The data were analyzed to detect a trimming effect on the
understory fish community of Rookery Bay using a number of
methods. First, two-way repeated measures ANOVAs with year (i.e.
pre-trimming, post-trimming) and month as factors, were run to
identify changes in the paired differences in the density or biomass
of the fish assemblages in the different plot types (i.e. impact versus
control). A statistically significant year×month interaction was
interpreted as an indication that mangrove trimming had an effect
on fish density or biomass. This test was performed for the total
density and biomass of all fish as well as for the following feeding
guilds, independently: all fish (H1), benthic foraging fishes (H2),
piscivorous fishes (H3), and water column foraging fishes (H4). The
Student–Newman–Keuls tests were used to perform multiple comparisons
of the treatment factor means while controlling for family
wise experimental error (˛= 0.05). Retroactive power analysis was
performed for each parametric test (˛= 0.05; ˇ = 0.8).
In order to identify a mangrove trimming effect on the fish
community (H5), a nonmetric MDS ordination of square root
transformed Bray–Curtis similarity measures between the average
monthly species densities in each of the plots, both before
and after trimming, was performed. A significant separation of
the ordination points representing trimmed plots from all others
(i.e. control and pre-trimming experimental) as determined
by an Analysis of Similarities Procedure (ANOSIM) was considered