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historical data, if available, and if restoring the historical state (e.g., before any
human activities occurred) is the objective. Alternatively, the reference state for
the natural role of ecosystem components could be that at a certain period in
time, not necessarily very far in the past, when the ecosystem was considered
healthy based on the current knowledge.
The goal to maintain the quality of the environment may be expressed as:
“Conserve the geological, physical and chemical properties of the ecosystem
so as to maintain the overall environmental quality, i.e., water,
sediment, biota and habitat quality”
To ensure that this goal will be met, two different but complementary categories
of objectives are needed: the first deals with conserving the natural
chemical (e.g., seawater salinity, nutrients and oligo-elements), physical (e.g.,
temperature, currents, structural habitat features) and geological properties
(e.g., nature of bottom, sediment grain size, seascape integrity).
The second category of objectives focuses on physical or chemical elements
such as contaminants, which contribute to the degradation of the overall quality
of the environment and ultimately affect marine life. It must be noted that
a natural component could also become a contaminant when its naturally occurring
level is exceeded (e.g., trace metals, nutrients), or a limiting factor (e.g.,
dissolved oxygen) when it is depleted as a result of human impacts.
Step 3: Develop specific EBM objectives based on the overall goal
statements
Based on the three overall goals, specific management objectives dealing with
each of the ecosystem properties are developed. Examples of specific objectives
are given in Table 4-1.
These conceptual objectives must be broken down in terms of increasing specificity
(“unpacking” process) until EBM objectives can be expressed in operational
terms, i.e., as narrative and/or quantitative statements, with indicators
that can be routinely measured and associated reference points (sometimes
called limits and targets) that can be set up based on the scientific knowledge
available.
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A handbook
for measuring the progress and outcomes of integrated coastal and ocean management
Step 4: Select indicators most suitable for monitoring ecosystem properties
reflected in EBM objectives
Once the objectives have been established, selection of appropriate indicators
can proceed. If the objective is specific enough, it may be possible to use a single
indicator to monitor its achievement. On the other hand, several indicators
can serve to monitor a high-level objective. The indicators of most relevance to
the operational objective(s) are selected from among those proposed. In some
cases, certain indicators are related to more than one objective (Figure 4-2),
thus providing additional means of verification of progress. A set of ecological
indicators and parameters are given in Table 4-1.
When selecting ecological indicators to ICOM, the aim is to develop an indicator
menu specifically tailored to national/regional constraints and issues, i.e.,
the most pertinent approach (Top-down versus Bottom-up), while taking into
consideration characteristics of “good” ecological indicators (see: Chapter 2),
their significance, reliability and limits (Rice, 2003) as well as the environmental
context of use (Salas et al., 2006).
Although the development or selection of ecological indicators – and associated
measurements – may be influenced by the environmental conditions and
management context, a set of high-level indicators relevant to EBM themes
and key elements may be proposed as starting point for moving to a specifically
designed suite of indicators. Detailed descriptions of these thematic indicators
are given in Annex III.
4.5 Measurement of ecological indicators
This section presents some general guidance and considerations to be borne in
mind when measuring and interpreting ecological indicators for management
purposes.
Biological organization
Changes in ecosystem organization or structure are reflected in changes in
biodiversity. A major management challenge, however, is to distinguish between
the natural variability of biodiversity (or productivity) and that caused
by anthropogenic pressures. In some cases, such as eutrophication of coastal
areas, it may be relatively easy to correlate the observed change in biodiversity
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