149 Netherlands Journal of Sea Research 23 (2): 149-160 (1989) SPECIES ASSEMBLAGES AND PHENOTYPES OF MUSHROOM CORALS (FUNGIIDAE) RELATED TO CORAL REEF HABITATS IN THE FLORES SEA BERT W. HOEKSEMA 1 and WILLEM MOKA 2 1National Museum of Natural History, P.O. Box 9517, 2300 RA Leiden, The Netherlands 2Centre for Marine Resources Studies, Hasanuddin University, Ujung Pandang, Indonesia ABSTRACT Corals belonging to the family Fungiidae were studied at coral reefs in and around the Flores Sea. Our aims were (1) to obtain a better insight into the factors affecting species richness and (2) to investigate the relations between reef habitats and coral phenotypeso Some fungiid species oc- curred on almost all reefs, others on very few. Examples are given of coral reefs which are cha- racterized by extreme environmental conditions. Bottom inclination, water turbulence and substra- tum type appear to be important environmental factors controlling fungiid species composition. Areas with a great variety of reef habitats are usu- ally rich in species, some of which are rare. Three major reef types are recognized in relation to eco- morphological variation: (1) reefs in open sea, (2) sheltered coastal reefs facing open sea and (3) reefs in inland bays. Field observations suggest that growth forms are primarily related to light in- tensity but also to water turbulence and type of substratum. 1. INTRODUCTION One of the five themes of the Indonesian-Dutch Snellius-II Expedition (1984-1985) was focussed on coral reefs (BEST et al., 1985). Scleractinian corals are the most important reef-building organisms. The Fungiidae constitute about 10% of all zooxanthellate scleractinian coral species observed during the ex- pedition (BEST et al., 1989: Table 1). Animals of most species are unattached and monostomatous, of so- me they are free-living and polystomatous, and of on- ly a few they are attached, having either one stoma or more (HOEKSEMA, 1989). We studied assemblages of Fungiidae occurring in various reef habitats and investigated to what extent these habitats vary in fungiid species richness and composition. In addition, the relations between abio- tic environmental components and coral shapes we- re studied by comparing fungiid corals from different habitats. Acknowledgements.--The Snellius-II Expedition was organized by the Indonesian Institute of Science (LIPI) and the Netherlands Council of Oceanic Re- search (NRZ). The first author benefitted from a grant of the Netherlands Foundation for the Advan- cement of Tropical Research (WOTRO grant W77-96). We would like to thank Dr. J. van der Land and Mr. D. Setiapermana, chief-scientists on board of R.V. 'Tyro' and K.M. 'Samudera', respectively, for leading cruise 2 of theme 4. We want to thank our colleagues for co-operation in the field. We are grate- ful to Dr. R.P.M. Bak, Prof. Dr. K. Bakker, Dr. M.R.R.B. Best and Prof. Dr. E. Gittenberger for valu- able comments on the text. The photographs were made by Miss Brigit Benders. 2. AREAS AND HABITATS Six areas in the Flores Sea region (Fig. 1) were visi- ted for detailed research during cruise 2 of the coral reef survey: (1) the Spermonde Archipelago (off SW Sulawesi), (2) SW Salayer, (3) Taka Bone Rate, (4) NE Komodo, (5) Sanggar Bay (N Sumbawa) and (6) Bima Bay (NE Sumbawa). A total of 30 stations was visited. Observations at the shallowest reef zones were made by skin-diving, whereas the deeper parts, up to 30 m depth, were investigated with the help of scuba. At each station about an hour could be spent on making an inventory of the fungiids. The presen- ce of fungiid species was noted with a pencil on a plastic board. If corals could not directly be identified in the field, they were collected for further study. 2.1. THE SPERMONDE ARCHIPELAGO The shelf-based patch reefs of the Spermonde Archi- pelago (Kepulauan Sangkarang Fig. 2) can be classi- fied in four strips according to their distribution pat- tern and the bathymetry of the shelf (VANVUUREN,