Gómez-Cubillos, Martha Catalina; Duque-Diaz, Richard; Gómez-Cubillos, Camila; Sanjuan-Muñoz, Adolfo; Zea, Sven (2026): Interactions of massive corals with turf algae and other reef organisms in Tayrona National Natural Park [dataset]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.988007 (DOI registration in progress)

In coral reefs, competition between sessile benthic organisms for access to space and other resources is a determining factor in community structuring. Recent coral mortality has favored the development of algal turfs, which are now competing with corals, often displacing them, although slowly. To determine the frequency of interactions between coral-turf and coral-other benthic categories, and how their distribution and results (coral wins or coral loses) are modulated by environmental factors, band photo transects were evaluated for 12 stations in the Parque Nacional Natural Tayrona, Santa Marta, Colombian Caribbean. It was found that algal turfs are the most frequent competitors of massive corals, and that the frequency of coral-turf interactions depends on the particular susceptibility of a coral species to the loss of tissue, and past disturbances that have affected the reef in which it lives. Furthermore, the results of these interactions depend on the ways the colonies are organized, meandroid and cerioid colonies being the most successful in competition against turfs, as their vertical growth constitutes an effective avoidance mechanism. By contrast, plocoid colonies are more prone to lose. In general, biological factors (the coral species in question and type of colonial organization) were determinants in the frequency and apparent result of coral-turf interactions, while environmental factors (disturbance gradient, depth, and degree of wave exposure) appear not to play a predominant role. As a consequence, historical and future changes in coral species cover, and the nature of colony organization in the Santa Marta area, should reflect a combination of their susceptibility to deleterious agents and their capacity to counteract or evade competition, especially with algal turfs.

At each station, two belt transects (10x2m) were surveyed following the permanent transects established by SIMAC (Colombian National Coral Reef Monitoring System).

Per transect we were taking photograps (Canon Powershot G16 digital camera) of PVC quadrats (0.25 m 2) divided into 25 grid squares for a total of 2.5 m2 being evaluated per transect.

The photographs were processed using the ImageJ program. Per quadrant, the number of interactions per grid square was counted, and the perimeter of each interaction measured (cm).

Frequency (%) was calculated on the basis of the percentage relation between the total number of grid squares occupied by each kind of interaction and the total number of grid squares in each quadrat (n = 25).

The apparent result of the interactions was determined according to the suggestions made by Barott et al. (2012), Márquez and Zea (2012) and Gowan et al. (2014).