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Spatial variability in community structure of Dictyoceratid sponges across Torres Strait, Australia. Alan Duckworth, Carsten Wolff, Elizabeth Evans-Illidge, Stephan Whalan and Stanley Lui Australian Institute of Marine Science Torres Strait Regional Authority CRC Torres Strait.
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Spatial variability in community structure of Dictyoceratid sponges across Torres Strait, Australia Alan Duckworth, Carsten Wolff, Elizabeth Evans-Illidge, Stephan Whalan and Stanley Lui Australian Institute of Marine Science Torres Strait Regional Authority CRC Torres Strait
Survey methods • At each location, 5-7 sites, 2 km apart • At each site, 4 x 100 m2 transects, 5-15 m deep on reef • Record every dictyoceratid sponge • Record environmental factors: substrate type and slope, visibility
25 dictyoceratid species, known and unknown Dysidea herbacea Carteriospongia flabellifera Hyrtios reticulata Phyllospongia lamellosa Phyllospongia papyracea Ircinia ramosa Coscinoderma sp. Dysidea sp. 3 Ircinia sp. 4
Species Richness • No dictyoceratid species found at all four locations • 12 of 25 species found at only one location Richness among locations: P=0.02
Dendrogram showing similarity of dictyoceratid communities among sites B=Badu T=Thursday Y=Yorke D=Darnley Numbers=sites 7 clusters, sites similar… within a location between neighbouring locations between locations 100’s km apart
CCA plot showing distribution to environmental factors Distribution and abundance patterns only partially explained by environmental factors
Environmental factors Among locations rock varied, highest at Darnley and Yorke rubble varied, highest at Badu and Thursday sand similar Reef slope, survey depth and water visibility also similar Among sites(locations) Rock, rubble, sand, slope, depth and visibility all varied
Conclusions • Abundance patterns can vary greatly between neighbouring sites • Species richness can vary greatly between neighbouring locations • Complex dictyoceratid community structure • Similar patterns between neighbouring sites and among sites 100’s km apart • Great variation between neighbouring sites 2 km apart • Measured environmental factors only partially explain distribution patterns • Spatial variation of dictyoceratid sponges in Torres Strait influenced by a combination of environmental, biological and stochastic processes