BSEP116B Biodiversity in the Baltic Sea - Helcom

Aerial photo of harbours seals (Phoca vitulina) in Roedsand, Denmark
erable to agree upon and use common guidelines
for the indicators to be included and the way they
are grouped.
tion collapse and regime shifts. In most of the case
studies presented here, only general references to
various literature sources were given.
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One of the clear strengths of the approach tested
here is the flexibility of the size of assessment units
as well as the potential to compare ecologically
widely different areas with each other through the
assessed status (e.g., ’good’ vs. ’bad’). A possible
weakness lies in the assumption that the overall
status of biodiversity can be defined by fixed values
of a set of indicators (see, e.g., Moss 2007). Owing
to the inherent natural stochasticity in many of the
parameters, this can be questioned. However, by
a rigorous selection of topics and the way they are
evaluated, even this can be overcome (Moss 2007).
Many indicators, such as those developed for zoobenthos
(see, e.g., Chapter 3.4), explicitly try to
circumvent such problems.
For future implementation of this approach, more
focus should be given to the reasoning and ecological
validity behind defined acceptable deviations
and the reference values. This is necessary in order
to estimate the range of natural variation as well as
threshold values that are linked to a risk of popula-
The possibility to rate the confidence in the reference,
present and acceptable deviation values
of a given indicator is one important aspect for
future consideration. This option, used in the
HELCOM Eutrophication Assessment Tool (HEAT,
see HELCOM 2009a), was not available during the
time the national case studies presented here were
collected but would likely increase the overall confidence
in the results of an indicator-based assessment.
The sub-basin approach illustrated by Table
5.4 should also be utilized more extensively.
Finally, the case studies presented assessed the
status of the marine biodiversity. They did not
focus on the human pressures affecting the status.
However, pressure indicators are important as a
means of linking biodiversity status to management
actions. Owing to the inherent complexity of
the concept, an assessment of the overall status of
marine biodiversity is currently difficult to translate
into a targeted management response unless it is
directly related to, e.g., pollution (inputs of nutrients