A comparison of sedimentary and diatom-inferred phosphorus profiles: implications for defining pre-disturbance nutrient conditions

Abstract

Interpreting sedimentary phosphorus profiles in terms of changes in the historical P load is difficult due to variable retention and post-depositional diagenesis. An alternative approach is to use diatom assemblages in surface sediments and derive a transfer function for epilimnetic SRP and total P concentrations using weighted average regression and calibration. The obtained relationship can then be applied to down-core changes in sedimentary diatom assemblages and diatom-inferred P (DI-P) used to assess historical changes in epilimnetic P-concentrations. A diatom-phosphorus calibration data set for 43 eutrophic lakes in Northern Ireland has been constructed and applied to two small eutrophic lakes (Lough Mann, White Lough). DI-total P (i.e. predicted) is highly correlated with observed TP (r 2 = 0.75) for the surface-sediment training data-set. The resultant changes in DI-P derived from application of the transfer function to down-core changes in diatom assemblages are compared to sedimentary P concentrations. The latter are highly variable, presumably due to redox-derived effects, while DI-P profiles are more readily interpretable, and agree with other stratigraphic records of lake eutrophication. The method offers a good possibility of defining pre-disturbance (i.e. natural) phosphorus concentrations in lakes with associated implications for lake-restoration programmes.

Linking spatial distributions of sediment diatom assemblages with hydrological depth profiles in a plateau deep-water lake system of subtropical China.

“…dubius preferred deep waters with the highest calculated depth optima (28, 33 and 36 m, respectively). All the planktonic species in this study can be classified as eutrophic taxa (anDerson 1990(anDerson , 1997anDerson et al 1993;Håkansson & regnell 1993;BraDsHaW et al 2005). …”

Refining the palaeoecology of lacustrine testate amoebae: insights from a plant macrofossil record from a eutrophic Scottish lake

“…These include plant macrofossils (Davidson et al 2005;Sayer et al 2010b), diatoms (Anderson et al 1993;Bennion et al 2011), cladocerans (Brodersen et al 1998;Davidson et al 2011), chironomids (Brooks et al 2001;Zhang et al 2012) and non-pollen palynomorphs (NPP) (Drljepan et al 2014;Volik et al 2016). Due to a lack of instrumental monitoring of lake conditions, palaeolimnological approaches are essential for assessing long-term trends, determining pre-disturbance conditions ) and for informing conservation strategies (Kowalewski et al 2013).…”

Reorganization of algal communities in the Lake of the Woods (Ontario, Canada) in response to turn‐of‐the‐century damming and recent warming

“…In contrast, geochemical estimates of past lake water [TP] that are derived directly from phosphorus (P) stored in lake sediments are often problematic as a result of the highly mobile and labile nature of P, which frequently results in variable retention in the sediment and post-depositional, upward migration (Carignan and Flett 1981;Reitzel et al 2007). This may result in a falsely recorded increase in [TP] upcore (Anderson et al 1993;Søndergaard et al 1996;Trolle et al 2009), and therefore these geochemical data are rarely a reflection of water column [TP]. Therefore, DI-TP models have become the standard for paleolimnological studies on cultural eutrophication (Hall and Smol 1992;Bennion et al 2004;see Hall and Smol [2010] for a review).…”