Tayrona National Natural Park Research Articles

Distribution of anemones (Anthozoa: Actiniaria and Corallimorpharia) in the area of Santa Marta, Colombian Caribbean

This work characterizes and compares the community of anemones at two coralline areas in the Tayrona National Natural Park, in the Colombian Caribbean, and also relates the species that were found with some important characteristics of the reef community as well as with factors that can condition its structure. The statistical tests performed allowed to differentiate two kinds of landscapes: the shallow mixed coral reef and the deep one. A total of 15 species of anemones were found, four belonging to the Order Corallimorpharia and 11 to the order Actiniaria, distributed over the coralline landscapes of the area. The tests used to determine the distribution of anemones inside the corridors measured, showed the formation of two similar groups of corridors to those obtained for the landscape that in its turn, represent two groups of anemones, those of shallow reefs and those of deep reefs. The tests used for each kind of anemone in respect to the characteristics of the reef environment suggest that each species has its own preferences regarding the habitat selection. However, relating the anemones with the landscape, anemones with the presence of certain coral species and anemones with the general reef landscape can create two basic categories.

Seasonality in Algal Assemblages on Upwelling-influenced Coral Reefs in the Colombian Caribbean

Seasonal changes of benthic algal assemblages have been Studied mainly in temperate and sub-tropical areas. It is not clear how natural processes contribute to the seasonal dynamics of algal assemblages on coral reefs, particularly in areas influenced by relatively cold upwelling waters. To investigate the seasonality in algal assemblages we monitored the percent cover of species and algal groups over one year (1994-1995) at two rocky-coral reefs at depths of 9-12 m on the Colombian Caribbean coast (Bahia Chengue,Tayrona National Natural Park, TNNP). The presence of relatively cold waters with temperatures of 25 degreesC and salinities of 36 ppt is indicative of upwelling events, while warm waters of 28-29 degreesC and salinities of 33 ppt indicate the rainy seasons in the area. The algal assemblage changed in composition and abundance throughout the year with a bimodal cover pattern observed for macroalgae and turf algae. During the rainy seasons (May to June and October to December) the assemblage was dominated by algal turfs (up to 43 % cover) and showed low macroalgal cover (< 20 %). In contrast, during the two upwelling periods (February and July to August) it was dominated by macroalgae (up to 44 % cover). Cover of brown macroalgae Dictyota spp. (mainly D. bartayresiana) declined from A 34 % during the upwelling to only 5 % in the non-upwelling rainy seasons. Environmental data revealed a significant inverse correlation between water temperature and macroalgal cover, suggesting that increases in macroalgae are favoured by the presence of cold, upwelling events. It is likely that upwelling events bring nutrient rich waters that stimulate macroalgal growth, however, the role of nutrients regulating the abundance of macroalgae in the TNNP is yet to be investigated. The results of this study support the argument that benthic algal assemblages of coral reefs are a highly dynamic component of these ecosystems.