BSEP116B Biodiversity in the Baltic Sea - Helcom

5 TOWARDS AN INDICATOR-BASED ASSESS-
MENT OF THE BALTIC SEA BIODIVERSITY
This chapter presents the results of testing an
indicator-based approach to assessing Baltic marine
biodiversity based on a set of 22 national case
studies and an overall assessment of the Baltic
Proper sub-basin.
According to the new HELCOM Monitoring and
Assessment Strategy (HELCOM 2005a), the entire
HELCOM system of assessments will be based on
indicators, compiled in regular thematic assessments,
such as this one on biodiversity, and eventually
in overall regional holistic assessments covering
the whole Baltic Sea and all relevant topics.
It is clear that to be measurable, the HELCOM
goals and especially the three objectives for biodiversity
(HELCOM 2007a, Backer & Leppänen
2008) must be further defined in quantitative
terms. The status of a selection of indicators
can be evaluated by comparing the desired, or
historically observed, situations with the present
status (Andersen & Backer 2008). This allows, at
least in principle, a more exact definition of goals
such as ’favourable conservation status’ and a
better possibility to monitor the progress towards
these goals (Backer 2008). Another advantage of
such quantitative approaches is that they enable
explicit links to ecosystem models for estimating,
for example, the distribution of habitats (see
Chapter 3.2) and in some cases even exploring
available policy options (e.g., Wulff et al. 2007).
This kind of explicit indicator-based approach is
already in use in the recently published assessment
of eutrophication status in the Baltic Sea
(HELCOM 2009a).
Exact definitions of the status and targets of these
issues are particularly politically sensitive.
Owing to such challenges, the overall aim of this
chapter is mainly to provide a case study of, and
with it initiate further discussion on, the role and
functions of indicators in HELCOM marine biodiversity
assessments. The aim is not to conclude
on an established method, indicators or a definite
assessment of the areas covered. Hopefully, the
material presented will serve not only to develop
HELCOM biodiversity assessments and indicators
but also as a source of inspiration for other
organizations and regions that are working with
similar issues.
Compared to the well-defined topic of eutrophication,
‘marine biodiversity’ is a complex concept
covering a wide range of issues and ecosystem
components. The selection of concrete indicators
required to represent biodiversity involves some
inevitably arbitrary choices. Another complicating
factor is the fact that many of the characteristic
features commonly associated with marine biodiversity,
such as habitats or marine mammals, are
difficult and costly to monitor. Overall, this has
resulted in fewer data available to produce indicators
for the topic, both for defining a desired or
target level, but also for assessing current status.
In the case of economically exploited or hunted
species, for example, fish and marine mammals,
Macrophyte meadows and beds (shallow Fucus, red algae reef)
5.1 Assessing the status of
biodiversity with indicators
Using the terminology of Pressure, State,
Response (PSR; OECD 1993) or Driver, Pressure,
State, Impact, Response (DPSIR), mainly status
indicators have been assessed in this trial. Assessing
the status of marine biodiversity within a
given area requires that a number of challenges
be addressed. The first is to gather data for a
sufficient number of indicators, describing a sufficiently
broad array of biodiversity components
data certainly exist but there are other difficulties. 83