standardization of environmental data and information - International ...

1 4 0
.
1 2 0
1 0 0
1
2
8 0
6 0
4 0
2 0
0
0 5 1 0 1 5 2 0 2 5 3 0
T i m e
Figure 1
Temporal variation in the population size of a hypothetical
species at two stations (blue and red lines represent the different
stations). The dots marked 1 and 2 represent two times each
station was sampled with three replicate box cores. See text for
explanation.
Finally, we need to determine what the response variable(s) will be for
detecting an impact. Potential response variables could be macrofaunal
abundance; biomass; the relative abundance, diversity or composition of
species (functional groups, trophic modes, etc.) within communities; local
extinctions, or global extinctions. Because each of these variables has
different natural spatial and temporal patterns of variation and different
sensitivities to environmental changes, these decisions will also have
important implications for the sampling strategies, amount of work involved,
technical expertise necessary to conduct the work, ability to detect change and
the nature of what is considered an impact.
2. Sampling Strategies to Detect Anthropogenic Impacts
Early studies of environmental impacts from anthropogenic activities
(e.g. sewage outfalls, nuclear power plant effluents, oil spills) used a very
simple sampling design – a series of replicate samples (e.g. box cores) were
taken from a potential impact site and compared to a series of samples from a
reference (control) site (e.g. figure 2). Any differences between the reference
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