epilithic diatom samples were taken along the Damavand River basin between the summer of 2017 and the spring of 2019 to determine the benthic diatom flora. As a result, five species within the genera Gomphonema, Cymbella, Cymbopleura, and Sellaphora were found as new records from the Central Alborz. These species include Cymbella affinis var. angusta (Krammer) W. Silva, Cymbopleura similiformis Krammer, Gomphonema innocens Reichardt, Sellaphora capitata D.G. Mann & S.M. McDonald and Sellaphora lanceolata D.G. Mann & S.J.M. Droop.  The morphology of these taxa, comparisons to similar taxa, and geographic distributions are discussed. These results expand the knowledge of diatom diversity in the Central Alborz Region.

Diatoms are well-known indicators of water quality in rivers. Therefore, the composition and abundance of diatoms are used as a tool to monitor rivers in different countries. In Iran, few studies have been conducted on biomonitoring the rivers using diatoms. For diatom-based water quality assessment, it is necessary to determine the characteristic diatom species and the pollution tolerance level of the species. The present study investigates the indicator diatom assemblage from upstream (least polluted) to downstream (most polluted) stations along the Damavand River at different seasons from 2017 to 2019. The study of relative abundance and presence of species along the river showed that several species, sensitive to pollution, were dominant upstream. However, they were present as rare species and disappeared at high pollution levels in downstream stations. Several species had moderate resistance to pollution. Therefore, they reached the highest abundance in the river's middle course, and their abundance was highly reduced downstream. The most resistant species appeared in the lower reaches of the river, which had a very high level of pollution. This research introduces the indicator species of diatoms and their pollution tolerance in the Damavand water basin. Thus, this study can be a baseline for diatom-based water quality monitoring at aquatic resources in Central Alborz.

This study was performed to identify the anatomical responses of lemon balm to zinc oxide nanoparticles (nZnO) at the concentrations of 100 and 300 mg/l. The microscopic observation showed that the nZnO300 had the largest diameter of the central cylinder and the diameter of xylem and phloem in the root compared to the control. The study of stem cross-section revealed that the highest stem diameter was observed in response to the nZnO100 group. The maximum thickness of collenchyma and the highest diameter of the central cylinder and the diameter of phloem and xylem were also recorded in the nZnO100 group. Comparing the leaf cross sections indicated that the thickness of the upper and lower epidermis, the diameter of the xylem, the thickness of the spongy parenchyma in the nZnO100 group were significantly increased relative to the control. Comparison of petiole cross sections showed that the thickness of the upper and lower epidermis and the diameter of the central/lateral phloem and xylem in all nZnO-treated seedlings were significantly reduced compared to the control. This study provided anatomical evidence that indicates fundamental changes in the fate of cell differentiation and tissue formation in response to nZnO. Future research is needed to link physiological, molecular, and anatomical evidence to accurately understand the impact of nanoproducts on the entire life of plants, especially crops and medicines.

The aim of this study was to investigate the effect of application of selenium nanoparticles on anatomy and pattern of tissue differentiation in lemon balm. Plants were treated with nano-selenium (nSe; 0, 10 and 50 mg/l) and bulk selenium (BSe). The results of this study indicated that nanoselenium had a positive and beneficial effect at a concentration of 10, but a concentration of 50 induced toxicity. The microscopic assessment of stem cross sections showed that the diameter of the central cylinder was increased compared to the control. The highest increase was related to the seedlings exposed to the 50 and 10 mg/l. Stem thickness and diameter in the nSe-treated seedlings at 50 mg/l and bulk 10 mg/l were increased compared to the control. Xylem diameter decreased in response to the supplements, the lowest belongs to the nSe50. Monitoring the leaf cross sections showed that nSe10 increased thickness of xylem diameter, palisade and sponge parenchyma compared to the control. Comparison of petiole cross-sections indicated that the thickness of the epidermis and the diameter of the central the central and lateral xylem were changed. While, 50 mg/l nSe declined these traits. Therefore, the results of this study indicate that the application of applied concentration-dependent selenium, in addition to inducing physiological and molecular changes, causes anatomical changes and tissue differentiation. Further research is needed in the future to determine the mechanism of these responses.

Diatoms are robust indicators of water quality in aquatic ecosystems. So far, many diatom indices have been defined based on the diversity of diatoms in different countries. Studying diatom biodiversity in the reference conditions, under no human pressure and pollution, is necessary for evaluating the water quality in rivers. Cheshme-Ala is one of the springs of the Damavand River basin with high water quality. In this study, Cheshme-Ala is considered as a reference site for the Damavand River. This study aims to study sensitive diatom species to organic pollution and introduce Odontidium mesodon (Ehrenb.) Kützing as the indicator species for high water quality in Cheshme-Ala. Samples were collected from the substrates of the Damavand River and Cheshme-Ala in eight stations seasonally. Results showed that Odontidium mesodon was observed as a dominant species in Cheshme-Ala in March. The high abundance of this species indicates the favorable habitat for growth in Cheshme-Ala. Furthermore, this species was not observed in the polluted sites along the river seasonally. Therefore, this study demonstrated that Odontidium mesodon was the indicator of high water quality. Our data are congruent with the researches in the USA, Europe, and Russia, introducing this species as a sensitive species to organic pollution. The information can be used in water quality monitoring projects of the rivers.

Iran is a country that serves as the spot for diverse landscapes and aquatic ecosystems. Zagros Mountains, as one of its main ranges and the important segment of Alpine-Himalayan orogenic system are known as the biodervisity hotspots for plants and animals worldwide. Despite the numerous rivers flowing in the area, little survey has been conducted about the diatom flora of its rivers. Diatoms are the most diverse microalgae that have great contribution to the primary production in the aquatic ecosystems. Due to importance of diatoms in the aquatic ecosystems and the ecological and geological importance of the Zagros in the world, we aim to study the diatom flora in the Kashkan River flowing in the Zagros Mountains. In this research, 48 epipelic and epilithic samples were collected along the Kashkan River in Spring 2019. A total of 91 taxa was identified from which four species were recorded as new for the diatom flora of Iran. Furthermore, identification of 10 taxa are provisional which are designated as cf., when finalized, these may also be recognized as new records. Meanwhile, twenty unidentified taxa which are marked as sp., are potetilly new species, in need of furthere investigations. These novel taxa are highlights and prominence of this study. Our results serves as a baseline for the diatoms biodiversity in the Zagros Mountain.

Diatoms are the most diverse group of single-celled algae that contain fucoxanthin, clorophyll a and c. They are the beginners at the food chain in aquatic ecosystems. Didymosphenia geminata (Lyngbye) M.Schmidt is a diatom species, considered as an invasive species which has caused many environmental problems in North America, Europe, New Zealand and Australia. In an investigation on diatom flora of the Karaj River, Didymosphenia geminata was found as a dominant species with a relative abundance of 10% in January 2011. The dominance of this species in the Karaj River is a threat for the ecosystem of the river. Therefore, to protect the river ecosystem, monitoring programs should be conducted annually and in case of high prevalence of the species, measures should be taken to clear the species from the river.

Water is the most essential factor for life, and rivers are the main drinking source for human. Therefore, assessing the quality and management of rivers is essential for the protection and health of these rivers. Diatoms are one of the best monitoring tools used in European and American water quality monitoring programs. Due to the importance of diatoms in water quality assessment, the present study was designed and carried out to investigate the water quality of Karaj River based on diatom species and indicator diatoms for pollution. Diatom specimens were collected from the surface of the rocks at six stations along the river during 2011 to 2012 monthly. In this study, 128 species were identified and their relative abundance was calculated, of which 19 were dominant. Evaluation of water contamination based on minerals and biological oxygen demand showed that Karaj River water had moderate to very high pollution at the stations. The results of the ecology of the dominant species showed that most of these species increased with increasing organic and inorganic contamination and could be introduced as indicator diatoms for pollution. The present study is a baseline for future studies on diatom-based monitoring of mountainous rivers in the Alborz region.

Diatoms are the most diverse algae of the aquatic ecosystems and springs are of high value as the habit of high biodiversity and an important source of drinking for mankind. Therefore, study of the springs' algae flora is very important at the conservation view. In this research, the diatom biodiversity of the Tizab Spring and the spring-fed river was studied for the first time. Thirty species were identified of which one species (Achnanthidium gracillimum) is a new record for diatom flora of Iran. The data revealed that the flora is much similar to the Karaj River flora. This similarity can be due to the close geographical locations as both rivers are located in the Central Alborz region. The distribution pattern of the species were studied in Iran based on the present references on the Iranian aquatic ecosystems. This study presented that two-third of the species had a widespread distribution. The comparison of the flora with known European and American database showed that most species are the elements of the northern hemisphere. Diatom biodiversity studies in the Central Alborz region is in its first steps. Therefore, much research should be performed to reveal the diatom biodiversity and the potential new species in the region.

Marbareh river is one of the tributaries of Sezar and Dez rivers which is used for irrigating the agricultural lands of villages around the cities of Azana and Dorud. In this research, Diatom flora of Marbareh river was investigated for the first time. Sampling was done from rocks and sediments of the river seasonally from July 2013 till June 2014. Navicula, Cymbella, Nitzschia, Gomphonema and Diatoma occurred in all sites during the sampling period. It is in the case that some other genera such as Cymbopleura, Gyrosigma, Stauroneis, Meridion, Didymosphenia and Ulnaria were observed seasonally. Totally, 30 species were identified which belong to pennate diatoms. Comparing the diatom flora of Marbareh river with those of other Iranian waterbodies Iran showed that some species like Diatoma vulgaris, Diatoma moniliformis, Gomphonema olivaceum, Cocconeis placentula var. lineata, Gomphonema parvulum and Ulnaria ulna are widespread in Iran. However, more research work should be done to reveal the distribution pattern of other species.