Patterns of macrofaunal diversity of selected tropical intertidal sedimentary habitats

Barrio Froján, Christopher R.S (2005) Patterns of macrofaunal diversity of selected tropical intertidal sedimentary habitats. University of Southampton, Doctoral Thesis.

Abstract

Ten sites at three locations (Northern, Central and Southern) along the SW cost of Thailand (8.1-9.6°N, 98.3-98.8°E) were sampled at low tide for macrofauna (i.e. organisms retained on a 0.5 mm sieve).  Each sampling site represented one of two selected intertidal sedimentary habitats: vegetated (with seagrass) or non-vegetated exposed tidal flats.  Mean macrofaunal densities (± 95% CI) at each sampling site ranged between 813 ± 213 individuals m^-2 and 2,460 ± 909 ind. m^-2.  Overall, polychaetes constituted 76% of the sampled macrofauna. 178 nominal species of polychaetes were identified, 116 of which could not be assigned to published taxonomic descriptions. 66% of all species were also considered rare. Most species displayed a random spatial distribution within each sampling site.

Although each sampling site had a distinctly characteristic polychaete assemblage composition, no site was unique in having a statistically different polychaete species richness or diversity value (as measured by expH’, Simpson’s D and Pielou’s J’).  The Northern location, however, did have a lower diversity, evenness and higher dominance values than the Central and Southern locations.

The principal factor determining polychaete assemblage composition at the sampling scale of the present study was the distance between sampling sites.  Over the maximum distance separating assemblages in the present study (c. 175 km), faunal similarity between assemblages was halved.  Overall, the diversity of the tropical sedimentary ecosystem studied was similar to that reported for other tropical sedimentary ecosystems and higher than that of temperate systems.

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