Project properties
Title Determining effects of counting methodology on phytoplankton diversity indicators
Group Marine Animal Ecology
Project type thesis
Credits 24-39
Supervisor(s) Dr. Katja Philippart
Léon Serre-Fredj
Dr. Myron Peck
Examiner(s) Tinka Murk, Reindert Nijland, Ronald Osinga, Rosa van der Ven, Diede Maas
Contact info Diede Maas (diede.maas@wur.nl) for an information leaflet
Myron Peck (myron.peck@nioz.nl)
Begin date 2023/11/15
End date 2024/11/15
Description The Royal Netherlands Institute for Sea Research (NIOZ) located in Texel has at its disposal a
marine environmental time series that started as early as 1861 and is maintained until
nowadays in the Wadden Sea (Philippart et al., 2010). This includes a long-term time series of
phytoplankton cell measurements of 48 years (Jacobs et al., 2020). These measurements
allow the calculation of diversity-specific indicators (Chiarucci et al., 2011) giving information
on the evolution of biodiversity supporting decisions in environment management and
allowing a better understanding of the marine ecosystem. These diversity indicators differ in
calculation and emphasize different aspects of diversity (e.g. rare species or common species).
As the importance of the biodiversity issue is rising (Henson et al., 2021), the robustness of
the method that allows the calculation of the index should be assessed. The Utermöhl method
is the most common technique used for counting phytoplankton species, usually a partial
count is done to save time inducing a risk of miscounting the phytoplankton community.
Assessing the potential error induced by the method would allow us to characterize better
the robustness of the method to calculate the diversity indicator. Following this assessment,
studying the variation of these different parameters through time using a 50-year times series
in order will allow us to better understand how diversity should be interpreted and how it
evolved in the last decade. The result will allow us to better choose an indicator fitting to a
problematic or a specific dataset while being critical when using it.
Used skills
Requirements