Interim report of the HELCOM CORESET project

GES and classifi cation method
A problem related to non-indigenous species is that once a marine organism has been introduced and
established in a new environment it is nearly impossible to eradicate it. The consequence is that assessing
a status of an area as bad depending on the presence of invasive species means that the area will stay in a
bad status without a possibility of improvement.
The goal is to minimize human mediated introductions of non-indigenous species. GES boundary for
non-indigenous species should be ‘no new introductions’. For the indicator in question the GES boundary
should be ‘No new non-indigenous species with known impacts’. This means that when an assessment
is made only the species, which have been introduced after the previous assessment will be taken into
account. GES is met when further impacts from NIS are minimized, with the ultimate goal of no adverse
alterations to the ecosystems.
A contrasting point against the assessment of new arrivals only is that some NIS are known not to cause
any impacts for a long time and when environmental conditions change they suddenly become invasive.
Hence at least the species that were shown to have BPL≤1 should be reassessed. Furthermore, 6 years does
not even leave enough time for research on impacts in situ.
Increasing biopollution indicates additional stress for the ecosystem. It is a signal of failed management
concerning introductions of NIS.
Methodology for indicator calculation
The assessment is performed on 4 levels;
1. abundance and distribution (ADR)
2. impacts on communities
3. impacts on habitats
4. impacts on ecosystem functioning
and should be delivered on a defi ned aquatic area (e.g. a coastal lagoon, offshore sand bank, or even
entire sub-basins) and for a defi ned period of time. After ADR is estimated, it is related to the magnitude of
bioinvasion impacts, in order to reach the biopollution level index ranging from 0 to 4:
(0) no impact
(1) weak impact
(2) moderate impact
(3) strong impact
(4) massive impact.
211