Guidelines for monitoring of phytoplankton species composition, abundance and biomass.

Abstract

Long-term monitoring has enabled determination of the annual phytoplankton succession and facilitates the recognizing of aberrant phenomena and their progression in the phytoplankton community (e.g. Hajdu et al. 2006, Fleming & Kaitala 2006, Klais et al. 2011, Majaneva et al. 2012, Olli et al. 2013). Phytoplankton monitoring also provides data on the biodiversity of phytoplankton communities (Uusitalo et al. 2013, Hällfors 2013, Olli et al. 2014), on harmful taxa (Leppänen et al. 1995, Wasmund 2002), and makes possible the detection of invasive alien species (Olenina et al. 2010). In addition, phytoplankton indicators derived from the monitoring data can be used for assessing the status of the marine environment (Uusitalo et al. 2013, Lehtinen et al. 2016, Wasmund et al. 2017). Phytoplankton species composition, abundance and biomass are monitored by counting phytoplankton from preserved water samples using the Utermöhl inverted light microscopical method (Utermöhl 1958), by the relevant authorities. 1.2 Purpose and aims In short, analysis of phytoplankton species composition, abundance and biomass is carried out for the following purposes: •to describe temporal trends in phytoplankton species composition, phytoplankton abundance,biomass as well as the intensity and occurrence of blooms •to describe the spatial distribution of phytoplankton species •to identify key phytoplankton species (e.g. dominating, harmful, potential non-indigenous and/orinvasive species, as well as indicator species)

• to provide basic data for complex ecosystem analyses, food web studies, modelling as well as political and social requirements such as indicators in the frame of the Marine Strategy Framework Directive of the European Union (MSFD; European Union 2008) and the EU Water Framework Directive (WFD; European Union 2000).