Nitzschia Amphibia Research Articles

Periphytic algae from rice fields: taxonomic and functional analysis in a harsh environment (NW Italy)

Rice fields are one of the most important agricultural environments in Northern Italy. These agroecosystems are characterized by high variations in water temperature, shading by rice plants, and sporadic droughts that affect the life of aquatic organisms. In the present study, we carried out an analysis within the limits of two rice fields and their water supply canal in the Lomellina (Lombardy; NW Italy). The aims of this study were (1) to quantify the main benthic primary producers colonizing the two rice fields and their feeding canal, focusing on diatoms, green algae, and cyanobacteria; and (2) to shed light on the taxonomic and functional composition of diatom communities living in these three environments. The study was conducted during the spring and summer 2023, corresponding to the growth phases of rice plants and the peak of diatom primary productivity. A total of 54 samples were collected from these three environments, by using artificial substrates. Diatoms dominated the canal channeling water to the rice fields, while diatoms and cyanobacteria were co-present in the two rice fields. Among the diatoms, low-profile and motile guilds were dominant in the water canal while, to the contrary, we observed a higher percentage of motile tolerant species in the rice fields, such as Navicula veneta, Nitzschia amphibia and Planothidiun incuriatum, a recently described species. The analysis of the microalgae communities can be useful to define the proper management of wetland-like environments and the conservation of their biodiversity.

Taxonomic composition of epilithic diatoms and indicator role in freshwater pools and the effect of pollution in the Keban Dam lake, Turkey

The aim of this study is to determine the epilithic diatom flora of stations exposed to pollutants of different characteristics, to test the relationships of these diatoms with water quality and the suitability of environmental quality indicators, and to determine different indicators of various quality pollutants for the rapid assessment of ecological pollution. Additionally, determining the ecological impact of both industrial and domestic waste on the reservoir in the region and determining whether the diatom community changes when exposed to various pollutants (including potential mortality), especially its role as an indicator of metal pollution; Samples taken from stations where domestic and industrial wastes were discharged with different chemical properties were evaluated and investigated. A total of 100 species were identified for Bacillariophyta. Although there was no significant change in the number of the species among the stations, significant changes were observed in the community structure. While Achnanthidium minutissimum, Fragilaria capucina, Gomphonema parvulum, Nitzschia palea and Surirella angustatum were the dominant diatoms in the impermeable artificial pool where the industrial wastewater of the factory was collected, Nitzschia amphibia, N. palea, N. recta and Ulnaria ulna were the dominant diatoms of the station where domestic wastewater was discharged. In the dam area where domestic wastewater is discharged, Fragilaria capucina Ulnaria ulna and Diatoma vulgaris are the dominant diatoms. Achnanthidium minutissimum, Gomphonema parvulum Navicula cinta and Nitzschia amphibia, N. angustata were the dominant diatoms of the station where both domestic and industrial wastewater was discharged. It was determined that benthic diatoms responded to different types of waste by changing their species composition, and that the change in the benthic community was not due to seasonal differences in stations under the influence of pollutants with different chemical properties. Diatom taxa which are known to tolerate metal concentrations, diatom diversities, and teratologies were determined.

Diatoms and water quality indices in Thamirabarani river help environmental impact assessment of stretch between Naranammalpuram and Punnakayal, Tamil Nadu, India

The present study reports the occurrence of diatom taxa, their distribution and ecology in Thamirabarani River between the study areas Naranammalpuram and Punnakayal, covering the districts of Tirunelveli and Thoothukudiin Tamil Nadu, India. The study employs diatoms collected from 10 different locations in the Thamirabarani River to monitor its quality. A total of 40 diatom taxa belonging to 20 genera were recorded in the study area. The dominant presence of diatom taxa, such as Aulacoseira ambigua, Cocconeis placentula, Cyclotella meneghiniana, Cymbella tropica, Discostella stelligera, Gyrosigma acuminatum, Navicula cryptonella, Nitzschia amphibia, Planothidium lanceolatum, Staurosirella pinnata, and the water quality index values (29–48) recorded at sites 1 to 7 indicate oligotrophic due to good flow of water. The abundant of diatom taxa, such as Diadesmis confervacea, Gomphonema parvulum, Nitzschia palea and Pinnularia gibba, were recorded at sites 8–10, and the water quality indices (100–110) indicate eutrophication attributable to less flow of water, high dispersion of cremation ashes (the casting ceremony) and anthropogenic activities. Particularly, locations around Punnakayal are most polluted due to the dumping of fish wastes as well as stagnant water.

Distribution of the Diatoms and Water Quality Assessment of the Thamirabarani River, Tamil Nadu, South India


 
 
 
 
 
 The diatoms are one of the most significant organisms beneficial for biomonitoring investigations. The present study deals with the diatom and water samples collected from 10 different localities in the Thamirabarani River, Southern India. Diatom samples were collected by scraping stones with a toothbrush and squeezing macrophytes. Study of diatom valve morphology and measurements of diatoms were carried out using an optical miccroscope. The present study recorded 58 diatom taxa belonging to 25 genera. Among the diatoms, the taxonomical characters of 20 abundant diatom taxa viz. Aulacoseira granulata, Discostella stelligera, Navicula cryptocephala, Encyonema minutum, Gomphonema gandhii, Eunotia asterionelloides, Gomphonema parvulum, Brachysira neglectissima, Aulacoseira ambigua, Diadesmis confervacea, Nitzschia palea, Nitzschia amphibia, Sellaphora Americana, Staurosirella pinnata, Gomphonema affine, Fragilaria pararumpens, Eunotia incisa, Navicula erifuga, Navicula cryptotenella and Navicula rostellata are described and illustrated. In the present study abundant diatom genera were observed such as Aulacoseira, Discostella, Navicula, Encyonema, Gomphonema, Brachysira, Nitzschia, Sellaphora, Staurosirella, Fragilaria and Euno- tia. In abundant diatom taxa such as Aulacoseira granulate, Discostella stelligera, Gomphonema gandhii, Fragilaria pararumpens, Navicula cryptocephala, Navicula rostellata, Staurosirella pinnata water quality index values between 21-42 were recorded at Sites 1-9, which indicates unpolluted water. The abundant diatom taxa Diadesmis confervacea, Nitzschia palea, and Gomphonema parvulum were present at Site 10 and a water quality index value of 101 was recorded, indicating water polluted due to anthropogenic activity. The diatom assemblage of the present study was compared with various river systems to understand the environmental condition assessment. The water samples were analysed for assessment of the water quality.
 
 
 
 
 
 
 

Spatial and Temporal Heterogeneity and Ecological Health Evaluation of Diatom Community Based on eDNA

In recent years, environmental DNA (eDNA) has been widely used in aquatic biodiversity monitoring, and how to establish a river ecological health assessment method based on eDNA has become a hot topic. This study was intended to develop a molecular diatom index based on eDNA to indicate the ecological health status of rivers under the influence of human activities. Firstly, the diatom community composition and structural changes in the Shaying River basin in spring and autumn were monitored through eDNA, and the driving environmental factors of the diatom community were diagnosed. Further, four strategies (OTU-taxonomy, OTU-free, ASV-taxonomy, and ASV-free) based on eDNA metabarcoding data were compared, and a molecular diatom index suitable for ecological health assessment in the Shaying River basin was constructed. The results showed that: ① there were seasonal differences in diatom community structure, and Discostella pseudostelligera, Nitzschia amphibia, Diatoma vulgaris, and other groups were the main factors to distinguish the seasonal differences. ② Mn, Fe, and TN were the main environmental factors affecting diatom community structure in spring, whereas COD and Cu were the main environmental factors affecting diatom community structure in autumn. ③ Among the four strategies, the diatom index calculated based on OTU-free data better reflected the environmental gradient change; the diatom index showed that the ecological health status of the Shaying River Basin was better in autumn than that in spring in time and better in the upstream than that in the downstream in space. In conclusion, this study monitored diatom community in Shaying River in spring and autumn through eDNA and constructed the molecular diatom index in the Shaying River basin, which promoted the application of eDNA to evaluate river ecological health.

Long-term manganese exposure-mediated benthic diatom assemblage in a subtropical stream: Distribution, substrate preferences and Mn-tolerance

Long-term manganese exposure-mediated benthic diatom assemblage in a subtropical stream: Distribution, substrate preferences and Mn-tolerance

Riqueza y distribución de las diatomeas epilíticas indicadoras de contaminación en el río Angulo afluente del río Lerma, Méxic

Background. The Angulo River has been subject to environmental deterioration as a result of agriculture practices and industrial discharges to its tributary. Goal. Determine the species of diatoms that indicate contamination and their distribution in the Angulo river, a tributary of the Lerma river. Methods. Twelve sites including 2 springs were selected during the low-water and post-rain periods of 2005. The samples were obtained by scraping the rocks to separate the attached diatoms. These were cleaned by oxidizing the sample with hydrochloric acid and hydrogen peroxide; permanent preparations were made with Naphrax® resin, for review with light microscopy. Results. 50 taxa belonging to 20 genera were identified, of which 5 species belong to central forms and 45 to pennate species. The taxa present in both periods were Achnanthidium minutissimum, Amphora pediculus, Luticola geoppertiana, Nitzschia amphibia, Nitzschia dissipata var. dissi- pata, Pleurosira laevis, Staurosira pinnata and Ulnaria ulna. The temperature, pH, dissolved oxygen and total dissolved solids in the Angulo river presented spatial variations and with it the species records. Conclusions. Representative taxa of eutrophic and non-eutrophic environments were found throughout the tributary, such as Nitzschia palea and Amphora pediculus, respectively. This study has provided relevant information re- garding the presence and distribution of diatom species that can be used as bioindicators of environmental conditions. specific.

Phytoplankton Community of a Boron Mine Waste Storage Reservoir

This study aimed to assess the composition, seasonality, and abundance of the phytoplankton community of a Boron (B) mine effluent storage reservoir, Çamköy Reservoir, Balıkesir, Turkey. For this purpose, phytoplankton and certain physicochemical parameters were sampled seasonally between April 2015 and January 2016. B concentrations ranged from 554 mg L-1 to 689 mg L-1. A total of 39 taxa were identified during the study. The percent composition for each phytoplankton group was as follows: Bacillariophyta 67%, Chlorophyta 10%, Cyanobacteria 8%, Euglenophyta 8%, Mioza 5%, and Charophyta 2%. In summer 2015 no phytoplankton was detected in the samples and the excessive B concentrations (above 600 mg L-1) in the reservoir seem to be the reason for the lack of phytoplankton in the summer samples. The most common taxa were Navicula digitoradiata (Bacillariophyta), Surirella ovata (Bacillariophyta), and Nitzschia amphibia (Bacillariophyta). The reservoir had a low number of phytoplankton taxa and abundance compared with the natural lakes probably due to the excessive B levels. The phytoplankton community of the reservoir was composed of taxa that preferred alkaline waters.

Response of epilithic diatom assemblages to weir construction on the Nakdong River, Republic of Korea

Response of epilithic diatom assemblages to weir construction on the Nakdong River, Republic of Korea

Periphyton colonization and changes in the diatom assemblages of an artificial urban pond

Artificial ecosystems are sometimes the only opportunity for citizens to experience nature. Maintaining their quality is essential for continuing to enjoy the ecosystem services. We studied an urban pond in the Northwest Iberian Peninsula (Aveiro, Portugal) as a model for testing the suitability of diatom assemblages and indices of water quality in these particular ecosystems. Weekly sampling of three replicas was performed over 28 days on stones and ceramic tiles in a shaded site (Site-SH) and in a sunnier one (Site-SU). The best model of the distance-based analysis included temperature and NH4+as the variables that best explained the diatom assemblages (R 2= 0.43). Chlorophyll-α taken as a proxy for algae biomass, and ash-free dry mass increased until the third week, when a turbid runoff entered the system. After this disturbance, chlorophyll-α increased only at Site-SH (from 14.4 mg m –2 to 62.4 mg m–2); ash-free dry mass increased at Site-SU (from 7.2 mg m–2 to 42.3 mg m–2). The Specific Polluosensitivity Index of the diatoms showed low values below 16 that further decreased with the incubation time. Shannon diversity did not vary between sites, while ANOSIM (analysis of similarity) enabled the identification of differences in the species composition among sites and over time. Cyclotella meneghiniana and Sellaphora nigri were abundant at both sites, but other species showed a prevalence to one of the sites: Nitzschia amphibia and Gomphonema parvulum dominated at site-SH, whereas Amphora pediculus and Grunowia solgensis were abundant at site-SU. This study provides evidence that the use of benthic diatoms is a useful tool for evaluating the ecological potential of artificial ecosystems. Moreover, such systems in the close vicinity of urban areas need better management and monitoring to reduce the risk of deterioration.

Soil diatom communities and their relation to environmental factors in three types of soil from four cities in central-west China

Soil diatom communities and their relation to environmental factors in three types of soil from four cities in central-west China

Nanoporous Silica of Some Egyptian Diatom Frustules as a Promising Natural Material

Background:Diatoms are a large unique group of unicellular microalgae with a significant ornamented cell wall made of hydrated silica, which is called "frustule". Their ornamented siliceous shells are usually composed of multi-layer structures with multi-scale porosity, which can be used as a promising source to obtain hierarchical macro and mesoporous silica microparticles. The present study is one step forward through a long road seeking for green nanofabrication techniques of such porous materials that will be economically more efficient with large design flexibility.Materials and Methods:For seeking different porosity scales, architectures, and distribution patterns, a total of 237 diatom species and varieties belonging to 68 genera were identified from 59 samples, which were collected from different Egyptian habitats and environments. Of these eight species were selected to study their frustules' ultra-structures in details, including; Aulacoseira granulata (Ehrenberg) Simonsen, Actinocyclus octonarius Ehrenberg, Cyclotella meneghiniana Kützing, Pleurosira laevis (Ehrenberg) Compére, Synedra ulna (Nitzsch) Ehrenberg, Achnanthes brevipes Agardh, Nitzschia amphibia Grunow and Nitzschia palea (Kützing) W. Smith. Nitzschia palea (Kützing) W. Smith was also isolated and cultivated.Results:The ultrastructure and porosity of all studied species had been revealed. The porosity scale was ranged from 5 to 500 nm in diameter.Conclusion:The obtained results showed the potential of diatom frustules in nanotechnology as a source of natural silica microparticles with macro and mesoporous structures could be of a large interest for applications including ultra, micro and nanofiltration, drug delivery systems, optoelectronics, or other novel nanotechnology applications.

Diversity, ecology and distribution of benthic diatoms in thermo-mineral springs in Auvergne (France) and Sardinia (Italy).

This study investigated and compared the diatom flora from thermo-mineral springs in Auvergne (France) and Sardinia (Italy). Samples were collected from rock/cobbles and fine sediments in 16 springs between January 2015 and March 2017. A total of 207 taxa (59 genera) were found. Multivariate analyses revealed significant differences in species composition and abundance among diatom assemblages both within each geographic region and between Auvergne and Sardinia (global R = 0.516; p = 0.002), suggesting the importance of local and climatic factors in species distribution. Based on abundance and common occurrence in multiple sites, some taxa can be considered more representative of springs in each region: Crenotia thermalis for Auvergne and Lemnicola exigua, Nitzschia amphibia, N. inconspicua and Rhopalodia operculata for Sardinia. pH, conductivity and HCO3− were the most significant environmental variables for diatom assemblages. Our results highlight the high heterogeneity of these spring systems. Future taxonomic insights can be useful to define the identity of some abundant and dominant taxa not identified at the species level in this study. Their identification is a crucial step for a more precise ecological characterization and comparison of these peculiar spring systems.

Bio-assessment of surface waters in the south-east of Gaziantep (Turkey) using diatom metrics

Diatom metrics can be used to identify the ecological status of water bodies due to their good responses to anthropogenic disturbances. Our study is aimed to use diatom metrics developed from different ecoregions for assessing the ecological status of 11 surface waters in the south-east of the Gaziantep catchment (Turkey). Ecological characterizations of the sampling stations were introduced by Trophic Index Turkey (TIT), Trophic Index (TI), and Eutrophication and/or Pollution Index-Diatom (EPI-D). According to TIT and TI, Karkamış Reservoir had a good ecological condition while it had high ecological status based on EPI-D. This good ecological condition was approved by the presence of pollution sensitive species (e.g.,Cymbella affinis,Encyonema minutum,E. silesiacum,Cymbopleura amphicephala, andNavicula radiosa) and relatively low nutrients. Kayacık (TIT ranging 3.15–3.23) and Hancağız (TIT = 3.35) reservoirs had poor and bad ecological conditions, respectively. High nutrient, conductivity, and pollution-tolerant species (e.g.,Nitzschia amphibia,N. palea,N. umbonata,N. linearis,N. phyllepta,Tryblionella calida, andPinnularia brebissonii) supported the ecological statuses of the Hancağız and Kayacık reservoirs. The first two axes of canonical correspondence analysis explained 0.943 of relationships between diatom species and explanatory variables. Explanatory variables,e.g., calcium, conductivity, orthophosphate, nitrate, nitrite, sodium, pH, and sulfur, had strong impacts on the distribution of diatom assemblages among the sampling stations. TIT and TI separated ecological statuses of sampling stations in the south-east of the Gaziantep catchment, which correlated well with the evidence of water chemistry and response of diatom assemblages.

ALGAE AS BIOINDICATORS FOR DETERMINING THE WATER QUALITY OF EUPHRATES RIVER IN HADITHA CITY

The current study included the use of algae as bioindicators to assess the quality of the Euphrates River within the city of Haditha. Four sites on the river were selected and samples were collected every month for a year since March 2017. Some important environmental factors have been studied for the growth of algae, including water temperature, electrical conductivity, pH, dissolved oxygen, and nutrient concentrations such as phosphates and nitrates. Two biological indices were applied: (Shannon Weaver Diversity Index) and (Algal Genus Pollution Index), which are based on water quality. The results showed that the water ranged from clean to medium pollution except site 2, which is likely to have a high level of pollution. During the study, 206 species of algae were identified. The predominance was to Bacillarophyta followed by Chlorophyta then Cyanophyta and Euglenophyta and then Pyrrophyta. The predominant species were: Bacillaria paxillifer, Cocconeis placentula, Nitzschia amphibia, N.cryptocephala, N.dissipata and Fragilaria crotensis

Examination of original material for Navicula nigri De Notaris with some notes on the Erbario Crittogamico Italiano (1858–1885)

The discovery of exsiccata no 632 of De Notaris’s Erbario Crittogamico Italiano now provides a lectotype for Sellaphora nigri (De Notaris) C.E. Wetzel & Ector, a common and widely distributed freshwater species originally described from the River Po (Italy). The lectotype takes precedence over the neotype previously designated by Wetzel and co-authors. New observations were made using light and scanning electron microscopy. A few notes on diatoms described in Erbario Crittogamico Italiano are briefly presented, along with illustrations of species present in the original protologue, including Nitzschia amphibia var. padana De Notaris nomen nudum.

Glacial and interglacials in the Neotropics: a 130,000-year diatom record from central Panama

The last interglacial was the most recent time when temperatures were 1–2 °C above modern, but little is known of this period in the lowland Neotropics. Equally, data for the full glacial period are very limited. A detailed analysis of the period between ~ 137 and 100 ka was completed to provide a paleoecological history of the last interglacial in central Panama. Two additional fossil diatom records from the same depositional basin provided records of the glacial period. Diatom assemblages were compared across all cores and the dominant species of both glacial and interglacial periods was almost always Aulacoseira granulata. Other species, e.g. Aulacoseira agassizii, Achnanthidium minutissimum, Nitzschia amphibia, and Navicula radiosa, had distinctive patterns of abundance within the record, indicating a shallowing of the lake in the last millennia of MIS5e. The period between 119 and 108 ka witnessed the most change within the high-resolution portion of the record suggesting an increased lake level, with expanding lake margins. Other sediment cores collected within the caldera revealed the continued presence of a lake at El Valle through much of the glacial period, with shallowing evident at the time of the LGM. The changes in diatom assemblages at El Valle provide one of the oldest precipitation records from Central America tracking mean ITCZ position between the last interglacial and glacial periods. Furthermore, the evidence for both a wet interglacial and glacial period support palynological findings that the humid environments of Central Panama were not interrupted by glacial aridity.

Applicability and efficacy of diatom indices in water quality evaluation of the Chambal River in Central India.

Diatom indices have gained considerable popularity in estimation of the trophic state and degree of pollution in lotic ecosystems. However, their applicability and efficacy have rarely been tested in Indian streams and rivers. In the present study, benthic diatom assemblages were sampled at 27 sites along the Chambal River in Central India. PCA revealed three groups of sites, namely, heavily polluted (HVPL), moderately polluted (MDPL), and least polluted (SANT). A total of 100 diatom taxa belonging to 40 genera were identified. Brachysira vitrea (Grunow) was the most abundant species recorded from the least polluted sites with an average relative abundance of 29.52. Nitzschia amphibia (Grunow) was representative of heavily polluted sites (average relative abundance 31.71) whereas moderately polluted sites displayed a dominance of Achnanthidium minutissimum (Kϋtzing) with an average relative abundance of 26.33. CCA was used to explore the relationship between diatom assemblage composition and environmental variables. Seventeen different diatom indices were calculated using diatom assemblage data. The relationship between measured water quality variables and index scores was also investigated. Most of the diatom indices exhibited strong correlations with water quality variables including BOD, COD, conductivity, and nutrients, particularly phosphate. Best results were obtained for TDI and IPS indices which showed a high level of resolution with respect to discrimination of sites on the basis of pollution gradients. Water quality maps for the Chambal River were hence prepared in accordance with these two indices. However, satisfactory results with respect to water quality evaluation were also obtained by the application of EPI-D and IGD indices. The present study suggests that TDI and IPS are applicable for biomonitoring of rivers of Central India. Diatom indices, which are simpler to use such as IGD, may be considered, at least for a coarser evaluation of water quality.

Epilithic diatom assemblages and their relationships with environmental variables in the Nilüfer Stream Basin, Bursa, Turkey.

Patterns of epilithic diatom species distribution in relation to environmental variables from 12 sampling sites on the main stream and some of its tributaries in the Nilüfer Stream Basin were determined using multivariate statistical techniques. The stream basin has been heavily influenced by anthropogenic effects. The upper part of the basin that is distant from pollution sources mostly has a spring water quality, while the lower part where the stream flows through the urban area and receives domestic and industrial wastewater has a quite low quality. Ordination techniques using both diatom taxa and 21 environmental variables revealed non- to slightly polluted upper basin sites and highly polluted lower basin sites along the stream. The results showed that the stream catchment is polluted gradually from upstream to downstream and that most of the downstream sites have very low water quality especially in summer months. A total of 134 epilithic diatom taxa belonging to 50 genera were recorded for 12 sample sites. Partial CCA results indicated that water temperature (T), discharge (Q), and total phosphorus (TP) were the most important variables affecting the distribution of diatom species. Unpolluted or slightly polluted upper basin sites were dominated by Achnanthidium minutissimum, Cocconeis placentula var. euglypta, Gomphonema olivaceum, and Navicula tripunctata. Highly polluted lower basin sites were characterized by high levels of organic and inorganic matters and low dissolved oxygen (DO) values. Species widespread in the highly polluted lower basin sites such as Nitzschia umbonata, Nitzschia amphibia, Nitzschia capitellata, Nitzschia palea, Nitzschia paleacea, Luticola mutica, and Stephanodiscus niagarae were mostly related to pollution indicator variables such as ammonium nitrogen (NH4+-N), sodium (Na+), total phosphorus (TP), and total organic matter (TOM).

Comparative responses of dominant and subordinate periphytic diatom species to environmental gradients in Donghu Lake, China

An annual investigation on periphytic diatoms and physicochemical parameters was performed in Donghu Lake, China, to explore a suitable method to differentiate the dominant and subordinate taxa, and how they responded to the change of environmental factors. The results showed that: (1) a combined consideration of species frequency of occurrence and relative abundance for defining the dominant index was more appropriate than using solely relative abundance; (2) the dominant taxa Fragilaria capucina var. vaucheriae (Kutzing) Lange-Bertalot and Melosira varians Agardh responded insensitively to the environmental factors, whereas the subordinate species Fragilaria capucina Desmazieres var. capucina, Nitzschia amphibia Grunow, Achnanthidium exiguum (Grunow) Czarnecki and Melosira italica (Ehrenberg) Kutzing showed the potential to be indicators; F. capucina var. radians (Kutzing) Lange-Bertalot increased along the gradient of higher water temperature (WT) and nutrients concentration, however, Fragilaria bidens Heiberg and Cymbella affinis Kutzing were affected in the opposite direction. Our findings revealed that periphytic diatoms varied seasonally and were useful for assessing water quality of different trophic status. Especially the subordinate species showed the potential to be better indicators than the dominant species in Donghu Lake.