Oecologia

, Volume 153, Issue 4, pp 997–1008

Identifying cardinal dates in phytoplankton time series to enable the analysis of long-term trends

Authors

    • Institute of HydrobiologyTechnische Universität Dresden
  • Heidemarie Horn
    • Limnology of Reservoirs, Neunzehnhain Ecological StationSaxon Academy of Sciences
  • Thomas Petzoldt
    • Institute of HydrobiologyTechnische Universität Dresden
  • Lothar Paul
    • Neunzehnhain Ecological StationTechnische Universität Dresden
Global Change and Conservation Ecology

DOI: 10.1007/s00442-007-0783-2

Cite this article as:
Rolinski, S., Horn, H., Petzoldt, T. et al. Oecologia (2007) 153: 997. doi:10.1007/s00442-007-0783-2

Abstract

Phenology and seasonal succession in aquatic ecosystems are strongly dependent on physical factors. In order to promote investigations into this coupling, methods of characterising annual time series of phytoplankton were derived and applied to a 31-year data set from Saidenbach Reservoir (Saxony, Germany). Field data are often scarce and irregularly sampled, particularly in the transition period from winter to spring, so reliable methods of determining cardinal dates in the time series are necessary. The proposed methods were used to determine the beginning, maximum and end of the spring mass development of phytoplankton by estimating the inflexion points (A), fitting a Weibull-type function (B) and fitting linear segments to the logarithmic values (C). For the data set from Saidenbach Reservoir, all three methods proved to be relevant to the analysis of long-term trends. Differences between the maxima determined by the different methods seemed small, but there were deviations when the maximum was related to physical factors such as ice-out. The Weibull-type fit gave the most reliable and comprehensible results and is recommended for trend analyses. For all methods, long-term analysis of the duration of the spring mass development and the duration of the spring full circulation revealed a period of consistently low values (1975–1990) followed by a period of higher values (1990–2005). These periods were also identified for the date of ice-out, although in this case there was a period of high values followed by a period of low values. A sensitivity analysis that compared results from subsampled time series with increasing time intervals indicated that a minimum of one sample every three weeks is needed to obtain reliable results.

Keywords

Spring mass developmentClimate changeSaidenbach ReservoirLimnologyPhysical–biological couplingPeak detection

Supplementary material

442_2007_783_MOESM1_ESM.doc (40 kb)
ESM (DOC 39.5 kb)

Copyright information

© Springer-Verlag 2007