Genus Navicula Research Articles

The Diatom Genus Navicula in Spring Ecosystems with the Description of Navicula aquaesuavis sp. nov.

The Diatom Genus Navicula in Spring Ecosystems with the Description of Navicula aquaesuavis sp. nov.

High-throughput sequencing of Diatoms using V4 region of 18S rRNA gene in Bayug Island, Iligan City, Philippines

Abstract. Estor DEP, Tabugo SR. 2023. High-throughput sequencing of Diatoms using V4 region of 18S rRNA gene in Bayug Island, Iligan City, Philippines. Biodiversitas 24: 6343-6350. Diatoms are the main contributors to aquatic primary production and are the most dominant phytoplankton. Their adaptability and growth in diverse natural resources enable them to thrive in various climates and geographical areas, making them suitable for monitoring and biotechnology applications. This study aimed to analyze the diatom composition in two study sites: a mangrove area and the estuary in Bayug Island. The analysis was conducted using metabarcoding of the V4 region of the 18S rRNA gene, amplified and sequenced on the Illumina MiSeq platform. Four amplicon libraries were generated, representing the diatom composition at the two study sites. Data processing was performed using the Parallel-Meta-Suite software. Following quality control and processing, 20,433 amplicon sequence variants (ASVs) were obtained. Among these, the genera Navicula, Thalassiosira, Chaetoceros, Guinardia, Amphora, and Minidiscus were the most abundant ASVs. The assessment of diatom alpha diversity using the Shannon index indicated a higher diversity in the estuary site. Furthermore, the analysis done within the Parallel Meta Suite suggested that the presence of these specific diatom species can be linked to salinity levels, and may indicate environmental disturbances such as water pollution. The presence of these diatoms has the potential to be utilized in ecological treatments, disease prevention, biotechnology, and as nutrient indicators for other marine organisms. Physico-chemical parameters were recorded in the estuary area (S1), with the average water pH measuring around 7.6, salinity at approximately 36.6 ppt, and water temperature at 26.7?. In contrast, the measurements in the mangrove area (S2) revealed an average water temperature of 30?, salinity of around 35 ppt, and a water pH of 7.7. This research will serve as baseline data for diatom community in the area and a pioneering work on using NGS and eDNA for diatom study.

Gandhia gen. nov.—A New Diatom Genus with Unusual Morphology Split Off from the Genus Navicula Bory

Gandhia gen. nov.—A New Diatom Genus with Unusual Morphology Split Off from the Genus Navicula Bory

Gas Chromatography-Mass Spectrometric Study of Low-Molecular-Weight Exogenous Metabolites of Algae-Bacterial Communities in the Laboratory Accumulative Culture

The study of exogenous metabolites of algae-bacterial communities in the laboratory accumulative culture obtained from natural river water was conducted using gas chromatography-mass spectrometry. Exometabolites of the algae-bacterial community (including microalgae and cyanobacteria) in the culture medium were represented by saturated, unsaturated, and aromatic hydrocarbons, carboxylic acids, phenolic, and terpene compounds and their derivatives. Possible biological activities of the discovered exometabolites are considered. The study has demonstrated that an increase in the number of main groups of microorganisms, along with changes in the composition of algae and cyanobacteria, are responsible for the increase in the composition and concentration of metabolites in the microecosystem’s culture medium after one month of cultivation. The presence of octacosane in high concentration (0.0603 mg/L; 23.78% of the total content of low molecular weight organic compounds) by the end of exposure accumulative culture is associated with the strong development of the cyanobacterium Gloeocapsa sp. in the presence of diatom algae of the genus Navicula and green algae of the genera Chlorella and Scenedesmus. Due to the need to comprehend the ecological and biochemical mechanisms of the formation and functioning of algae-bacterial communities, as well as to predict potential paths of transformation and evolution of aquatic ecosystems, the specificity of exometabolite complexes of algae and microorganisms, as well as their allelopathic and other biochemical interactions in freshwater ecosystems, requires further serious study.

МОРФОЛОГИЯ, ТАКСОНОМИЯ И ЭКОЛОГИЯ NAVICULA PHYLLEPTA (BACILLARIOPHYTA)

This scanning electron microscopical study of algae from lakes in the in vicinity of the Ust-Lena Reserve made it possible to obtain new information on the morphology of a number of representatives of the genus Navicula: N. phyllepta and N. phylleptosoma. A wider variability of the main quantitative (valve length and width, the number of striae and areolae in 10 µm) and qualitative (structure of the raphe) diagnostic features as well as the conspecificity of the two species were shown. It is proposed to reduce N. phylleptosoma to synonymy of N. phyllepta and extend the diagnosis of the latter.

Navicula sinicomeniscus sp. nov. (Bacillariophyta; Naviculaceae), a new species from southwestern China

Based on light and scanning electron microscopy observations, Navicula sinicomeniscus sp. nov. is described here as a new species from oligotrophic Lake Fuxian in Yunnan Province, China. Characteristics of this new species used to assign it to the genus Navicula include filiform, almost straight to slightly curved raphe structure, lineolate striae, and a row of visible, horizontal areolae positioned on the valve mantle at the apices. The key diagnostic features between the new species and other similar species include: valve shape and size, stria and areola densities, as well as the straightness or degree of bending of the raphe. Comparison with morphologically similar species is discussed in detail. These results can help us further understand the morphological and ecological information of the genus Navicula in Fuxian Lake.

Phytoperiphyton in watercources rivers of the north coast of Onega Lake

A survey of a phytoperiphyton study in the 11 watercourses of the North Coast of Onega Lake is presented. Taxonomic composition, ecology, and spatial dynamics of attached communities are analyzed. A total of 232 species, varieties, and forms of algae from 6 divisions were identified: Cyanophyta (Cyanoprokaryota) (16), Bacillariophyta (166), Chlorophyta (38) and others (7). The most diverse in phytoperiphyton are diatoms from the genera Navicula, Fragilaria, and Achnanthes (23, 17 and 16 taxa respectively). Fragilariaceae (24 species), Naviculaceae (78), and Desmidiaceae (23) are the most important families in terms of phytocenology. In total, they comprise 125 species: more than 50% of revealed algal species. Dominant complex is represented by moderate range of species being resistant to dynamic water load. It is indicated that ecologo-geographical composition of algae is dominated by widespread oligohalobial species being alkaliphilic or indifferent to medium pH. Most saprobity-indicator species are oligo-, oligo-beta- forms, suggesting that human activities do not have a considerable impact on the water bodies.

Composição e estrutura da comunidade de diatomáceas bentônicas de marismas do sul do Brasil e sua relação com variáveis ambientais

Abstract: Aim This study focused on the spatiotemporal variation of the benthic diatom community structure in salt marshes from the Patos Lagoon estuary and their relationship with environmental variables. Methods Samplings were carried out in the winter of 2010 and summer of 2011 (during El Niño and La Niña) in sites with different sediment granulometry, salinity, and distances from the Atlantic Ocean. The surface sediment was collected using a core (10 cm in diameter and 2 cm in depth) and the benthic diatoms were removed following the Trapping method, allowing the observation of live diatoms. Results The richness values (18 and 48 taxa), evenness (0.41 and 0.68), and Shannon diversity indices (2.02 and 3.31 bits/ind.) variations were not significative between the sites and seasons, although temperature and salinity differed significatively between winter and summer. However, the diatom's composition and distribution were related to temperature, salinity, and sediment particle size. Mainly the species Hippodonta hungarica, Luticola simplex Navicula cf. cryptotenelloides, N. erifuga, N. jacobii, Nitzschia filiformis var. conferta, Planothidium frequentissimum and Tryblionella calida were associated with lower temperature and lower salinity in the winter. The species Navicula cf. cryptocephala, N. phylleptosomaformis, Nitzschia pusilla, N. frustulum, N. scalpelliformis and Pseudostaurosiropsis geocollegarum were associated with higher temperature and higher salinity in the summer. Birraphid diatom taxa, mainly species of the genus Navicula and Nitzschia, were frequent or abundant in sandy sediments, and monoraphids, such as Planothidium frequentissimum, were frequent in sites where silt and clay predominated. Conclusions The composition of the benthic diatoms revealed variation between the sites in the winter and summer seasons, during El Niño and La Niña episodes. In winter, high rainfall and freshwater runoff maintained oligohaline condition in the marshes, while in summer, flooding with meso-poly-euhaline waters changed the diatom composition. The granulometry was an important factor in explaining the distribution of the birraphid and monorhapid taxa.

Comparative Analysis of Bacillariophyceae Chloroplast Genomes Uncovers Extensive Genome Rearrangements Associated with Speciation.

The Bacillariophyceae is a species-rich, ecologically significant class of Bacillariophyta. Despite their critical importance in marine ecosystems as primary producers and in the development of harmful algal blooms (HABs), taxonomic research on Bacillariophyceae species has been hindered because of their limited morphological features, plasticity of morphologies, and the low resolution of common molecular markers. Hence molecular markers with improved resolution are urgently needed. Organelle genomes, which can be constructed efficiently with the recent development of high throughput DNA sequencing technologies and the advancement of bioinformatics tools, have been proposed as super barcodes for their higher resolution for distinguishing different species and intra-species genomic variations. In this study, we tested the value of full-length chloroplast genomes (cpDNAs) as super barcodes for distinguishing diatom species, by constructing cpDNAs of 11 strains of the class Bacillariophyceae, including Nitzschia ovalis, Nitzschia traheaformis, Cylindrotheca spp., Psammodictyon constrictum, Bacillaria paxillifer, two strains of Haslea tsukamotoi, Haslea avium, Navicula arenaria, and Pleurosigma sp. Comparative analysis of cpDNAs revealed that cpDNAs were not only adequate for resolving different species, but also for enabling recognition of high levels of genome rearrangements between cpDNAs of different species, especially for species of the genera Nitzschia, Cylindrotheca, Navicula and Haslea. Additionally, comparative analysis suggested that the positioning of species in the genus Haslea should be transferred to the genus Navicula. Chloroplast genome-based evolutionary analysis suggested that the Bacillariophyceae species first appeared during the Cretaceous period and the diversity of species rose after the mass extinction about 65 Mya. This study highlighted the value of cpDNAs in research on the biodiversity and evolution of Bacillariophyceae species, and, with the construction of more cpDNAs representing additional genera, deeper insight into the biodiversity and evolutionary relationships of Bacillariophyceae species will be gained.

Navicula fuxianturriformis sp. nov. (Bacillariophyceae), a new species from southwest China

Navicula fuxianturriformis sp. nov., collected from Lake Fuxian, Yunnan Province, China, is described as a new species based on light and scanning electron microscope observations. N. fuxianturriformis sp. nov. has lineolate areolae closed by hymenes internally and a peculiar structure of the raphe system where the raphe is elevated internally on a thin longitudinal rib that is laterally expanded at the central area; features that assign it to the genus Navicula. The key diagnostic features of this new species include: 1) lanceolate valves with the cuneate to apiculate apices, 2) mostly long, slit-like, partly round-rectangular areolae on the valve exterior and round to rectangular areolae internally, 3) external distal raphe fissures that are hooked opposite one another, and 4) the oval-elliptical central area, with two to five pairs of irregularly shortened striae. This combination of features distinguishes N. fuxianturriformis from congers such as N. turriformis, N. turris, N. reinhardtii, N. hoevsgoelreinhardtii, N. mongolreinhardtii, N. apiculatoreinhardtii or N. apiculatoreinhardtii f. biseriata. A discussion of the morphological features of this taxon and morphologically-similar species is presented. These findings increase our understanding about the morphology and distribution of the genus Navicula in China.

Род Navicula (Bacillariophyta) из эстуария Порья Губа (Мурманская область, Россия) с описанием нового вида и изучением типового материала N. eidrigiana и N. pseudosalinarum

During the study of diatom samples from a brackish estuary near the reserve headquarters of the Kandalaksha State Nature Reserve at Por’ya Guba 16 taxa belonging to the genus Navicula were found. One taxon, N. curtisternoides sp. nov., is described and compared with morphologically similar species. The type specimens of two names (N. eidrigiana and N. pseudosalinarum) were studied to verify the identifications of these taxa. Four species (N. hanseatica, N. kefvingensis, N. microcari, N. paul-schulzii) were recorded for the first time in the Murmansk Region.

<strong><em>The genus Navi</em>cula (Bacillariophyceae, Naviculaceae) from the valley of the Adegoy River (Krasnodar Territory, Russia) and description of two new species</strong>

This is the first detailed taxonomic study of the genus Navicula in the Krasnodar Territory of the Caucasus region, Russia. During the study of the genus in waterbodies of the Adegoy River valley 15 taxa were recorded. Two species, N. adegoyensis sp. nov. and N. pseudocryptofallax sp. nov., are described as new to science. Their morphology is studied by light and scanning electron microscopy, and comparisons with morphologically similar species are provided. The use of the name N. avenacea for N. lanceolata sensu auct. is discussed. Navicula diversity was higher in the Adegoy River than in pools elsewhere in the river valley.

Benthos Algae Communities of Saline Rivers in the Lake Elton Basin: Taxonomic and Quantitative Structure

For the first time, an assessment was given of the taxonomic and quantitative structure of the phytobenthos of seven saline rivers in the basin of the hypersaline lake Elton (Volgograd Region). Main types of algacenoses developing on substrates were revealed, namely: diatom phytobenthos, communities of diatoms with cyanoprokaryotes, cyanobacterial films and mats, and epiphyton. The phytobenthos consists of local, mosaic-distributed communities with a small similarity of their species composition. The algacenosis structure is determined by Bacillariophyta (with the predominance of species of the genus Navicula) and Cyanoprokaryota (of the genera Phormidium, Leptolyngbya, and Geitlerinema). The abundance and biomass values vary widely, reaching their highest values (109,834–417,472 mln cells/m2 and 523.6–567.6 g/m2 ) in cyanobacterial communities of mesohaline rivers with their salinity up to 16–19 g/L. Mineralization as a factor influencing the structure of communities, most rigidly acts in the estuarine sections of rivers, by controlling the composition of the dominant species. For critical salinity values (> 70 g/L), characteristic structural transformations of communities by the type of replacement of planktonic and benthic Bacillariophyta and Cyanoprokaryota by planktonic Chlorophyta (of the Dunaliella genus) and picoplankton were established.

Two new species of the diatom genus Navicula Bory (Bacillariophyceae) from Vietnam (Southeast Asia)

We present light and scanning electron microscopical observations on two new species of Navicula Bory sensu stricto from Vietnam. These new species, Navicula babeiensis Chudaev, Glushchenko, Kulikovskiy & Kociolek sp. nov. and Navicula pseudokuseliana Chudaev, Glushchenko, Kulikovskiy & Kociolek sp. nov. are described and distinguished from others in the genus on the basis of valve outline and shape of the apices, as well as stria and areola densities. These species possess all the typical morphological features for the genus, including uniseriate lineolate striae covered by internal convex hymenes, median raphe with accessory rib, and external distal raphe ends that are hooked in the characteristic way for the genus. Comparisons with similar taxa are given. Our new data extend the information about the diversity of diatoms in general and for Navicula taxa specifically, in Southeast Asia.

Progressive and Regressive Algae of the Genus <i>Navicula</i> Bory (<i>Bacillariophyta</i>) of Water Bodies of the Chirchik River Basin (Uzbekistan) and Protecshion

In the article, the authors present for the first time the progressive and regressing algae of the genus Navicula Bory (Bacillariophyta) the water bodies of the Chirchik River basin. The research was carried out during 2005-2012, 2018-2020 yy. with the National Universities of Uzbekistan and the Institutes and Botany of the Academy of Sciences of the Republic of Uzbekistan. 122 species and varieties of algae of the genus Navicula Bory have been identified. Among them, new species for water bodies, saprobic indicators were noted, the seasonality of algae was studied. The main new ideas the article are as follows: among the algae found, it is progressive algae 6. They are found very often, in or mass one field of view of the objective, their frequency of occurrence is equal to 5, 7, 9 points and is considered a resistant species various environmental conditions, being a promising algae with full life. 96 - less progressive algae, occurs rarely, the occurrence is equal to 5, 3 points and is less resistant and less promising algae with a sex life. 20 species and varieties are regressing algae, water bodies it meets only units (single), the frequency of occurrence is equal to 1 (one) point and is considered unstable algae of the investigated water bodies, the future, there is a threat to safety and Not Live! (No Life!) Needs protection. It was proposed to include the next issue of the Red Book of the Institute of Botany of the Academy of Sciences of the Republic of Uzbekistan, as well as to accept and include the list of protected microorganisms water bodies of Uzbekistan under the Committee for Ecology and Nature Protection of the Republic of Uzbekistan.

Tropical marine Navicula salinicola NBO: morphology, genetic identification, and biochemical properties

Indonesia’s oceans are rich in microalgae as unicellular photosynthetic organisms. So far, most of Indonesia’s diverse microalgae have yet been explored. An Isolate NBO of microalgae has been collected from Bokor Island in the Jakarta Bay, Indonesia. This study aimed to identify the isolate NBO and to characterize its biochemical properties. The identification was carried out based on the physical morphology of cell and the nucleotide sequence of 18S rDNA-V4 and LSU D2/D3 DNA regions, meanwhile, the biochemical properties were characterized based on the content of carbohydrate, lipid and fatty acid of cells. The results showed that the morphological characteristics of NBO cells possessing a color of pale yellow, an oval shape ranging from 11.00–15.00 μm in length and 4.67–5.00 μm in width, and a silica frustule that bilaterally symmetrical oval closed to genus Navicula. Based on the homology of sequences 402-bp of 18S rDNA-V4 and 591-bp of LSU D2/D3, the isolate was identified as Navicula salinicola. Total carbohydrate and lipid contents of Navicula salinicola NBO were 13.13 and 3.74% (w/w), respectively. Fatty acids of Navicula salinicola NBO were dominated by palmitic acid (C16:0), palmitoleic acid (C16:1), and eicosapentaenoic acid (EPA; C20:5) with a total concentration of 38.24, 37.23, and 12.54% (w/w, fatty acid/lipids), respectively, indicating a promising candidate for biodiesel and nutrition/ pharmaceutical.

The diatom genus Luticola D.G. Mann (Bacillariophyceae) in the Western Ghats of India and its biogeography

ABSTRACT Nine species of the diatom genus Luticola D.G.Mann were collected from wet walls and other subaerial habitats from the Western Ghats of India and analysed using light and scanning electron microscopy. Of these, seven are considered to be new species and they are formally described here. They are compared with congeners based on valve size and shape, and ultrastructural features. Another two species described previously by H.P. Gandhi and originally assigned to the genus Navicula are formally transferred to Luticola. Over 25 species of Luticola have been reported from south-east Asia, most of them endemic to the region. The morphological variation of the genus is considered along with its systematics, biogeography and ecology. It appears that south-east Asia, Antarctica and South America are the areas of endemism for this genus.

Three new Navicula (Bacillariophyta) species from an oligotrophic, deep lake, China

Three new freshwater diatoms are described from China's Yunnan Plateau region in sediments from Lake Fuxian. Navicula australasiatica nov. sp., Navicula perangustissima nov. spec., and Navicula turriformis nov. spec. were identified from light and scanning electron micrographs. All new species are sufficiently different from other similar species based on valve outline, shape of the axial and center areas, and stria density. These three new species are all observed in surficial sediment from Lake Fuxian and compared to morphologically similar species from the genus Navicula.

<p><strong><em>Navicula gogorevii—</em></strong><strong>a new, large-celled diatom species from Vietnam (Southeast Asia)</strong></p>

We describe a new member from the genus Navicula Bory sensu stricto using light and scanning electron microscopy. The new species was found in Vietnam, and is a large-celled species with longitudinal grooves present on the valve exterior. Taxa sharing this feature are known from the genus Navicula, as well as the genera Haslea Simonsen, Craticula Grunow, Gyrosigma Hassall and Proschkinia Karajeva. The new species from Vietnam is compared with other, similar taxa of Navicula, and comments are presented about the systematics and biogeography of the group of Navicula species with this characteristic feature.

Culturable diversity of Arctic phytoplankton during pack ice melting

Massive phytoplankton blooms develop at the Arctic ice edge, sometimes extending far under the pack ice. An extensive culturing effort was conducted before and during a phytoplankton bloom in Baffin Bay between April and July 2016. Different isolation strategies were applied, including flow cytometry cell sorting, manual single cell pipetting, and serial dilution. Although all three techniques yielded the most common organisms, each technique retrieved specific taxa, highlighting the importance of using several methods to maximize the number and diversity of isolated strains. More than 1,000 cultures were obtained, characterized by 18S rRNA sequencing and optical microscopy, and de-replicated to a subset of 276 strains presented in this work. Strains grouped into 57 phylotypes defined by 100% 18S rRNA sequence similarity. These phylotypes spread across five divisions: Heterokontophyta, Chlorophyta, Cryptophyta, Haptophyta and Dinophyta. Diatoms were the most abundant group (193 strains), mostly represented by the genera Chaetoceros and Attheya. The genera Baffinella and Pyramimonas were the most abundant non-diatom nanoplankton strains, while Micromonas polaris dominated the picoplankton. Diversity at the class level was higher during the peak of the bloom. Potentially new species were isolated, in particular within the genera Navicula, Nitzschia, Coscinodiscus, Thalassiosira, Pyramimonas, Mantoniella and Isochrysis. Culturing efforts such as this one highlight the unexplored eukaryotic plankton diversity in the Arctic and provide a large number of strains for analyzing physiological and metabolic impacts in this changing environment.