On post-tertiary sand containing diatomaceous exuviae, from Glenshira, near Inverary

Gregory, William

doi:10.5962/bhl.title.64234

Cited by 6 publications

(5 citation statements)

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“…There is also a record in the early Holocene from the other side of the Baltic in south central Sweden (Hedenstr} om & Risberg, 1999). An undated post-Tertiary sand stained with peaty residue below a layer of alluvial soil not far from the mouth of a valley entering Loch Fine, Scotland, had a mixture of marine and freshwater species, including D. geminata (Gregory, 1857). A study of a sediment core taken in 2003 from Naknek Lake, Katmai National Park, Alaska, found that D. clavaherculis was present at a constant abundance during the previous 786-year period .…”

Section: Fossil Recordsmentioning

confidence: 97%

Biology of the freshwater diatom Didymosphenia: a review

2009

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Features of the colonial diatom Didymosphenia are reviewed, especially D. geminata. Although there is a long record of its occurrence in north temperate regions, mass growths have been reported much more widely in recent years. Contrary to some statements in the literature, there are also reliable older records for the southern hemisphere, though the first report of mass growth was in New Zealand in 2004. The annual cycle of morphological changes in D. geminata in northern England, and probably elsewhere, includes a winter period when motile cells are attached to the substratum followed by spring when stalks start to develop. These raise cells into the water column and provide a site for phosphatase activity. Environmental factors associated with success include absence of extreme floods, high light, pH above neutral and nutrient chemistry. D. geminata often, but not always, occurs in waters where the N:P ratio is high for much of the year, but the key factor is the ratio of organic to inorganic phosphate. D. geminata thrives where organic P is predominant and the overall P concentration is low enough for organic P to be an important P source. It is unknown whether organic N can be used. Environmental changes increasing the relative importance of organic P are likely to favour D. geminata. Likely examples are increased N:P due to atmospheric N deposition and changes in form and seasonality of P release from organic-rich soils due to climatic warming. The nutrient chemistry of deep water released from dams to rivers also needs investigation. To what extent are genetic changes occurring in response to environmental changes and are new ecotypes spreading round the world? In spite of many adverse reports about D. geminata, such as detached mats blocking water pipes, there is still doubt about the extent to which it causes problems, particularly for fish. There have been few adverse effects on migratory salmonids in Europe and North America, but at least one report of harm to a brown trout population in USA. In New Zealand, it has caused serious problems for water sports, although it remains open to question how much adverse effect it has had on fish populations. If the presence of microcystins in or associated with D. geminata, as indicated recently for two populations, proves to be widespread and at sufficiently high concentration, their possible accumulation in fish requires study. Where control is required, this could Handling editor: Pierluigi Viaroli be achieved by enhancing the ratio of inorganic to organic phosphate in the water early in the growth season. Practical ways to achieve this are suggested.

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Section: Fossil Recordsmentioning

confidence: 97%

Biology of the freshwater diatom Didymosphenia: a review

2009

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“…1). Gregory discussed his figures noting that "It must be borne in mind that some of the figures represent varieties of known forms, and that the two first belong to the two new forms observed by me in the Lillhaggsjon and Luneberg deposits, and described in the last number of the 'Journal"' (Gregory 1855). Further he noted that E. falx ".…”

Section: Taxonomic Historymentioning

confidence: 94%

“…. .has not yet occurred as a British form", a point he felt worth making, as the subject of this particular paper was specimens found in diatomite from Glenshira in Scotland (Gregory 1855). Gregory had doubts about the genus but Ralfs assumed that Ehrenberg's Synedra hemicyclus and Gregory's E. falx were one and the same species, uniting them under the name Eunotia hemicyclus (Ehrenberg) Ralfs in Pritch.…”

Section: Taxonomic Historymentioning

confidence: 95%

NOTES ON THE GENUSSEMIORBISPATRICK WITH A DESCRIPTION OF A NEW SPECIES

Reid

Williams

2010

Diatom Research

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A review of the genus Semiorbis is given, including its taxonomic history, a discussion of its current taxonomic position and morphological descriptions. One new species is described and one new combination. Comments on the relationships of Semiorbis with the family Eunotiaceae are made. Semiorbis rotundus sp. nov., is known only from North America;Eunotia catillifera is transferred to the genus Semiorbis.

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“…A close examination of the literature describing the two species found that, before comparing the two taxa, there were two morphotypes in the C. distans, small form and very large form in terms of dimensions of valves. As a result of referring to the literature describing small forms (Gregory 1855, De Stephano et a. 2006, Riaux-Gobin et al 2011) and large forms (Cleve 1895, Peragallo and Peragallo 1897-1908, Hustedt 1933, Hendey 1964, Riaux-Gobin et al 2014a), these two morphotypes are clearly distinguished in valve length (18-31 : 28-60 μm) and valve width (10-20 : 17-40 μm), density of stria (7-11 : 4-5 rows in 10 μm), and density of areolae on a stria (4-8 : 12-14 in 10 μm of SV).…”

Section: Cocconeis Distans Gregory (Figs 12-19)mentioning

confidence: 99%

Distribution of the genus Cocconeis (Bacillariophyceae) along the Seogwipo coast of Jeju Island, South Korea

Joh

2021

Phytotaxa

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Cocconeis Ehrenberg species (Bacillariophyceae) are documented from benthic samples collected along the Seogwipo coast of Jeju Island, the southernmost region of Korea. The 25 taxa were identified from seaweeds, sand, and sediments, their morphological features are described, and the distributions of the taxa are summarized. Three groups of Cocconeis e.g., Cocconeis dirupta var. flexella, C. pseudomarginata var. intermedia, Cocconeis scutellum, and their similar taxa were dominant in this area. Many other Cocconeis that grows mainly along the coasts of warmer oceans were also identified. The floristic study reveals the existence of rare or retrieved species that were not well known until recently, and expands some of their geographical distributions; Cocconeis cf. callosa, C. conspicua, C. cyclophora var. decora, C. cyclophora var. meisteri, C. delicata, C. schmidtii, C. shikinensis, C. suzukii, C. voigtii. In this floristic study, 14 Cocconeis taxa are new records in South Korea.

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On post-tertiary sand containing diatomaceous exuviae, from Glenshira, near Inverary

Cited by 6 publications

References 0 publications

Biology of the freshwater diatom Didymosphenia: a review

Biology of the freshwater diatom Didymosphenia: a review

NOTES ON THE GENUSSEMIORBISPATRICK WITH A DESCRIPTION OF A NEW SPECIES

Distribution of the genus Cocconeis (Bacillariophyceae) along the Seogwipo coast of Jeju Island, South Korea

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