Establishing boundary classes for the classification of UK marine waters using phytoplankton communities

Abstract

This paper presents a description of three of the proposed phytoplankton indices under investigation as part of a classification framework for UK and ROI marine waters. The three indices proposed for the classification process are (i) phytoplankton biomass measured as chlorophyll, (ii) the frequency of elevated phytoplankton counts measuring individual species and total cell counts and (iii) Seasonal progression of phytoplankton functional groups through the year. Phytoplankton biomass is calculated by a 90th percentile measurement of chlorophyll over the growing season (April to September) compared to a predetermined reference value. Calculation of functional groups and cell counts are taken as proportional counts derived from the presence of the indicator species or group as compared to the total phytoplankton count. Initial boundary conditions for the assessment of high/good status were tested for each index. Chlorophyll reference conditions were taken from thresholds developed for previous EU directives with the setting of offshore concentrations as a reference condition. Thresholds for elevated counts of phytoplankton taxa were taken from previous EU assessments describing counts that could be impact negatively on the environment. Reference seasonal growth curves are established using phytoplankton counts from ''high status'' waterbodies. To test the preliminary boundaries for each index, a risk assessment integrating nutrient enrichment and susceptibility for coastal and transitional waters was carried out to identify WFD waterbodies in England and Wales at different levels of risk. Waterbodies assessed as having low or medium risk from nutrient enrichment were identified as type 1 and type 2 waterbodies, and waterbodies assessed as high risk were identified as type 3 waterbodies. Phytoplankton data was extracted from the risk assigned waterbodies and applied to each phytoplankton index to test the robustness of the preliminary classification ranges for each phytoplankton index.

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“…Chlorophyll is a useful expression of phytoplankton biomass and is arguably the single most responsive indicator of N and P enrichment in the marine system. (Harding, 1994;Devlin et al, 2007). In the Mediterranean Geographical Intercalibration Group meeting (Med-GIG) held in Rome in 2011, Mediterranean member states agreed that: "Chl-a index will be an effective and relevant BQE for coastal ecosystems and this is universally accepted" (MED-GIG Report, 2011).…”

Development of tools for ecological quality assessment in the Polish marine areas according to the Water Framework Directive. Part IV — preliminary assessment

“…Since only a few worldwide monitoring programs date from prior to the 1970s, there is a general lack of historical measurement data with regard to biological quality elements. Therefore, the reference values and class boundaries were to be derived from functional relations (Aigars et al 2008, Devlin et al 2007, Andersen et al 2010. The marine environment of the southern Baltic Sea, including the Polish sector, has been heavily impacted by human activity for a long time (Głowińska 1963, Trzosińska 1978, Łysiak-Pastuszak 2000, HELCOM 2009), and it is therefore not possible to obtain reference conditions from the data collected within the marine monitoring programs, which were generally initiated during the 1970s or later (HELCOM 2006).…”

PHYMED: Un sistema de indicadores ecológicos para la Directiva Marco del Agua basado en la composición de la comunidad fitoplanctónica

“…Por tanto, la clasificación de las masas de agua en estados ecológicos es una manera de informar sobre el estado ambiental de forma normalizada que permite comparar el estado ecológico de los diferentes tipos de masas de agua y observar los cambios a través del tiempo (Devlin et al, 2007).…”

“…La primera respuesta biológica a un enriquecimiento por nutrientes en ambientes acuáticos, en condiciones de no limitación lumínica, es el crecimiento de las células fitoplanctónicas y este crecimiento conlleva generalmente cambios en la composición de la comunidad fitoplanctónica (Devlin et al, 2007) y en última instancia afecta a las relaciones presa-predador (Mitra y Flynn, 2006;Sunda, 2006).…”

“…Estas diferentes respuestas en la comunidad fitoplanctónica a lo largo de un gradiente de eutrofia pueden ser utilizadas para establecer la escala que define los límites entre las cinco clases de estado (Muy Bueno, Bueno, Moderado, Malo y Muy Malo) (Devlin et al, 2007). Para la clase de estado "Muy Bueno" la composición y abundancia del fitoplancton tiene que ser consecuente con condiciones ambientales sin alteraciones antrópicas (Devlin et al, 2007).…”