A phosphorus-based biological classification system and threshold indicators

Løvstad, Øivind

doi:10.1080/03680770.2008.11902190

Cited by 2 publications

(5 citation statements)

References 2 publications

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“…In experiments, D. geminata cell division rates have been found to be stimulated by high N (500 NO 3 lg/L) and P (50 PO 4 lg/L) concentrations , which may limit stalk production and therefore biomass. These concentrations are also well above those expected within a realised niche Lindstrøm & Skulberg, 2008;Løvstad, 2008). It has been suggested that high nutrients may preclude D. geminata colonisation or halt stalk production and limit competitive ability.…”

Section: (A) (C) (B)mentioning

confidence: 67%

“…Upper P limits for D. geminata persistence have also been suggested, although these related to TP and not DRP (i.e. TP <20 μg/L in Lindstrøm & Skulberg, ; TP <25 μg/L in Løvstad, ). These observations may also be explicable, however, by direct toxicity effects or allelopathy.…”

Section: Discussionmentioning

confidence: 99%

“…In contrast, D. geminata is sensitive to eutrophication and was shown to be absent from waters in which total P exceeded 20 lg/L (Lindstrøm & Skulberg, 2008). Similarly, Løvstad (2008) identified D. geminata from rivers only where total P < 25 lg/L, while Bray, Harding, Kilroy, Broady, and Gerbeaux (2016) identified proliferations only where nitrate + nitrite concentrations were low (c. 2-4 lg/L). At phosphorus concentrations above 2 lg/L DRP D. geminata is less likely to bloom and, where present, often persists only as a minor component of periphyton (Beltrami et al, 2008;Bothwell et al, 2014;Bray, 2014;Kilroy & Larned, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…In contrast, D. geminata is sensitive to eutrophication and was shown to be absent from waters in which total P exceeded 20 μg/L (Lindstrøm & Skulberg, ). Similarly, Løvstad () identified D. geminata from rivers only where total P < 25 μg/L, while Bray, Harding, Kilroy, Broady, and Gerbeaux () identified proliferations only where nitrate + nitrite concentrations were low ( c . 2–4 μg/L).…”

Section: Introductionmentioning

confidence: 99%

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Ecological eustress? Nutrient supply, bloom stimulation and competition determine dominance of the diatom Didymosphenia geminata

Bray

Kilroy

Gerbeaux³

2017

Freshwater Biology

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Nuisance proliferations of the invasive benthic alga Didymosphenia geminata (Bacillariophyceae) are of major concern in many temperate regions due to their severe effects on river habitats and communities. Proliferations result from the production of basal stalk material, stimulated by phosphorus limited, high light conditions. An unresolved disconnect occurs where nitrogen and phosphorus are observed to stimulate D. geminata cell division, but, within a realised niche, disappearance or establishment failure occurs where dissolved reactive phosphorus (DRP) concentrations occur above c. 2–5 μg/L. Our aims were to examine the mechanisms behind D. geminata bloom stimulation and absence/disappearance. We examined: (1a) whether prolonged nitrogen (NaNO3 – N) and phosphorus (NaH2PO4 – P) addition would stimulate cell division, and (1b) whether subsequent nutrient limitation stimulated stalk production; (2) whether the mechanism behind D. geminata absence at >5 μg/L DRP, occurred either as (2a) a deleterious consequence of prolonged N + P exposure or (2b) was associated with increasing densities of co‐occurring algae; and (3) whether water velocity stimulated D. geminata cell division thereby influencing outcomes. Didymosphenia geminata cell densities, frequencies of dividing cells, stalk production and densities of competing algae were examined in flow‐through channel mesocosms over 8 weeks. Treatments included: Waitaki River water (control); N + P amended water; and two treatments in which nutrient amendments were changed over time, these being N + P to N, and N + P to Waitaki water. Continued N + P amendment was positively correlated with D. geminata cell densities. N‐replete P‐limited channels, however, accrued greatest densities of D. geminata cells, stalk fragments and dividing cells. Results suggest that within a realised niche short term N + P amendment followed by chronic P limitation could either hasten and/or worsen bloom development. Water velocity influenced community successional trajectories and D. geminata fitness outcomes. Across all nutrient and velocity treatments, a decline in D. geminata cell densities and cell division was correlated with increasing densities of competing algae. Phosphorus limitation stimulating stalk production appears to be an example of physiological stress resulting in increased fitness (known as eustress) and D. geminata dominance. This contrasts with a general pattern of competitive exclusion as nutrient concentrations increase.

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Section: (A) (C) (B)mentioning

confidence: 67%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ecological eustress? Nutrient supply, bloom stimulation and competition determine dominance of the diatom Didymosphenia geminata

Bray

Kilroy

Gerbeaux³

2017

Freshwater Biology

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“…Among possible explanations are the influence of calcium in the catchment on nutrient release, its effect on another element important for D. geminata physiology or that it reduces the suitability of Didymosphenia for grazers. Lindstrøm (2008) reported for Norway that D. geminata is pollution sensitive and tends to disappear when total P exceeds 20 lg L -1 and organic C exceeds 6.5 mg L -1 C. A survey (Løvstad, 2008) of rivers in the Oslo Region of Norway involving 100 samples in each of five TP classes found 23 records in the lowest (0-12.5 lg L -1 P), 5 in the next highest (12.5-25 lg L -1 P), but none in the others. The mean value for the five streams and rivers in Poland with D. tatrensis and D. geminata was 34 lg L -1 P (Mrozińska et al, 2006a: unclear whether FRP or TP), while that for streams with D. geminata in northern Italy was 42 lg L -1 TP (Beltrami et al, 2008c).…”

Section: Calciummentioning

confidence: 99%

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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A phosphorus-based biological classification system and threshold indicators

Cited by 2 publications

References 2 publications

Ecological eustress? Nutrient supply, bloom stimulation and competition determine dominance of the diatom Didymosphenia geminata

Ecological eustress? Nutrient supply, bloom stimulation and competition determine dominance of the diatom Didymosphenia geminata

Biology of the freshwater diatom Didymosphenia: a review

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