We examine potential causal relations
between ecosystem variables in four regions of the
Gulf of Maine under two major assumptions: (i) a
causal cyclic variable will precede, or lead, its effect
variable; e.g., a peak (through) in the causal variable
will come before a peak (through) in the effect variable.
(ii) If physical variables determine regional ecosystem
properties, then independent clusters of observations
of physical, biological and interaction variables from
the same stations will show similar patterns.Weuse the
leading–lagging-strength method to establish leading
strength and potential causality, and we use principal
component analysis, to establish if regions differ in
their ecological characteristics. We found that several
relationships for physical and chemical variables were
significant, and consistent with ‘‘common knowledge’’
of causal relations. In contrast, relationships that
included biological variables differed among regions.
In spite of these findings, we found that physical and
chemical characteristics of near shore and pelagic
regions of the Gulf of Maine translate into unique
biological assemblages and unique physical–biological
interactions.
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