Field and laboratory investigations of the macroalgae of Enmedio Coral Reef, with specific reference to the genus Caulerpa

Vita.A topographic description of Enmedio Reef, Veracruz, Mexico describes the reef's structure as that of a platform type. Four ecological zones are identified and described: the lagoon, reef flat, reef slope and deep water areas (>4 m). Results indicate that the lagoon is dominated by Thalassia testudinum with a substrate composed primarily of coral rubble and sand. The reef flat is most prevalent on the windward side and is characterized as a shelf-like structure of a shallow depth, with a hard substrate dominated by encrusting red coralline algae. The windward reef slope is the least diverse zone and is dominated by an algal turf composed primarily of Gelidium crinale which is pruned constantly by herbivores. Most live coral heads were found in the deep zones surrounding the reef. A systematic list of the benthic marine macroalgae is presented. A total of 91 species of macroalgae, including 34 Chlorophyta, 11 Phaeophyta and 46 Rhodophyta is listed, including three species that have not been reported from eastern Mexico - Predaea feldmanni Borgesen, Ceramium nitens (C. Agardh) Montagne, and Rhodogorgon carriebowensis J. Norris and Bucher. A comparison of abundance and location of macroalgae in relationship to depth and ecological zonation is included. Species composition, frequency, diversity, and richness are compared between the different ecological zones and leeward vs windward conditions. The calm, shallow waters of the leeward lagoon has the highest diversity, whereas the windward reef slope has the least diverse community. Red coralline algae and the brown alga, Dictyota dichotoma are the dominant algae and were identified in all ecological zones. Six species of Caulerpa were collected and identified from the reef: The most common is Caulerpa sertularioides which is found in both leeward and windward areas of the lagoon. An analysis of historical species concepts and the identification of characters used to identify species of Caulerpa is discussed. Restriction site analysis of cpDNA of Caulerpa species indicate that this may be a satisfactory method for the identification and/or confirmation of species of Caulerpa