Diatom/Dinoflagellate Ratio

Transcription

1 Diatom/Dinoflagellate Ratio Concept: Norbert Wasmund, IOW/Germany, partly based on Klais et al (Est., FI); support from national WG on Eutrophication, Nutrients and Plankton Interest signalled also from other researchers, (Heidi Hällfors and colleagues, FI); FI: food web indicator 2018 Work in our national waters will be taken up soon, joint development with other HELCOM CPs under CORESET umbrella would be perfect Changes in main phytoplankton composition affect higher trophic levels First step: develop it as trend indicator; definition of GES as second step (challenge; and GES values may need to vary between areas/basins)

2 Diatom-Dinoflagellate Ratio: Concept Calculation of Dia/Dino Index (given in values between 0 and 1): Biomass of Diatoms_[in carbon units] Biomass of Diatoms + Biomass of Dinoflags [in carbon units] Prerequisites: - Only autotrophic and mixotrophic cells to be considered - Biomass should preferably be given in carbon units (biomass of diatoms based on biovolume or wet weight is easily overestimated due to vacuole!) - Representative sample from mixed surface layer is needed (surface water samples should be o.k.)

3 Diatom-Dinoflagellate Ratio: Concept - Index to be calculated for certain seasons (spring for a start, probably strongest reactions to eutrophication and climate change; spring West of Darss sill = Feb - April, spring East of Darss sill = March May - Index to be calculated as seasonal mean of the (at least) monthly measurements - Missed the diatom spring bloom peak? Solution: use silicate consumption to calculate diatom biomass development (needs silicate measurements from Jan to May). Dinos usually have a broader biomass peak and are not as easily affected by undersampling.

4 Legislative linkage: BSAP Segment and Objective: Eutrophication and Biodiversity segment MSFD Descriptors and Criteria: D1, D4, D5 Diatom/Dinoflagellate ratio Stage of development Core/pre-core/candidate Primary importance Indicator type Natural distribution and occurrence of plants and animals Thriving and balanced communities of plants and animals Viable populations of species 1.6. Habitat condition: Condition of the typical species and communities, relative abundance and/or biomass Abundance trends of functionally important selected groups/species (key trophic groups) 5.2: Direct effects of nutrients: species shift in floristic composition such as diatom/ flagellate ratio State/Pressure/Impact Secondary importance none stated 1.1 Species distribution (range, pattern, covered area) 1.2 Population size (abundance) 4.1 Productivity of key species or trophic groups (productivity, biomass) Other relevant legislation: (e.g. WFD) To my knowledge not used in coastal water assessment (WFD)

5 Fill in for current situation Example Concept/ design A ) in place B) under development C ) not available, what needs - action level? Diatom-dinoflagellate ratio Coordinated monitoring Monitoring strategy (method, frequency, spatial resolution) in relation to relevant indicator parameters Technical guidelines Geographic scale A ) monitoring in place B ) monitoring needs revision C ) monitoring not available, what needs - action level? A) In place A) In place (needs to (COMBINE), be agreed higher upon and frequency tested for would be whole Baltic nice, but though) A ) in place B ) needs revision, what needs doing C ) not available, what needs - action level? A) Should be in place Action: TMs and CPs HELCOM assessment units: A ) identified B) Identified not described C) not identified, what needs - action level? Assessment Assessment method A ) available and described B ) available not described C ) not available, what needs - action level? B A: trend suggested: assessment (17 subbasins is available plus differentiation coastal/ open sea) Needs to be agreed upon (TMs, CPs) but GES definition would be more difficult GES / assessment criteria (currently all GES are provisional) A ) proposed and described B ) proposed but needs more supporting data C ) not available, what needs - action level? C not yet available, major task, need to be elaborated and agreed upon for the different sea areas/basins (western Baltic differs from Eastern Baltic) TMs and CPs Research needs for operationalization (in relation to needs stated under the coordinated monitoring and assessment columns) Literature/data study regarding diat/dino ratio in former years/times to but derivation of GES on a broader basis, plus linkage to nutrient status (correlations) Experts/CPs Finnish lit. study! Data arrangements A ) in place B ) needs revision, what needs doing C ) not available, what needs - action level? B - data submission arrangements to be incorporated into the indicator to be discussed, many data not yet submitted to ICES - TM, HELCOM TM, CPs, Helcom

6 Diatom/Dinoflagellate Ratio HELCOM Assessment Unit Level: suggested 3 The indicator is/should be applicable in: all open sea areas of the Baltic Sea (different sea areas may require different GES values) Currently data is available : from COMBINE and research data, but not all existing data are in ICES database yet

7 Diatom/Dinoflagellate Ratio List of issues that still need to be solved for the indicator Needs to get support by other CPs willing to provide data, test the indicator and give input to GES definition Decide whether it is a biodiversity, food web or eutrophication indicator Needs to be accepted even if indicator is not directly linked to measures Practical work: colllect data, analyse for time trends, try to define GES Describe what is hindering solving the issue Candidate status plus no TML until very recently Com Dec says Eutrophication, we would rather say food web indicator (like FI) and biodiversity is also touched Measures will not directly aim at this indicator, but improving nutrient status should improve indicator status. And in particular for food web indicators there will be no direct links to measures except for fisheries regulations Availability of ready-to-use datasets (time series)

8 Other plankton indicators discussed in Germany: Cyanobacteria biomass (HELCOM EFS) biodiversity and eutrophication index; basically in place, GES value could easily be derived, might need to be sea-area-specific Phytoplankton assessment method by Sagert et al. used for WFD Zooplankton indicator under development as food web indicator

9 German WFD phytoplankton assessment method (Sagert et al. 2008) Seasonal mean (May Sept) per year of the components, transformation into EQR values: secchi depth, total biovolume, diatom biovolume, chlorophyte biovolume, chlorophyll Calculation of PPL cw -index using weighing factors For 6 year assessment period calculate mean of 6 PPL cw -indices and assign result to quality status class