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Frequency of Reef Fishes in the Florida Keys National Marine
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Abstract
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School of blue tang, (Acanthurus coeruleus).
(Photo credit: Matt Kendall)
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This study analyzed species richness, distribution, and
sighting frequency of selected reef fishes to describe
species assemblage composition, abundance, and spatial
distribution patterns among sites and regions (Upper Keys,
Middle Keys, Lower Keys, and Dry Tortugas) within the
Florida Keys National Marine Sanctuary (FKNMS) barrier reef
ecosystem. Data were obtained from the Reef Environmental
Education Foundation (REEF) Fish Survey Project, a volunteer
fish-monitoring program. A total of 4,324 visual fish
surveys conducted at 112 sites throughout the FKNMS were
used in these analyses. The data set contained sighting
information on 341 fish species comprising 68 families.
Species richness was generally highest in the Upper Keys
sites (maximum was 220 species at Molasses Reef) and lowest
in the Dry Tortugas sites. Encounter rates differed among
regions, with the Dry Tortugas having the highest rate,
potentially a result of differences in the evenness in
fishes and the lower diversity of habitat types in the Dry
Tortugas region. Geographic coverage maps were developed for
29 frequently observed species. Fourteen of these species
showed significant regional variation in mean sighting
frequency (%SF). Six species had significantly lower mean
%SF and eight species had significantly higher mean %SF in
the Dry Tortugas compared with other regions. Hierarchical
clustering based on species composition (presence-absence)
and species % SF revealed interesting patterns of
similarities among sites that varied across spatial scales.
Results presented here indicate that phenomena affecting
reef fish composition in the FKNMS operate at multiple
spatial scales, including a biogeographic scale that defines
the character of the region as a whole, a reef scale
(~50-100 km) that include meso-scale physical oceanographic
processes and regional variation in reef structure and
associated reef habitats, and a local scale that includes
level of protection, cross-shelf location and a suite of
physical characteristics of a given reef. It is likely that
at both regional and local scales, species habitat
requirements strongly influence the patterns revealed in
this study, and are particularly limiting for species that
are less frequently observed in the Dry Tortugas. The
results of this report serve as a benchmark for the current
status of the reef fishes in the FKNMS. In addition, these
data provide the basis for analyses on reserve effects and
the biogeographic coupling of benthic habitats and fish
assemblages that are currently underway.
Key Words:
Florida Keys National Marine Sanctuary, biogeography,
distribution, reef fish, volunteer data, Reef Environmental
Education Foundation
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