B A S E L I N E S & R E F E R E N C E VA L U E S
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Understanding Baselines
· How do linkages between reef ecosystem health
and social well-being indicators affect the reference
Baseline data describe reference conditions of an
values?
ecological system and act as a reference point or
· How can we use this information and the available
standard to compare change over time. Baseline data
data to set benchmarks, targets, and red flag values
are often used to describe conditions existing before
for each indicator (see below)?
some event (such as Hurricane Mitch) or management
action (such as the prohibition of fishing in a new
Because few historical data are available for most
marine reserve). Modern-day baselines often have
indicators, we often could not summarize baseline
already been affected by earlier (e.g., pre-modern)
data. Instead, we have characterized the current
changes, which are more difficult to quantify29,30.
status of each indicator (when possible), covering
approximately the last 5 to 6 years. These combined
For each of the 58 indicators, we have identified existing
data were then used to develop preliminary reference
data sets where available. Unfortunately, baseline
values for most of the indicators.
data are either lacking for most indicators or were
collected at different times or with different methods.
Reference
Reference Values
For practical purposes in this guide, we generally
consider baseline data to be those that precede the
To interpret our data and apply them wisely, we need
1998 disturbance events. We acknowledge that this
context for our measured values. Reference values help
time-frame reflects a "shifted baseline" which is likely
provide that context. They are thresholds or conditions
quite different from earlier "pristine" conditions.
that have been determined (at least provisionally) to
be meaningful indicator "meter sticks." These meter
Nevertheless, it is important to determine current
sticks or reference values can greatly enhance the
reef ecosystem conditions, as today's measurements
effectiveness of monitoring programs and increase
provide a valuable marker for assessing future
our understanding of how reef health affects people
changes. Reef managers need to know the normal
and their livelihoods. They can help guide data
ranges of the various indicators in order to determine
interpretation and can be applied to making informed
how healthy (or not) a reef may be. For managers
decisions. They serve as practical tools to help reef
in the MAR this may entail comparisons of the data
stewards decide when to take action31. To better use
ranges at their site as compared to the MAR, the
reference values, we developed three categories:
MAR compared to the wider Caribbean, or the MAR
benchmarks, targets, and red flags (defined in inset).
compared at the global scale (for some indicators).
Reference values have been (or will be) established
Understanding the normal ranges of indicators
for each indicator based on historical data, current
involves consideration of many factors, such as:
conditions around the Caribbean and the consensus
· Are historical data available to determine baseline
BENCHMARK
values for each indicator? If not, are there any
potential sources (published and unpublished) to fill
A benchmark is the minimally
data gaps?
acceptable
acceptable limit for the next five years.
TA R G E T
· To what temporal scale does the baseline correspond
(e.g., historical or current conditions, 10 or 100
A target is the optimally feasible
years ago)?
condition or goal to aim for in the next
· On what spatial scales are the data representative
15
15 to 20 years in order to achieve long-
[e.g., site-specific (1-10 km) or regional (>100 km)
term ecological integrity.
levels]?
RED FL AG
· How does the indicator vary with different
A red flag is a value that provides a
environmental and stressor conditions (e.g., depth,
warning signal indicates a level of
reef type, disturbance history)?
concern.
concern.
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