Interim report of the HELCOM CORESET project

9. Pressure(s) that the indicator refl ect
Input of fertilizers, changes in siltation, Abrasion, Smothering, Changes in salinity regime, Changes in
thermal regime.
10. Spatial considerations
Baltic-wide but eventually with sub-basin specifi c and even site-specifi c GES boundaries
11. Temporal considerations
Timing of measurement is important (adjusted to local conditions). Harmonization of the sampling
method may be required (time of sampling, depth, species lists, variables measured, etc.). Frequency of
monitoring not necessarily high as change in perennial macroalgae is slow.
12. Current monitoring
Part of WFD monitoring in several member states (see 7.) and in several national monitoring programs.
13. Proposed or perceived target setting approach with a short justifi cation.
Diffi cult defi nition of reference values, as historical data are more or less only qualitatively available. Use
of current WFD values, expert judgement and ecological models. Modelling approaches should be used,
based on abundance ratios along a water quality gradient. The GES boundaries will be site-specifi c.
A fast reacting indicator due to high productivity of opportunists.
4.13. Cladophora length
1. Working team: Benthic habitats and associated communities
Author: Ari Ruuskanen
2. Name of candidate indicator
Length of Cladophora glomerata
3. Unit of the candidate indicator
mm
4. Description of proposed indicator
Several macroalgal species of the ephemeral life cycle are effi cient in assimilating nutrients from the
surrounding sea water. They use the nutrients in their growth, which can be measured in the length or
biomass of the fi laments. Especially nitrate has been found to be the limiting nutrient for the ephemeral
macroalgae.
The length/biomass of ephemeral macroalgae is an indicator for long term nutrient availability. Nutrient
concentrations fl uctuate widely in the sea water, which affects their reliability as an indicator. As the
algae assimilate nutrients over the whole growing season, they indicate the total availability of nutrients
over a longer time period. The use of this indicator relies on prior work for length/biomass –nitrate correlation
in laboratory conditions as well as in marine environment. Such experimental work is going on
in Finland in the summer 2011. As a result, response curves for the use of the indicator will be published.
The indicator will fi rst apply to Cladophora glomerata, a dominant species all over the Baltic Sea, but
other species can be included at later stages.
There are scientifi c studies of the use of color as an indicator of the nitrate concentration in C. glomerata.
The use of colour as a supporting or alternative parameter need to be studied.
The indicator will not require costly monitoring as the data can be collected without diving from shores,
navigational buoys and other man-made structures.
The indicator will be developed also in the LIFE+ MARMONI project.
5. Functional group or habitat type
Hydrolittoral and infralittoral hard substrata and/or sediments (large stones, other structures).
6. Policy relevance
Descriptor 1, criterion 1.6 Habitat condition
Descriptor 5, criterion 5.2 Direct effect of nutrient enrichment
Descriptor 6, criterion 6.2 Condition of the benthic community
BSAP: Ecological objectives “Natural distribution and occurrence of plants and animals” (Eutrophication)
and “Thriving communities of plants and animals” (Nature conservation)
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