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Planothidium frequentissimum: (a-c) raphid valves; Dandenong Creek, VIC, x2300; (d-g) araphid valves; (d) Dandenong Creek, VIC, x2300; (e) Surrey River, VIC, x2090; (f) Surrey River, VIC, x2090; (g) Adelong River, NSW, x2100.
Contexts in source publication
Context 1
... O. Müller Valve extremely narrow, length:width ratio relatively higher, up to 10 Notes: Widespread but not as abundant as A. ambigua and A. granulata. Planktonic taxon but can be deposited in epipelic and epilithic habitats. Valves can be very variable. Form subborealis is the most common variety, the nominate form is rarely encountered. Fig. 19. Aulacoseira subartica f. subborealis, Murray River, Mildura, VIC; (a) x2600; (b) x2000; (c) valve view, x2600. Notes: Widespread and may be moderately abundant. Can be planktonic but also lives in epipelic and epilithic assemblages. A very distinctive valve. ...
Context 2
... 1-5. Holland & Clark 1989, p. 21, pl. 16, fig. 1. John 1983, p. 99, pl. 41, figs 11, 12. Krammer & Lange-Bertalot 1986, p. 114, fig. 37: 1-9. Patrick & Reimer 1966 fig. 8, p. 507, pl. 48, fig. 12. Thomas 1983, p. 56, pl. 7, fig. 12. Notes: Widespread and can be moderately abundant. Mostly a planktonic taxon although can also inhabit the benthos. Fig. 90. Nitzschia acicularis, Adelong River, NSW, ...
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Citations
... aestatis (Giffen, 1973;Witkowski et al., 2016). To visualize and compare the morphological characteristics of paraphyletic diatom genera, we redrew the illustrations of several representative diatom species based on their previously reported morphological descriptions and images as follows: Pseudo-nitzschia simulans (Li et al., 2017b;Ajani et al., 2020), Pseudo-nitzschia micropora (Priisholm et al., 2002;Rivera-Vilarelle et al., 2013), Pseudo-nitzschia multiseries (Hasle, 1995;Evans et al., 2004), Pseudonitzschia pungens (Lim et al., 2012;Kim et al., 2015), Pseudo-nitzschia americana (Lundholm et al., 2002a;Rivera-Vilarelle et al., 2013), Fragilariopsis cylindrus (Von Quillfeldt, 2001;Cefarelli et al., 2010), Nitzschia inconspicua (Sonneman et al., 2000;Trobajo et al., 2013), Nitzschia alba (Lewin and Lewin, 1967), Nitzschia palea (Crowell et al., 2019;Wang et al., 2020), Cylindrotheca closterium (Reimann and Lewin, 1964;Ryabushko et al., 2019), Tryblionella apiculata (Gregory, 1857;Yamamoto et al., 2017), Psammodictyon constrictum (Yamamoto et al., 2017), Nitzschia traheaformis (Witkowski et al., 2016), Nitzschia dissipatoides (Archibald, 1982; this study), Bacillaria paxillifer (B. paxillifera; Jahn and Schmid, 2007), Skeletonema marinoi (Jung et al., 2009), Thalassiosira nordenskioeldii (Cleve, 1873;Shevchenko et al., 2020), Discostella pseudostelligera (Houk and Klee, 2004;Guerrero and Echenique, 2006), Minidiscus spinulatus (Li et al., 2020), Cyclotella tecta (Prasad and Nienow, 2006), Thalassiosira pseudonana (Horvat et al., 2021), and Conticribra weissflogii (Cavalcante et al., 2013). ...
Diatoms (Bacillariophyta) are abundant phytoplankton groups in marine environments, which contribute approximately 20% of global carbon fixation through photosynthesis. Moreover, diatoms exhibit the highest species diversity (approximately 18,000 diatom species) among marine photosynthetic eukaryotes, which were identified by morphological characteristics. Molecular phylogenetic analyses could shed new insights into the evolutionary relationships of diverse diatom species. Nevertheless, a comprehensive understanding of the phylogenetic relationships of diatom species still remains unclear because the available molecular data are insufficient compared with their high species diversity. Furthermore, several novel diatom species were reported from field samples with no molecular evidence. In particular, the phylogenies of diatom species constructed using organelle genomes revealed that several diatom genera are paraphyletic with high supporting values. We constructed high-resolution phylogenetic trees of diatom species using organelle genomes (plastids and mitochondria) and compared the morphologies in several paraphyletic diatom genera. Especially, the clades Nitzschia and Thalassiosira include several different diatom genera with high phylogenetic supports. Our study demonstrated that some morphological characteristics (e.g., genus characters) of several diatom genera could not represent current genus boundaries. Based on the results, we highlight the necessity for taxonomic reinvestigation. To reestablish this in diatoms, it will be essential to incorporate more genome data from a broader range of taxon samples, along with a comparison of morphological characteristics.
... agnita in shape and valve dimensions but not in fibula density and most likely also in stria density (Table 1, footnote). Krammer & Lange-Bertalot (1988) gave N. capensis as a possible synonym of N. agnita, as did Sonneman et al. (1999). ...
... 18), India (Bharati et al. 2019, fig. 1I) and Australia (Sonneman et al. 1999; see our Table 1). However, since they are LM views of isolated valves or complete frustules and there is no information about valve ultrastructure, stria density or girdle, the records cannot be regarded as definitive. ...
Durinskia capensis is a kleptoplastic dinoflagellate species from high intertidal marine rock pools, which can use a variety of diatoms for photosynthesis. However, very few of the diatoms permit indefinite survival of the dinoflagellate and rbcL sequences show that D. capensis isolated from nature contains one of two closely related Nitzschia species as its kleptoplastids. In culture, without a supply of these ‘essential’ Nitzschia cells to replenish the intracellular store of diatom plastids and other organelles, D. capensis eventually loses all its kleptoplastids and dies. Inside Durinskia, diatoms do not possess frustules and so cannot be compared morphologically with free-living forms. Recently, one of the essential Nitzschia species was isolated from the type locality of D. capensis and grown in culture, allowing comparison with similar Nitzschia species, particularly N. agnita and N. kuetzingioides, examined from type material. We conclude that the ‘essential diatom’ of D. capensis differs morphologically from these and other Nitzschia species and it is therefore described as N. captiva sp. nov. Nitzschia agnita and N. kuetzingioides, on the other hand, are conspecific and N. agnita has priority. Nitzschia captiva and N. agnita are extremely similar in valve shape, dimensions, pattern and ultrastructure, but can be separated by their girdle structure. Nitzschia agnita appears to be a freshwater species, though somewhat salt-tolerant. In contrast, N. captiva, which is known principally from records of the kleptoplastids of D. capensis rather than from frustules, is so far marine.
... A minimum of 300 diatoms valves were counted and identified under oil immersion at 1,000 × magnification. Diatom taxa were identified using standard literature (KKrammer and Lange-Bertalot 1986, 2000, 2004, Gell et al. 1999, Sonneman et al. 2000, Taylor 2007a, 2016, Bahl 2017, Bahl et al. 2018, and by checking photomicrographs in AlgaBase.org (Guiry and Guiry 2021). ...
Diatoms, silicious microalgae, have been used successfully as bioindicators of water quality assessment in aquatic ecosystems. Diatoms have a degree of tolerance to the water quality and some diatoms are a good indicator for several water quality variables. Diatom indices have been developed to assess river water quality, mostly in Europe. This study aims to apply diatom indices developed in Europe for the tropical lake of Galela adjacent to residential areas influenced by human activities. Galela Lake is one of the biggest lakes in Halmahera Utara, Indonesia with its main functions being domestic water supply, irrigation, fisheries, and tourism. Human activities have impacted the area around the lake. The 90-cm and 85-cm long sediment cores were collected using a piston corer from Site 1 and 2, respectively. Sediment samples were sliced every 5 cm, separated from sediment by adding HCl and H2O2. The diatom valves were identified under a microscope with 1,000 × magnification. The water quality status of each layer was inferred with diatom indices performed using OMNIDIA software version 6.0. Forty-nine and 63 diatoms species were identified from Site 1 and Site 2, respectively. The number of species and diversity of diatoms was higher in the lower layers than those in the upper layers. The preserved diatom assemblages reflect past physical and chemical water quality. Generic Diatom Index and Specific Pollution Sensitivity Index provided the best evidence for change in Galela Lake—they integrated 70–100% of the diatom taxa from the sediment core samples.
... Five sample replicates were used to estimate the dry mass, AFDM, Chl-a, and Chl-b. An authentication key, algal flora, and some recent related references were carefully used for the correct identification of the isolated microalgae (Krammer 2000; Ling and Tyler Sonneman et al. 2000). All samples and slides were examined using a light microscope (Olympus CKX41). ...
The Kani Barazan and Yadegarlou wetlands in the southern part of Lake Urmia (Iran) have been substantially modified due to human activities and anthropogenic use. In recent years, freshwater-based eco-biological studies to recognize the quality of water resources have been greatly expanded. Microalgae and Cyanophyta are considered important bioindicators for the evaluation of water quality and wetland health worldwide. Herein, 22 microalgae and 5 Cyanophyta genera were identified in both wetlands, in which Cyanophyta has mainly caused blooms. Principal components analysis (PCA) was carried out based on links between the distribution of microalgae and Cyanophyta with physical and chemical parameters. The data showed that depth, turbidity, and the temperature had a significant influence on the microalga and Cyanophyta communities in both wetlands. Based on the biological properties, it seems that the Kani Barazan and Yadegarlou international wetlands experience meso-eutrophic conditions. The integration of the physical, chemical and biological parameters with the water quality index (WQI) revealed that both wetlands were polluted as a consequence of human activities. Moreover, a close relationship between WQI and the biological parameters was documented. Thus, we concluded that microalgae and Cyanophyta communities, their abundance patterns, and water quality changes could provide valuable data for the conservation of the Kani Barazan and Yadegarlou international wetlands.
... We used these proxies to infer past local ecological changes (influenced by lake levels) at Crystal Lagoon. Non-pollen palynomorphs (NPPs) were counted in pollen slides and identified using a key (Sonneman et al., 1999) and Kiel University's online database (https://www.wikis.uni-kiel.de/non_ pollen_palyn omorp hs/doku.php/home). ...
Aim
The Last Glacial Maximum (LGM) remains an enigmatic period in southeast Australia due to the limited spatial and temporal resolution of its palaeoclimatic records. A major feature of the LGM landscape was the existence of the Bassian Land Bridge, joining Tasmania with the mainland of Australia during periods of low sea level, and potentially facilitating increased biotic movement between these regions. To better understand biogeographical changes on the land bridge and in southeast Australia generally during the LGM, we present a 35 ka‐year palaeoecological record from one of the larger islands of Bass Strait.
Location
Bass Strait, southeast Australia.
Taxon
Eucalyptus , Poaceae, Monotoca , Myriophyllum , Zygnemataceae, Botryococcus , Pediastrum .
Methods
Pollen, charcoal, and non‐pollen palynomorphs were analysed in a 1.75‐m sediment core from truwana/Cape Barren Island, Bass Strait, to reconstruct changes in vegetation, fire regimes and lake levels on the Bassian Land Bridge. Results were then compared to existing palaeoenvironmental studies in the region to develop a broader context of the prevailing land bridge environment and the potential influence on biotic dispersals in Australia during the last glacial period.
Results
Results suggest a major vegetation shift on the Bassian Land Bridge in response to the establishment of the LGM climate, with grassland expansion at the expense of woodland from ~29–11 ka. Floristic richness, biomass burned and lake levels also markedly decreased through this period, with the driest interval being ~25–18 ka. Dryland herbaceous taxa dispersed between the mainland and Tasmania when the landbridge was fully exposed.
Main conclusions
In agreement with previous studies, our results show that the dry grassland that dominated southeast Australia (and Southern Hemisphere mid‐latitude areas) during the LGM also extended across the Bassian Land Bridge. The prevailing environment on the land bridge is likely to have exerted a selective influence on biotic dispersals in Australia during glacial periods.
... Diatoms were identified to species level where possible up to 1500Â magnification on a Nikon Eclipse E600 with differential interference contrast optics and using a variety of taxonomic sources (e.g. Foged, 1978;Krammer and Lange-Bertalot, 1986, 1988, 1991a, 1991bSonneman et al., 2000). ...
Hot springs are characterised by water temperatures above 36.7 °C. Temperature decreases with distance in flow away from spring vents; this natural gradient provides a unique opportunity to investigate the influence of water temperature on aquatic biota. This study investigated the relationship between water temperature and the aquatic invertebrates and benthic diatoms in outflows from a hot spring complex in tropical north Queensland, Australia. Water temperature ranged from 62.7 °C at the vents to 26.0 °C at the location furthest downstream. Richness of benthic diatoms and aquatic invertebrates increased linearly in response to decreasing temperature, with no species present in the hot vents. Multivariate analysis showed that both community assemblages had a response to the temperature gradient. A drop in aquatic invertebrate richness and a change in assemblage composition occurred between 40 °C and 42 °C, indicating a threshold at this temperature. The nearby Einasleigh River has experienced several contemporary peaks in water temperature over 40 °C, which corresponds to this threshold level. The relationships indicate that consistent increases in water temperature expected under climate change could decrease biological richness and precipitate changes in the aquatic invertebrate and benthic diatom taxa of tropical aquatic ecosystems.
... Approximately 300 valves were counted on each slide using an Olympus BH2 (Olympus Corporation, Tokyo, Japan) brightfield microscope at a magnification of 1000Â, with additional identifications undertaken on a Nikon Eclipse E600 microscope (Nikon Instruments Inc., Tokyo, Japan). Diatoms were identified to species level using Krammer and Lange-Bertalot (1986, 1988, 1991a, 1991b and Sonneman et al. (2000). ...
... In this study, the five taxa with the highest overall relative abundance were Achnanthidium minutissimum (16%), Cocconeis placentula (14%), Planothidium lanceolatum (5%), Tabularia fasciculata (5%) and Planothidium delicatulum (5%; Fig. 2). These species are commonly found in south-east Australian lowland streams (Sonneman et al. 2000;Chessman et al. 2007). ...
... A. coffeaeformis and T. fasciculata, in particular, were strongly associated with high salinity streams in Victoria, with M. smithii also exhibiting a preference for high EC streams (Blinn and Bailey 2001). A. oblongella and R. musculus are not discussed in Blinn and Bailey (2001); however, the respective low-and highsalinity preferences of these taxa in the present study are consistent with the qualitative assessment of their preferences by Sonneman et al. (2000). ...
Water quality guidelines are an important tool that guide stream protection. In South Australia, as in other Australian states, guidelines have been set using statistical properties of physical and chemical stressors in reference streams. Given that water quality guidelines are designed to protect ecosystems, biologically based guidelines are more desirable. In this context, we investigated diatom–water quality relationships in South Australian streams. Our analysis focused on electrical conductivity (EC) and total phosphorus (TP), which explained significant variance in diatom assemblages. Threshold indicator taxa analysis was conducted to determine thresholds of diatom community change along EC and TP gradients. There were significant declines in the relative abundance of sensitive species at an EC of ~280μScm–1 and a TP concentration of 30μgL–1. The TP threshold is considerably lower than the trigger value in South Australia’s guidelines (100μgTPL–1). The change in species composition in relation to EC is considerably lower than the upper limit of the water quality guidelines (which range from 100 to 5000μScm–1). Hence, particularly in the case of TP, but also for EC, the current water quality guideline trigger values are too high in South Australia, and indeed in other temperate Australian states.
... Diatoms were identified to species level where possible at 1500Â magnification using a Nikon (Tokyo, Japan) Eclipse E600 with differential interference contrast optics with reference to a variety of taxonomic sources (e.g. Foged 1978;Krammer and Lange-Bertalot 1986, 1988, 1991a, 1991bSonneman et al. 2000). Several diatom taxa could not be identified as known species and were given descriptive epithets or descriptor affinities where they had strong affinities to known species but did not completely fit their description. ...
Contemporary benthic diatom assemblages were examined from 52 riverine and palustrine wetlands on Cape York Peninsula, Australia, to determine their environmental sensitivities and develop inference models. Multivariate analyses identified strong relationships between nine environmental variables and the diatom assemblage composition, with the aim to select variables for developing models. Total alkalinity, bicarbonate concentration, pH, electrical conductivity (EC) and latitude were most consistently and strongly correlated with diatom composition. The river basins sampled generally have an east–west orientation, so latitude potentially represents biogeographic differences between basins. Comparison of diatom assemblages between river basins showed significant differences, but substantial overlap in species. Diatom-based transfer functions were developed for each environmental variable and tested using the relationships between measured values and values predicted by the transfer functions. These were significant, and had low root mean square errors. An independent validation dataset for EC was analysed and applied to the EC transfer function. Results showed good predictions, giving confidence in its relevance beyond the training dataset. These understandings and models of the environmental effects on diatom assemblages allow for their application to future monitoring programs and reconstruction of past water quality conditions using fossilised diatoms in layered aquatic sediments of Cape York.
... Species were also classed, based on preferred habitat type, as epipelic (occurring on sediment surfaces), epiphytic (occurring attached to aquatic macrophytes), planktonic (occurring in the water column), facultative plankton (occurring both in the water column and on surfaces), and aerophilic (occurring in soils and other moist environments). Habitat preference classifications were based on a range of published sources Lange-Bertalot 1986, 1988;Krammer and Lange-Bertalot 1991a, b;Sonneman et al. 2000;Kelly et al. 2005;Spaulding et al. 2010). Due to low concentrations of valves, counts were stopped after 100 valves were recorded. ...
Ecosystems worldwide are subject to the deleterious effects of multiple anthropogenic stressors. Understanding and mitigating the effects of these stressors is difficult both because stressors are confounded in space and have the potential to act both synergistically and antagonistically. Palaeoecological approaches applied to systems where stressors may be confounded in space but not in time offer a way to explore the effects of multiple stressors. This multi-proxy study of sediment records from four floodplain lakes (billabongs) on a dryland river floodplain subject to grazing, commencing in the late 1800s, and irrigated cropping, commencing in the late 1900s, tests this approach. The results suggest that the effects of both grazing and irrigation on floodplain ecosystems can be detected in the pollen and diatoms preserved in sedimentary records of billabongs. For the pollen, these changes are inconsistent, but appear to reflect local shifts in dominance among major tree taxa and among key understorey plant families. For the diatoms, the changes were also not consistent across sites, but can be generalised as reductions in epiphytic diatoms and increases in planktonic and facultative planktonic taxa that likely reflect increased fluxes of sediments and nutrients and reduced flood frequency. Overall, the effects of grazing appear to have been greater than irrigated cropping. The results also show that the relative effects of grazing and irrigated cropping on floodplain and riparian vegetation and on diatom communities vary between billabongs, with some evidence that at least some of this variation relates to the level of hydrological connection to the mainstream. Finally, the study suggests that for the most part, grazing and irrigated cropping act antagonistically in the way they impact these floodplain ecosystems, a pattern that likely reflects a release from grazing pressure associated with the increase in irrigated cropping. Future applications of the approach should increase spatial and temporal replication and develop more sophisticated frameworks that account for temporal variation in driver intensity and proxy indicators of the specific stressors that influence ecosystem structure and function.
... While most diatom taxa in western Tasmania are adapted to high acidity and dystrophic/oligotrophic waters , the diatom compositional shifts represented by the diatom PC reflect shifts between more acidic/more dystrophic to less acidic/less dystrophic conditions ( Figure 5). Indeed, Eunotia spp., Brachysira spp., and Actinella spp., which are important components of the diatom community prior to ca. 6 ka, are associated with generally high dystrophy and lower pH in temperate southeast Australia and Tasmania (Hodgson et al., 1996;Philibert et al., 2006;Sonneman et al., 1999;Vyverman et al., 1995Vyverman et al., , 1996, while taxa that increase in importance after ca. 6 ka, such as Gomphonema, Aulacoseira, and Frustulia species, are associated with slightly higher pH (Philibert et al., 2006;Vyverman et al., 1995Vyverman et al., , 1996. ...
Environmental changes such as climate, land-use, and fire activity affect terrestrial and aquatic ecosystems at multiple scales of space and time. Due to the nature of the interactions between terrestrial and aquatic dynamics, an integrated study using multiple proxies is critical for a better understanding of climate- and fire- driven impacts on environmental change. Here we present a synthesis of biological and geochemical data (pollen, spores, diatoms, µXRF-scanning, CN content and stable isotopes) from Dove Lake, Tasmania, allowing us to disentangle long-term terrestrial-aquatic dynamics through the last 12 kyrs. We found that aquatic dynamics at Dove Lake are tightly linked to vegetation shifts dictated by regional hydro-climatic variability in western Tasmania. A major shift in the diatom composition was detected at ca. 6 ka and it was likely mediated by changes in regional terrestrial vegetation, charcoal and iron accumulation. High rainforest abundance prior ca. 6 ka is linked to increased terrestrially-derived organic matter delivery into the lake, higher dystrophy, anoxic bottom conditions and lower light penetration depths. The shift to a landscape with a higher proportion of sclerophyll species following the intensification of El Niño Southern Oscillation since ca. 6 ka corresponds to a decline in terrestrial organic matter input into Dove Lake, lower dystrophy levels, higher oxygen availability and higher light availability for algae and littoral macrophytes. This record provides new insights on terrestrial-aquatic dynamics that could contribute to the conservation management plans in the Tasmanian World Heritage Area and in temperate high-altitude dystrophic systems elsewhere.
