/ Ratio

• Concept: Norbert Wasmund, IOW/Germany, partly based on Klais et al. 2011 (Est., FI); support from national WG on , Nutrients and • Interest signalled also from other researchers, (Heidi Hällfors and colleagues, FI); FI: food web indicator 2018 • Work in our national will be taken up soon, joint development with other HELCOM CPs under CORESET umbrella would be perfect • Changes in main 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) Diatom-Dinoflagellate Ratio: Concept Calculation of Dia/Dino Index (given in values between 0 and 1):

Biomass of Diatoms_[in carbon units]___ of + 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 !)

- Representative sample from mixed surface layer is needed (surface samples should be o.k.)

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 peak? Solution: use 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.

Diatom/Dinoflagellate ratio Stage of development Indicator type Core/pre-core/candidate State/Pressure/Impact Legislative linkage: Primary importance Secondary importance BSAP  Natural distribution and occurrence of none stated Segment and and Objective:  Thriving and balanced communities of Eutrophication and plants and animals Biodiversity segment  Viable populations of MSFD 1.6. Habitat condition: Condition of the 1.1 Species distribution (range, Descriptors and typical species and communities, relative pattern, covered area) Criteria: abundance and/or biomass 1.2 Population size (abundance) D1, D4, D5 4.3.1 Abundance trends of functionally 4.1 of key species or important selected groups/species (key trophic groups (productivity, trophic groups) biomass) 5.2: Direct effects of nutrients: species shift in floristic composition such as diatom/ ratio

Other relevant legislation: (e.g. WFD) To my knowledge not used in coastal water assessment (WFD) Diatom-dinoflagellate ratio Coordinated monitoring Assessment Monitoring strategy GES / assessment Concept/ (method, frequency, criteria spatial resolution) in (currently all GES are Data design relation to relevant Assessment provisional) indicator parameters Technical guidelines Geographic scale method arrangements A ) in place A ) monitoring in A ) in place HELCOM assessment A ) available and A ) proposed and A ) in place B) under place B ) needs revision, units: described described development B ) monitoring needs what needs doing A ) identified B ) available not B ) proposed but needs B ) needs C ) not available, revision C ) not available, B) Identified not described more supporting data what needs - C ) monitoring not what needs - action described C ) not available, C ) not available, what revision, what action level? available, what needs level? C) not identified, what needs - needs - action level? Research needs doing - action level? what needs - action action level? level? needs for C ) not operationalization (in available, what relation to needs stated under the needs - action coordinated level? monitoring and assessment columns)

A) In place A) In place A) Should be B – A: trend C – not yet Literature/data B - data sub- (needs to (COMBINE), in place suggested: assessment available, study regard- mission arran- be agreed higher (17 subbasins is available major task, ing diat/dino gements to be

upon and frequency plus differen- need to be ratio in former incorporated Example

tested for would be tiation elaborated /times to into the indica- whole Baltic nice, but… coastal/ open and agreed but derivation tor to be dis-

though) ) upon for the of GES on a cussed, many different sea broader basis, data not yet areas/basins plus linkage to submitted to (western Baltic nutrient status ICES - TM, Fill in Fill for differs from (correlations) HELCOM

Eastern Baltic) current situation current Action: TMs Needs to be but GES TMs and CPs Experts/CPs TM, CPs, definition would and CPs agreed upon be more difficult Finnish lit. Helcom (TMs, CPs) study! 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 Diatom/Dinoflagellate Ratio

List of issues that still need Describe what is hindering solving the issue to be solved for the indicator Needs to get support by other CPs Candidate status plus no TML until very recently willing to provide data , the indicator and give input to GES definition Decide whether it is a biodiversity, Com Dec says Eutrophication, we would rather say food web indicator (like FI) and food web or eutrophication indicator biodiversity is also touched Needs to be accepted even if indicator Measures will not directly aim at this indicator, but improving nutrient status should is not directly linked to measures improve indicator status. And in particular for food web indicators there will be no direct links to measures except for fisheries regulations Practical work: colllect data, analyse Availability of ready-to-use datasets (time series) for time trends, try to define GES Other plankton indicators discussed in Germany: • 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 • indicator under development as food web indicator German WFD phytoplankton assessment method (Sagert et al. 2008)

• Seasonal mean (May – Sept) per of the components, transformation into EQR values: • secchi depth, total biovolume, diatom biovolume, chlorophyte biovolume,

• Calculation of PPLcw-index using weighing factors • For 6 year assessment period calculate mean of 6

PPLcw-indices and assign result to quality status class