REEF-BUILDING GUILDS AND A CHECKLIST FOR DETERMINING GUILD MEMBERSHIP - A NEW APPROACH FOR STUDY OF COMMUNITIES

The need for rapid descriptive and interpretive surveys of diverse and structurally complex communities has led to several field techniques for use by taxonomic non-specialists. A new approach to such surveys is the application of Root's guild concept to reef communities. In addition to its taxonomic simplicity, other advantages of the reef guild concept include its applicability to a great variety of reef community types: e.g. both living and fossil, shallow and deep water, diverse and depauperate. Additionally, the impacts of geologic mass extinction events on reef communities may be more readily interpreted by changes in guild structure. Assignment of individuals, colonies and taxa to one of the three reef-building guilds (i.e. Constructor, Baffler, Binder) is based on three fundamental skeletal properties: (a) dominant growth direction in relation to the substrate, (b) functional morphology and (c) skeletal size and strength/rigidity. These properties, combined with aspects of the occurrence and distribution of the skeletons, are used to create a hierarchical checklist for guild assignment consisting of six criteria (which range from 1 as most important to 6 as least important): (1) habit; growth habit, (2) life-form; growth form, (3) skeletonization; skeletal strength/rigidity, (4) skeletal volume; coloniality, (5) biostratonomy; taphonomy and (6) skeletal packing density. To demonstrate the method of determining guild membership, these criteria are used for analysis of the algae and sponges in the Upper Capitan Limestone (Late Permian), Guadalupe Mountains, New Mexico. Such analysis indicates that the guild structure of this reef community is quite similar to those in other algal-sponge Late Carboniferous-Middle Triassic reefs and very dissimilar to those in Oligocene-Holocene reefs.