Diatoms associated with the order Bacillariales, Rhopalodiales and Surirellales are well known to be present in marine and brackish waters. In this study, diatoms in the western Black Sea coasts of ...Turkey were investigated with ultrastructure details. Species belonging to the Bacillariales, Rhopalodiales and Surirellales were subject to light microscopy (LM) and scanning electron microscopy (SEM) analysis, and a total of twenty-four taxa were investigated. This study examines details on the morphology and biogeography of the taxa with remarks on their distribution in Turkey. The results revealed that four species were reported on the Turkish coasts for the first time. These species were Nitzschia liebethruthii, N. volvendirostrata, Epithemia guettingeri and Campylodiscus scalahs. Keywords: Bacillariophyceae, biodiversity, diatoms, scanning electron microscopy, the Black Sea
Coastal lakes are shallow lakes that have variable characteristics through fluctuations and marine
winds. In this study, benthic diatom composition in the coastal lake of Iztuzu, Dalyan of Muğla was
...investigated from the material collected in 2011 and 2015. Little research has been done on coastal
lakes and lagoon diatom flora in Turkey; this study contributes a total of 49 taxa identified to
species level and 9 of the taxa for the first time recorded for diatom flora of Turkey. The most
abundant taxa were; Cocconeis placentula Ehrenberg, Diploneis bombus (Ehrenberg) Ehrenberg,
Mastogloia sp. and Chamaepinnularia alexandrowiczii Witkowski, Lange-Bertalot and Metzeltin.
The results reveal a habitat-specific flora for Iztuzu Lake and give an aspect of understanding the
marine-brackish distribution of diatoms in coastal lakes and lagoons. The results extend the
knowledge of marine and brackish diatoms in Turkey and could provide data for similar lagoon
and lakes which are under protection.
The Aegean Sea coast of Turkey hosts one of the most important nesting grounds for loggerhead sea turtles (
) in the Mediterranean Sea. Previous studies have revealed that the sea turtle carapace ...provides favourable conditions for various epibiontic organisms. Epibionts occurring on the carapace have been examined from different locations in the oceans.
This is the first time such a high number (39) of samples collected from nesting turtles during such a long time period (extending from 2011 to 2018) has been used for the study of the diatom component of the microbiome on the turtle carapaces. A total of 33 samples were investigated in terms of light microscopy (LM) and scanning electron microscopy (SEM). Six unprocessed biofilm fragments were subject to SEM observations.
A total of 457 epizoic diatom taxa belonging to 86 genera were identified. Epizoic forms, e.g.,
spp.,
spp. or
spp. (also identified by SEM observations of the undisturbed pieces of the microbiome) dominated in terms of relative abundance, but the highest numbers of taxa were ubiquitously represented by
(79),
(45),
(40),
(32),
(25) and
(23).
and
were the most frequent taxa, present in 65% of the samples, both with an average relative abundance of 10%. The results of our study revealed that diatoms are an essential component of the loggerhead sea turtles' microbiome, in terms of high biodiversity and abundance. Although strict epibionts provide a signature of the turtle microbiome, the carapace as a solid substrate attracts numerous benthic diatom species which are considered opportunistic forms and can be found in the surrounding benthic habitats of the vast ocean littoral space.
Marine phytoplankton are widely used to monitor the state of the water column due to their rapid changes in response to environmental conditions. In this study, we aimed to investigate the coastal ...phytoplankton assemblages, including bloom-forming species using high-throughput sequencing of 18S rRNA genes targeting the V4 region and their relationship with environmental variables along the Istanbul coasts of the Sea of Marmara. A total of 118 genera belonging to six phyla were detected. Among them, Dinoflagellata (36) and Bacillariophyta (26) were represented with the highest number of genera. According to the relative abundance of DNA reads, the most abundant taxa were Dinoflagellata_phylum (18.1%), Emiliania (8.4%), Biecheleria (8.4), and Noctiluca (8.1%). The ANOSIM test showed that there was a significant temporal difference in the assemblages, while the driving environmental factors were pH, water temperature, and salinity. According to the TRIX index, the trophic state of the coasts was highly mesotrophic and eutrophic. In addition, 45 bloom-forming and HAB taxa were detected and two species of Noctiluca and Emiliania, which frequently cause blooms in the area, were recorded in high abundance. Our results provide insight into the phytoplankton assemblages along the urbanized coastlines by analysing the V4 region of 18S rRNA. This data can support future studies that use both traditional methods and metabarcoding, employing various primers and targeting different genes and regions.
•Phytoplankton was diverse according to metabarcoding in meso-eutrophic environment.•NGS confirmed many HAB and bloom-forming species present in the Sea of Marmara.•NGS successfully detected Noctiluca and Emiliana blooms.•Environmental factors had a temporal influence on phytoplankton assemblages.
The importance of sustainable bioassessment and management of coasts to maintain good trophic status is increasing due to the high anthropogenic impacts on marine ecosystems. Diatoms are one of the ...most important assemblages and useful tools for assessing the state of the environment due to their advantages over other organisms such as short life span and rapid reaction to environmental changes in aquatic systems. In this study, our objective was to investigate marine benthic diatoms and compare them using three different methods: light microscopy (LM), scanning electron microscopy (SEM), and molecular metabarcoding (MB). LM observations were supported by SEM; in addition, 18S rRNA metabarcoding was used to reveal the diatom flora. The results showed that the highest number of genera was observed with LM (49), followed by SEM (27) and MB (21). Eight genera were found to be common by all three methods. Although MB identified a small number of genera, it verified the presence of common taxa through a rigorous analysis. However, all the methods used gave consistent results in confirming that the diatom assemblages found along the coasts of Istanbul in the Sea of Marmara exhibited low diversity. Our results suggest that the morphological approach to the study of marine benthic diatoms can be complemented by the metabarcoding approach, which showed encouraging results, and that both approaches can be mutually supportive.
In this study, the diatoms of three alternative habitats (epilithon, epiphyton and artificial sub-strate) were compared to understand the differences in composition on artificial and natural ...sub-strates. For this purpose, the samples were collected weekly between 11th August and 2nd Septem-ber 2016 at a sampling site in a shallow marine lake, Mrtvo More (Dead Sea) on Lokrum Island near Dubrovnik (South Adriatic, Croatia). In addition to detailed light microscopic analysis, ultrastructural analysis of benthic diatoms from Lake Mrtvo More was performed for the first time using scanning electron microscopy (SEM). A total of 97 taxa were identified in 12 samples. Cocconeis scutellum Ehrenberg and Halamphora coffeiformis (C.Agardh) Levkov were the most frequent taxa in the samples. Shannon-Wiener diver-sity index (H’) values varied from 1.78 (in September on Padina sp.) to 4.52 (in August on glass). According to non-metric multidimensional scaling ordination, there were two groups: epilithon and artificial glass substrate as Group1 and macroalgae as Group2. The results of the analysis showed that the diatom communities developing on artificial sub-strates accurately correspond to the diatom community of a rock substrate and thus can be used as a representative alternative tool for studies of epilithic diatoms in further experiments.
Kako bi se razumjele razlike između naseljavanja na umjetnim i prirodnim podlogama, u ovom istraživanju uspoređivani su sastavi dijatomeja s tri alternativna staništa (epiliton, epifiton i umjetni supstrat). U tu svrhu uzorci su sakupljani tjedno između kolovoza i rujna 2016. na jednoj lokaciji u plitkom morskom jezeru Mrtvo More na otoku Lokrumu kod Dubrovnika (Južni Jadran, Hrvatska). Osim detaljne analize svjetlosnim mikroskopom, po prvi put je provedena i ultrastrukturna analiza bentoskih dijatomeja iz jezera Mrtvo More pomoću elektronske mikroskopije (SEM). U 12 uzoraka identificirano je ukupno 97 vrsta dijatomeja. Vrste Cocconeis scutellum Ehrenberg i Halamphora coffeiformis (C.Agardh) Levkov bile su najčešće vrste u uzorcima. Vrijednosti Shannon-Wiener (H’) indeksa varirale su od 1,78 (u rujnu na vrsti Padina sp.) do 4,52 (u kolovozu na staklu). Prema nMDS ordinaciji, razlikuju se dvije skupine zajednica bentoskih dijatomeja: epiliton i umjetna staklena podloga kao Grupa 1 i makroalge kao Grupa 2. Rezultati analize pokazali su da zajednice bentoskih dijatomeja koje se razvijaju na umjetnim podlogama, odgovaraju dijatome-jskoj zajednici kamene podloge i da se stoga mogu koristiti kao reprezentativni alternativni alat za proučavanje epilitskih dijatomeja u daljnjim eksperimentima.
The Sea of Marmara, located in northwest Turkey, comprises challenging environmental conditions and is an important bridge between the Black Sea and the Aegean Sea. In this study, we assessed the ...trophic situation of the coasts of the Sea of Marmara using the benthic diatom composition and their relation to the environmental variables in the spring and autumn of 2019 and 2020. A total of 120 samples were collected and 452 species were observed; Navicula Bory and Nitzschia Hassal were represented with the highest numbers of taxa. Analysis of Similarity (ANOSIM) revealed that diatom communities differed significantly between the spring-autumn periods and years. Canonical Correspondence Analysis (CCA) showed that diatoms grouped under water, temperature, salinity, dissolved oxygen, and TIN influence. TRIX observations revealed a highly mesotrophic-eutrophic status along the coasts. Our study contributes to the knowledge of diatom diversity, distribution and community changes in spring and autumn on the coasts Sea of Marmara. Our findings suggest that marine benthic diatoms could be used as eutrophication indicators in the coastal waters for long-term monitoring with the support of environmental parameters.
•The first detailed marine benthic diatom study in the coasts of the Sea of Marmara.•91 diatom species recorded for the first time for Turkish coastal waters.•Trophic status varied from highly-mesotrophic to eutrophic along the coasts.•Diatom mainly influenced by water temperature, salinity, dissolved oxygen and TIN.•Pollution tolerant Navicula and Nitzschia comprised the highest number of species.
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