Interim report of the HELCOM CORESET project

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11. Temporal considerations
Sampling should be made outside spawning season. Timing of sampling/survey is important as Cyprinids
have some feeding and spawning migration (aggregation) patterns. Timing should be adjusted locally/
regionally.
12. Current monitoring
No current monitoring. The methods are under development.
13. Proposed or perceived target setting approach with a short justifi cation.
GES boundaries are not set yet. GES boundary can be set by expert judgment.
4.12. Ratio of opportunistic and perennial macroalgae
1. Working team: Benthic habitats and associated communities
Author: Karin Furhaupter
2. Name of candidate indicator
Biomass relation perennials/opportunists
3. Unit of the candidate indicator
% (based on g DW m -2 values)
4. Description of proposed indicator
The candidate core indicator for the Biomass relation of perennial and opportunist macrophytes is an
indicator which is used by Germany, Denmark, Poland and Estonia in the WFD assessment. The indicator
has not been further developed in the CORESET project and it has not been tested in the northern Baltic
Sea, e.g. in Finland and Sweden. Moreover, there seem to be differences in the monitoring procedures
among the countries using it.
The indicator basically follows the biomass relation between K- and r-species. K-species are habitat-structuring,
perennial species (usually key-species) with a persistent biomass for a certain time scale adapted
to stable conditions. R-species are fast growing small, tiny species adapted to instable conditions and
opportunistic responses to, e.g. nutrient availability.
This is indicator for the relation of most important functional groups and for the habitat condition.
5. Functional group or habitat type
Hydrolittoral and infralittoral hard substrata and/or sediments
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 benthic communities
BSAP: Ecological objectives “Natural distribution and occurrence of plants and animals” (Eutrophication)
and “Thriving communities of plants and animals” (Nature conservation)
7. Use of the indicator in previous assessments
WFD assessment in Estonia and Germany (not in the hydrolittoral zone in Germany) and Poland (only for
infralittoral sediments)
8. Link to anthropogenic pressures
The indicator refl ects a shift from perennial species (macroalgae and angiosperms) towards opportunistic
species as a consequence of
increased nutrients causing rapid growth of opportunistic species, which overgrow and displace perennial
vegetation – direct impact
increased nutrients and increased amounts of organic matter and silt preventing the attachment of perennial
species – direct/indirect impact
increased physical disturbance (due to abrasion, extraction, dredging) favouring opportunistic species,
which are adopted to “instable” conditions resulting in a displacement of perennials – direct impact
changes in salinity and thermal regime favouring growth of opportunistic species resulting in a displacement
of perennials – direct impact