Publisher :
Place of publication :
Publication year : 2009
Thematic : Biodiversity
Language : English
Note
Aim We examined comparative data for cryptobenthic reef fishes to determine
how variation in regional species richness relates to local species richness,
abundance, and taxonomic and trophic composition, and to test whether systems
with higher species richness exhibit finer habitat partitioning.
Locations Lizard Island, Great Barrier Reef (GBR), Australia; Bahý´a de Loreto,
Gulf of California (GoC), Mexico.
Methods Cryptobenthic reef fish assemblages from four habitats (coral heads,
rubble, and horizontal and vertical surfaces of boulders) were collected using
clove oil. Differences in density, species richness and biomass were examined
between regions and among habitats. Habitat associations were identified for
each habitat/location based on multivariate ordination, and the statistical
significance of patterns was tested using analysis of similarity (ANOSIM). In
addition, the trophic group composition of the assemblages for both regions
was examined.
Results A total of 91 species in 20 families were recorded (GBR, 66 species;
GoC, 25 species). Total and habitat species richness were higher on the GBR,
whereas biomass was higher in the GoC. No difference in fish density between
regions was found. Habitat division among assemblages was greater in the
depauperate GoC. Only coral head associations proved to be distinctive on the
GBR, whereas three sample groups were found in the GoC (coral heads,
horizontal boulders and vertical boulders/rubble). Trophic composition in the
two regions was markedly different, with omnivores dominating the GBR
fauna and planktivores the GoC.
Main conclusions A positive regional–local relationship in fish diversity was
found between regions, but fish abundance in both regions remained similar.
Contrary to expectations, habitat partitioning, at a community level, was greater
in the depauperate GoC. Differences in trophic composition and patterns of
habitat use appear to reflect the disparate history of the regions, whereas patterns
of abundance may reflect the influence of fundamental relationships between size
and abundance in communities. This study highlights the potential of reef faunas
to conform to universal numerical trends while maintaining an ability to respond
ecologically to local/evolutionary influences. The GoC fauna appears to be
exceptionally vulnerable to natural and anthropogenic disturbance owing to the
high numerical dominance of habitat-specific species and to the limited potential
for functional redundancy within the system.
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Keywords : Sphenomorphus leucospilos
Encoded by : Pauline Carmel Joy Eje
