ABSTRACT
Distribution patterns were studied in two species of aspidochirotes (Holothuria (Halodeima) atra and Stichopus chloronotus ) on a reef flat near Lizard Island, Great Barrier Reef. Abundance and wet weight of all specimens were monitored during six consecutive months (Nov. 1992 — April 1993) in three permanent transects. Additionally, the following physical parameters were determined along the transects: type of bottom coverage, water movement and water depth. As sediment parameters bacterial numbers, chlorophyll and protein content were measured. The mean body weight of both species decreased significantly in quadrats with high coral rubble cover. The main factor influencig the distribution was found to be by water movement. The biomass and abundance of S. chloronotus is lower in areas of high flow while H. atra is more adapted to these zones. The calculated mean growth rate was 12 g ww/month for S. chloronotus during the observation period, but evidence is found that the average annual growth is less then 144 g (12 × 12 g). For H. atra no growth rates could be obtained with the chosen method.
