Links
between forced variables and internal variables
based on Clarke
and Ainsworth’s method.
With
the method developed by Clarke and Ainsworth
(1993), the similarity matrixes between the
samples (in this case, the lagoons) are
accounted for by the internal descriptors (the
IVs) and the environmental descriptors (the
FVs).
This method is based on a fairly logical
principle, according to which if the series of
FVs on which the structure of the system depends
is known, a similar pattern of resemblance
between the atolls should emerge to that
calculated using the IVs. In other words,
the map based on the IVs should be similar to
that based on the FVs. If any of the main FVs.
are omitted, the two maps will match less
satisfactorily. Likewise, upon introducing the
FVs, which do not contribute to the internal
structure of the lagoons, the degree of
similarity between the two maps will again
deteriorate and there will be some background
noise.
In
the framework of the present analysis, the fit
between the two similarity matrices based on the
FVs and the IVs was expressed in terms of a
matrix correlation coefficient. This coefficient
is equal to zero if the two matrices compared
are completely dissimilar and equal to 1 if they
are identical. A matrix correlation coefficient
greater than 0.5 definitely indicates the
existence of some link between the FV and IV
maps, whereas the significance of a coefficient
of only 0.4 or 0.3 is difficult to assess.
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