Performance of the Redfield Ratio and a Family of Nutrient Limitation Indicators as Thresholds for Phytoplankton N vs. P Limitation

Ptáčník, Robert; Andersen, Tom; Tamminen, Timo

doi:10.1007/s10021-010-9380-z

Cited by 148 publications

(118 citation statements)

References 27 publications

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“…Then, models for quantitative relationships between loads and these parameters are needed to estimate the maximum acceptable loads required to reach these target values. Recent research has demonstrated that dual-nutrient (N, P) reduction strategies are needed to alleviate eutrophication in estuaries and other coastal waters in the land-sea continuum (Boynton and Kemp, 2008;Conley et al, 2009;Paerl, 2009), and that the Redfield ratio for N and P in marine waters (16 : 1, molar) cannot be considered a universally optimal ratio between N and P, but rather an average of species-specific N : P ratios (Klausmeier et al, 2004;Ptacnik et al, 2010).…”

Section: Estimate Of Maximum Acceptable Loadsmentioning

confidence: 99%

Threshold values and management options for nutrients in a catchment of a temperate estuary with poor ecological status

Hinsby

Markager

Kronvang

et al. 2012

Hydrol. Earth Syst. Sci.

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Abstract.Intensive farming has severe impacts on the chemical status of groundwater and streams and consequently on the ecological status of dependent ecosystems. Eutrophication is a widespread problem in lakes and marine waters. Common problems are hypoxia, algal blooms, fish kills, and loss of water clarity, underwater vegetation, biodiversity and recreational value. In this paper we evaluate the nitrogen (N) and phosphorus (P) concentrations of groundwater and surface water in a coastal catchment, the loadings and sources of N and P, and their effect on the ecological status of an estuary. We calculate the necessary reductions in N and P loadings to the estuary for obtaining a good ecological status, which we define based on the number of days with N and P limitation, and the corresponding stream and groundwater threshold values assuming two different management options. The calculations are performed by the combined use of empirical models and a physically based 3-D integrated hydrological model of the whole catchment. The assessment of the ecological status indicates that the N and P loads to the investigated estuary should be reduced to levels corresponding to 52 and 56 % of the current loads, respectively, to restore good ecological status. Model estimates show that threshold total N (TN) concentrations should be in the range of 2.9 to 3.1 mg l −1 in inlet freshwater (streams) to Horsens estuary and 6.0 to 9.3 mg l −1 in shallow aerobic groundwater (∼ 27-41 mg l −1 of nitrate), depending on the management measures implemented in the catchment. The situation for total P (TP) is more complex, but data indicate that groundwater threshold values are not needed. The stream threshold value for TP to Horsens estuary for the selected management options is 0.084 mg l −1 . Regional climate models project increasing winter precipitation and runoff in the investigated region resulting in increasing runoff and nutrient loads to the Horsens estuary and many other coastal waters if present land use and farming practices continue. Hence, lower threshold values are required in many coastal catchments in the future to ensure good status of water bodies and ecosystems.

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Section: Estimate Of Maximum Acceptable Loadsmentioning

confidence: 99%

Threshold values and management options for nutrients in a catchment of a temperate estuary with poor ecological status

Hinsby

Markager

Kronvang

et al. 2012

Hydrol. Earth Syst. Sci.

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show abstract

“…2). On the contrary, Ptacnik et al (2010) found seston N:P to be the poorest, among a suite of indicators, to predict nutrient limitation, which at least in part is explained by the mixed nature of seston composition. Phytoplankton does not obey homeostatic rules in their elemental household, but rather show, at least in cultures, strong variability in their C:P and N:P (less for C:N) ratios depending on growth conditions (cf.…”

Section: Seasonal Variation In Seston Concentrations and Ratiosmentioning

confidence: 99%

“…Our data is in support of Marañón (2005), who based on studies of phytoplankton growth rates in the subtropical areas of the north Atlantic, concluded that the frequent observation of seston C:N-ratios close to Redfield even in situations with slow growing, nutrient limited phytoplankton could be accredited bacterial and detrital contributions to seston. One should therefore be careful in interpreting sestonic C:N-ratios as indicators of nutritional status of phytoplankton, as also emphasized by Ptacnik et al (2010).…”

Section: Variable Sestonic Composition May Stabilize Elemental Ratiosmentioning

confidence: 99%

Seasonal variation in marine C:N:P stoichiometry: can the composition of seston explain stable Redfield ratios?

Frigstad¹,

Andersen²,

Hessen³

et al. 2011

Biogeosciences

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Abstract. Seston is suspended particulate organic matter, comprising a mixture of autotrophic, heterotrophic and detrital material. Despite variable proportions of these components, marine seston often exhibits relatively small deviations from the Redfield ratio (C:N:P = 106:16:1). Two timeseries from the Norwegian shelf in Skagerrak are used to identify drivers of the seasonal variation in seston elemental ratios. An ordination identified water mass characteristics and bloom dynamics as the most important drivers for determining C:N, while changes in nutrient concentrations and biomass were most important for the C:P and N:P relationships. There is no standardized method for determining the functional composition of seston and the fractions of POC, PON and PP associated with phytoplankton, therefore any such information has to be obtained by indirect means. In this study, a generalized linear model was used to differentiate between the live autotrophic and non-autotrophic sestonic fractions, and for both stations the non-autotrophic fractions dominated with respective annual means of 76 and 55 %. This regression model approach builds on assumptions (e.g. constant POC:Chl-a ratio) and the robustness of the estimates were explored with a bootstrap analysis. In addition the autotrophic percentage calculated from the statistical model was compared with estimated phytoplankton carbon, and the two independent estimates of autotrophic percentage were comparable with similar seasonal cycles. The estimated C:nutrient ratios of live autotrophs were, in general, lower than Redfield, while the non-autotrophic C:nutrient ratios were higher than the live autotrophic ratios and above, or close to, the Redfield ratio. This is due to preferential Correspondence to: H. Frigstad (helene.frigstad@gfi.uib.no) remineralization of nutrients, and the P content mainly governed the difference between the sestonic fractions. Despite the seasonal variability in seston composition and the generally low contribution of autotrophic biomass, the variation observed in the total seston ratios was low compared to the variation found in dissolved and particulate pools. Sestonic C:N:P ratios close to the Redfield ratios should not be used as an indicator of phytoplankton physiological state, but could instead reflect varying contributions of sestonic fractions that sum up to an elemental ratio close to Redfield.

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“…In contrast, 70% of DSi/DIP atomic ratios were higher than the Si/P ratio of freshwater diatoms. However, Ptacnik et al (2010) concluded the ratio of DIN to TP as the best performing indicator for phytoplankton N versus P limitation considering the availability, suggesting that the DSi/DIN ratio is the adequate indicator for inferring nutrient limitations, but not the DSi/DIP ratio. These findings suggest that DSi might be one of the main factors limiting the growth of diatoms in the lake during a bloom season.…”

Section: Discussion Nutrient Limitation For Diatomsmentioning

confidence: 97%

Impacts of long-term increase in silicon concentration on diatom blooms in Lake Kasumigaura, Japan

Arai

Fukushima

2014

Ann. Limnol. - Int. J. Lim.

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-In the eutrophic Lake Kasumigaura in Japan, a trend of dissolved Si (DSi) concentration was detected over the last three decades, probably caused by the DSi release enhanced by an increase in sediment resuspension for the same period (Arai et al., Limnol., 13, 81-95, 2012). The present study described the long-term trends of the magnitude and seasonality of diatom blooms in the lake during 1981-2010 using the database and assessed the influencing factors for the trends by the numerical simulation of DSi and diatoms. The box model was developed based on the lake budgets (inflow, outflow, release and sedimentation) and the simple diatom growth model depending on DSi, temperature and light condition. As results, database analysis detected a long-term trend of increasing diatom abundance and a shift of blooming season from spring and autumn to the winter-spring period. Si could be regarded as a main nutrient factor limiting diatom growth by analyzing N:P:Si ratios. Our model simulation relatively well-reproduced the increasing trend and the shift of seasonality of DSi and diatoms, even though peaks of diatom blooms were underestimated in some years. Among input variables, the concentration of resuspended sediments radically increased. The model simulation with the input variables or parameters changed suggested as follows: (1) the recent DSi release from resuspended sediments enhanced diatom abundance and (2) the degradation of light condition caused by resuspension affected the shift of blooming season. These findings implicate the significance of the interactions between sediments and water to phytoplankton blooms.

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Performance of the Redfield Ratio and a Family of Nutrient Limitation Indicators as Thresholds for Phytoplankton N vs. P Limitation

Cited by 148 publications

References 27 publications

Threshold values and management options for nutrients in a catchment of a temperate estuary with poor ecological status

Threshold values and management options for nutrients in a catchment of a temperate estuary with poor ecological status

Seasonal variation in marine C:N:P stoichiometry: can the composition of seston explain stable Redfield ratios?

Impacts of long-term increase in silicon concentration on diatom blooms in Lake Kasumigaura, Japan

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