Local Distribution and Habitats

A. gemmata is restricted to the littoral zone of coral reefs and it is also found in some mangrove areas. ⁽¹⁶⁾A. gemmata is restricted to a beachrock platform (Figure 1). A recent study conducted on Heron Island (Athousis 2011, unpublished work), showed that

 
Figure 1. A picture of the beachrock platform. Can you spot where A. gemmata is hiding?

The abundance of A. gemmata on this beachrock platform was estimated to be between 5193-7267 individuals. A. gemmata was mostly found on the lower end of the platform that was closest to the water (Athousis 2011, unpublished work). No chitons were found on the higher end of the platform (which was higher than the high tide mark) (Athousis 2011, unpublished work). This may be due to high dessication rates (so the chitons cannot persist there) or there may be a low abundance of food. ⁽¹⁾


The environmental ranges for A. gemmata to persist within a habitat are quite narrow. ⁽³⁾

Environmental Ranges:

Depth range (m): 0-6.5

Temperature range (°C): 25.622-28.409

Nitrate (umol/L): 0.213-0.895

Salinity (PPS): 33.821-35.069

Oxygen (ml/l): 4.450-4.663

Phosphate (umol/l): 0.073-0.187

Silicate (umol/l): 1.464-3.620

This data was provided by: http://eol.org/data_objects/12171669