Y =( n i / N ) f i
where N is the total abundance of all the stations; n i is the
abundance of the species i at all the stations; and f i is the
occurrence frequency of species i at all the stations.
where N is the total abundance of all the stations; n i is the
abundance of the species i at all the stations; and f i is the
occurrence frequency of species i at all the stations.
With the exception of the analysis of community
characteristics, rare or opportunistic species were
excluded from the cluster analysis to reduce the
infl uence of rare or opportunistic species when
comparing sites and relationships with environmental
variables. Species that accounted for less than 1% of
the total abundance of the research region were
deleted from the analysis unless the species made up
more than 3% of the abundance at any of the stations
in the trawl areas