Biology of the freshwater diatom Didymosphenia: a review
By B. Whitton, N. Ellwood, B. Kawecka. Hydrobiologia, 2009
145 citations recorded by the source corpus.
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 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.
Subfields: Biomaterials, Ecology, Environmental Chemistry
View Paper: https://www.semanticscholar.org/paper/e2bbe0a2364db8dc5e62158f2fba075ffea0ce70
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Citations in the corpus
- Harmful Algal Blooms (2015, background): “Calcium concentration or conductivity are usually quite high at sites with abundant D. geminata, at least during the main growing season (Whitton et al., 2009), but current belief on the importance of other environmental factors is based largely on statistical correlations.”
- The arrival and spread of the bloom-forming, freshwater diatom, Didymosphenia geminata, in New Zealand. (2011, background): “geminata is its tendency to form the highest biomass in lownutrient rivers (Whitton et al. 2009; Bothwell and Kilroy 2011, but see also Kawecka and Sanecki 2003) not normally susceptible to algal blooms, which are typically induced by high nutrients (Biggs 2000).”